* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 13 - tanabe homepage
Action potential wikipedia , lookup
Neuroscience in space wikipedia , lookup
Brain morphometry wikipedia , lookup
Brain Rules wikipedia , lookup
Axon guidance wikipedia , lookup
Activity-dependent plasticity wikipedia , lookup
Embodied language processing wikipedia , lookup
Cognitive neuroscience wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Embodied cognitive science wikipedia , lookup
Human brain wikipedia , lookup
History of neuroimaging wikipedia , lookup
Aging brain wikipedia , lookup
Microneurography wikipedia , lookup
Neuroplasticity wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Metastability in the brain wikipedia , lookup
Neuropsychology wikipedia , lookup
Biological neuron model wikipedia , lookup
Development of the nervous system wikipedia , lookup
Chemical synapse wikipedia , lookup
End-plate potential wikipedia , lookup
Synaptic gating wikipedia , lookup
Neural engineering wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Circumventricular organs wikipedia , lookup
Neurotransmitter wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Single-unit recording wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Evoked potential wikipedia , lookup
Node of Ranvier wikipedia , lookup
Synaptogenesis wikipedia , lookup
Nervous system network models wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Neuroregeneration wikipedia , lookup
Human Biology Sylvia S. Mader Michael Windelspecht Chapter 13 Nervous System Lecture Outline See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Points to Ponder • • • • • • • • • • • • • What are the three types of neurons? What are neuroglia? What is the structure of a neuron? What is the myelin sheath? Saltatory conduction? Schwann cell? Node of Ranvier? Explain the resting and action potential as they relate to a nerve impulse. How does the nerve impulse traverse the synapse? What are the two parts of the nervous system? What 3 things protect the CNS? What are the 4 parts of the brain and their functions? What is the reticular activating system and the limbic system? What are some higher mental functions of the brain? What are the 2 parts of the peripheral nervous system? Be able to explain the abuse of several drugs. 13.1 Overview of the nervous system The nervous divisions • 2 divisions: – Central nervous system (CNS): Brain and spinal cord – Peripheral nervous system (PNS): Nerves and ganglia (cell bodies) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. brain Central Nervous System (CNS) cranial nerves brain spinal cord spinal cord spinal nerves Peripheral Nervous System (PNS) sensory (afferent) nerves — carry sensory information into brain and spinal cord somatic sensory nerves: signals from skin, muscles, joints, special senses a. b. visceral sensory nerves: signals from body organs motor (efferent) nerves — carry motor information from CNS to effectors somatic motor nerves: signals to skeletal muscles, voluntary autonomic motor nerves: signals to smooth muscle, cardiac muscle, glands, involuntary sympathetic division “fight or flight” parasympathetic division “rest and digest” 13.1 Overview of the nervous system The nervous system • Nervous system – Allows for communication between cells through sensory input, integration of data, and motor output • 2 cell types: neurons and neuroglia 13.1 Overview of the nervous system Expanding on neurons • 3 types of neurons: • Sensory – takes impulses from sensory receptor to CNS • Interneurons – receive information in the CNS and send it to a motor neuron • Motor – takes impulses from the CNS to an effector (i.e., gland or muscle fiber) • Neuron structure (Ch. 4 review): • Cell body – main cell where organelles and nuclei reside • Dendrite – many, short extensions that carry impulses to a cell body • Axon (nerve fiber) – single, long extension that carries impulses away from the cell body 13.1 Overview of the nervous system Types of neurons Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. Sensory neuron sensory receptor cell body axon myelin sheath direction of conduction Schwann cell b. Interneuron 400 nm axon dendrite c. Motorneuron cell body axon node of Ranvier 2.7 μm axon terminal direction of conduction a(myelin): © M.B. Bunge/Biological Photo Service; c(cell body): © Manfred Kage/Peter Arnold/Photolibrary 13.1 Overview of the nervous system The myelin sheath • A lipid covering on long axons that acts to increase the speed of nerve impulse conduction, insulation, and regeneration in the PNS • Schwann cells – neuroglia that make up the myelin sheath in the PNS • Nodes of Ranvier – gaps between myelination on the axons • Saltatory conduction – conduction of the nerve impulse from node to node 13.1 Overview of the nervous system Neuron structure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. Sensory neuron sensory receptor cell body axon myelin sheath direction of conduction Schwann cell b. Interneuron 400 nm axon dendrite c. Motorneuron cell body axon node of Ranvier 2.7 μm axon terminal direction of conduction a(myelin): © M.B. Bunge/Biological Photo Service; c(cell body): © Manfred Kage/Peter Arnold/Photolibrary 13.1 Overview of the nervous system The nerve impulse: resting potential (RP) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Resting potential – when the axon is not conducting a nerve impulse recording electrode inside axon + + + + + + + + + • More positive ions outside axonal membrane than inside the membrane + • There is a negative charge inside axon of -65mV inside the axon • More Na+ outside than inside • More K+ inside than outside outside axon reference electrode outside axon + + + + + + + + + + K+ Na+ gated K+ channel gated Na+ channel Resting potential: Na+ outside the axon, K+ and large anions inside the axon. Separation of charges polarizes the cell and causes the resting potential. 13.1 Overview of the nervous system The nerve impulse: action potential • Action potential – rapid change in the axon membrane that allows a nerve impulse to occur • Sodium gates open letting Na+ in • Depolarization occurs • Interior of axon loses negative charge (+40mV) • Potassium gates open letting K+ out • Repolarization occurs • Interior of axon regains negative charge (-65mV) • Wave of depolarization/repolarization travels down the axon • Resting potential is restored by moving potassium inside and sodium outside 13.1 Overview of the nervous system The nerve impulse: stimulus causes the axon to reach its threshold Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. + + + + + + + + + + direction of signal + + + + + + + + + + open Na+ channel b. Stimulus causes the axon to reach its threshold; the axon potential increases from -70 to -40. The action potential has begun. 13.1 Overview of the nervous system The nerve impulse: action potential Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. +60 + + + + + + + + + + + + + + + + + + + + + + + + + + + direction of signal Voltage (mV) +40 direction of signal + + + + + + + + + + + open Na+ channel c. Depolarization continues as Na+ gates open and Na+ moves inside the axon. + + + + + + + + + open K+ channel d. Action potential ends: repolarization occurs when K+ gates open and K+ moves to outside the axon. The sodium—potassium pump returns the ions to their resting positions. Na+ moves to inside axon. +20 K+ moves to outside action axon. potential 0 20 40 threshold 60 resting potential 0 1 2 3 4 5 Time (milli seconds) 6 e. An action potential can be visualized if voltage changes are graphed over time. Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer. Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer. Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer. 13.1 Overview of the nervous system The synapse • A small gap between the sending neuron (presynaptic membrane) and the receiving neuron (postsynaptic membrane) • Transmission is accomplished across this gap by a neurotransmitter (e.g., ACh, dopamine, and serotonin) • Neurotransmitters are stored in synaptic vesicles in the axon terminals 13.1 Overview of the nervous system How does transmission across the synapse occur? • Nerve impulse reaches the axon terminal • Calcium ions enter the axon terminal that stimulate the synaptic vesicles to fuse with the presynaptic membrane • Neurotransmitters are released and diffuse across the synapse and bind with the postsynaptic membrane to inhibit or excite the neuron 13.1 Overview of the nervous system A synapse and how it functions Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. arriving action potential Sending neuron Ca2+ axon of sending neuron axon terminal 1. After an action potential arrives at an axon terminal (arrow), Ca2+ enters, and synaptic vesicles fuse with the plasma membrane of the sending neuron. Synaptic vesicles enclose neurotransmitter. Synapse receiving neuron Receiving neuron Synaptic cleft 2. Neurotransmitter molecules are released and bind to receptors on the membrane of the receiving neuron. Receiving neuron neurotransmitter neurotransmitter receptor Na+ Receiving neuron ion channel 3. When an excitatory neurotransmitter binds to a receptor, Na+ diffuses into the receiving neuron, and an action potential begins. Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer. 13.1 Overview of the nervous system Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Synaptic integration • Integration is the summation of the inhibitory and excitatory signals received by a postsynaptic neuron axon branches of sending neurons Cell body of the receiving neuron axon terminals dendrite inhibitory synapse excitatory synapse • This occurs because a neuron receives many signals a. +20 0 excitatory signal integration inhibitory signal 20 40 threshold 70 resting potential 80 Time (milli seconds) b. Courtesy Dr. E.R. Lewis, University of California Berkeley 13.1 Overview of the nervous system The nervous divisions • 2 divisions: – Central nervous system (CNS): Brain and spinal cord – Peripheral nervous system (PNS): Nerves and ganglia (cell bodies) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. brain Central Nervous System (CNS) cranial nerves brain spinal cord spinal cord spinal nerves Peripheral Nervous System (PNS) sensory (afferent) nerves — carry sensory information into brain and spinal cord somatic sensory nerves: signals from skin, muscles, joints, special senses a. b. visceral sensory nerves: signals from body organs motor (efferent) nerves — carry motor information from CNS to effectors somatic motor nerves: signals to skeletal muscles, voluntary autonomic motor nerves: signals to smooth muscle, cardiac muscle, glands, involuntary sympathetic division “fight or flight” parasympathetic division “rest and digest” 13.2 The central nervous system The central nervous system • Consists of the brain and spinal cord • Both are protected by: • Bones – skull and vertebral column • Meninges – 3 protective membranes that wrap around CNS • Cerebral spinal fluid (CSF) – space between meninges is filled with this fluid that cushions and protects the CNS • Both made up of 2 types of nervous tissue: • Gray matter – contains cell bodies and nonmyelinated fibers • White matter – contains myelinated axons 13.2 The central nervous system The CNS: Spinal cord • Extends from the base of the brain and along the length of the vertebral canal formed by the vertebrae • Functions to provide communication between the brain and most of the body • Center for reflex arcs • Gray matter in the center is a butterfly shape • White matter surrounds the gray matter 13.2 The central nervous system What does the spinal cord look like? Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. white matter gray matter central canal a. gray matter white matter spinal cord vertebra dorsal root dorsal root ganglion spinal nerve vertebra ventral root b. central canal dorsal root dorsal root ganglion dorsal dorsal root branches gray matter white matter dorsal root ganglion ventral spinal nerve ventral root cut vertebrae meninges c. d. Dorsal view of spinal cord and dorsal roots of spinal nerves. a: © Karl E. Deckart/Phototake; d: © The McGraw-Hill Companies, Inc./Rebecca Gray, photographer and Don Kincaid, dissections 13.2 The central nervous system The CNS: Brain Four major parts: 1. 2. 3. 4. Cerebrum Diencephalon Cerebellum Brain stem 13.2 The central nervous system The CNS: Overview of the brain Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. lateral third ventricle ventricle pineal gland Cerebrum skull meninges corpus callosum Diencephalon thalamus (surrounds the third ventricle) hypothalamus pituitary gland Brain stem midbrain pons medulla oblongata a. Parts of brain Cerebellum fourth ventricle spinal cord b. Cerebral hemispheres 13.2 The central nervous system The brain: Cerebrum • Cerebral hemisphere • Cerebral cortex • Primary motor and sensory areas of the cortex • Association areas • Processing centers • Central white matter 13.2 The central nervous system 1. The brain: Cerebrum – the lobes • Cerebrum – largest portion of the brain • Divided into 4 lobes/hemispheres: • Frontal lobe: primary motor area and conscious thought • Temporal lobe: primary auditory, smell, and speech area • Parietal lobe: primary somatosensory and taste area • Occipital lobe – primary visual area 13.2 The central nervous system 1. The brain: Cerebrum – the cerebral hemispheres Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. central sulcus Frontal lobe Parietal lobe primary somatosensory area primary motor area premotor area leg motor speech (Broca’s) area trunk somatosensory association area primary taste area arm prefrontal area hand general interpretation area face anterior ventral tongue posterior dorsal Occipital lobe primary olfactory area lateral sulcus Temporal lobe auditory association area primary auditory area sensory speech (Wernicke’s) area primary visual area visual association area 13.2 The central nervous system 1. The brain: Cerebrum – the cerebral cortex • Cerebral cortex – thin, outer layer of gray matter: - Primary motor area – voluntary skeletal muscle - Primary somatosensory area – sensory information from skeletal muscle and skin - Association areas – integration occurs here - Processing centers – perform higher level analytical functions including Wernicke’s and Broca’s areas both involved in speech 13.2 The central nervous system 1. The brain: Cerebrum – the cerebral cortex Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. arm trunk forearm thumb, fingers, and hand swallowing foot and toes a. Primary motor area hand, fingers, and thumb thigh leg facial expression salivation vocalization mastication arm neck trunk pelvis forearm thigh pelvis longitudinal fissure leg upper face foot and toes lips teeth and gums tongue and pharynx genitals b. Primary somatosensory area longitudinal fissure 13.2 The central nervous system 2. The brain: Diencephalon • Includes the: • Hypothalamus – helps maintain homeostasis (hunger, sleep, thirst, body temperature, and water balance) and controls pituitary gland • Thalamus – 2 masses of gray matter that receive all sensory input except smell; involved in memory and emotions • Pineal gland – secretes melatonin that controls our daily rhythms 13.2 The central nervous system 2. The brain: Diencephalon Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. lateral third ventricle ventricle pineal gland Cerebrum skull meninges corpus callosum Diencephalon thalamus (surrounds the third ventricle) hypothalamus pituitary gland Brain stem midbrain pons medulla oblongata a. Parts of brain Cerebellum fourth ventricle spinal cord b. Cerebral hemispheres 13.2 The central nervous system 3. The brain: Cerebellum • Receives and integrates sensory input from the eyes, ears, joints, and muscles about the current position of the body • Functions: • Maintains posture • Coordinates voluntary movement • Allows learning of new motor skills (i.e., playing the piano or hitting a baseball) 13.2 The central nervous system 4. The brain: The brain stem • Includes: • Midbrain – relay station between the cerebrum and spinal cord or cerebellum; reflex center • Pons – a bridge between cerebellum and the CNS; regulate breathing rate; reflex center for head movements • Medulla oblongata – reflex centers for regulating breathing, heartbeat, and blood pressure • Reticular formation – major component of the reticular activating system (RAS) that regulates alertness 13.2 The central nervous system The reticular activating system Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. RAS radiates to cerebral cortex. thalamus reticular formation ascending sensory tracts (touch, pain, temperature) 13.3 The limbic system and higher mental functions The limbic system • Joins primitive emotions (i.e., fear, pleasure) with higher functions such as reasoning • Can cause strong emotional reactions to situations but conscious thought can override and direct our behavior • Includes: • Amygdala – has emotional overtones • Hippocampus – important to learning and memory 13.3 The limbic system and higher mental functions The limbic system Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. corpus thalamus callosum hypothalamus olfactory bulb olfactory tract amygdala hippocampus 13.3 The limbic system and higher mental functions Higher mental functions • Learning – what happens when we recall and use past memories • Memory – ability to hold a thought or to recall past events • Short-term memory – retention of information for only a few minutes • Long-term memory – retention of information for more than a few minutes and includes the following: • Episodic memory – persons and events • Semantic memory – number and words • Skill memory – performing skilled motor activities (i.e., riding a bike) • Language – depends on semantic memory 13.3 The limbic system and higher mental functions What parts of the brain are active in reading and speaking? Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. primary auditory cortex visual cortex 1. The word is seen in the visual cortex. Wernicke’s area 2. Information concerning the word is interpreted in Wernicke’s area. primary motor cortex Broca’s area 3. Information from Wernicke’s area is transferred to Broca’s area. (all): © Marcus Raichle 4. Information is transferred from Broca’s area to the primary motor area. 13.4 The peripheral nervous system The peripheral nervous system (PNS) • Includes cranial (12 pr) and spinal nerves (31 pr) and ganglia outside the CNS - Spinal nerves conduct impulses to and from the spinal cord - Cranial nerves conduct impulses to and from the brain • Divided into 2 systems: - Somatic - Autonomic 13.4 The peripheral nervous system The peripheral nervous system Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. cranial nerves PNS Spinal Cranial Nerve spinal nerves artery and vein Cranial Nerves III from olfactory receptors from retina of eyes to eye muscles IV to eye muscles V from mouth and to jaw muscles VI to eye muscles I II single nerve fiber bundle of nerve fibers VII from taste buds and to facial muscles and glands VIII from inner ear IX blood vessels SEM 200× © Dr. Richard Kessel & Dr. Randy Kardon/Tissues & Organs/Visuals Unlimited from pharynx and to pharyngeal muscles XII to tongue muscles X from and to internal organs XI to neck and back muscles 13.4 The peripheral nervous system The PNS: Somatic division • Serves the skin, skeletal muscles and tendons Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. pin central canal dorsal root ganglion white matter sensory receptor (in skin) Dorsal gray matter dorsal horn cell body of sensory neuron • Automatic responses are called reflexes axon of sensory neuron cell body of interneuron effector (muscle) axon of motor neuron ventral root cell body of motor neuron ventral horn Ventral 13.4 The peripheral nervous system The PNS: Autonomic division • Regulates the activity of involuntary muscles (cardiac and smooth) and glands • Divided into 2 divisions: – Sympathetic: coordinates the body for the “fight or flight” response by speeding up metabolism, heart rate, and breathing while slowing down and regulating other functions – Parasympathetic: counters the sympathetic system by bringing up a relaxed state by slowing down metabolism, heart rate, and breathing and returning other functions to normal 13.4 The peripheral nervous system The PNS: Autonomic division Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. stimulates tears constricts pupils inhibits tears dilates pupils Sympathetic Division ganglion Parasympathetic Division inhibits salivation stimulates salivation cranial nerves slows heart speeds heart dilates air passages cervical nerves constricts bronchioles stimulates liver to release glucose stimulates gallbladder to release bile stimulates adrenal secretion thoracic nerves vagus nerve increases activity of stomach and pancreas inhibits activity of kidneys, stomach, and pancreas increases intestinal activity decreases intestinal activity lumbar nerves ganglion inhibits urination causes orgasmic contractions sympathetic ganglia stimulates urination causes erection of genitals sacral nerves Acetylcholine is neurotransmitter. Norepinephrine is neurotransmitter. 13.5 Drug Therapy and Drug abuse Drugs and drug abuse Both pharmaceuticals and illegal drugs have several basic modes of action: • Promote the action of a neurotransmitter • Interfere with or decrease the action of a neurotransmitter • Replace or mimic a neurotransmitter or neuromodulator 13.5 Drug Therapy and Drug abuse Drugs and drug abuse • Most drug abusers take drugs that affect dopamine and thus artificially affect this reward circuit to the point they ignore basic physical needs in favor of the drug • Drug abusers tend to show a physiological and psychological effect • Once a person is physically dependent they usually need more of the drug for the same effect because their body has become tolerant 13.5 Drug Therapy and Drug abuse Drug abuse: Alcohol • Alcohol – a depressant directly absorbed from the stomach and small intestine • Most socially accepted form of drug use • About 80% of college-aged people drink • Alcohol denatures proteins, causes damage to tissues such as the brain and liver; chronic consumption can damage the frontal lobe • High blood alcohol levels can lead to poor judgment, loss of coordination, or even coma and death 13.5 Drug Therapy and Drug abuse Drug abuse: Nicotine and Cocaine • Nicotine – stimulant derived from tobacco plant – Causes neurons to release dopamine that helps lead to dependence – Adversely affects a developing embryo or fetus – Increases heart rate and blood pressure – Psychological and physiological dependency • Cocaine – stimulant derived from a plant – Results in a rush sensation (5-30 minutes) and an increased sex drive – Results in hyperactivity and little desire for food and sleep – Extreme physical dependence with this drug – “Crack” is a street name for cocaine that is processed to a free base for smoking 13.5 Drug Therapy and Drug abuse Drug abuse: methamphetamine • Powder form is called speed and crystal form is called meth or ice • A stimulant that reverses the effects of fatigue and is a mood elevator • High agitation is common after the rush and can lead to violent behavior • Causes psychological dependency and hallucinations • “Ecstasy” is the street name for a drug that has the same effects as meth without the hallucinations 13.5 Drug Therapy and Drug abuse Drug abuse: Heroin • Heroin: depressant from the sap of the opium poppy plant • Leads to a feeling of euphoria and no pain because it is delivered to the brain and is converted into morphine • Side effects are nausea, vomiting, and depression of the respiratory and circulatory systems • Can lead to HIV, hepatitis, and other infections due to shared needles • Extreme dependency 13.5 Drug Therapy and Drug abuse Drug abuse and its use: Marijuana • Marijuana: psychoactive drug derived from a hemp plant called Cannabis • Most often smoked as a “joint” • Mild euphoria and brain damage • Alterations to vision and judgment as well as impaired motor coordination with slurred speech • Heavy users may experience depression, anxiety, hallucinations, paranoia, and psychotic symptoms 13.5 Drug Therapy and Drug abuse Bioethical focus: Medical Marijuana • Banned in the US in 1937 but recently has been legalized in a few states for medical use in seriously ill patients. – Should marijuana be available to more patients? Why or why not? – Should people in states where it is legal for medical purposes be prosecuted? – How should the use of medical marijuana be regulated?