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Biology 235 > Chapter 12 > Flashcards

Chapter 12 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

brain

A

part of the CNS that is located in the skull

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2
Q

cranial nerves

A

nerves that emerge from the brain and spinal cord (12 pairs)

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3
Q

nerve

A

bundle of hundreds to thousands of axons plus associated connective tissue and blood vessels that lies outside the brain and spinal cord

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4
Q

spinal cord

A

part of the CNS; connected to the brain; contains 100 million neurons

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5
Q

spinal nerves

A

nerves that emerge from the spinal cord (31 pairs)

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6
Q

ganglia

A

small masses of nerves tissue (consisting primarily of neutron cell bodies) that are located outside the brain and spinal cord

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7
Q

enteric plexus

A

extensive networks of neutrons located in the walls of organs of the GI tract; help regulate the digestive system

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8
Q

sensory receptor

A

a structure of the nervous system that monitors change in the external or internal environment (i.e. touch receptors in the skin)

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9
Q

sensory function of nervous system

A

sensory receptors detect internal stimuli (i.e. increase in BP) or external stimuli (i.e. something touching your arm)

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10
Q

integrative function of nervous system

A

nervous system processes sensory info by analyzing it and making decisions for appropriate responses

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11
Q

motor function of nervous system

A

once sensory info is integrated, the nervous system may elicit an appropriate motor response by activating effectors (muscles and glands) through cranial and spinal nerves. Stimulation of the effectors causes muscles to contract and glands to secrete

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12
Q

Effector

A

muscles and glands

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13
Q

electrical excitability

A

the ability to respond to a stimulus and covert it into an action potential

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14
Q

action potential/ nerve impulse

A

electrical signal that propagates along the surface of the membrane of a neuron

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15
Q

neuron

A

nerve cell

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16
Q

cell body (perikaryon or soma) of a neuron

A

contains a nucleus surrounded by cytoplasm that includes typical cellular organelles i.e. lysosomes, mitochondria and and Golgi Complex

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17
Q

Nissl bodies

A

prominent clusters of rough endoplasmic reticulum within the cell body; used to replace cellular components, and to regenerated damaged axons in the PNS

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18
Q

dendrite

A

receiving/input portion of a neuron; contain receptor sites for binding chemical messengers from other cells

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19
Q

axon

A

propagates nerve impulses toward another neuron, muscle fibre or gland cell; long, thin, cylindrical projection; contains mitochondria, microtubules and neurofibrils but NO rough ER so protein synthesis does NOT occur here

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20
Q

axon hillock

A

the cone shaped elevation where the axon meets the cell body

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21
Q

initial segment

A

the part of the axon closes to the axon hillock

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22
Q

trigger zone

A

junction of the axon hillock and the initial segment; most nerve impulses arise here

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23
Q

axon collateral

A

side branches of the axon

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24
Q

axon terminal

A

fine processes that the axon and its collaterals end by dividing into

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25
Q

synapse

A

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

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26
Q

synaptic end bulb

A

bulb shaped structures that the tips of some axon terminals swell into

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27
Q

synaptic vesicle

A

tiny membrane enclosed sacs that store neurotransmitters

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28
Q

neurotransmitter

A

chemical that excites or inhibits another neuron

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29
Q

structural diversity of neurons

A

neurons display diversity in size and shape

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30
Q

multipolar neuron

A

have several dendrites and one axon; i.e. brain and spinal cord and motor neurons

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31
Q

bipolar neuron

A

one main dendrite and one axon i.e. retina of eye, inner ear and olfactory parts of the brain

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32
Q

unipolar neuron

A

have dendrites and one axon that are fused together to form a continuous process that emerges from the cell body

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33
Q

neuroglia or glia

A

don’t propagate action potentials but they can divide and multiply in the mature nervous system

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34
Q

astrocytes

A

star shaped neuroglia, largest and most numerous neuroglia

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35
Q

oligodendrocytes

A

small neuroglia, responsible for forming and maintaining the myelin sheath around CNS axons

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36
Q

myelin sheath

A

multilayered lipid and protein covering around some axons that insulates them and increases the speed of nerve impulse conduction

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37
Q

myelinated

A

axons that are covered in myelin sheath

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38
Q

microglia

A

neuroglia cells that function as phagocytes to remove cellular debris formed during normal development of nervous system

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39
Q

ependymal cells

A

cuboidal to columnar cells arranged in a single layer that possess microvilli and cilia; line ventricles of the brain and central canal of the spinal cord; produce and assist the circulation of cerebrospinal fluid

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40
Q

Schwann cells

A

cells that encircle PNS axons; each cell myelinated a single axon

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41
Q

satellite cells

A

flat cells that surround the cell bodies of neurons of PNS ganglia; provide structural support and regulates exchanges of materials between neuronal cell bodies and interstitial fluid

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42
Q

nodes of ranvier

A

gaps in the myelin sheath at intervals along the axon

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43
Q

white matter

A

composed primarily of myelinated axons (myelin is white)

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44
Q

gray matter

A

contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia

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45
Q

nucleus

A

a cluster of neuronal cell bodies located in the CNS

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46
Q

Central Nervous System (CNS)

A

consists of the brain and spinal cord

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47
Q

brain and spinal cord connection

A

spinal cord is connected to the brain through the foramen magnum of the occipital bone and is encircled by the bones of the vertebral column

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48
Q

Peripheral Nervous System (PNS)

A

consists of all nervous tissue outside the CNS. Components include nerves, ganglia, enteric plexuses and sensory receptors

49
Q

somatic nervous system (SNS)

A

Division of PNS that consists of sensory neurons that convey info from somatic receptors in the head, body wall, and limbs and from receptors for the special senses of vision, hearing, taste and smell to the CNS and motor neurons that conduct impulses from the CNS to the skeletal muscles only. VOLUNTARY ACTIONS

50
Q

Autonomic Nervous System (ANS)

A

division of PNS; consists of sensory neurons that convey info from autonomic sensory receptors (located mostly in visceral organs i.e. stomach and lungs) to the CNS and motor neurons that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle and glands; INVOLUNTARY ACTIONS

51
Q

sympathetic division

A

division of ANS; fight or flight responses (support exercise and emergency actions)

52
Q

parasympathetic division

A

division of ANS; rest and digest activities

53
Q

Enteric Nervous System (ENS)

A

operation of the brain and gut; sensory neurons of ENS monitor chemical changes within the GI tract as well as the stretching of the walls; enteric motor neurons govern contraction of GI tract smooth muscle to propel food through the GI tract, secretion of the GI tract organs (i.e. acid from the stomach) and activity of GI tract endocrine cells (secrete hormones)

54
Q

electrochemical gradient

A

a concentration (chemical) difference plus an electrical difference

55
Q

leak channel

A

gates randomly alternate between open and closed positions

56
Q

gated channel

A

ion channels open and close due to the presence of gates; the gate is part of the channel protein that can seal the channel pore shut or move aside to open the pore

57
Q

ligand-gated channel

A

opens and closes in the response to the binding of a ligand (chemical) stimulus- including neurotransmitters, hormones and particular ions

58
Q

mechanically gated channel

A

opens or closes in response to mechanical stimulation in the form of vibration (i.e. sound waves), touch, pressure, or tissue stretching; the force distorts the channel from its resting position, opening the gate

59
Q

voltage gated channel

A

opens in response to a change in membrane potential (voltage); participate in generation and conduction of action potentials in the axons of all types of neurons

60
Q

polarized

A

a cell that exhibits a membrane potential

61
Q

graded potential

A

a small deviation from the membrane potential that makes the membrane either more polarized (inside more negative) or less polarized (inside less negative)

62
Q

hyperpolarizing graded potential

A

when the response makes the membrane more polarized (inside more negative)

63
Q

depolarizing graded potential

A

when the response makes the membrane less polarized (less negative)

64
Q

decremental conduction

A

the mode of travel by which graded potentials die out as the spread along the membrane

65
Q

summation

A

the process by which graded potentials add together (i.e. two depolarizing potentials = a larger depolarizing graded potential)

66
Q

action potential (AP)

A

a sequence of rapidly occurring events that decrease and reverse the membrane potential and then eventually restore it to the resting state

67
Q

threshold

A

an action potential occurs in the membrane of the axon of a neutron when depolarization reaches a certain potential (around -55mV for most neurons)

68
Q

all or none principle

A

an action potential either occurs completely or it does not occur at all

69
Q

depolarizing phase

A

when membrane potentials of axon reaches threshold, Na+ channel activation gates open. As Na+ ions move through these channels into neuron, buildup of positive charges form along inside surface of membrane and membrane becomes depolarized

70
Q

repolarizing phase

A

Na+ channel inactivation gates close and K+ channels open. Membrane starts to become depolarized as some K+ ions leave the neuron and few negative charges begin to build up along inside surface of membrane. K+ outflow continues. As more K+ ions leave neuron, more negative charges build up along inside surface of membrane. K+ outflow eventually restores resting membrane potential. Na+ channel inactivation gates open. Return to resting state occurs when K+ gates close

71
Q

after hyper polarizing phase

A

while K+ channels are open, outflow of K+ may be large enough to cause this phase; the voltage gated K+ channels remain open and the membrane potential becomes even more negative (around -90mV)

72
Q

refractory period

A

the period of time after an action potential begins during which an excitable cell cannot generate another action potential in response to a normal threshold stimulus

73
Q

absolute refractory period

A

period of time after an action potential begins where even a very strong stimulus cannot initiate a second action potential

74
Q

relative refractory period

A

the period of time during which a second action potential can be initiated , but only by a larger than normal stimulus

75
Q

nerve impulse propagation

A

an action potential keeps it’s strength as it spreads along the membrane

76
Q

continuous conduction

A

step by step depolarization and depolarization of each adjacent segment of the plasma membrane; occurs in unmyelinated axons and muscle fibres

77
Q

saltatory conduction

A

special mode of action potential propagation that occurs along myelinated axons; occurs because of uneven distribution of voltage cared channels

78
Q

effect of axon diameter on propagation speed

A

larger diameter axons propagate action potentials faster than smaller ones due to larger surface area

79
Q

encoding of stimulus intensity

A

frequency of action potentials and number of sensory neurons recruited (activated) by the stimulus

80
Q

comparison of electrical signals produced by excitable cells (action potential vs. graded potential)

A

action potential permits communication over long distances; graded potential only short distances since they aren’t propagated. (table on page 472)

81
Q

presynaptic neuron

A

a nerve cell that caries a nerve impulse towards a synapse

82
Q

postsynaptic neuron

A

a nerve cell that carries a nerve impulse away from a synapse or an effector cell that responds to the impulse at the synapse

83
Q

electrical synapse

A

action potentials (impulses) conduct directly between the plasma membranes of adjacent neurons

84
Q

gap junction

A

action potentials conduct directly between the plasma membranes of adjacent neurons through a gap junction

85
Q

chemical synapse

A

action potentials conduct over the synaptic cleft using neurotransmitters that diffuse across the synaptic cleft

86
Q

synaptic cleft

A

a space between the presynaptic and postsynaptic neurons; filled with interstitial fluid

87
Q

postsynaptic potential

A

a type of graded potential produced when the postsynaptic neuron receives the chemical signal

88
Q

Excitatory Postsynaptic Potential (EPSP)

A

a depolarizing postsynaptic potential

89
Q

Inhibitory Postsynaptic Potential (IPSP)

A

a hyperpolarizing postsynaptic potential

90
Q

Neurotransmitters are removed from the synaptic cleft in 3 ways:

A
  1. Diffusion: diffuse away from the synaptic cleft
  2. Enzymatic Degradation: inactivated by enzyme
  3. Uptake by cells: actively transported back into the neuron that released them (reuptake)
91
Q

spatial summation

A

summation of postsynaptic potentials in response to stimuli that occur at different locations

92
Q

temporal summation

A

summation of postsynaptic potentials in response to stimuli that occur at the same location in the membrane of the postsynaptic cell but at different times

93
Q

summation of EPSP

A

if the total excitatory effects are greater than the total inhibitory effects but less than the threshold level of stimulation= an EPSP that does not reach threshold

94
Q

summation of nerve impulses

A

if the total excitatory effects are greater than the total inhibitory effects and threshold is reached, one or more nerve impulses will be triggered (will continue as long as EPSP is at or above threshold level)

95
Q

summation of IPSP

A

if the total inhibitory effects are greater than the excitatory effects, the membrane hyperpolarizes (IPSP) = the inhibition of the postsynaptic neuron and an inability to generate a nerve impulse

96
Q

acetylcholine

A

small molecule neurotransmitter; excitatory where binding to receptors opens cation channels; inhibitory when binding opens K+ channels; CNS and PNS

97
Q

amino acids

A

neurotransmitters in the CNS; i.e. Glutamate, Aspartate,

98
Q

glutamate

A

small molecule neurotransmitter; excitatory

99
Q

glycine

A

small molecule neurotransmitter; inhibitory

100
Q

biogenic amines

A

modified amino acid and decarboxylated (carboxyl group removed); norepinephrine, epinephrine, dopamine and serotonin

101
Q

norepinephrine

A

biogenic amine; plays role in arousal (awakening), dreaming and regulating mood

102
Q

epinephrine

A

aka adrenaline; biogenic amine; plays role in arousal; smaller number of neurons in the brain use epinephrine over norepinephrine

103
Q

dopamine

A

biogenic amine; emotional responses, addictive behaviours, pleasurable experiences

104
Q

catecholamines

A

chemical classification of norepinephrine, dopamine and epinephrine; include an amino group (NH2) and a catechol ring composed of 6 C and two adjacent hydroxyl (OH) groups

105
Q

serotonin

A

small molecule neurotransmitter; biogenic amine; involved in sensory perception, temperature regulation, control of mood, appetite and induction of sleep

106
Q

Nitric oxide

A

small molecule neurotransmitter; excitatory neurotransmitter in the brain, spinal cord and adrenal glands and nerves to the penis; widespread effects throughout the body

107
Q

neuropeptides

A

neurotransmitters consisting of 3-40 amino acids linked by peptide bonds; numerous and widespread in CNS and PNS

108
Q

neural circuit

A

networks of neurons in the CNS that process specific types of info

109
Q

simple series

A

presynaptic neuron stimulates a single postsynaptic neuron, the second neuron stimulates another and so on

110
Q

diverging circuit

A

the nerve impulses from a single presynaptic neuron causes the stimulation of increasing numbers of cells along the circuit; amplifies the signal

111
Q

converging circuit

A

the postsynaptic neuron receives nerve impulses from several different sources

112
Q

reverberating circuit

A

the stimulation of the presynaptic cell causes the postsynaptic cell to transmit a series of nerve impulses; the 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

113
Q

parallel after-discharge circuit

A

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

114
Q

plasticity

A

the capability to change based on experience; changes include sprouting of new dendrites, synthesis of new proteins and changes in synaptic contacts with other neurons

115
Q

neurogenesis

A

the birth of new neurons from undifferentiated stem cells

116
Q

damage and repair in the PNS

A

meylinated axons in the peripheral nervous system may be repaired if the cell body remains intact and if Schwann cells remain active

117
Q

multiple sclerosis (MS)

A

disease causes a progressive destruction of myelin sheaths surrounding neurons of the CNS

118
Q

epilepsy

A

short, recurrent attacks of motor, sensory or psychological malfunctions

Biology 235 (17 decks)

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