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BIOL 235 - Section 2 > Chapter 12 - Nervous Tissue > Flashcards

Chapter 12 - Nervous Tissue Flashcards

1
Q

brain

A

Connected to spinal cord through foramen magnum of occipital bone

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2
Q

spinal cord

A

100mil neurons, encircled by bones of the vertebral column

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3
Q

peripheral nervous system

A

all nervous tissue outside the CNS

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4
Q

nerve

A

bundle of hundreds to thousands of axons plus associated connective tissue and blood vessels.

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5
Q

cranial nerves

A

12 pairs

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6
Q

spinal nerves

A

31 pairs

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7
Q

ganglion

A

small masses of nervous tissue, located outside of the brain and spina cord, consisting of neuron cell bodies.

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8
Q

enteric plexus

A

extensive networks of neurons within walls of organs of the GI tracts

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9
Q

sensory receptor

A

structure of the nervous system that monitors changes in external or internal environment

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10
Q

somatic nervous system

A

consists of sensory neurons CNS to receptors for special senses. & motor neurons that conduct impulses from CNS to skeletal muscles. voluntary.

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11
Q

autonomic nervous system

A

1) sensory neurons from autonomic sensory receptors, in visceral organs 2) motor neurons to smooth muscle, cardiac muscle, glands. involuntary.

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12
Q

sympathetic

A

exercise / emergency actions

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13
Q

parasympathetic

A

rest and digest activities

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14
Q

enteric nervous system

A

brain of the gut. secretions and activities of GI tract.

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15
Q

sensory functions

A

detect stimuli

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16
Q

integrative functions

A

processes sensory information

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17
Q

motor functions

A

activates effectors

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18
Q

effector

A

muscles and glands for contraction / secretion

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19
Q

electrical excitability

A

possessed by neurons, respond to stimulus and convert to action potential

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20
Q

action potentials

A

nerve impulse, electrical signal that propagates along the surface of the membrane of a neuron.

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21
Q

cell body

A

contains a nucleus surrounded by cytoplasm, includes typical cellular organelles.

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22
Q

nissl bodies

A

prominent clusters of rough ER

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23
Q

dendrites

A

the receiving or input portions of a neuron, bind chemical messengers from other cells.

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24
Q

axon

A

propogates nerve impulses toward another neuron.

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25
Q

axon hillock

A

cone-shaped elevation joining the cell body to axon

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26
Q

initial segment

A

part of axon closest to the hillock

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27
Q

trigger zone

A

where nerve impulses arise, junction of hillock and initial segment

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28
Q

axon collateral

A

side branches

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29
Q

axon terminal

A

ending, fine processes

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30
Q

synpase

A

site of communication between two neurons or between a neuron and an effector

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31
Q

synaptic end bulb

A

tips of axon terminals swell into bulb-shaped structures

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32
Q

varicosities

A

string of swollen bumps at tips of axon terminals

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33
Q

synaptic vesicle

A

tiny membrane-enclosed sacs, storing neurotransmitters

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34
Q

neurotransmitter

A

Molecule released from a synaptic vesicle that excites or inhibits another neuron, muscle fiber or gland cell.

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35
Q

fast axonal transport

A

Carries materials from cell body to axon terminals and back, 200-400mm per day, uses proteins that function as motor to move materials along surfaces of microtubules

(forward) direction moves organelles and synaptic vesicles from the cell body to the axon terminals.
(backward) direction moves membrane vesicles and other cellular materials from the axon terminals to the cell body to be degraded or recycled.

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36
Q

slow axonal transport

A

.1-5mm per day, conveys axoplasm in one direction from body to terminal.

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37
Q

structural classification

A

according to the number of processes extending from the cell body

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38
Q

multipolar neuron

A

several dendrites, one axon, most neurons in brain and spinal cord are this type

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39
Q

bipolar neuron

A

one main dendrite, one axon. retina, inner ear, olfactory area.

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40
Q

unipolar neuron

A

dendrites and one axon that are fused together, forming continuous process that emerges from the cell body.

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41
Q

sensory functional classification

A

afferent, either contain sensory receptors at their dendrites, or are located just after sensory receptors. AP conveyed into CNS. generally unipolar.

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42
Q

motor functional classification

A

efferent, AP away from CNS to effectors, periphery, multipolar.

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43
Q

interneurons

A

association neurons, within CNS between sensory and motor neurons. Process and elicit motor response.

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44
Q

astrocytes

A

largest and most numerous neuroglia. Protoplasmic astrocytes in gray. Fibrous astrocytes in white.
Contain microfilaments for strength. Isolate neurons of CNS from harmful substance
Secrete chemicals in embryo.
Maintain appropriate chemical environment for generation of nerve impulses.
Learning and memory by influencing formation of neural synapses.

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45
Q

oligodendrocytes

A

forming and maintaining the myelin sheath around CNS axons.

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46
Q

myelin sheath

A

multilayered lipid and protein covering to insulate axons and increase speed of impulse conduction.

47
Q

microglia

A

Small, slender, function as phagocytes.

48
Q

ependymal cells

A

produce, monitor, assist in circulation of cerebrospinal fluid. form barrier.

49
Q

schwann cells

A

encircle PNS axons, form myelin sheath 1:1.

50
Q

satellite cells

A

surround the cell bodies of neurons of PNS ganglia. regulate exchanges, between cell bodies and it fluid, provide support.

51
Q

neurolemma

A

outer nucleated cytoplasmic layer of the schwann cell, encloses the myelin sheath. only around axons in PNS.

52
Q

nodes of ranvier

A

gaps in myelin sheath.

53
Q

clusters of neuronal cell bodies - nucleus

A

neuronal cell bodies in PNS = ganglion. Neuronal cell bodies in CNS = nucleus

54
Q

bundles of axons - tracts

A

bundle of axons located in PNS. tract= bundle of axons in CNS.

55
Q

white matter

A

composed of myelinated axons.

56
Q

gray matter

A

contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia. Nissil bodies make it gray, little or no myelin.

57
Q

graded/action/muscle/nerve potentials

A

electrical signals Short - long - muscle - neuron

58
Q

membrane potential

A

electrical potential difference

59
Q

resting membrane potential

A

voltage in excitable cells.

60
Q

leak channel

A

randomly alternate. generally plasma membranes have more K+ leak channels.

61
Q

ligand-gated ion channel

A

opens and closes in response to the binding of a ligand (chemical) stimulus.

62
Q

voltage-gated ion channel

A

opens in response to a change in membrane potential (voltage)

63
Q

resting membrane potential

A

small buildup of negative ions in the cytosol along the inside of the membrane, buildup of positive ions in the ECF. exhibits membrane potential = polarized.

64
Q

factors that contribute to the resting membrane potential

A

1) unequal distribution of ions in the ECF and cytosol
2) Inability of most anions to leave the cell
3) Electrogenic nature of the Na+ - K+ ATPases

65
Q

graded potential

A

small deviation from the resting membrane potential, makes membrane more or less polarized. A graded potential occurs when a stimulus causes mechanically-gated or ligand-gated channels to open or close in an excitable cell’s plasma membrane

66
Q

decremental conduction

A

localized current gradually dies out as the charges are lost across the membrane through leak channels.

67
Q

summation

A

becomes stronger and last longer by summating with other graded potentials.

68
Q

action potential / impulse

A

sequence of rapidly occurring events that decrease and reverse the membrane potential, restoring to resting state.

69
Q

threshold

A

depolarization reaches threshold to generate action potential.

70
Q

subthreshold stimulus

A

weak depolarization that cannot bring the membrane potential to threshold.

71
Q

threshold stimulus

A

stimulus just strong enough to depolarize the membrane to thrshold.

72
Q

suprathreshold stimulus

A

Above threshold, Several action potentials will form.

73
Q

depolarizing phase

A

membrane of axon depolarizes to threshold, sodium channels open rapidly.

74
Q

repolarizing phase

A

Inactivation gates close. Because the voltage-gated K􏰑 channels open more slowly, their opening occurs at about the same time the voltage-gated Na􏰑 channels are closing. Sodium inflow slows, potassium outflow accelerates.

75
Q

after hyperpolarizing phase

A

alternate between closed (resting) and open (activated) states.

76
Q

refractory period

A

an excitable cell cannot generate another action potential in response to a normal threshold stimulus

77
Q

absolute refractory period

A

even a very strong stimulus cannot initiate a second action potential. This period coincides with the period of Na+ channel activation and inactivation

78
Q

relative refractory period

A

a second action potential can be initiated, but only by a larger than normal stimulus. It coincides with the period when the voltage-gated K􏰑 channels are still open after inac- tivated Na􏰑 channels have returned to their resting state

79
Q

nerve impulse propagation

A

positive feedback, an action potential keeps its strength as it spreads along the membrane

80
Q

continuous conduction

A

step-by- step depolarization and repolarization of each adjacent segment of the plasma membrane. ions flow through their voltage-gated channels in each adjacent segment of the membrane. Continuous conduction occurs in unmyelinated axons and in muscle fibers.

81
Q

saltatory conduction

A

special mode of action potential propagation that occurs along myelinated axons, occurs because of the uneven distribution of voltage-gated channels.

82
Q

factors that affect the speed of propagation

A

1) amount of myelination.
2) axon diameter
3) temperature

83
Q

acodendritic

A

axon to dendrite

84
Q

axoaxonic

A

axon to cell body

85
Q

electrical synapse

A

action potentials (impulses) conduct directly between the plasma membranes of adjacent neurons through structures called gap junctions.

86
Q

advantages of electrical synapses

A

faster communication and synchronization.

87
Q

synaptic cleft

A

space filled with IT fluid separating plasma membranes of pre and post synaptic neurons in a chemical synapse.

88
Q

postsynaptic potential

A

Nerve impulses cannot conduct across the synaptic cleft, so the pre-syn-neur releases a neurotransmitted that diffuses through the fluid and binds to receptors, post-syn-neur receives and produces post-syn potential.

89
Q

excitatory postsynaptic potential (EPSP)

A

neurotransmitter causes depolarization of the postsynaptic membrane is excitatory because it brings the membrane closer to the threshold.

90
Q

inhibitory postsynaptic potential (IPSP)

A

neurotransmitter causes hyperpolarization of the postsynaptic membrane is inhibitory.

91
Q

neurotransmitter receptors

A

in plasma membrane of a postsynaptic cell.

92
Q

removal of neurotransmitter

A
  1. diffusion. 2. enzymatic degradation. 3. update by cells
93
Q

spatial summation

A

is summation of post- synaptic potentials in response to stimuli that occur at different locations in the membrane of a postsynaptic cell at the same. time.

94
Q

temporal summation

A

sum- mation of postsynaptic potentials in response to stimuli that occur at the same location in the membrane of the postsynaptic cell but at different times.

95
Q

neurosecretory cells

A

Within the brain, certain neurons, called neurosecretory cells, also secrete hormones

96
Q

neurotransmitters

A

The small-molecule neurotransmitters include acetylcholine, amino acids, biogenic amines, ATP and other purines, nitric ox- ide, and carbon monoxide.

97
Q

acetylcholine

A

best-studied neurotransmitter, released by many PNS neurons and by some CNS neurons. ACh is an excitatory neurotransmitter at some syn- apses, such as the neuromuscular junction, where the binding of ACh to ionotropic receptors opens cation channels. It is also an inhibitory neurotransmitter at other syn- apses, where it binds to metabotropic receptors coupled to G pro- teins that open K􏰑 channels

98
Q

glutamate

A

neurotransmitter in CNS, powerful excitation. bind- ing of the neurotransmitter to ionotropic receptors opens cation channels. The consequent inflow of cations (mainly Na􏰑 ions) produces an EPSP. Inactivation of glutamate occurs via reuptake. Glutamate transporters actively transport glutamate back into the synaptic end bulbs and neighboring neuroglia.

99
Q

gamma-aminobutyric acid & glycine

A

inhibitory transmitter in CNS. At many synapses, the binding of GABA to ionotropic receptors opens Cl– channels

100
Q

biogenic amines

A

Certain amino acids are modified and decarboxylated (carboxyl group removed) to produce biogenic amines. most bind to metabotropic receptors

101
Q

norepinephrine & epinephrine.

A

Awakening from deep sleep, dreaming, regulating mood. Both epinephrine and norepinephrine also serve as hormones. Cells of the adrenal medulla, the inner portion of the adrenal gland, release them into the blood.

102
Q

dopamine

A

are active during emotional responses, addictive behaviors, and pleasurable experiences. In addition, dopamine-releasing neurons help regulate skeletal muscle tone and some aspects of movement due to contraction of skeletal muscles.

103
Q

seratonin

A

involved in sensory perception, temperature regulation, control of mood, appetite, and the induction of sleep.

104
Q

nitric oxide

A

excitatory neuro- transmitter secreted in the brain, spinal cord, adrenal glands, and nerves to the penis and has widespread effects throughout the body.

105
Q

neuropeptides

A

bind to metabotropic receptors and have excitatory or inhibitory actions, depending on the type of metabotropic receptor at the synapse. Neuropeptides are formed in the neuron cell body, packaged into vesicles, and transported to axon terminals. Besides their role as neurotransmitters, many neuropeptides serve as hormones that reg- ulate physiological responses elsewhere in the body.

106
Q

neural circuits

A

The CNS contains billions of neurons organized into complicated networks called neural circuits, functional groups of neurons that process specific types of information.

107
Q

simple series

A

a presynaptic neuron stimulates a single postsynaptic neuron. The second neuron then stimulates another, and so on.

108
Q

diverging circuit

A

the nerve impulse from a single presynaptic neuron causes the stimulation of increasing numbers of cells along the circuit

109
Q

converging circuit

A

the postsynaptic neuron receives nerve impulses from several different sources.

110
Q

reverberating circuit

A

incoming impulse stimulates the first neuron, which stimulates the second, which stimulates the third, and so on. Branches from later neurons synapse with earlier ones. This arrangement sends impulses back through the circuit again and again.

111
Q

parallel after discharge circuit

A

In this circuit, a single presynaptic cell stimulates a group of neurons, each of which synapses with a common postsynaptic cell. A differing number of synapses between the first and last neurons imposes varying synaptic delays, so that the last neuron exhibits multiple EPSPs or IPSPs. If the input is excitatory, the postsynaptic neuron then can send out a stream of impulses in quick succession.

112
Q

neurogenesis

A

the birth of new neurons from undifferentiated stem cells

113
Q

plasticity

A

the capability to change based on experience. At the level of individual neurons, the changes that can occur include the sprouting of new dendrites, synthesis of new proteins, and changes in synaptic contacts with other neurons.

BIOL 235 - Section 2 (8 decks)

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