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Chapter 9 Nervous System 1 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Introduction: A. The nervous system is composed of neurons and neuroglia. 1. Neurons are typically divided into: a) cell body b) axon c) dendrites 2. Neurons transmit nerve impulses along nerve fibers to other neurons. 3. Neuroglia carry out a variety of functions to aid and protect components of the nervous system. 4. Nerves are made up of bundles of nerve fibers. 2 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Organs of the nervous system can be divided into 1. Central nervous system (CNS) a) Brain b) Spinal cord 2. Peripheral nervous system (PNS) a) Peripheral nerves b) Connect the CNS to the rest of the body C. The nervous system provides 1. Sensory 2. Integrative 3. Motor functions a) Somatic nervous system - consciously controlled b) Autonomic system - unconscious 3 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. General Functions of the Nervous System A. Sensory receptors 1. At the ends of peripheral nerves 2. Gather information 3. Convert it into nerve impulses B. Sensory impulses are integrated in the brain as perceptions (integrative function) C. Conscious or subconscious decisions follow D. Lead to motor functions via effectors 4 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Supporting cells A. Function of Neuroglial Cells 1. Fill spaces 2. Support neurons 3. Provide structural frameworks 4. Produce myelin 5. Carry on phagocytosis B. Classification of Neuroglial Cells 1. Four are in the CNS and the last in the PNS 2. Microglial cells a) Small b) Phagocytize bacterial cells and cellular debris 5 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Oligodendrocytes a) Form myelin in the brain and spinal cord 4. Astrocytes a) Near blood vessels and support structures b) Aid in metabolism c) Respond to brain injury by filling in spaces. 5. Ependyma a) Cover the inside of ventricles b) Form choroid plexuses within the ventricles. 6. Schwann cells a) Peripheral nervous system only b) Produce myelin 6 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Structure A. Nerve fibers include: 1. Numerous dendrites a) Branching b) Carry impulses from other neurons (or from receptors) toward the cell body 2. A solitary axon a) Transmits the impulse away from the axonal hillock of the cell body b) May give off side branches 7 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Larger axons are enclosed by sheaths of myelin a) Provided by Schwann cells b) Outer layer of myelin surrounded by a neurilemma (neurilemmal sheath) made up of the cytoplasm and nuclei of the Schwann cell. c) Narrow gaps in the myelin sheath between Schwann cells are called nodes of Ranvier. 4. The smallest axons lack a myelin sheath and so are called unmyelinated fibers. 8 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. White matter in the CNS is due to myelin sheaths in this area 4. Unmyelinated nerve tissue in the CNS comprise the gray matter. 5. Peripheral neurons are able to regenerate because of the neurilemma 6. CNS axons are myelinated by oligodendrocytes thus lacking neurilemma and usually do not regenerate 9 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Classification of Neurons A. Neurons can be grouped in two ways: 1. Structural differences a) Bipolar neurons 1) found in the eyes, nose, and ears 2) have a single axon and a single dendrite extending from opposite sides of the cell body. b) Unipolar neurons 1) found in ganglia outside the CNS 2) have an axon and a dendrite arising from a single short fiber extending from the cell body c) Multipolar neurons 1) found in the brain and spinal cord 2) have many nerve fibers arising from their cell bodies 10 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. Functional differences a) Sensory neurons (afferent neurons) 1) usually unipolar 2) some bipolar 3) conduct impulses from peripheral receptors to the CNS b) Interneurons 1) multipolar neurons 2) within the CNS 3) form links between other neurons c) Motor neurons 1) multipolar neurons 2) conduct impulses from the CNS to effectors 11 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cell Membrane Potential A. A cell membrane is usually polarized 1. Excess of negative charges on the inside of the membrane 2. Polarization is important to the conduction of nerve impulses 12 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Distribution of Ions 1. Distribution of ions is determined by the membrane channel proteins 2. MCPs selective for certain ions 3. Potassium ions (K+) pass through the membrane more readily than do sodium ions (Na+) 4. Potassium ions a major contributor to membrane polarization 13 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Resting Potential 1. Due to active transport a) Cells maintain a greater concentration of sodium ions outside b) Greater concentration of potassium ions inside the membrane 2. Inside the membrane - excess negative charge 3. Outside - excess positive charge 4. This separation of charge, or potential difference, is called the resting potential 14 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Potential Changes 1. Stimulation of a membrane can locally affect its resting potential 2. When the membrane potential becomes less negative, the membrane is depolarized 3. If sufficiently strong depolarization occurs, a threshold potential is achieved as ion channels open 4. At threshold, an action potential is reached 5. Action potentials may be reached when a series of subthreshold stimuli combine to reach threshold 15 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Action Potential 1. At threshold potential a) Na+ channels open b) Membrane permeability to Na+ quickly changes in the region of stimulation. c) Na+ rushes in d) Membrane potential changes and becomes depolarized. e) K+ channels open allowing K+ to leave the cell f) The membrane becomes repolarized g) Resting potential is reestablished. 2. This rapid sequence of events is the action potential. 3. Active transport mechanisms then restore the original concentrations of Na+ and K+ 16 Flash x2 17 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nerve Impulse A. A nerve impulse is conducted as an action potential is reached at the trigger zone. B. This spreads by a local current flowing down the fiber, and adjacent areas of the membrane reach action potential. 18 19 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Impulse Conduction 1. Unmyelinated fibers conduct impulses over their entire membrane surface. 2. Myelinated fibers conduct impulses from one Node of Ranvier to the next (saltatory conduction) 3. Saltatory conduction is many times faster conduction over the complete membrane surface D. All-or-None Response 1. Nerve fibers respond to a stimulus completely by conducting an impulse or not at all 2. Greater intensity of stimulation triggers more impulses per second, not stronger impulses. Flash 20 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Synapse A. Nerve impulses travel from neuron to neuron along complex nerve pathways. B. The junction between two communicating neurons is called a synapse C. A synaptic cleft is the space between them across which the impulse must be conveyed. 21 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Synaptic Transmission 1. When an impulse reaches the synaptic knobs of an axon, synaptic vesicles release a neurotransmitter into the synaptic cleft 2. The neurotransmitter from the presynaptic neuron reacts with specific receptors on the postsynaptic membrane 3. This process by which the impulse in the presynaptic neuron is transmitted across the synaptic cleft to the postsynaptic neuron is called synaptic transmission 22 Flash 23 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Excitatory and Inhibitory Actions 1. Neurotransmitters that increase postsynaptic membrane permeability to Na+ may trigger impulses and are thus excitatory 2. Other neurotransmitters may decrease membrane permeability to Na+, reducing the chance that it will reach threshold, and are thus inhibitory 3. The effect on the postsynaptic neuron depends on which presynaptic knobs are activated 24 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. F. Neurotransmitters 1. 50+ different neurotransmitters are produced by the nervous system a) most are synthesized in the cytoplasm of synaptic knobs b) stored in synaptic vesicles. 2. When an action potential reaches the synaptic knob a) calcium ions rush inward b) in response some synaptic vesicles fuse with the membrane releasing their contents to the synaptic cleft 3. Synaptic cleft and on postsynaptic membrane enzymes rapidly decompose the neurotransmitters 4. Removal of the neurotransmitter prevents continuous stimulation of the postsynaptic neuron 25 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Impulse Processing A. How impulses are processed is dependent upon how neurons are organized in the brain and spinal cord. B. Neuronal Pools 1. Neurons within the CNS are organized into neuronal pools with varying numbers of cells. 2. Each pool receives input from afferent nerves and processes the information according to the special characteristics of the pool. 26 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Facilitation 1. A particular neuron of a pool may receive excitatory or inhibitory stimulation 2. If the net effect is excitatory but subthreshold, the neuron becomes more excitable to incoming stimulation (facilitation). D. Convergence 1. A single neuron within a pool may receive impulses from two or more fibers (convergence) 2. Makes it possible for the neuron to summate (combine) impulses from different sources. 27 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Divergence 1. Impulses leaving a neuron in a pool may be passed into several output fibers (divergence) 2. This pattern serves to amplify an impulse. 28 Convergence Divergence 29 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Types of Nerves A. A nerve is a bundle of nerve fibers held together by layers of connective tissue. B. Nerves can be: 1. Sensory 2. Motor 3. Mixed, carrying both sensory and motor fibers. 30 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nerve Pathways A. The routes nerve impulses travel are called pathways, the simplest of which is a reflex arc. B. Reflex Arcs include: 1. Sensory receptors 2. Sensory neurons 3. Interneurons in the spinal cord 4. Motor neurons 5. Effectors 31 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Reflex Behavior 1. Reflexes are automatic subconscious responses to stimuli 2. Help maintain homeostasis (heart rate, blood pressure, etc.) 3. Carry out automatic responses (vomiting, sneezing, swallowing, etc.) 4. The knee-jerk reflex (patellar tendon reflex) is an example of a monosynaptic reflex (no interneuron) 5. The withdrawal reflex involves a) b) c) d) Sensory neurons Interneurons Motor neurons Simultaneously the antagonistic extensor muscles are inhibited 32 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Meninges A. The brain and spinal cord are surrounded by membranes called meninges B. Meninges lie between the bone and the soft tissues. C. Dura mater 1. Outermost meninx 2. Tough, white dense connective tissue 3. Contains many blood vessels 4. Forms the inner periosteum of the skull bones. 5. Forms partitions between lobes of the brain 6. Forms dural sinuses. 7. The sheath around the spinal cord is separated from the vertebrae by an epidural space. 33 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Arachnoid mater 1. The middle meninx 2. Thin and lacks blood vessels 3. Does not follow the convolutions of the brain 4. Subarachnoid space a) Between the arachnoid and pia mater b) Contains cerebrospinal fluid E. Pia mater 1. Innermost 2. Thin and contains many blood vessels and nerves 3. Attached to the surface of the brain and spinal cord 4. Follows the contours of the brain and spinal cord 34 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Functions of the Spinal Cord 1. The spinal cord has two major functions: a) to transmit impulses to and from the brain b) to house spinal reflexes 2. Nerve tracts are identified by the origin and termination of the fibers in the tract 3. Ascending tracts tracts carry sensory information to the brain 4. Descending tracts carry motor information from the brain 5. Many spinal reflexes also pass through the spinal cord. 35 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Brain A. The brain is the largest most complex portion of the nervous system B. Contains 100 billion multipolar neurons C. Can be divided into the: 1. Cerebrum a) largest portion b) associated with higher mental functions 2. Diencephalon - processes sensory input 3. Cerebellum - coordinates muscular activity 4. Brain stem - coordinates and regulates visceral activities 36 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Structure of the Cerebrum 1. Largest portion of the mature brain 2. Consists of two cerebral hemispheres. 3. The corpus callosum, a deep ridge of nerve fibers, connects the hemispheres. 4. The surface of the brain is marked by convolutions, sulci, and fissures. 37 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6. The cerebral cortex a) A thin layer of gray matter b) Lies on the outside of the cerebrum c) Contains 75% of the cell bodies in the nervous system 7. Beneath the cortex lies a mass of white matter a) Made up of myelinated nerve fibers b) Connects the cell bodies of the cortex with the rest of the nervous system 38 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Functions of the Cerebrum - higher brain functions 1. Interpretation of sensory input 2. Initiating voluntary muscular movements 3. Memory 4. Integrating information for reasoning 39 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. G. Hemisphere Dominance 1. Both cerebral hemispheres function in receiving and analyzing sensory input and sending motor impulses to the opposite side of the body. 2. Most people exhibit hemisphere dominance for the language-related activities of speech, writing, and reading. 3. The left hemisphere is dominant in 90% of the population 4. The non-dominant hemisphere specializes in nonverbal functions and controls emotions and intuitive thinking 40 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. I. Diencephalon 1. Lies above the brain stem 2. Composed of the: a) Thalamus b) hypothalamus c) optic tracts d) optic chiasma e) infundibulum (attachment for the pituitary) f) posterior pituitary g) mammillary bodies h) pineal gland 41 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. The thalamus a) functions in sorting and directing sensory information arriving from other parts of the nervous system b) performing the services of both messenger and editor 4. The hypothalamus a) maintains homeostasis by regulating a wide variety of visceral activities including: 1) 2) 3) 4) 5) 6) 7) heart rate and arterial blood pressure body temperature water and electrolyte balance hunger and body weight movements and secretions of the digestive tract growth and reproduction sleep and wakefulness b) Links the endocrine system with the nervous system 42 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. The limbic system a) In the area of the diencephalon b) Controls emotional experience and expression c) Generates pleasant or unpleasant feelings about experiences d) Guides behavior that may enhance the chance of survival using these feelings 43 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. J. Brain Stem 1. Lies at the base of the cerebrum 2. Connects the brain to the spinal cord 3. Consists of the: a) Midbrain b) Pons c) Medulla oblongata 44 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Midbrain a) Located between the diencephalon and pons b) Contains bundles of myelinated axons that convey impulses to and from higher parts of the brain c) Masses of gray matter that serve as reflex centers, including centers for auditory and visual reflexes. 5. Pons a) lies between the midbrain and medulla oblongata b) transmits impulses between the brain and spinal cord c) contains centers that regulate the rate and depth of breathing 45 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. Medulla Oblongata a) transmits all ascending and descending impulses between the brain and spinal cord b) houses nuclei that control visceral functions, including 1) the cardiac center that controls heart rate 2) the vasomotor center for blood pressure control 3) the respiratory center that works, along with the pons, to control the rate and depth of breathing 4) Other nuclei associated with coughing, sneezing, swallowing, and vomiting 46 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6. Reticular Formation a) Throughout the brain stem, hypothalamus, cerebrum, cerebellum, and basal ganglia, is a complex network of nerve fibers connecting tiny islands of gray matter; this network is the reticular formation. b) Decreased activity in the reticular formation results in sleep; increased activity results in wakefulness. c) The reticular formation filters incoming sensory impulses 47 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. K. Cerebellum 1. Two hemispheres connected by a vermis 2. The cerebellar cortex is a thin layer of gray matter that lies outside a core of white matter 3. Communicates with other parts of the CNS via cerebellar peduncles 4. Integrates sensory information about the position of body parts 5. Coordinates skeletal muscle activity and maintains posture 48 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Peripheral Nervous System A. The peripheral nervous system (PNS) consists of the cranial and spinal nerves that arise from the central nervous system and travel to the remainder of the body. B. Includes two components 1. The somatic nervous system that oversees voluntary activities 2. The autonomic nervous system that controls involuntary activities. 49 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. The main branches of some spinal nerves form plexuses. a) Cervical plexuses 1) Lie on either side of the neck 2) Supply muscles and skin of the neck b) Brachial plexuses 1) Arise from lower cervical and upper thoracic nerves 2) Lead to the upper limbs c) Lumbrosacral plexuses 1) arise from the lower spinal cord 2) Lead to the lower abdomen, external genitalia, buttocks, and legs 50 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Autonomic Nervous System A. The autonomic nervous system (ANS) maintains the homeostasis of visceral activities without conscious effort B. General Characteristics 1. Motor pathways include two fiber types: a) preganglionic fibers leave the CNS b) postganglionic fibers innervate the effectors 51 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. Includes two divisions exerting opposing effects on target organs: a) sympathetic 1) operates under conditions of stress or emergency 2) Fibers arise from the thoracic and lumbar regions of the spinal cord 3) synapse in paravertebral ganglia close to the vertebral column 4) Postganglionic axons lead to an effector organ b) Parasympathetic 1) operates under normal conditions 2) Fibers arise from the brainstem and sacral region of the spinal cord 3) synapse in ganglia close to the effector organ 52 Sympathetic Parasympathetic 53 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Autonomic Neurotransmitters a) Preganglionic fibers of both sympathetic and parasympathetic divisions release acetylcholine. b) Parasympathetic postganglionic fibers are cholinergic fibers and release acetylcholine c) Sympathetic postganglionic fibers are adrenergic and release norepinephrine d) The effects of these two divisions are generally antagonistic due to the effects of releasing different neurotransmitters to the effector 54 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Control of Autonomic Activity a) largely controlled by reflex centers in the brain and spinal cord b) The limbic system and cerebral cortex alter the reactions of the autonomic nervous system through emotional influence 55 Chapter 10 Somatic and Special Senses 56 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Introduction A. Sensory receptors detect changes in the environment B. Stimulate neurons to send nerve impulses to the brain. C. Sensations are formed based on the sensory input 57 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Receptors and Sensations A. Each receptor is more sensitive to a specific kind of environmental change and less sensitive to others B. Types of Receptors 1. Five general types: a) b) c) d) Chemoreceptors detect changes in chemical concentration Pain receptors detect tissue damage Thermoreceptors detect temperature differences Mechanoreceptors detect changes in pressure or movement e) Photoreceptors 1) In the eyes 2) Detect light energy 58 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Sensations 1. Sensations are feelings that occur when the brain interprets sensory impulses. 2. Projection sends the sensation from the CNS to its point of origin a) Simultaneous to sensation formation b) Allows pinpointing of area of stimulation D. Sensory Adaptation 1. When stimuli are constant sensory impulses are sent at rates decreasing to zero 2. Prevents sensory overload from static ‘background’ stimuli 59 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Somatic Senses A. Receptors associated with the skin, muscles, joints, and viscera make up the somatic senses. B. Temperature Senses 1. Warm receptors a) Work best within a range of temperatures b) Adapt quickly c) Temperatures near 45o C stimulate pain receptors 2. Cold receptors a) Work best within a range of temperatures b) Adapt quickly c) Temperatures below 10o C stimulate pain receptors and produce a freezing sensation 60 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Sense of Pain 1. Pain receptors consist of free nerve endings that are stimulated when tissues are damaged 2. Little or no adaptation 3. Many stimuli affect pain receptors such as chemicals and oxygen deprivation 4. Visceral pain receptors are the only receptors in the viscera that produce sensations a) Respond differently than surface tissues b) Referred pain can occur because of the common nerve pathways leading from skin and internal organs 61 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Pain Nerve Fibers a) Acute pain fibers 1) Thin, myelinated fibers 2) Carry impulses rapidly to CNS 3) Cease when the stimulus stops. b) Chronic pain fibers 1) Thin, unmyelinated fibers 2) Conduct impulses slowly 3) Continue sending impulses after the stimulus stops c) Impulses processed in the gray matter of the dorsal horn of the spinal cord d) Impulses are conducted to the 1) Thalamus 2) Hypothalamus 3) cerebral cortex 62 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. Regulation of Pain Impulses a) Awareness of pain begins with the impulse reaching the thalamus b) The cerebral cortex judges the intensity and location of the pain and determines emotional and motor response c) Areas of gray matter in the brain stem regulate the flow of pain impulses from the spinal cord d) The brain stem can trigger the release of enkephalins and serotonin, which inhibit the release of pain impulses in the spinal cord e) Endorphins released by the hypothalamus and pituitary provide naturally suppress pain (similar to morphine) 63 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Special Senses A. The special senses are associated with relatively large and complex structures located in the head B. These include: 1. Smell 2. Taste 3. Hearing 4. Static equilibrium 5. Dynamic equilibrium 6. Sight 64 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sense of Smell A. Olfactory Receptors 1. Olfactory receptors are chemoreceptors 2. The senses of smell and taste operate together to aid in food selection 65 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Olfactory Organs 1. Olfactory organs a) located in the upper nasal cavity b) olfactory receptors c) epithelial supporting cells 2. Receptor cells a) bipolar neurons b) hair-like cilia covering the dendrites project into the nasal cavity 3. Chemicals that enter the nasal cavity must dissolve into the watery fluid surrounding the cilia to be detected 66 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Olfactory Nerve Pathways 1. When olfactory receptors are stimulated, their fibers synapse with neurons in the olfactory bulbs lying on either side of the crista galli. 2. Sensory impulses are first analyzed in the olfactory bulbs 3. Then travel along olfactory tracts to the limbic system 4. Then finally to the olfactory cortex within the temporal lobes 67 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Olfactory Stimulation 1. Scientists are uncertain of how olfactory reception operates 2. It is thought that each odor stimulates a set of specific protein receptors in cell membranes 3. The brain interprets different receptor combinations as an olfactory code 4. Olfactory receptors adapt quickly but selectively 68 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sense of Taste A. Taste buds are the organs of taste B. located within papillae of the tongue and scattered throughout the mouth and pharynx 69 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Taste Receptors 1. Taste cells (gustatory cells) a) Modified epithelial cells that function as receptors b) Contain taste hairs 1) Protrude from openings called taste pores 2) Sensitive to taste 2. Chemicals must be dissolved in water (saliva) in order to be tasted 3. Taste probably involves specific membrane protein receptors that bind with specific chemicals in food 70 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Five types of taste cells: a) Sweet receptors plentiful near the tip of the tongue b) Sour receptors occurring along the lateral edges of the tongue c) Salt receptors abundant in the tip and upper portion of the tongue d) Bitter receptors are at the back of the tongue e) Umami receptors responds to certain amino acid derivatives such as monosodium glutamate (MSG) 5. Taste buds may be responsive to at least two taste sensations but one is likely to dominate 6. Taste receptors adapt rapidly 71 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sense of Hearing A. The ear has external, middle, and inner sections B. Provides the senses of hearing and equilibrium C. External Ear 1. The auricle collects sound 2. Sound travels down the external auditory meatus 72 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Middle Ear 1. Begins with the tympanic membrane 2. Tympanic cavity (an air-filled space) houses the auditory ossicles a) Malleus b) Incus c) Stapes 3. The tympanic membrane vibrates the malleus, which vibrates the incus, then the stapes 4. The stapes vibrates the fluid inside the oval window of the inner ear 5. Auditory ossicles both transmit and amplify sound waves 73 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sense of Equilibrium A. Static equilibrium 1. Maintains stability when the head and body are still 2. Organs located a) Within the vestibule (a bony chamber) of the inner ear b) Inside the utricle and saccule (expansions of the membranous labyrinth). 74 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. A macula, consisting of hair cells and supporting cells, lies inside the utricle and saccule 4. Hair cells contact gelatinous material holding otoliths 5. Gravity causes the gelatin and otoliths to shift, bending hair cells generating a nerve impulse 6. Impulses travel to the brain via the vestibular branch of the vestibulocochlear nerve, indicating the position of the head 75 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Dynamic Equilibrium 1. Maintains balance when the head and body suddenly move and rotate 2. The three semicircular canals a) Detect motion of the head b) Aid in balance during sudden movement c) Canals lie at right angles to each other 3. Cristae ampullaris a) Located in the ampulla of each semicircular canal b) Hair cells extend into a dome-shaped gelatinous cupula c) Rapid turning of the head or body generates impulses as the cupula and hair cells bend 4. Propriopceptors (Mechanoreceptors) associated with joints and changes detected by the eyes aid in maintaining equilibrium 76 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sense of Sight A. Visual Accessory Organs 1. The eyelid a) Protects the eye from foreign objects b) Made up of the thinnest skin of the body c) Lined with conjunctiva 2. The lacrimal apparatus a) Produces tears 1) lubricate and cleanse the eye 2) contain an antibacterial enzyme b) Two small ducts drain tears into the nasal cavity 3. The extrinsic muscles a) attach to the sclera b) move the eye in all directions 77 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Structure of the Eye 1. The eye is a fluid-filled hollow sphere with three distinct layers, or tunics. 2. The Outer Tunic a) b) c) d) Fibrous Transparent cornea at the front of the eye White sclera of the anterior eye The optic nerve and blood vessels pierce the sclera at the posterior of the eye 78 3. The Middle Tunic a) The vascular tunic includes: 1) The choroid coat a. vascular and darkly pigmented b. Nourishes other tissues of the eye c. Keeps the inside of the eye dark 2) The ciliary body a. forms a ring around the front of the eye b. contains ciliary muscles and suspensory ligaments c. hold the lens in position and change its shape (focus) d. The ability of the lens to adjust shape to facilitate focusing is called accommodation 79 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3) The iris 1) a thin, smooth muscle 2) has a circular set of and a radial set of muscle fibers 3) hole in its center 4) adjusts the amount of light entering the pupil 4) The anterior cavity 1) The anterior chamber (between the cornea and iris) 2) the posterior chamber (between the iris and vitreous body and housing the lens) 3) Filled with aqueous humor 4) The aqueous humor circulates from one chamber to the other through the pupil 80 4. The Inner Tunic a) Covers the back side of the eye to the ciliary body b) Consists of the retina which contains photoreceptors c) In the center of the retina is the macula lutea 1) the fovea centralis in its center 2) the point of sharpest vision in the retina d) the optic disk 1) Medial to the fovea centralis 2) where nerve fibers leave the eye 3) a blind spot e) The large cavity of the eye is filled with vitreous humor 81 D. Visual Receptors 1. Rods a) b) c) d) Elongated Function in dim light More sensitive to light Produce colorless vision 82 2. Cones a) b) c) d) e) Blunt cone-shaped Function in bright light Provide sharp images Enable color vision The fovea centralis 1) contains the highest concentration of cones 2) proportion of cones decreases with distance from fovea centralis 3) To see something in detail, a person moves the eyes so the image falls on the fovea centralis 83 Chapter 11 Endocrine System 84 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Introduction A. The body has two kinds of glands: 1. Endocrine - secrete products into body fluids 2. Exocrine - secretes products into ducts B. The function of the endocrine system is to communicate with cells using hormones C. The cells, tissues, and organs of the endocrine system secrete hormones into body fluids D. Hormones diffuse into the bloodstream to act on specific target cells elsewhere in the body 85 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Endocrine glands and their hormones regulate a number of metabolic processes within cells, tissues, and organs F. Their actions are precise, they only affect specific target cells G. Endocrine glands include the: 1. Pituitary gland 2. Thyroid gland 3. Parathyroid glands 4. Adrenal glands 5. Pancreas 6. and other hormone-secreting glands and tissues 86 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hormone Action A. Hormones are: 1. Steroids 2. Amines 3. Peptides 4. Proteins 5. Glycoproteins B. They can influence target cells even if they are present only in minute concentrations 87 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Steroid Hormones 1. Steroid hormones are lipid-soluble and so can pass through cell membranes 2. Receptors for steroid hormones are located in the targeted cell’s nucleus 3. The hormone-receptor complex: 1. Binds with target cell DNA 2. Activates specific genes 3. Genes direct the synthesis of specific proteins 88 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Nonsteroid Hormones 1. Nonsteroid hormones combine with receptors in target cell membranes 2. Receptors have a binding site and an activity site 3. The hormone-receptor complex (as first messenger) triggers a cascade of biological activity 4. The hormone-receptor complex generally activates a G protein 5. G protein then activates the enzyme adenylate cyclase that is bound to the inner cell membrane 89 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6. This enzyme removes two phosphates from ATP to produce cyclic AMP (the second messenger) 7. cAMP in turn activates protein enzymes that activate proteins 8. These activated proteins induce changes in the cell 9. Not all nonsteroid hormones use cAMP 10. Others use diacylglycerol (DAG) or inositol triphosphate 90 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Control of Hormonal Secretions A. Hormone levels are very precisely regulated. B. Control Mechanisms: 1. Release of tropic hormones from the hypothalamus controls secretions of the anterior pituitary 2. The nervous system influences certain endocrine glands directly 3. Other glands respond directly to changes in the internal fluid composition 91 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Negative Feedback Systems 1. Commonly, negative feedback mechanisms control hormonal releases 2. In a negative feedback system, a gland is sensitive to the concentration of the substance it regulates or which regulates it 3. When the concentration of the regulated substance reaches a certain level (high or low), it inhibits the gland from secreting more hormone until the concentration returns to normal Flash 92 93 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pituitary Gland A. The pituitary gland is attached to the base of the brain B. Has an anterior lobe (anterior pituitary) and a posterior lobe (posterior pituitary). 94 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. The brain controls the activity of the pituitary gland 1. Releasing hormones from the hypothalamus control the secretions of the anterior pituitary 2. The releasing hormones are carried in the bloodstream directly to the anterior pituitary by hypophyseal portal veins 3. The posterior pituitary releases hormones into the bloodstream in response to nerve impulses from the hypothalamus 95 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Anterior Pituitary Hormones 1. Growth hormone (GH) a) Stimulates body cells to grow and reproduce b) Speeds the rate at which cells use carbohydrates and fats c) Growth hormone-releasing hormone from the hypothalamus increases the amount of GH released d) GH release-inhibiting hormone inhibits its release e) Nutritional status affects the release of GH; more is released when nutrients are insufficient. 96 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. Prolactin (PRL) a) Promotes milk production following the birth of an infant b) The effect of PRL in males is less-well understood, although it may cause a deficiency of male sex hormones 97 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Thyroid-stimulating hormone (TSH) 1. Controls the secretion of hormones from the thyroid gland 2. Thyrotropin-releasing hormone (TRH) from the hypothalamus regulates the release of TSH 3. As blood concentrations of thyroid hormones increases, secretions of TRH and TSH decrease 98 99 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. Adrenocorticotropic hormone (ACTH) a) Controls secretion of hormones from the adrenal cortex b) Regulated by corticotropin-releasing hormone from the hypothalamus c) Stress can also increase its release 100 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are gonadotropins affecting the male and female sex organs. 101 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Posterior Pituitary Hormones 1. The posterior lobe consists of nerve fibers and neuroglial cells 2. Supports nerve fibers arising in the hypothalamus 3. Neurons in the hypothalamus produce a) Antidiuretic hormone (ADH) 1) Produces its effect by causing the kidneys to conserve water 2) hypothalamus regulates the secretion of ADH based on the amount of water in body fluids 3) Stored in the posterior pituitary 102 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. b) Oxytocin 1) Plays a role in childbirth by contracting muscles in the uterine wall 2) Forces milk into ducts from the milk glands 3) Stretching of the uterus in the latter stages of pregnancy stimulates release of oxytocin 4) Suckling of an infant at the breast stimulates release of oxytocin after childbirth 103 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Thyroid Gland A. The thyroid gland is located below the larynx and consists of two broad lobes connected by an isthmus B. The thyroid consists of secretory parts called follicles filled with hormone-storing colloid 104 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Thyroid Hormones 1. The hypothalamus and pituitary gland control release of thyroid hormones 105 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. Follicular cells produce two iodine-containing hormones: a) Thyroxine (T4 ) (tetraiodothyronine) b) Triiodothyronine (T3) c) Essential for normal growth and development d) Together regulate energy metabolism 1) Increase the rate at which cells release energy from carbohydrates 2) Enhance protein synthesis 3) Stimulate the breakdown and mobilization of lipids 106 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Extrafollicular cells of the thyroid secrete calcitonin a) Lowers blood levels of calcium and phosphate ions when they are too high b) Increases the rate at which calcium is stored in bones and excreted in the urine c) Secretion is regulated by negative feedback involving blood concentrations of calcium 107 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Parathyroid Glands A. The four, tiny parathyroids are located on the posterior of the thyroid B. Parathyroid glands consist of tightly packed secretory cells covered by a thin capsule of connective tissue 108 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Parathyroid Hormone 1. Parathyroid hormone (PTH) increases blood calcium ion concentration 2. Decreases phosphate ion concentration 3. PTH stimulates bone resorption by osteoclasts, which releases calcium into the blood 4. PTH also influences the kidneys to conserve calcium and causes increased absorption of calcium in the intestines 5. A negative feedback mechanism involving blood calcium levels regulates release of PTH D. Calcitonin and PTH exert opposite effects in regulating calcium ion levels in the blood 109 110 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Adrenal Glands A. The adrenal glands sit atop the kidneys enclosed in a layer of fat B. The pyramid-shaped glands consist of 1. Inner adrenal medulla a) Made up of modified postganglionic neurons b) Connected to the sympathetic nervous system 2. Outer adrenal cortex a) Makes up most of the adrenal glands b) Consists of epithelial cells in three layers 1) Outer zone 2) Middle zone 3) Inner zone 111 112 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Hormones of the Adrenal Medulla 1. The adrenal medulla secretes epinephrine and norepinephrine into the blood stream 2. The effects of these hormones resemble those of the sympathetic division neurotransmitters of the same name 3. They last up to 10 times longer when they are secreted as hormones 4. Used in times of stress and for “fight or flight” 5. Release of medullary hormones is regulated by nervous impulses from the central nervous system 113 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Hormones of the Adrenal Cortex 1. The cells of the adrenal cortex produce over 30 different steroids 2. Some are vital to survival 3. Most important are a) Aldosterone 1) A mineralocorticoid 2) Causes the kidneys to conserve sodium ions and thus water 3) Causes the kidneys to excrete potassium ions 4) secreted in response to decreasing blood volume and blood pressure as a result of changes in the kidney 114 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. b) Cortisol 1) a glucocorticoid 2) influences the metabolism of glucose, protein, and fat 3) response to conditions that stress the body and require a greater supply of energy in the bloodstream 4) A negative feedback mechanism involving CRH from the hypothalamus and ACTH from the anterior pituitary controls the release of cortisol 5) Stress, injury, or disease can also trigger increased release of cortisol 115 116 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pancreas A. Elongated organ posterior to the stomach B. The pancreas secretes digestive juices to the digestive tract as an exocrine gland C. Secretes hormones as an endocrine gland D. Islets of Langerhans, its endocrine portions, include two cell types: 1. Alpha cells that secrete glucagon 2. Beta cells that secrete insulin 117 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Hormones of the Islets of Langerhans 1. Glucagon a) Increases the blood levels of glucose by stimulating the breakdown of glycogen and the conversion of noncarbohydrates into glucose b) Release is controlled by a negative feedback system involving low blood glucose levels 118 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. Insulin a) Decreases the blood levels of glucose by stimulating the liver to form glycogen b) Increasing protein synthesis, and stimulating adipose cells to store fat c) The release of insulin is controlled by a negative feedback system involving high blood glucose levels 3. Insulin and glucagon coordinate to maintain a relatively stable blood glucose concentration Flash 119 120 121 Chapter 12 Blood 122 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Introduction A. Blood is a connective tissue B. A complex mixture of cells, chemicals, and fluid C. Transports substances throughout the body D. Helps to maintain a stable internal environment E. Includes: 1. Red blood cells 2. White blood cells 3. Platelets 4. Plasma 123 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood Cells A. Red Blood Cells 1. Erythrocytes a) Biconcave disks b) Discard their nuclei during development so: 1) Cannot reproduce 2) Cannot produce proteins c) Contain one-third hemoglobin by volume 1) Hemoglobin carries O2 2) When combined with O2 oxyhemoglobin results (bright red) 3) Deoxygenated blood (deoxyhemoglobin) is darker 124 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Red Blood Cell Production and Control a) In the embryo and fetus RBC production occurs in 1) Yolk sac 2) Liver 3) Spleen b) After birth RBC production in red bone marrow c) Average life span of RBCs is 120 days d) The total number of RBCs remains relatively constant due to a negative feedback mechanism 1) Detection of low O2 in blood 2) Erythropoietin is released from the kidneys and liver 3) More RBCs produced 4) O2 carrying capacity of blood increases 125 126 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Dietary Factors Affecting RBC Production a) Vitamins B12 and folic acid are needed for DNA synthesis, so are necessary for the reproduction of all body cells b) Iron is needed for hemoglobin synthesis c) Deficiency in RBCs or quantity or hemoglobin is anemia 127 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. Destruction of Red Blood Cells a) With age RBCs 1) Become increasingly fragile 2) Are damaged by passing through narrow capillaries b) Macrophages in the liver and spleen phagocytize damaged red blood cells c) Hemoglobin is then converted into: 1) Heme - an iron carrying porphyrin ring 2) Globin - its protein carrier d) Heme is decomposed into 1) Iron which is stored or recycled 2) Biliverdin and bilirubin which are excreted in bile Flash 128 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. White Blood Cells 1. Leukocytes help defend the body against disease 2. Formed from hemocytoblasts (hematopoietic stem cells) 3. Five types of WBCs are in circulating blood a) Distinguished by: a) b) c) d) Size Granular appearance of the cytoplasm Shape of the nucleus Staining characteristics 129 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. b) Granular 1) Neutrophils a. Red-staining fine cytoplasmic granules b. Multi-lobed nucleus c. 54-62% of leukocytes 2) Eosinophils a. Coarse granules that stain deep red b. Bilobed nucleus c. 1-3% of circulating leukocytes 3) Basophils a. Fewer granules that stain blue b. < 1% of leukocytes 130 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. c) Agranular 1. Monocytes a. Largest blood cells b. Variably-shaped nuclei c. 3-9% of circulating leukocytes 2. Lymphocytes a. Long-lived b. Large round nucleus c. 25-33% of circulating leukocytes 131 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Functions of White Blood Cells a) Leukocytes can squeeze between cells lining walls of blood vessels by diapedesis b) Attack and remove bacteria and debris 1) Neutrophils a. Phagocytic 2) Eosinophils a. Moderate allergic reactions b. Defend against parasitic infections 3) Basophils a. Migrate to damaged tissues b. Release histamine to promote inflammation c. Release heparin to inhibit blood clotting 132 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4) Monocytes 1) phagocytic 2) engulf the larger particles 5) Lymphocytes a. major players in specific immune reactions b. Some produce antibodies 133 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Blood Platelets 1. Blood platelets are fragments of megakaryocytes 2. Help repair damaged blood vessels by adhering to their broken edges 3. Normal counts vary from 130,000 to 360,000 platelets per mm3 134 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood Plasma A. Plasma 1. Clear, straw-colored fluid portion of the blood 2. Mostly water (~90%) 3. Contains a variety of substances 4. Transports a) Nutrients b) Gases 5. Regulates fluid and electrolyte balance 6. Maintains a favorable pH 135 136 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Plasma Proteins 1. Most abundant dissolved substances in plasma (~7%) 2. Not used for energy 137 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Fall into three groups: a) Albumins 1) ~ 60% of plasma proteins 2) help maintain osmotic pressure of the blood b) Globulins 1) ~ 36% of plasma proteins 2) Designated as alpha, beta, and gamma globulins a. Alpha and beta globulins function in transporting lipids and fat-soluble vitamins b. Gamma globulins are a type of antibody c) Fibrinogen 1) ~ 4% of plasma proteins 2) plays a primary role in blood coagulation 138 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Nutrients and Gases 1. The most important blood gases are a) Oxygen (O2) b) Carbon dioxide (CO2) 2. Plasma nutrients include a) Amino acids b) Monosaccharides c) Nucleotides d) Lipids 1) Not soluble in the water of the plasma 2) Surrounded by protein molecules for transport through the bloodstream as lipoproteins 139 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. e) Lipoproteins are classified based on their densities 1) Density reflects composition 2) Types of lipoproteins include: a. HDL – high density b. LDL – low density c. VLDL – very low density d. Chylomicrons 140 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Nonprotein Nitrogenous Substances 1. generally include amino acids, urea, and uric acid a) Urea and uric acid are the by-products of protein and nucleic acid catabolism 141 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Plasma Electrolytes 1. Are absorbed by the intestines or are by-products of cellular metabolism 2. Include a) b) c) d) e) f) g) h) Sodium Potassium Calcium Magnesium Chloride Bicarbonate Phosphate Sulfate (Na+) (K+) (Ca2+) (Mg2+) (Cl-) (HCO3-) (PO43-) (SO42-) 3. Some are important in maintaining a) Osmotic pressure b) pH 142 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hemostasis A. Hemostasis 1. Stoppage of bleeding 2. Follows injury to a vessel 3. Three steps: a) Blood vessel spasm 1) Cutting a blood vessel causes the muscle in its walls to contract in a reflex (vasospasm) 2) Lasts only a few minutes 3) Long enough to initiate the second and third steps of hemostasis 143 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. b) Platelet plug formation 1) Platelets stick to the exposed edges of damaged blood vessels, forming a net with spiny processes protruding from their membranes 2) A platelet plug is most effective on a small vessel 144 145 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. c) Blood coagulation 1) 2) 3) 4) 5) 6) 7) 8) Most effective means of hemostasis Very complex process involving clotting factors Damaged tissues release tissue thromboplastin Thromboplastin activates the first in a series of factors Leads to production of prothrombin activator Prothrombin activator converts prothrombin in the plasma into thrombin Thrombin catalyzes a reaction that converts soluble fibrinogen into net-like insoluble fibrin Fibrin causes the blood cells to catch 146 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 9) The amount of prothrombin activator formed is proportional to the amount of tissue damage 10) Once a blood clot forms, it promotes still more clotting through a positive feedback system 11) After a clot forms fibroblasts invade the area and produce fibers throughout the clots 12) A clot that forms abnormally in a vessel is a thrombus 13) A thrombus that dislodges is an embolus 147 148 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood Groups and Transfusions A. After mixed success with transfusions, scientists determined that blood 1. was of different types 2. only certain combinations were compatible 149 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Antigens and Antibodies 1. Clumping of red blood cells following transfusion is called agglutination 2. Agglutination is due to the interaction of antigens on the surfaces of RBCs with antibodies carried in the plasma 3. Only a few of the antigens on RBCs produce transfusion reactions 1. ABO group 2. Rh group 150 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. ABO Blood Group 1. Type A blood a) A antigens on RBCs b) anti-B antibodies in the plasma 2. Type B blood a) B antigens on RBCs b) anti-A antibodies in the plasma 3. Type AB blood a) Both A and B antigens on RBCs b) No antibodies in the plasma 151 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Type O blood a) Neither antigen b) Both antibodies in the plasma 5. Adverse transfusion reactions a) Due to the agglutination of RBCs b) Avoided by preventing the mixing of blood that contains matching antigens and antibodies Flash 152 153 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Rh Blood Group 1. Named after the rhesus monkey 2. Rh factor surface protein a) b) c) d) Present on RBCs then blood is Rh positive Absent on RBCs then blood is Rh negative No corresponding antibodies in the plasma If a person with Rh-negative blood is transfused with Rh-positive antibodies for the Rh factor will develop in the plasma 3. Erythroblastosis fetalis a) develops in Rh-positive fetuses of Rh-negative mothers b) can now be prevented 154 Chapter 13 Cardiovascular System 155 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Introduction A. The cardiovascular system consists of 1. Heart 2. Blood vessels a) Arteries b) capillaries c) veins B. Supplies oxygen and nutrients to tissues C. Removes wastes from tissues D. The pulmonary circuit carries deoxygenated blood to the lungs E. The systemic circuit sends oxygenated blood to all body cells 156 157 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Heart Chambers and Valves 1. The heart has four internal chambers: a) Two atria on top 1) receive blood returning to the heart 2) thin walls 3) ear-like auricles projecting from their exterior b) Two ventricles below 1) The thick-muscled 2) Pumps blood to the body 158 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. A septum divides the atrium and ventricle on each side 3. Each also has an atrioventricular (A-V) valve to ensure one way flow of blood a) Right A-V valve (tricuspid) b) Left A-V valve (bicuspid or mitral valve) c) Have cusps to which chordae tendinae attach d) Chordae tendinae attach to papillary muscles in the inner heart wall 1) Contract during ventricular contraction 2) Prevent the backflow of blood through the A-V valves 159 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. The superior and inferior vena cavae bring blood from the body to the right atrium 5. The right ventricle has a thinner wall than does the left ventricle because it must pump blood only as far as the lungs rather than the entire body 6. Pulmonary valve a) At the base of the pulmonary trunk leading to the lungs b) Prevents a return flow of blood to the ventricle 7. The left atrium receives blood from 4 pulmonary veins 8. The left ventricle a) Pumps blood into the entire body through the aorta b) Guarded by the aortic valve c) Prevents backflow of blood into the ventricle 160 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. G. Path of Blood through the Heart 1. Blood low in oxygen returns to the right atrium via a) Venae cavae b) Coronary sinus 2. The right atrium contracts 3. Blood forced through the tricuspid valve into the right ventricle 4. The right ventricle contracts, closing the tricuspid valve 5. Blood forced through the pulmonary valve into the pulmonary trunk and arteries 161 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6. Pulmonary arteries carry blood to the lungs where it: a) Rids itself of excess carbon dioxide b) Picks up a new supply of oxygen 7. Freshly oxygenated blood is returned to the left atrium of the heart through the pulmonary veins 8. The left atrium contracts 9. Blood forced through the left bicuspid valve into the left ventricle 10. The left ventricle contracts closing the bicuspid valve 11. Aortic valve is forced open 12. Blood enters the aorta for distribution to the body 162 163 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. H. Blood Supply to the Heart 1. The first branches off of the aorta a) Right and left coronary arteries b) Feed the heart muscle itself c) Carry freshly oxygenated blood 2. Branches of the coronary arteries feed capillaries of the myocardium 3. Heart requires a continuous supply of freshly oxygenated blood 4. Smaller branches of arteries often have anastomoses as alternate pathways for blood 5. Cardiac veins a) Drain blood from the heart muscle b) Carry it to the coronary sinus c) Coronary sinus empties into the right atrium 164 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Heart Actions A. Cardiac cycle consists of 1. Atria beating in unison (atrial systole) 2. Followed by the contraction of both ventricles, (ventricular systole) 3. Then the entire heart relaxes for a brief moment (diastole) 165 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Cardiac Cycle 1. Pressure within the heart chambers rises and falls with contraction and relaxation of atria and ventricles 2. When atria fill pressure in the atria is greater than that of the ventricles forcing the A-V valves open 3. Pressure inside atria rises further as they contract forcing the remaining blood into the ventricles 4. When ventricles contract pressure inside them increases sharply a) A-V valves forced closed b) aortic and pulmonary valves forced open c) papillary muscles contract pulling on chordae tendinae and prevent the backflow of blood through the A-V valves 166 167 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Cardiac Muscle Fibers 1. A mass of merging fibers that act as a unit is called a functional syncytium 2. One exists in the atria (atrial syncytium) 3. One in the ventricles (ventricular syncytium) 168 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Cardiac Conduction System 1. Specialized cardiac muscle tissue conducting impulses throughout the myocardium 2. A self-exciting mass of specialized cardiac muscle called the sinoatrial node (S-A node or pacemaker) is located on the posterior right atrium 3. S-A node generates the impulses for the heartbeat 4. Impulses spread next to the atrial syncytium and it contracts 169 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. Impulses travel to the junctional fibers a) Junctional fibers are small b) Lead to atrioventricular node (A-V node) in the septum c) Allow the atria to contract before the impulse spreads rapidly over the ventricles 6. Branches of the A-V bundle give rise to Purkinje fibers leading to papillary muscles 7. These fibers stimulate contraction of the papillary muscles at the same time the ventricles contract 170 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. F. Electrocardiogram 1. Record of the electrical changes that occur during a cardiac cycle 2. The first wave, the P wave, corresponds to the depolarization of the atria 3. The QRS complex corresponds to the depolarization of ventricles and hides the repolarization of atria 4. T waves end the ECG pattern and corresponds to ventricular repolarization 171 172 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. G. Regulation of the Cardiac Cycle 1. The amount of blood pumped at any one time must adjust to the current needs of the body (more is needed during strenuous exercise) 2. The S-A node is innervated by branches of the sympathetic and parasympathetic divisions a) CNS controls heart rate b) Sympathetic impulses increase heart rate c) Parasympathetic impulses decrease heart rate 173 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Baroreceptors detect changes in blood pressure and signal medulla oblongata 4. The cardiac control center of the medulla oblongata maintains a balance between the sympathetic and parasympathetic divisions 5. Impulses from the cerebrum or hypothalamus may also influence heart rate 6. Body temperature and the concentrations of certain ions may influence heart rate as well 174 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood Vessels A. Form a closed tube B. Carry blood away from the heart, to the cells, and back again C. Consist of 1. Arteries 2. Arterioles 3. Capillaries 4. Venules 5. Veins 175 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Arteries and Arterioles 1. Arteries a) Strong, elastic vessels b) Adapted for carrying high-pressure blood 2. Arteries become smaller as they divide and give rise to arterioles 3. The wall of an artery consists of a) Endothelium b) Tunica media (smooth muscle) c) Tunica externa (connective tissue) 4. Vasoconstriction directed by the sympathetic impulses 5. Vasodilation results when impulses are inhibited 176 177 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Capillaries 1. Capillaries are the smallest vessels 2. Consist of only of a layer of endothelium through which substances are exchanged with tissue cells 3. Capillary permeability varies from one tissue to the next a) Generally more permeability in: 1) Liver 2) Intestines 3) certain glands b) Less permeability in: 1) Muscles 2) Brain (blood-brain barrier) 178 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. The pattern of capillary density also varies from one body part to the next. 5. Areas with a great deal of metabolic activity have higher densities of capillaries 6. Precapillary sphincters a) Controlled by oxygen concentration in the area b) Regulate the amount of blood entering a capillary bed c) If blood is needed elsewhere in the body the capillary beds in less important areas are shut down 179 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. F. Exchanges in the Capillaries 1. Blood entering capillaries contain: a) High concentrations of oxygen and nutrients b) Diffuse through capillary walls into the tissues c) Diffusion driven by hydrostatic pressure 2. Plasma proteins remain in the blood due to their large size 3. Osmotic pressure of the blood causes much of the tissue fluid to return to venules 4. Lymphatic vessels collect excess tissue fluid and return it to circulation 180 181 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. G. Venules and Veins 1. Venules leading from capillaries merge to form veins that return blood to the heart. 2. Veins a) Do not carry high-pressure blood b) Thinner and less muscular than arteries c) Have the same three layers as arteries 1) Endothelium 2) Tunica media (smooth muscle) 3) Tunica externa (connective tissue) d) Flap-like valves prevent backflow of blood e) Function as blood reservoirs 182 183 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood Pressure A. Blood pressure is the force of blood against the inner walls of blood vessels B. The term "blood pressure" usually refers to arterial pressure 184 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Arterial Blood Pressure 1. Arterial blood pressure rises and falls following a pattern established by the cardiac cycle a) During ventricular contraction, arterial pressure is at its highest (systolic pressure) b) When ventricles are relaxing, arterial pressure is at its lowest (diastolic pressure) 2. The surge of blood that occurs with ventricular contraction can be felt as a pulse 185 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Factors that Influence Arterial Blood Pressure 1. Heart action a) Dependent upon Stroke volume and heart rate (together called cardiac output) b) Increased cardiac output increases → increased blood pressure 2. Blood volume a) Normally directly proportional to blood pressure b) Varies with age, body size, and gender 3. Resistance to flow a) Friction between blood and walls of blood vessels is peripheral resistance b) Peripheral resistance increases → blood pressure increases 4. Blood viscosity a) Greater the viscosity → greater resistance b) Greater resistance → higher blood pressure 186 187 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Control of Blood Pressure 1. Blood pressure is determined by cardiac output and peripheral resistance 2. The body maintains normal blood pressure by adjusting cardiac output and peripheral resistance 3. Cardiac output depends on a) stroke volume and heart rate b) a number of factors can affect these actions 4. Blood volume entering the right atrium ~ the volume leaving the left ventricle 188 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. The cardiac center of the medulla oblongata responds to arterial blood pressure a) Arterial pressure increases → parasympathetic impulses to slow heart rate are sent b) Arterial pressure drops → sympathetic impulses to increase heart rate are sent 6. Emotional upset, exercise, and increased temperature can result in increased cardiac output and increased blood pressure 7. The vasomotor center of the medulla oblongata can adjust the sympathetic impulses to smooth muscles in arteriole walls, adjusting blood pressure 189 190 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5. CO2, O2, and H+ can affect peripheral resistance 6. Venous Blood Flow a) Partially the result of heart action b) Contractions of skeletal muscle squeeze blood back up veins one valve at a time c) Breathing movements and vasoconstriction of veins d) Differences in thoracic and abdominal pressures draw blood back up the veins 191 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Paths of Circulation A. Pulmonary circuit 1. Blood from the right ventricle to the pulmonary arteries 2. To the lungs and alveolar capillaries 3. Pulmonary veins lead from the lungs to the left atrium B. Systemic circuit 1. The aorta and its branches lead to all body tissues 2. Veins return blood to the right atrium 192 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Arterial System A. The aorta is the largest artery B. Principal Branches of the Aorta 1. Ascending aorta a) Right and left coronary arteries b) Lead to heart 2. Principal branches of the aortic arch a) Brachiocephalic b) Left common carotid c) Left subclavian arteries 193 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Venous System A. Veins return blood to the heart after exchange of substances in the tissues B. Venous Pathways 1. Larger veins parallel the courses of arteries and are named accordingly 2. Smaller veins take irregular pathways and are unnamed 3. Veins from the head and upper torso drain into the superior vena cava 4. Veins from the lower body drain into the inferior vena cava 5. The vena cavae merge to join the right atrium 194 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. Describe each of the five types of neuroglial cells. Describe the groupings of neurons by structural differences and by functional differences. Compare and contrast resting potential and action potential. How does a nerve impulse travel the length of a nerve? How is this process different in myelenated fibers vs unmyelinated fibers? Describe the process of synaptic transmission. Compare and contrast exitatory and inhibitory actions by neurons. What are neurotransmitters? Where are they synthesized and stored? How do they act? Compare and contrast facilitatation, convergence, and divergence. What is a reflex arc? List the steps involved. What are meninges? Describe the three types found in the skull. Compare and contrast white matter and gray matter. Describe each of the functional divisions of the brain. What is hemisphere dominance? What functions are performed by the dominant hemisphere? by the non-dominant hemisphere? Compare and contrast the sympathetic and parasympathetic nervous systems. List the 5 general types of receptors and state what each detects. What is sensory adaptation and why is it important? What is referred pain and why does it occur? Compare and contrast acute and chronic pain. Compare and contrast the olfactory and taste senses. Describe the process of hearing a sound beginning with the sound entering the external auditory meatus. Compare and contrast static and dynamic equilibrium. Compare and contrast rods and cones. Compare and contrast steroid and non-steroid hormones. Give a detailed example of a negative feedback mechanism involving hormones. Describe the three basic types of blood cells. What is hemoglobin? How is it broken down? What are the 5 types of leukocytes and how are they characterized? Describe blood plasma and list its major constituents. Describe the stages of hemostasis. Why is AB blood the universal acceptor? Why is O blood the universal donor? What would happen if AB type blood were transfused into a patient with type O blood? (be specific) Compare and contrast the pulmonary circuit and systemic circuit. Explain the steps of the cardiac cycle. What is an electrocardiogram and what does each point in the graph represent? Compare and contrast arteries, capillaries, and veins. Describe the exchange of substances between capillaries and surrounding tissues. 195 Describe the factors that effect arterial blood pressure.