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Nervous System Chapter 9 Master controlling and communicating system of the body Three overlapping functions Uses its sensory receptors to monitor changes occurring outside/inside body (sensory input) Processes and interprets the sensory input (integration) Causes a response by activating effector organs (motor output) 9.1: Introduction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dendrites • Cell types in neural tissue: • ______________ • ______________ Cell body Nuclei of neuroglia Axon © Ed Reschke 3 Divisions of the Nervous System • Central Nervous System (CNS) • _______ • __________ • Peripheral Nervous System (PNS) • Sensory Nervous system • Motor Nervous system • ____________ • ____________ • Cranial nerves • Spinal nerves 4 Divisions Nervous System Central Nervous System (Brain and Spinal Cord) Brain Peripheral Nervous System (Cranial and Spinal Nerves) Cranial nerves Sensory division Spinal cord Sensory receptors Spinal nerves Motor division (a) (b) Somatic Nervous System Skeletal muscle Autonomic Nervous System Smooth muscle Cardiac muscle Glands 6 9.2: General Functions of the Nervous System • Sensory Function • Sensory receptors gather information • Information is carried to the CNS • Integrative Function • Sensory information used to create sensations, memory, thoughts, decisions • Motor Function • Decisions are acted upon • Impulses are carried to __________ • Divisions of motor functions of PNS • Somatic – _______________ • Autonomic – _______________ 7 9.3 Neuroglia Required for neuron existence Provide structural framework Insulate Phagocytize Greatly outnumber neurons in CNS Can divide Types of Neuroglial Cells in the CNS 1) _________ 3) ___________ • Scar tissue • Phagocytic cell • Aid metabolism of certain • Form scars in areas of substances damage • Induce synapse formation • Connect neurons to blood 4) _________________ vessels • Line central canal of spinal • Part of Blood Brain Barrier cord • Line ventricles of brain 2) ___________ • Myelin sheath around brain •5) ____________ and spinal cord •Myelin sheath around axons • Insulation of myelinated neurons 9 Types of Neuroglial Cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Page 227 Fluid-filled cavity of the brain or spinal cord Neuron Ependymal cell Oligodendrocyte Astrocyte Microglial cell Axon Capillary Myelin sheath (cut) Node of Ranvier 12 Neuroglia and Axonal Regeneration Neurons _______ divide If cell body is injured, the neuron usually dies If a peripheral axon is injured, it may regenerate 13 Neuroglia and Axonal Regeneration Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Skeletal muscle fiber Motor neuron cell body Changes over time Site of injury Schwann cells Axon (a) Distal portion of axon degenerates (b) Proximal end of injured axon regenerates into tube of sheath cells (c) Schwann cells degenerate (d) Schwann cells proliferate (e) Former connection reestablished 14 9.4: Neurons • Neurons vary in size and shape • They may differ in length and size of their axons and dendrites • Neurons share certain features: • Dendrites – ___________ • A cell body – ___________ • An axon – ______________ 15 Neuron Structure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chromatophilic substance (Nissl bodies) Dendrites Cell body Nucleus Nucleolus Neurofibrils Axon hillock Impulse Axon Synaptic knob of axon terminal Nodes of Ranvier Myelin (cut) Axon Nucleus of Schwann cell Schwann cell Portion of a collateral 16 Microscopic Neuron Structure Cell body contains granular cytoplasm, mitochondria, lysosomes, a Golgi apparatus, and many microtubules A network of fine threads called neurofibrils extends into the axon and supports it ________ are highly branched, numerous and provide receptive surfaces for communication between neurons The ______ (only one) arises from a slight elevation of the cell body. It is a slender, cylindrical process with a nearly smooth surface and uniform diameter Specialized to conduct nerve impulses ______ from the cell body May have extensions near its end, each ending in an axon terminal with a synaptic knob Synaptic knob is separated from another cell by the synaptic cleft Larger axons of peripheral neurons are enclosed in sheaths composed of many Schwann cells Portions of the Schwann cells that contain most of the cytoplasm and nuclei remain outside the myelin sheath and comprise a neurilemma which surrounds the myelin sheath ___________– narrow gaps in the myelin sheath between Schwann cells Myelination of Axons Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Axons which are tightly wrapped by neuroglial cells are termed myelinated. •______ Matter • Contains myelinated axons • Considered fiber tracts • ______ Matter • Contains unmyelinated structures • Cell bodies, dendrites Dendrite Unmyelinated region of axon Myelinated region of axon Node of Ranvier Axon (a) Neuron Neuron cell body nucleus Enveloping Schwann cell Schwann cell nucleus Longitudinal groove (c) Unmyelinated axon 20 Classification of Cells of the Nervous System • Neurons vary in function • They can be sensory, motor, or integrative neurons • Neurons vary in size and shape, and in the number of axons and dendrites that they may have • Due to structural differences, neurons can be classified into three (3) major groups: • Bipolar neurons • Unipolar neurons • Multipolar neurons 22 Classification of Neurons: Structural Differences • __________ neurons • 99% of neurons • Many processes • Most neurons of CNS • _________ neurons • Two processes • Eyes, ears, nose • _________ neurons • One process • Ganglia of PNS • Sensory Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dendrites Peripheral process Axon Direction of impulse Central process Axon (a) Multipolar Axon (b) Bipolar (c) Unipolar 23 Classification of Neurons: Functional Differences • ____________ Neurons • Afferent • Carry impulse to CNS • Most are unipolar • Some are bipolar • _____________ • Link neurons • Multipolar • Located in CNS Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Central nervous system Peripheral nervous system Cell body Dendrites Sensory receptor Cell body Axon (central process) Axon (peripheral process) Sensory (afferent) neuron Interneurons Motor (efferent) neuron Axon Effector (muscle or gland) • _________ Neurons • Multipolar • Carry impulses away from CNS • Carry impulses to effectors Axon Axon terminal 25 9.5: The Synapse Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Nerve impulses pass from neuron to neuron at ________, moving from a __________to a ___________. •Neurotransmitters released at synapse Synaptic cleft Impulse Dendrites Axon of presynaptic neuron Axon hillock of Postsynaptic neuron Axon of presynaptic neuron Impulse Cell body of Impulse postsynaptic neuron 27 Synaptic Transmission Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Neurotransmitters are released when impulse reaches synaptic knob (synaptic transmission) Direction of nerve impulse Axon Ca+2 Synaptic knob •Some neurotransmitters increase (excitatory) actions and some decrease (inhibit) actions Synaptic vesicles Presynaptic neuron Ca+2 Cell body or dendrite of postsynaptic neuron Mitochondrion Ca+2 Synaptic vesicle Vesicle releasing neurotransmitter Axon membrane Neurotransmitter Synaptic cleft Polarized membrane Depolarized membrane (a) 28 Quiz 1 9.6: Cell Membrane Potential • A cell membrane is usually electrically charged, or polarized, so that the inside of the membrane is _________ charged with respect to the outside of the membrane (which is then positively charged). • This is as a result of unequal distribution of ions on the inside and the outside of the membrane. •A change in neuron membrane polarization and return to resting state (action potential) forms an impulse that is propagated along the axon 30 Distribution of Ions • Potassium (K+) ions are the major __________ positive ions (cations) and pass through the membrane easier than sodium; therefore, potassium major contributor to membrane polarization. • Sodium (Na+) ions are the major _________ positive ions (cations). • This distribution is largely created by the Sodium/Potassium Pump (Na+/K+ pump) but also by ion channels in the cell membrane. The pump actively transports sodium ions out of the cell and potassium ions into the cell. 31 Resting Potential Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Resting Membrane Potential (RMP): • _____ difference from inside to outside of cell • It is a polarized membrane • Inside of cell is negative relative to the outside of the cell • RMP = -70 mV • Due to distribution of ions inside vs. outside • Na+/K+ pump restores High Na+ Low Na+ Impermeant negative ions High K+ Axon Cell body Low K+ (a) If we imagine a cell before the membrane potential is established, concentration gradients are such that diffusion of potassium ions out of the cell exceeds diffusion of sodium ions into the cell, causing a net loss of positive charge from the cell. Axon terminal + – + – + – + + – – + + – + – – – + – + – + – + – + – + + – – + + – – + –70 mV + – + – High Na+ Low + – (b) The net loss of positive charges from the inside of the cell has left the inside of the cell membrane slightly negative compared to the outside of the membrane, which is left slightly positive. This difference (an electrical “potential difference”) is measured as –70 millivolts (mV) in a typical neuron, and is called the resting membrane potential. + – Na+ Pump K+ High K+ Low K+ + – + – + – Na+ – + – + – + – + – + + – – + + – – + –70 mV (c) With the membrane potential established, sodium diffusion into the cell is now aided, and potassium diffusion opposed, by the negative charge on the inside of the membrane. As a result, slightly more sodium ions enter the cell than potassium ions leave, but the action of the sodium/potassium pump balances these movements, and as a result the concentrations of these ions, and the resting membrane potential, are maintained. 32 Local Potential Changes • Caused by various stimuli: • Temperature changes Gate-like mechanism • Light • Pressure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protein Cell membrane (a) Channel closed Fatty acid tail Phosphate head (b) Channel open • Environmental changes affect the membrane potential by opening a gated ion channel • Channels are 1) ___________, 2) __________, 3) _____________ or 33 Local Potential Changes • Environmental changes can cause gated ion channels to open • As ions then flow through the membrane, the membrane potential changes • If membrane potential becomes more negative, it has ____________ • If membrane potential becomes less negative, it has __________ • Graded (or proportional) to intensity of stimulation reaching threshold potential • Reaching threshold potential triggers voltage gated channels to open, causing an action potential • 34 Local Potential Changes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Na+ Na+ –62 mV Neurotransmitter (a) Chemically-gated Na+ channel Presynaptic neuron Voltage-gated Na+ channel Trigger zone (axon hillock) Na+ Na+ Na+ Na+ Na+ –55 mV (b) 35 Action Potentials ________at first part of axon contains many voltage gated sodium channels Voltage gated Na+ channels open in response to threshold As Na+ moves in the membrane depolarizes until it reaches +30 mV (action potential) Na+ channels close and K+ channels open K+ moves out and membrane repolarizes As membrane potential drops below ______, the membrane is hyperpolarized Active transport reestablishes the resting potential of -70mV as Na+ and K+ concentrations are maintained 36 Action Potentials Page 238 • At rest, the membrane is polarized (RMP = -70) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Na+ • Threshold stimulus reached (-55) Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ –0 –70 Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ (a) • Sodium channels open and membrane depolarizes (toward 0) K+ Na+ Na+ K+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ –0 K+ Threshold stimulus K+ K+ Na+ Na+ channels open K+ channels closed K+ Na+ Na+ –70 • Potassium leaves cytoplasm and membrane repolarizes (+30) • Brief period of hyperpolarization (-90) Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Region of depolarization (b) K+ K+ Na+ K+ Na+ K+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ –0 K+ channels open Na+ channels closed –70 Na+ Region of repolarization (c) 37 Action Potentials Recording of an action potential Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Page 236 +40 Membrane potential (millivolts) Action potential +20 0 –20 Resting potential reestablished –40 Resting potential –60 –80 Hyperpolarization 0 1 2 3 4 5 6 7 8 Milliseconds 38 Action Potentials A nerve impulse is the propagation of action potentials down the length of an axon. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Region of action potential Page 239 + + + + + + + + + + + – – – – – – – – – + + – – – – – – – – – + + + + + + + + + + + + + + + – – – – – – – – – – – – + + + + (a) + + + – – – + + Direction of nerve impulse – – – + + + + + + + + + + – – – – – – – + + – – – – – – – – – + + – – + + + + + + + + + + + + (b) + (c) + + 39 All-or-None Response • If a neuron axon responds at all, it responds completely – with an ____________ (nerve impulse) • A nerve impulse is conducted whenever a stimulus of threshold intensity or above is applied to an axon • All impulses carried on an axon are the ____________ • A greater intensity of stimulation produces more impulses per second, not a stronger impulse 40 Refractory Period • _________ Refractory Period • Time when threshold stimulus does not start another action potential •The axon’s voltage-gated Na+ channels are not responsive at all and the axon can not be stimulated • _________ Refractory Period • Membrane is reestablishing its resting potential • Time when stronger threshold stimulus can start another action potential • Limits how many action potentials may be generated in a neuron in a given period 41 9.7 Impulse Conduction The speed of impulse conduction varies on different types of neurons. Myelinated axons transmit impulses through _________, which is faster than impulses along unmyelinated axons (jumps from node to node) Thick axon fibers transmit faster impulses than thin axon fibers. 42 Page 377 43 9.8: Synaptic Transmission • This is where released neurotransmitters cross the synaptic cleft and react with specific molecules called receptors in the postsynaptic neuron membrane. • Effects of neurotransmitters vary • Some are _________ (ones that release Na+ ions) • Some are _________ • Some neurotransmitters may open ion channels and others may close ion channels. • Chemically gated ion channels respond to neurotransmitter, creating synaptic potentials. 45 Neurotransmitters 100 types identified in the nervous system that are released by different neurons – some release more than one type Most synthesized in _________ and stored in ___________ After release some are decomposed by enzymes in the synaptic cleft while others can either diffuse to nearby neurons or be reabsorbed by the synaptic knob for future release 9.9 Impulse Processing Neurons organized into neuronal pools that work together to perform a common function Each pool receives input and generates output – either excites or inhibits __________ – stimulation of a neuron that increases responsiveness to further stimulation __________ – a neuron receives impulses from two or more neurons __________ – impulses leaving a neuron that pass to other output neurons 9.10 Types of Nerves _________ (afferent) = conduct impulses into the brain and spinal cord _________ (efferent) = carry impulses to muscles or glands ________ = nerves that include both sensory and motor 9.11 Nerve Pathways Routes that impulses follow as they travel through the nervous system __________= simplest and includes only a few neurons (sensory – inter – motor) Reflexes are automatic subconscious responses to changes (stimuli); help maintain homeostasis (ie. Heart rate, breathing rate, BP, swallowing, sneezing, coughing) Reflex Arcs • Reflexes are automatic, subconscious responses to stimuli within or outside the body • Simple reflex arc (sensory – motor) • Most common reflex arc (sensory – association – motor) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sensory or afferent neuron Receptor (a) Central Nervous System Motor or efferent neuron Effector (muscle or gland) 54 ________________________ = simple reflex that has only two neurons (sensory/motor) ______________ = rapid withdrawal of a body part from a painful stimulus Reflex Arcs Page 245 57 9.12: Meninges • Membranes of CNS • Protect the CNS • Three (3) layers: • __________ • Outer • internal periosteum of of skull bones • Blood vessels • __________ • Middle • Space contains cerebrospinal fluid (CSF) • _________ • Inner • Blood vessels • Nourishes CNS 58 Meninges of the Spinal Cord Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Spinal cord Ventral root Dorsal root Spinal nerve Dorsal root ganglion Subarachnoid space Pia mater Arachnoid mater Epidural space Dura mater Dorsal root Dorsal branch (dorsal ramus) Spinal nerve Ventral branch (ventral ramus) Dorsal root ganglion Spinal cord Ventral root Epidural space Thoracic vertebra (a) (b) Body of vertebra 60 Quiz 2 9.13: Spinal Cord Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Slender column of nervous tissue continuous with brain and brainstem • Extends downward through vertebral canal • Begins at the __________ and terminates ___________ Brainstem Foramen magnum Cervical enlargement Cervical enlargement Spinal cord Vertebral canal Lumbar enlargement Lumbar enlargement Conus medullaris Cauda equina Conus medullaris Filum terminale (a) (b) 62 Structure of Spinal Cord Consists of 31 segments – each giving rise to a pair of spinal nerves that branch to various body parts In the neck the cervical enlargement (thickened area) supplies nerves to the upper limbs In the lower back the lumbar enlargement supplies nerves to the lower limbs Two grooves extend the length of the spinal cord and divide it into right and left halves = _________ and ___________ Cross section reveals the cord consists of a core of gray matter within the white matter that is shaped like a butterfly that is surrounded with nerve tracts that are either ascending or descending Structure of the Spinal Cord Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Posterior median Posterior horn sulcus White matter Posterior funiculus Gray matter Lateral funiculus Gray commissure Central canal Dorsal root of spinal nerve Lateral horn Dorsal root ganglion Anterior horn Portion of spinal nerve (a) Ventral root of spinal nerve Anterior median fissure Anterior funiculus 65 Functions of spinal cord Conduct nerve impulses and serve as a center for spinal reflexes _____________carry sensory information to the brain _____________carry sensory information from the brain to the muscles and glands 9.14 The Brain Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Gyrus Sulcus Skull Meninges Cerebrum Diencephalon Corpus callosum Fornix Midbrain Brainstem Pons Medulla oblongata Cerebellum Spinal cord (a) Fornix Cerebrum Midbrain Pons Corpus callosum Transverse fissure Diencephalon Cerebellum Medulla oblongata Spinal cord (b) © Martin M. Rotker/Photo Researchers, Inc. 67 Brain • Major parts of the brain: • Functions of the brain: • Cerebrum • Interprets sensations • Frontal lobes • Determines perception • Parietal lobes • Stores memory • Occipital lobes • Reasoning • Temporal lobes • Makes decisions • Insula • Coordinates muscular movements • Diencephalon • Regulates visceral activities • Cerebellum • Determines personality • Brainstem • Midbrain • Pons • Medulla oblongata 68 Structure of Cerebrum Consists of two large masses (left and right hemisphere), a deep bridge of nerve fibers (__________), and a layer of dura mater (_________) Surface has many ridges (____) that are separates by grooves (sulcus = ______, fissure = _____) Frontal Lobe Forms the ______ portion of each hemisphere Bordered _______ by a central sulcus Responsible for ________, ________, _____________and _____________ Controls _________________ Parietal Lobe ________ to frontal lobe and separated from it by the _________ Provide sensations of ________, _____, ________, and ___________ Function in __________ and in _______________________ Temporal Lobe Lie ______ the frontal and parietal lobe and is separated from them by a ___________ Responsible for ________ Interpret sensory experiences and remember ________, _____, and other _______________ Occipital Lobe Forms __________________ and is separated from the cerebellum by the __________ Responsible for _______ Combine __________________ Insula (island) Located deep within the _________ and is covered by parts of the frontal, parietal and temporal lobes; ________ separates it from the lobes Believed to be associated with the _______ system as well Functions of the Cerebrum • Interpreting impulses • Initiating voluntary movements • Storing information as memory • Retrieving stored information • Reasoning • Seat of intelligence and personality 76 Functional Regions of the Cerebral Cortex • Cerebral cortex • Thin layer of gray matter that constitutes the outermost portion of cerebrum • Contains 75% of all neurons in the nervous system Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Central sulcus Motor areas involved with the control of voluntary muscles Concentration, planning, problem solving Frontal eye field Auditory area Sensory areas involved with cutaneous and other senses Parietal lobe Sensory speech area ( Wernicke’s area) Front lobe Occipital lobe Motor speech area (Broca’s area) Combining visual images, visual recognition of objects Lateral sulcus Interpretation of auditory patterns Temporal lobe Visual area Cerebellum Brainstem 77 Sensory Areas • __________ sensory area • Parietal lobe • Interprets sensations on skin • Sensory area for _______ • Near base of the central sulcus • Sensory area for ______ • Sensory ______ area (____________) • Temporal /parietal lobe Motor areas involved with the control • Usually left hemis. of voluntary muscles planning, • Understanding and Concentration, problem solving formulating language Frontal eye field • Arises from centers deep within the cerebrum Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • ________ area • Occipital lobe • Interprets vision • _______ area • Temporal lobe • Interprets hearing Central sulcus Sensory areas involved with cutaneous and other senses Parietal lobe Auditory area Sensory speech area ( Wernicke’s area) Front lobe Occipital lobe Motor speech area (Broca’s area) Combining visual images, visual recognition of objects Lateral sulcus Visual area Interpretation of auditory patterns Cerebellum Temporal lobe Brainstem 78 Sensory Areas Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Arm Forearm Trunk Pelvis Neck Forearm Arm Thigh Trunk Pelvis Thigh Thumb, fingers, and hand Leg Foot and toes Facial expression Hand, fingers, and thumb Upper face Leg Foot and toes Genitals Lips Salivation Vocalization Mastication Teeth and gums Swallowing Tongue and pharynx Longitudinal fissure (a) Motor area Longitudinal fissure (b) Sensory area Frontal lobe Motor area Sensory area Central sulcus Parietal lobe 79 Association Areas • Regions that are not primary motor or primary sensory areas • Widespread throughout the cerebral cortex • Analyze and interpret sensory experiences • Provide ________________________________________ Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Motor areas involved with the control of voluntary muscles Concentration, planning, problem solving Central sulcus Sensory areas involved with cutaneous and other senses Parietal lobe Frontal eye field Auditory area Sensory speech area ( Wernicke’s area) Front lobe Occipital lobe Combining visual images, visual recognition of objects Motor speech area (Broca’s area) Lateral sulcus Interpretation of auditory patterns Visual area Cerebellum Temporal lobe Brainstem 80 Association Areas • ______ lobe association areas • Concentrating • Planning • Complex problem solving • ________ lobe association areas • Interpret complex sensory experiences • Store memories of visual scenes, music, and complex patterns • _______ lobe association areas • Understanding speech • Choosing words to express thought • _______ lobe association areas • Analyze and combine visual images with other sensory experiences 81 Motor Areas • _______________ • Frontal lobes • ___________ • _____________ • Anterior to primary motor • Above Broca’s area • Control voluntary muscles cortex • Usually in left hemisphere • Controls muscles needed for speech • Controls voluntary movements of eyes and eyelids Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Motor areas involved with the control of voluntary muscles Concentration, planning, problem solving Central sulcus Sensory areas involved with cutaneous and other senses Parietal lobe Frontal eye field Auditory area Sensory speech area ( Wernicke’s area) Front lobe Occipital lobe Combining visual images, visual recognition of objects Motor speech area (Broca’s area) Lateral sulcus Interpretation of auditory patterns Visual area Cerebellum Temporal lobe Brainstem 82 Motor Areas Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Arm Forearm Thumb, fingers, and hand Facial expression Trunk Pelvis Neck Forearm Arm Thigh Trunk Pelvis Thigh Leg Foot and toes Hand, fingers, and thumb Upper face Leg Foot and toes Genitals Lips Salivation Vocalization Mastication Teeth and gums Swallowing Tongue and pharynx Longitudinal fissure (a) Motor area Longitudinal fissure (b) Sensory area Frontal lobe Motor area Sensory area Central sulcus Parietal lobe 83 Hemisphere Dominance • The ______ hemisphere is dominant in most individuals • _________ hemisphere controls: • Speech • Writing • Reading • Verbal skills • Analytical skills • Computational skills • _____________ hemisphere controls: • Nonverbal tasks • Motor tasks • Understanding and interpreting musical and visual patterns • Provides emotional and intuitive thought processes 84 Basal Nuclei • Also called basal ganglia • Masses of gray matter deep within cerebral hemispheres • Caudate nucleus, putamen, and globus pallidus • Produce ________ • Control certain muscular activities • Primarily by inhibiting motor functions •_________ disease •_________ disease Basal nuclei Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Longitudinal fissure Right cerebral hemisphere Caudate nucleus Putamen Globus pallidus Thalamus Cerebellum Hypothalamus Brainstem Spinal cord 85 Ventricles and Cerebrospinal Fluid • There are four (4) ventricles • The ventricles are interconnected cavities within cerebral hemispheres and brain stem • The ventricles are continuous with the central canal of the spinal cord • They are filled with ______________ Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lateral ventricle Interventricular foramen Third ventricle Cerebral aqueduct Fourth ventricle To central canal of spinal cord • The four (4) ventricles are: • _______ ventricles (2) • Known as the first and second ventricles • ______ ventricle • ______ ventricle • Cerebral aqueduct • Choroid plexuses Interventricular foramen (a) Lateral ventricle Third ventricle Cerebral aqueduct Fourth ventricle (b) To central canal of spinal cord 86 Cerebrospinal Fluid • Secreted by the ____________ Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Circulates in ventricles, central Arachnoid granulations canal of spinal cord, and the Choroid plexuses subarachnoid space of third ventricle • Completely surrounds the brain Third ventricle Cerebral aqueduct and spinal cord Fourth ventricle • Excess or wasted CSF is absorbed by the arachnoid granulations • Clear fluid • Volume is about __________. • Nutritive and protective • Helps maintain stable ion concentrations in the CNS Blood-filled dural sinus Pia mater Subarachnoid space Arachnoid mater Dura mater Choroid plexus of fourth ventricle Central canal of spinal cord Pia mater Subarachnoid space Filum terminale Arachnoid mater Dura mater 87 Diencephalon (limbic system) • Between _______________ and above the __________ • Surrounds the _______ ventricle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Thalamus • Hypothalamus • Optic tracts • Optic chiasma • Infundibulum • Posterior pituitary • Mammillary bodies • Pineal gland Superior colliculus Corpora quadrigemina Optic nerve Optic chiasma Inferior colliculus Pituitary gland Mammillary body Optic tract Pons Thalamus Third ventricle Cerebral peduncles Pyramidal tract Olive Pineal gland Fourth ventricle Cerebellar peduncles Medulla oblongata Spinal cord (a) (b) 88 Diencephalon The Limbic System • Consists of: • Functions: • Portions of frontal lobe • Controls emotions • Portions of temporal lobe • Produces feelings • Hypothalamus • Interprets sensory impulses • Thalamus • Basal nuclei • Other deep nuclei 90 Brainstem Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hypothalamus Diencephalon Three parts: 1. Midbrain 2. Pons 3. Medulla Oblongata Thalamus Corpus callosum Corpora quadrigemina Midbrain Cerebral aqueduct Pons Reticular formation Medulla oblongata Spinal cord 91 Midbrain • Between ________ and ______ • Contains bundles of fibers that join lower parts of brainstem and spinal cord with higher part of brain •Masses of gray matter that serve as reflex centers – (_____________) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superior colliculus Corpora quadrigemina Optic nerve Optic chiasma Inferior colliculus Pituitary gland Mammillary body Optic tract Pons Thalamus Third ventricle Cerebral peduncles Pyramidal tract Olive Pineal gland Fourth ventricle Cerebellar peduncles Medulla oblongata Spinal cord (a) (b) 92 Pons • Rounded bulge on underside of brainstem • Between __________ and ________ •________________ • Relays nerve impulses to and from medulla oblongata and cerebellum Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superior colliculus Corpora quadrigemina Optic nerve Optic chiasma Inferior colliculus Pituitary gland Mammillary body Optic tract Pons Thalamus Third ventricle Cerebral peduncles Pyramidal tract Olive Pineal gland Fourth ventricle Cerebellar peduncles Medulla oblongata Spinal cord (a) (b) 93 Medulla Oblongata • Enlarged continuation of spinal cord • Conducts ascending and descending impulses between brain and spinal cord • Contains ______________________ Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superior colliculus Corpora quadrigemina Optic nerve Inferior colliculus Pituitary gland Mammillary body Optic tract Pons • Contains various nonvital reflex control centers (___________________) Optic chiasma Thalamus Third ventricle Cerebral peduncles Pyramidal tract Olive Pineal gland Fourth ventricle Cerebellar peduncles Medulla oblongata Spinal cord (a) (b) 94 Cerebellum • Inferior to occipital lobes • Posterior to pons and medulla Longitudinal fissure oblongata • Two hemispheres Thalamus • Vermis connects hemispheres Superior • __________ (gray matter) – thin peduncle layer surrounding Arbor vitae Pons Middle peduncle • _________ (white matter) – primary Inferior peduncle substance Medulla oblongata • Cerebellar peduncles (nerve fiber tracts) – communication •Integrates _______ information concerning position of body parts • Coordinates ______ muscle activity • Maintains _______ Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Corpus callosum Cerebellum 96 Quiz 3 9.15: Peripheral Nervous System • __________ nerves (12 pairs) arising from the brain • Somatic fibers connecting to the skin and skeletal muscles • Autonomic fibers connecting to viscera • __________ nerves arising from the spinal cord • Somatic fibers connecting to the skin and skeletal muscles • Autonomic fibers connecting to viscera 98 Nervous System Subdivisions Pge 258 99 Cranial Nerves Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Olfactory bulb Olfactory (I) Olfactory tract Optic (II) Optic tract Oculomotor (III) Trochlear (IV) Trigeminal (V) Vestibulocochlear (VIII) Abducens (VI) Hypoglossal (XII) Facial (VII) Vagus (X) Glossopharyngeal (IX) Accessory (XI) 100 Cranial Nerves I and II • _________ nerve (I) • Sensory nerve • Fibers transmit impulses associated with smell •Located in the lining of the upper nasal cavity • ______ nerve (II) • Sensory nerve • Fibers transmit impulses associated with vision •Sensory nerve cell bodies of these nerve fibers are in ganglion cell layers within the eyes 101 Cranial Nerves III and IV • _________ nerve (III) • Primarily motor nerve • Motor impulses to muscles that: • Raise eyelids • Move the eyes • Focus lens • Adjust light entering eye • _________ nerve (IV) • Primarily motor nerve • Motor impulses to muscles that move the eyes • Some sensory • Proprioceptors • Some sensory • Proprioceptors 102 Cranial Nerve V Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • __________ nerve (V) • Largest cranial nerves • Mixed nerve • (1) Ophthalmic division • Sensory from surface of eyes, tear glands, scalp, forehead, and upper eyelids • (2) Maxillary division • Sensory from upper teeth, upper gum, upper lip, palate, and skin of face • (3) Mandibular division • Sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip • Motor to muscles of mastication and muscles in floor of mouth Lacrimal nerve Ophthalmic division Lacrimal gland Eye Maxillary division Infraorbital nerve Mandibular division Maxilla Lingual nerve Inferior alveolar nerve Tongue Mental nerve Mandible 103 Cranial Nerves VI and VII • ________ nerve (VI) • Primarily motor nerve • Motor impulses to muscles that move the eyes • Some sensory •Proprioceptors Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Temporal nerve Zygomatic nerve Buccal nerve • _______ nerve (VII) Facial nerve • Mixed nerve • Sensory from taste receptors Posterior auricular • Motor to muscles of facial nerve expression, tear glands, and Parotid salivary gland salivary glands Mandibular nerve Cervical nerve 68 104 Cranial Nerves VIII and IX • __________ nerve (VIII) • _____________ nerve (IX) • Acoustic or auditory nerve • Mixed nerve • Sensory nerve • Sensory from pharynx, tonsils, • Two (2) branches: tongue and carotid arteries • Vestibular branch • Motor to salivary glands and • Sensory from equilibrium muscles of pharynx receptors of ear • Cochlear branch • Sensory from hearing receptors 105 Cranial Nerve X Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • ________ nerve (X) • Mixed nerve • Somatic motor to muscles of speech and swallowing • Autonomic motor to viscera of thorax and abdomen • Sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen Meningeal branch Auricular branch Pharyngeal branch Palate Superior laryngeal nerve Superior ganglion of vagus nerve Inferior ganglion of vagus nerve Nerve XI Nerve XII Carotid body Recurrent laryngeal nerve Left vagus nerve Cardiac nerves Lung Heart Stomach Liver Spleen Pancreas Kidney Small intestine Large intestine 106 Cranial Nerves XI and XII • ________ nerve (XI) • _________ nerve (XII) • Primarily motor • Primarily motor nerve • Motor to muscles of the • We called this “Spinal” tongue (speaking, chewing, Accessory because: swallowing) • Cranial branch • Some sensory • Motor to muscles of • Proprioceptor soft palate, pharynx and larynx • Spinal branch • Motor to muscles of neck and back • Some sensory • Proprioceptor 107 Spinal Nerves • ALL are mixed nerves (except the first pair) • 31 pairs of spinal nerves: • 8 cervical nerves (C1 to C8) • 12 thoracic nerves (T1 to T12) • 5 lumbar nerves (L1 to L5) • 5 sacral nerves (S1 to S5) • 1 coccygeal nerve (Co) • Cauda equina Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. C1 C2 C3 C4 C5 C6 C7 C8 T1 T2 T3 T4 T5 T6 T7 Posterior view Cervical nerves Thoracic nerves T8 T9 T10 T11 Cauda equina T12 L1 L2 L3 L4 L5 S1 S2 S3 S4 S5 Co Lumbar nerves Sacral nerves Coccygeal nerve 108 Spinal Nerves • ___________________ • Sensory root • Dorsal root ganglion • Cell bodies of sensory neurons whose axons conduct impulses inward from peripheral body parts •___________________ • Motor root • Axons of motor neurons whose cell bodies are in the spinal cord Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dorsal root Dorsal branch of spinal nerve Ventral branch of spinal nerve Dorsal root ganglion Ventral root Dorsal root Posterior median sulcus Paravertebral ganglion Posterior horn (b) Lateral horn Anterior horn Central canal Anterior median fissure Ventral root (a) Visceral branch of spinal nerve Ventral branch of spinal nerve (ventral ramus) Dorsal branch of spinal nerve (dorsal ramus) Spinal nerve Paravertebral ganglion Visceral branch of spinal nerve 109 Nerve Plexuses • Nerve plexus • Complex networks formed by anterior branches of spinal nerves – they innervate particular regions of the body • The fibers of various spinal nerves are sorted and recombined • There are three (3) nerve plexuses: • (1) ________ plexus • Formed by anterior branches of C1-C4 spinal nerves • Lies deep in the neck • Supply to muscles and skin of the neck • C3-C4-C5 nerve roots contribute to muscle fibers of diaphragm 110 Brachial Plexus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • (2) ________ plexus • Formed by anterior branches C5-T1 • Lies deep within shoulders • Five (5) branches: Ventral rami: C5, C6, C7, C8, T1 Trunks: upper, middle, lower Anterior divisions Posterior divisions Dorsal scapular n. Suprascapular n. Lateral pectoral n. Medial pectoral n. Lower subscapular n. Thoracodorsal n. Musculocutaneous n. • 1. Musculocutaneous nerve •2. •3. •4. •5. Ulnar and Median nerves Radial nerve Axillary nerve C5 C6 C6 C7 Axillary n. C8 Humerus T1 Median n. Ulnar n. Axillary n. Radial n. (a) C7 C8 T1 C5 Median n. Musculocutaneous n. Radial n. Ulnar n. Ulna Radius (b) 111 Lumbosacral Plexus • (3) ______________ plexus • Formed by the anterior branches of L1-S5 roots • Can be a lumbar (L1-L5) plexus and a sacral (S1-S5) Lateral plexus femoral cutaneous n. • Extends from lumbar region Femoral n. Obturator n. into pelvic cavity Superior gluteal n. •3 major branches Inferior gluteal n. • ________ nerve Common Sciatic n. fibular • ________ nerve (peroneal) n. Tibial n. •________ nerve Pudendal n. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ventral rami Anterior divisions Posterior divisions (a) Superior gluteal n. L1 L2 Obturator n. Inferior gluteal n. L3 Sacral plexus Femoral n. L4 Sciatic n. Pudendal n. Posterior cutaneous n. Saphenous n. L5 Common fibular (peroneal) n. S1 S2 S3 S4 Tibial n. S5 (b) (c) •Anterior branches do not enter a plexus, instead they become intercostal nerves 112 Plexuses Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Posterior view Musculocutaneous nerve Axillary nerve Radial nerve Median nerve Ulnar nerve Phrenic nerve Cauda equina Femoral nerve Obturator nerve Sciatic nerve C1 C2 C3 C4 C5 C6 C7 C8 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 L2 L3 L4 L5 S1 S2 S3 S4 S5 Co Cervical plexus (C1–C4) Brachial plexus (C5–T1) Intercostal nerves Lumbosacral plexus (T12–S5) 113 9.16: Autonomic Nervous System • Functions without conscious effort • Controls visceral activities • Regulates smooth muscle, cardiac muscle, and glands •2 Divisions • _____________ NS – (speeds up) prepares the body for energy-expending, stressful, or emergency situations as part of “fight-or-flight” response • _____________ NS – (slows down) most active under ordinary, restful conditions and counterbalances the effect of the sympathetic NS 114 Autonomic Nerve Fibers • All of the neurons are _____________ • ___________ fibers • Axons of preganglionic neurons • Neuron cell bodies in brain Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Interneurons Dorsal root ganglion Dorsal root ganglion Sensory neuron Sensory neuron Spinal cord Autonomic ganglion Preganglionic fiber Somatic motor neuron Postganglionic fiber Viscera • _____________ fibers • Axons of postganglionic (a) Autonomic pathway neurons • Neuron cell bodies in ganglia • Extend to visceral effector Skin Skeletal muscle (b) Somatic pathway 116 Sympathetic Division Pge 264 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lacrimal gland Eye Parotid gland, submandibular and sublingual glands Blood vessels Heart Celiac and pulmonary plexuses Celiac ganglion Skin Fibers to skin, blood vessels, and adipose tissue Superior mesenteric ganglion Trachea Lungs Liver Gallbladder Stomach Pancreas Small intestine Spinal cord Inferior mesenteric ganglion Sympathetic chain ganglia Large intestine Adrenal gland Kidney Urinary bladder Ovary Uterus Preganglionic Postganglionic neuron neuron Penis Scrotum 117 Parasympathetic Division Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sphenopalatine ganglion Pge 265 Cranial nerve III Ciliary ganglion Submandibular Cranial ganglion Nerve VII Cranial Otic ganglion nerve IX Cranial nerve X (Vagus) Lacrimal gland Eye Submandibular and sublingual glands Parotid gland Heart Trachea Lung Cardiac and pulmonary plexuses Liver Gallbladder Stomach Spleen Pancreas Celiac plexus Superior hypogastric plexus Spinal cord Small intestine Inferior hypogastric plexus Large intestine Kidney Pelvic nerves Preganglionic Postganglionic neuron neuron Scrotum Penis Urinary bladder Uterus Ovary 118 Autonomic Neurotransmitters • ___________ fibers • Release acetylcholine • Preganglionic sympathetic and parasympathetic fibers • Postganglionic parasympathetic fibers • __________ fibers • Release norepinephrine • Most postganglionic sympathetic fibers Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ACh = acetylcholine (cholinergic) Brain NE = norepinephrine (adrenergic) Visceral effectors Cranial parasympathetic neurons Preganglionic fiber (axon) ACh Ganglion ACh Sympathetic neurons ACh Postganglionic fiber (axon) NE Paravertebral ganglion ACh NE Collateral ganglion Sacral parasympathetic neurons ACh ACh Page 266 119 Control of Autonomic Activity • Controlled largely by CNS • Medulla oblongata regulates ____________________ activities • Hypothalamus regulates visceral functions, _______________________________________________ • Limbic system and cerebral cortex control emotional responses 120 Quiz 4