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Pre-Pharm > A&P 11: Fundamentals of the Nervous System & Nervous Tissue > Flashcards

A&P 11: Fundamentals of the Nervous System & Nervous Tissue Flashcards

1
Q

Nervous system

A

master controlling and communicating system of the body

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2
Q

Sensory input

A

information gathered by the nervous system

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3
Q

Integration

A

process of the nervous system processing and interpreting sensory input and deciding what should be done at each moment

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4
Q

Motor output

A

the nervous system activates effector organs (muscles and glands) to cause a response, called this

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5
Q

Central nervous system

A

brain and spinal cord; integrating and control center of the nervous system; interprets sensory input and dictates motor output based on reflexes, current conditions, and past experience

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6
Q

Peripheral nervous system

A

part of the nervous system outside the CNS; consists mainly of nerves that extend from the brain and spinal cord

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7
Q

Sensory (afferent) division

A

part of the PNS; consists of nerve fibers (axons) that convey impulses TO the CNS from sensory receptors located throughout the body

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8
Q

Motor (efferent) division

A

part of the PNS; transmits impulses FROM the CNS to effector organs (muscle and glands)

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9
Q

Somatic nervous system

A

composed of somatic motor nerve fibers that conduct impulses from the CNS to skeletal muscles; often referred to as the voluntary nervous system because it allows us to consciously control our skeletal muscles

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10
Q

Autonomic nervous system (ANS)

A

consists of visceral motor nerve fibers that regulate the activity of smooth muscles, cardiac muscles, and glands; AKA the involuntary nervous system

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11
Q

Sympathetic division

A

division of the ANS that prepares the body for activity or to cope with some stressor (danger, excitement, etc.); the fight, fright, and flight subdivision

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12
Q

Parasympathetic division

A

division of the ANS that oversees digestion, elimination, and glandular function; the resting and digesting subdivision

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13
Q

Neuroglia

A

nonexcitable cells of neural tissue that support, protect, and insulate the neurons; glial cells

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14
Q

Astrocytes

A

shaped like delicate branching sea anemones, these are the most versatile glial cells; numerous radiating processes cling to neurons and their synaptic endings, and cover nearby capillaries; support/brace neurons and anchor them to their nutrient supply line

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15
Q

Microglial cells

A

small and ovoid with relatively long thorny processes, which touch nearby neurons, monitoring their health; phagocytizes microorganisms or neuronal debris

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16
Q

Ependymal cells

A

range in shape from squamous to columnar, and many are ciliated; line the central cavities of the brain and spinal cord, where they form a fairly permeable barrier between the cerebrospinal fluid that fills those cavities and the tissue fluid bathing the cells of the CNS

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17
Q

Oligodendrocytes

A

branch, but with fewer processes than astrocytes; line up along the thicker nerve fibers in the CNS and wrap their processes tightly around the fibers, producing an insulating covering (myelin sheath)

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18
Q

Satellite cells

A

surround neuron cell bodies in the PNS; thought to have the same function as astrocytes

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19
Q

Schwann cells

A

AKA neurolemmocytes; surround all nerve fibers in the PNS and form myelin sheaths around the thicker nerve fibers; functionally similar to oligodendrocytes; vital to regeneration of damaged peripheral nerve fibers

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20
Q

Neurons

A

nerve cells; structural units of the nervous system; typically large, specialized cells that conduct messages in the form of nerve impulses from one part of the body to another

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21
Q

Neuron cell body

A

consists of a spherical nucleus with a conspicuous nucleolus surrounded by cytoplasm

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22
Q

Perikaryon (soma)

A

another name for the neuron cell body; major biosynthetic center of a neuron; contains the usual organelles

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23
Q

Chromatophilic substance

A

rough ER of a neuron; AKA Nissl bodies; stains darkly with basic dyes; most active and best developed rough ER in the body

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24
Q

Neurofibrils

A

bundles of intermediate filaments; important in maintaining cell shape and integrity; form a network throughout the cell body

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25
Q

Nuclei

A

clusters of cell bodies in the CNS

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26
Q

Ganglia

A

cell bodies that lie along the nerves in the PNS

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27
Q

Processes

A

armlike ___ extend from the cell body of all neurons

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28
Q

Tracts

A

bundles of neuron processes in the CNS

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29
Q

Nerves

A

bundles of neuron processes in the PNS

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30
Q

Dendrites

A

short, tapering, diffusely branching extensions; convey incoming messages TOWARD the cell body

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31
Q

Receptive (input) regions

A

dendrites; provide an enormous surface area for receiving signals from other neurons

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32
Q

Axon

A

each neuron has a single one of these

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33
Q

Axon hillock

A

the initial region of the axon arises from a cone-shaped area of the cell body called this; then narrows to form a slender process that is uniform in diameter for the rest of its length

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34
Q

Nerve fiber

A

any long axon

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35
Q

Axon collaterals

A

branches of an axon; extend from the axon at right angles

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36
Q

Terminal branches

A

terminal arborizations; profuse branching at the end of an axon (10,000+)

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37
Q

Axon terminals (terminal boutons)

A

the knoblike distal endings of the terminal branches of an axon

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38
Q

Conducting region

A

axon is the ___ ___ of the neuron - it generates nerve impulses and transmits them, typically away from the cell body, along the plasma membrane

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39
Q

Axolemma

A

plasma membrane of the neuron

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40
Q

Secretory region

A

axon terminals are the ___ ___ of the neuron

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41
Q

Myelin sheath

A

many nerve fibers, particularly those that are long or large in diameter, are covered with this whitish, fatty (protein-lipoid), segmented ___ ___

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42
Q

Myelinated fibers

A

axons bearing a myelin sheath; conduct nerve impulses rapidly

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43
Q

Nonmyelinated fibers

A

axons without a myelin sheath; conduct impulses slowly; dendrites are always _____

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44
Q

Nodes of Ranvier

A

myelin sheath gaps; occur at regular intervals (1 mm apart) along a myelinated axon

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45
Q

White matter

A

regions of the brain and spinal cord containing dense collections of myelinated fibers; primarily fiber tracts

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46
Q

Gray matter

A

contains mostly nerve cell bodies and nonmyelinated fibers

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47
Q

Multipolar neurons

A

have 3+ processes - one axon and the rest dendrites; most common neuron type in humans (>99%); major type of neuron in the CNS

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48
Q

Bipolar neurons

A

neurons with 2 processes (axon and dendrite); extend from opposite sides of the cell body; rare; found in some of the special sense organs (retina, olfactory mucosa)

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49
Q

Unipolar neurons

A

neurons with a single short process that emerges from the cell body and divides T-like into proximal and distal branches; found chiefly in ganglia in the PNS, where they function as sensory neurons

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50
Q

Peripheral process

A

the more distal process of a unipolar neuron; often associated with a sensory receptor

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51
Q

Central process

A

proximal process of a unipolar neuron; enters the CNS

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52
Q

Pseudounipolar neurons

A

unipolar neurons are more accurately called this, because they originate as bipolar neurons

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53
Q

Sensory (afferent) neurons

A

transmit impulses from sensory receptors in the skin or internal organs toward or into the CNS

54
Q

Motor (efferent) neurons

A

carry impulses away from the CNS to the effector organs (muscles and glands) of the body periphery; multipolar; except for some neurons of the ANS, their cell bodies are located in the CNS

55
Q

Interneurons (association neurons)

A

neurons that lie between motor and sensory neurons in neural pathways and shuttle signals through CNS pathways where integration occurs; most are confined within the CNS; make up over 99% of the neurons of the body, including most of those in the CNS

56
Q

Voltage

A

measure of potential energy generated by separated charge; measured in volts (V) or millivolts (1 mV)

57
Q

Potential difference (potential)

A

voltage is always measured between 2 points and is called the ___ or the __ ___ between the points

58
Q

Current

A

flow of electrical charge from one point to another; can be used to do work

59
Q

Resistance

A

hindrance to charge flow provided by substances through which the current must pass; if high = insulator; if low = conductor

60
Q

Ohm’s Law

A

current (I) = voltage (V)/resistance (R); current is directly proportional to voltage; there is no net current between points that have the same potential; current is inversely related to resistance

61
Q

Leakage (nongated) channels

A

channels that are always open

62
Q

Chemically gated (ligand-gated) channels

A

channels that open when the appropriate chemical (in this case a neurotransmitter) binds

63
Q

Voltage-gated channels

A

channels that open and close in response to changes in the membrane potential

64
Q

Mechanically-gated channels

A

channels that open in response to physical deformation of the receptor (as in sensory receptors for touch and pressure)

65
Q

Electrochemical gradient

A

together, electrical and concentration gradients constitute this; ions flowing along these underlie all electrical events in neurons

66
Q

Resting membrane potential

A

potential difference in a resting neuron

67
Q

Polarized

A

state of a plasma membrane of an unstimulated neuron or muscle cell in which the inside of the cell is relatively negative in comparison to the outside; the resting state

68
Q

Sodium-potassium pump (Na+ - K+ ATPase)

A

stabilizes the resting membrane potential by maintaining the concentration gradients for sodium and potassium

69
Q

Depolarization

A

a decrease in membrane potential; the inside of the membrane becomes less negative (moves closer to zero) than the resting potential; also includes events in which the membrane potential reverses and moves above zero to become positive

70
Q

Hyperpolarization

A

an increase in membrane potential; the inside of the membrane becomes more negative (moves further from zero) than the resting potential

71
Q

Graded potentials

A

short-lived, localized changes in membrane potential that can be either depolarizations or hyperpolarizations; cause current flows that decrease in magnitude with distance

72
Q

Action potential (AP)

A

a brief reversal of membrane potential with a total amplitude (change in voltage) of about 100 mV

73
Q

Nerve impulse

A

in a neuron, an action potential; typically generated only in axons

74
Q

Threshold

A

when depolarization at the stimulation site reaches this certain critical level (often between -55 & -50 mV), depolarization becomes self-generating

75
Q

Repolarization

A

restoration of the internal negativity of the resting neuron; both the abrupt decline in Na+ permeability and the increased permeability to K+ contribute to repolarization

76
Q

All-or-none phenomenon

A

an action potential either happens completely or doesn’t happen at all

77
Q

Propagated

A

if it is to serve as the neuron’s signaling device, an AP must do this along the entire axon’s length

78
Q

Absolute refractory period

A

the period, from the opening of the Na+ channels until the Na+ channels begin to reset to their original resting state; ensure that each AP is a separate, all-or-none event and enforces one-way transmission of the AP

79
Q

Relative refractory period

A

interval following the absolute refractory period

80
Q

Continuous conduction

A

AP propagation involving nonmyelinated axons

81
Q

Saltatory conduction

A

AP’s are triggered only at the myelin sheath gaps; the electrical signal appears to jump from gap to gap along the axon; 30x faster than continuous conduction

82
Q

Multiple sclerosis

A

demyelinating disease; autoimmune; gradually destroys myelin sheaths in the CNS, reducing them to nonfunctional hardened lesions called scleroses

83
Q

Group A fibers

A

mostly somatic sensory and motor fibers serving the skin, skeletal muscles, and joints; have the largest diameter and thick myelin sheaths; conduct impulses at speeds ranging up to 150 m/s (>300mph)

84
Q

Group B fibers

A

lightly myelinated fibers of intermediate diameter; transmit impulses at an average rate of 15m/s (30mph)

85
Q

Group C fibers

A

smallest diameter; nonmyelinated; incapable of saltatory conduction and conduct impulses at a leisurely pace (1m/s or 2mph or less)

86
Q

Synapse

A

junction that mediates information transfer from 1 neuron to the next or from a neuron to an effector cell

87
Q

Axodendritic synapses

A

synapses between the axon endings of 1 neuron and the dendrites of other neurons

88
Q

Axosomatic synapses

A

synapses between axon endings of 1 neuron and cell bodies (soma) of other neurons

89
Q

Presynaptic neuron

A

the neuron conducting impulses toward the synapse

90
Q

Postsynaptic neuron

A

the neuron transmitting the electrical signal away from the synapse

91
Q

Electrical synapses

A

less common type of synapse; consist of gap junctions like those found between certain other body cells; contain protein channels (connexons) that intimately connect they cytoplasm of adjacent neurons and allow ions and small molecules to flow directly from 1 neuron to the next

92
Q

Chemical synapses

A

synapses specialized to allow the release and reception of chemical neurotransmitters

93
Q

Synaptic vesicles

A

tiny, membrane-bounded sacs, each containing thousands of neurotransmitter molecules

94
Q

Synaptic cleft

A

presynaptic and postsynaptic membranes are always separated by this fluid-filled space approximately 30-50 nm wide

95
Q

Synaptic delay

A

time required for a signal to cross a synapse between 2 neurons; rate-determining step of neural transmission

96
Q

Excitatory postsynaptic potentials (EPSPs)

A

local graded depolarization events that occur at excitatory postsynaptic membranes

97
Q

Inhibitory postsynaptic potentials (IPSPs)

A

hyperpolarizing changes in potential

98
Q

Summate

A

add together

99
Q

Temporal summation

A

occurs when 1 or more presynaptic neurons transmit impulses in rapid-fire order and bursts of neurotransmitter are released in quick succession

100
Q

Spatial summation

A

occurs when the postsynaptic neuron is stimulated simultaneously by a large number of terminals from one (or more commonly) many presynaptic neurons

101
Q

Facilitated

A

partially depolarized neurons are more easily excited by successive depolarization events because they are already near threshold

102
Q

Synaptic potentiation

A

repeated or continuous use of a synapse (even for short periods) enhances the presynaptic neuron’s ability to excite the postsynaptic neuron, producing larger-than-expected EPSPs

103
Q

Presynaptic inhibition

A

occurs when the release of excitatory neurotransmitter by one neuron is inhibited by the activity of another neuron via an axo-axonal synapse

104
Q

Acetylcholine (ACh)

A

1st neurotransmitter identified; best understood neurotransmitter because it is released at neuromuscular junctions (easier to study than synapses buried in the CNS)

105
Q

Acetylcholinesterase (AChE)

A

enzyme that releases ACh and degrades it to acetic acid and choline; located in the synaptic cleft and on postsynaptic membranes

106
Q

Biogenic amines

A

include the catecholamines (dopamine, norepinephrine, and epinephrine) and indolamines (serotonin, histamine)

107
Q

Catecholamines

A

dopamine, norepinephrine (NE), and epinephrine

108
Q

Indolamines

A

serotonin and histamine

109
Q

Amino acids (as neurotransmitters)

A

glutamate, aspartate, glycine, gamma-aminobutyric acid

110
Q

Neuropeptides

A

strings of amino acids; include a broad spectrum of molecules with diverse effects

111
Q

Substance P

A

neuropeptide; important mediator of pain signals

112
Q

Endorphins

A

include beta ____, dynorphin, and enkephalins; act as natural opiates, reducing our perception of pain under stressful conditions

113
Q

Gut-brain peptides

A

neuropeptides produced by nonneural body tissues; widespread in the gastrointestinal tract; examples: somatostatin and cholecystokinin

114
Q

Adenosine triphosphate (ATP)

A

cell’s universal form of energy; major neurotransmitter (perhaps the most primitive one) in both the CNS and the PNS

115
Q

Adenosine

A

part of ATP; acts outside of cells on adenosine receptors; potent inhibitor in the brain; caffeine’s well-known stimulatory effects result from blocking these receptors

116
Q

Nitric acid (NO)

A

activates guanylyl cyclase (enzyme that makes the 2nd messenger cyclic GMP; participates in a variety of processes in the brain, including the formation of new memories by increasing the strength of certain synapses; neurotransmitter binding to the postsynaptic receptors indirectly activates ___ ___ synthase, the enzyme that makes ___ ___; acts as a retrograde messenger that sends a signal to increase synaptic strength

117
Q

Carbon monoxide (CO)

A

activates guanylyl cyclase (enzyme that makes the 2nd messenger cyclic GMP; mode of action similar to NO

118
Q

Hydrogen sulfide (H2S)

A

most recently discovered gasotransmitter; appears to act directly on ion channels and other proteins to alter their function

119
Q

Endocannabinoids

A

natural neurotransmitters made by the brain; act at the same receptors as THC (active ingredient in marijuana); their receptors (cannabinoid receptors) are the most common G protein-linked receptors in the brain

120
Q

Neuromodulator

A

term used to describe a chemical messenger released by a neuron that does not directly cause EPSPs or IPSPs but instead affects the strength of synaptic transmission

121
Q

Channel-linked receptors

A

ionotropic receptors; ligand-gated ion channels that mediate direct neurotransmitter action; composed of several protein subunits in a rosette around a central pore; as the ligand binds to 1+ receptor subunits, the proteins change shape; this event opens the central channel and allows ions to pass; as a result the membrane potential of the target cell changes; always located precisely opposite sides of neurotransmitter release

122
Q

G protein-linked receptors

A

activity mediated by these is indirect, complex, slow, and often prolonged; receptors in this class are transmembrane protein complexes - include muscarinic ACh receptors and those that bind the biogenic amines and neuropeptides

123
Q

Second messengers

A

cyclic AMP, cyclic GMP, diaclglycerol, or Ca2; act as go-betweens to regulate (open/close) ion channels or activate kinase enzymes that initiate a cascade of enzymatic reactions in the target cells

124
Q

Neural integration

A

neuronal pools and their patterns of communicating with other parts of the nervous system

125
Q

Neuronal pools

A

functional groups of neurons that integrate incoming information received from receptors or different __ ___ and then forward the proceeded info to other destinations

126
Q

Circuits

A

patterns of synaptic connections in neuronal pools; determine the pool’s functional capabilities

127
Q

Serial processing

A

the whole system works in a predictable all-or-nothing manner

128
Q

Reflexes

A

rapid, automatic responses to stimuli, in which a particular stimulus always causes the same response

129
Q

Reflex arcs

A

reflexes occur over neural pathways called this that have 5 essential components - receptor, sensory neuron, CNS integration center, motor neuron, and effector

130
Q

Parallel processing

A

inputs are segregated into many pathways and different parts of the neural circuitry deal simultaneously with the information delivered by each pathway

131
Q

Neuroblasts

A

potential neurons

132
Q

Growth cone

A

the growing tip of an axon; a prickly fanlike structure that gives the axon the ability to interact with its environment

Pre-Pharm (182 decks)

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