* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download CHAPTER NINE: THE NERVOUS SYSTEM
Metastability in the brain wikipedia , lookup
Neural coding wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Central pattern generator wikipedia , lookup
Patch clamp wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Endocannabinoid system wikipedia , lookup
Membrane potential wikipedia , lookup
Multielectrode array wikipedia , lookup
Signal transduction wikipedia , lookup
Action potential wikipedia , lookup
Neural engineering wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Optogenetics wikipedia , lookup
Resting potential wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Axon guidance wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Microneurography wikipedia , lookup
Neurotransmitter wikipedia , lookup
Single-unit recording wikipedia , lookup
Biological neuron model wikipedia , lookup
End-plate potential wikipedia , lookup
Electrophysiology wikipedia , lookup
Neuroregeneration wikipedia , lookup
Node of Ranvier wikipedia , lookup
Synaptic gating wikipedia , lookup
Development of the nervous system wikipedia , lookup
Circumventricular organs wikipedia , lookup
Channelrhodopsin wikipedia , lookup
Nervous system network models wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Chemical synapse wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Neuroanatomy wikipedia , lookup
CHAPTER NINE: THE NERVOUS SYSTEM (Part 1 of 3) I. Nervous System Introduction A. Functions of the Nervous System a. Sensory input- ________________ gathered by sensory receptors about internal and external changes b. ______________- interpretation of sensory input c. Motor output- activation of ______________ (muscles & glands) produces a response B. Divisions of the Nervous System a. Central Nervous System (_____) i. ___________ and spinal cord ii. Integration and command center b. Peripheral nervous system (_____) i. Paired ____________ and cranial nerves carry messages to and from the CNS C. Peripheral Nervous System a. Functions i. Sensory (___________) division 1. Somatic afferent fibers- convey impulses from skin, skeletal muscles, and joints 2. Visceral afferent fibers- convey impulses from visceral organs ii. Motor (___________) division 1. Transmits impulses from the CNS to effector organs 2. Somatic (___________) nervous system a. Conscious control of skeletal muscles 3. Autonomic (___________) nervous system (ANS) a. Visceral motor nerve fibers b. Regulated smooth muscle, cardiac muscle, and glands c. Functional divisions i. Sympathetic ii. Parasympathetic D. Histology of nervous system a. Two cell types i. ___________ - excitable cells that transmit electrical signals 1. Characteristics a. Long lived, amitotic, high metabolic rate, electrical signaling and cell-to-cell interactions during development 2. Parts of a neuron a. ___________ - biosynthetic center of a neuron, network of neurofibrils (neurofilaments) i. Axon hillock- cone shaped area where the axon arises ii. Clusters of cell bodies in the ____ are called nuclei, and in the PNS are called ganglia b. Processes- bundles are classed tracts (CNS) and nerves (PNS) i. Dendrites 1. Short, tapering and diffusely branched 2. Receptive (input) region of the neuron 3. Convey electrical signals __________ the cell body ii. Axons 1. One long axon per cell body 2. Long axons are called nerve _______ 3. Knoblike axon terminals a. Secretory region of the neuron b. Release neurotransmitters to excite or inhibit other cells 4. Conducting region of the neuron, generates and transmits nerve impulses ___________ from the cell body 5. Unmyelinated axons are thin nerve fibers and one Schwann cell can incompletely enclose 15 or more unmyelinated axons CHAPTER NINE: THE NERVOUS SYSTEM (Part 1 of 3) 3. Structural classifications of neurons a. ___________ - 1 axon and several dendrites (most abundant) b. Bipolar- 1 axon and 1 dendrite (_______) c. ___________ (pseudounipolar)single, short process that has two branches i. Peripheral process- most distal branch ii. Central process- branch entering the CNS 4. Functional classification of neurons a. Sensory (___________)transmit impulses from sensory receptors toward the CNS b. Motor (___________)- carries impulses from the CNS to effectors c. Interneurons (association neurons)- Shuttle signals through CNS pathways ii. Neuroglia (glial cells)- supporting cells 1. ___________ (CNS) a. Most abundant, versatile, and highly branched glial cells b. Cling to neurons, synaptic endings, and capillaries c. Support and brace neurons d. Determine capillary permeability e. Guide migration of young neurons f. Control chemical environment g. Information processing in the brain 2. ___________ (CNS) a. Migrate toward injured neurons b. Phagocytize microorganisms and neuronal debris 3. ___________ cells (CNS) a. May be ciliated b. Line the central cavities of the brain and spinal column c. Separate the CNS interstitial fluid from the cerebrospinal fluid in the cavities 4. ___________ (CNS) a. Branched cells b. Processes wrap CNS nerve fibers, forming insulating myelin sheaths i. Myelin sheath- concentric ________ of Schwann cell membrane ii. Neurilemmal- peripheral bulge of Schwann cell cytoplasm iii. Nodes of Ranvier-myelin sheath gaps between Schwann cells, sites where axon collaterals can emerge iv. CNS 1. Formed by processes of oligodendrocytes, Nodes of Ranvier not present, no ___________, thinnest fibers are unmyelinated v. _______ matter 1. Dense collections of myelinated fibers vi. _______ matter 1. Mostly neuron cell bodies and unmyelinated fibers 5. ___________ cells (PNS) a. Surround neuron cell bodies in the PNS 6. ___________ cells (PNS) a. Surround peripheral nerve fibers and form myelin sheaths b. Vital to regeneration of damaged peripheral nerve fibers CHAPTER NINE: THE NERVOUS SYSTEM (Part 1 of 3) E. Membrane potentials a. Role of membrane ion channels i. Proteins serve as membrane ion channels ii. Two main types of channels 1. Leakage (___________) channelsalways open 2. ___________ channels a. Three types i. Chemical gated (ligand-gated) channels- open with binding of a specific neurotransmitter ii. ________-gated channelsopen and close in response to changes in membrane potentials iii. Mechanically gated channelopen and close in response to physical deformation of receptors b. When gated channels are _______ i. Ions diffuse quickly across the membrane along their electrochemical gradients 1. Chemical gradients go from high to low 2. Electrical gradients go from low to high ii. Ion flow creates an electrical current and voltage changes across the membrane b. Resting membrane potential i. Potential difference across the membrane of a resting cell 1. Approximately -_______ in neurons ii. Generated by 1. Differences in ____ (intracellular fluid) and ____ (extracellular fluid) 2. Differential permeability of the plasma membrane iii. Differences in ionic makeup 1. ICF has _______ concentration of Na+ and Cl- than ECF 2. ICF has _______ concentration of K+ and negatively charged proteins (A-) than ECF iv. Sodium-potassium pump stabilizes the resting membrane potential by maintaining the concentration gradients for Na+ and K+ c. Membrane potentials act as signals i. Changes when concentrations of _______ across the membrane change and permeability of membrane to ions changes ii. Signals used to receive, ___________, and send information iii. Two types of signals 1. Graded potentials- incoming shortdistance signals a. ___________ i. Reduction in membrane potential ii. Inside of the membrane becomes less negative than the resting potential iii. Increases the probability of producing a nerve impulse b. ___________ i. An increase in membrane potential ii. Inside of the membrane becomes more negative than the resting potential iii. Reduces the probability of producing a nerve impulse c. Occur when a stimulus causes gated ion channels to open d. Decrease in magnitude with distance as ions flow and diffuse through leakage channels 2. __________________ - longdistance signals of axons a. Brief reversal of membrane potential with an amplitude of ~100mV b. Occur in muscle cells and axons of neurons c. Does not decrease in magnitude over distance F. Nerve Fiber Classification a. Group ___ fibers i. Large diameter, myelinated somatic sensory and motor fibers b. Group ___ fibers i. Intermediate diameter, lightly myelinated ANS fibers CHAPTER NINE: THE NERVOUS SYSTEM (Part 1 of 3) c. Group ___ fibers i. Smallest diameter, unmyelinated ANS fibers G. The Synapse a. A ___________ that mediated information transfer form one neuron to another neuron or an effector cell b. Presynaptic neuron- conducts impulses ___________ the synapse c. Postsynaptic neuron- transmits impulses ________ from the synapse d. Types of synapses i. Axodendritic- between the axon of one neuron and the ___________ of another ii. Axosomatic- between the axon of one neuron and the _______ of another iii. Less common 1. Axoaxonic (axon to axon) 2. Dendrodendritic (dendrite to dendrite) 3. Dendrosomatic (dendrite to soma) e. Electrical ___________ i. Less common than chemical synapses ii. Neurons are electrically coupled (joined by gap junctions) iii. Communication is very _________ and may be unidirectional or bidirectional iv. Important in embryonic nervous tissue and some brain regions f. Chemical synapses i. Specialized in the ___________ of neurotransmitters ii. Composed of two parts 1. ________ terminal of the presynaptic neuron 2. ___________ region on the postsynaptic neuron g. Synaptic cleft i. Fluid-filled space separating the presynaptic and postsynaptic neurons ii. Prevents nerve impulses from ___________ passing from one neuron to the next iii. Transmission across the synaptic cleft 1. Is a chemical event that involves the release, ___________, and binding of neurotransmitters that ensures unidirectional communication between neurons H. Neurotransmitters and their receptors a. Most neurons make two or more neurotransmitters, which are released at different stimulation frequencies b. _____ or more neurotransmitters have been identified c. Classified by ___________ Structure and by Function i. Acetylcholine (Ach) 1. Released at neuromuscular ___________ and some ANS neurons 2. Synthesized by enzyme choline acetyltransferase 3. Degraded by the ___________ acetylcholinesterase (AChE) ii. Biogenic amines include 1. Catecholamines a. ___________, norepinephrine (NE), and epinephrine 2. Indolamines a. Serotonin and hisamine 3. Broadly distributed in the ___________ 4. Play roles in ___________ behaviors and the biological clock iii. Amino acids 1. GABA (Gamma-aminobutyric acid) 2. Glycine 3. ___________ 4. Glutamate iv. Peptides (neuropeptides) 1. Substance P a. Mediator of _______ signals 2. Endorphins a. Act as natural opiates; ________ pain perception 3. Gut-brain peptides a. Somatostatin and cholecystokinin v. Purines such as ATP 1. Act in both the CNS and PNS 2. Provoke ________ sensation vi. Gases and lipids 1. Nitric oxide (NO) a. Involved in _________ and memory 2. Carbon monoxide (CO) a. Regulator of cGMP in the brain CHAPTER NINE: THE NERVOUS SYSTEM (Part 1 of 3) I. 3. Endocannabinoids a. Lipid soluble and involved in learning and _________ d. Direct action i. Neurotransmitter binds to channellinked receptor and opens ion channels ii. Promotes ___________ responses 1. Ach and amino acids e. Indirect action i. Neurotransmitter binds to a G-proteinlinked receptor and acts through an intracellular second messenger ii. Promotes long –lasting effects 1. Biogenic amines, neuropeptides, and dissolved gases f. Types of ___________ receptors i. Channel-linked receptors ii. G protein-linked receptors Basic concepts of neural integration a. Neuronal pools ___________ incoming information and forward the processes information to other destinations b. Simple neuronal pool i. Single presynaptic fiber branches and synapses with ___________ neurons in the pool ii. Discharge zone- neurons most ___________ associated with the incoming fiber iii. Facilitated zone- neurons ___________ away from incoming fiber c. Types of circuits in neuronal pools i. ___________ circuit 1. One incoming fiber stimulated an ever-increasing number of fibers, often amplifying circuits 2. May affect a single pathway or several 3. Common in both sensory and motor systems ii. ___________ circuit 1. Opposite of diverging circuits; strong stimulation or inhibition 2. Also common in sensory and motor systems iii. Reverberating (___________) circuit 1. Chain of neurons containing collateral synapses with previous neurons in the chain iv. Parallel after-discharge circuit 1. Incoming fiber stimulates several neurons in parallel arrays to stimulate a common output cell d. Neural processing i. Serial processing 1. Input travels along one pathway to a ___________ destination 2. Works in all-or-none manner to produce a specific response 3. Ex. reflexes ii. Parallel processing 1. Input travels along ___________ pathways 2. Important in higher-level mental functioning 3. Ex. Smell reminds you of an odor and associated experience J. Developmental aspects of neurons a. Originates from the neural ________ and neural _________ formed from ectoderm b. Neural tube becomes the CNS c. Cell ___________ i. About 2/3 of neurons die before birth ii. Death results in cells that fail to make functional synaptic contacts iii. Many cells also die due to ___________ (programmed cell death) during development K. Multiple Sclerosis (MS) a. An autoimmune disease that mainly affects __________ adults b. Myelin sheaths in the CNS become nonfunctional scleroses c. Shunting and short-circuiting of nerve __________ occurs, impulse condition slows and eventually ceases d. Symptoms: visual disturbances, ___________, loss of muscular control, speech disturbances, and urinary incontinence. CHAPTER NINE: THE NERVOUS SYSTEM (Part 1 of 3)