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Anatomy and Physiology 210 > Chapter 12 Nervous Tissue > Flashcards

Chapter 12 Nervous Tissue Flashcards

1
Q

Central nervous system (CNS)

A

consists of the brain and the spinal cord

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2
Q

General functions of the nervous system

A

1- collect information
2-processes and evaluates information
3-initiate response to information

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3
Q

Peripheral nervous system (PNS)

A

consists of the nerves and ganglia

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4
Q

Types of nerves

A

Structural classification:
-caranial nerves
-spinal nerves
Functional classification:
-sensory nerves
-motor nerves
-mixed nerves (both sensory and motor)

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5
Q

Sensory nervous system

A

detects stimuli and transmits information from receptors to the CNS

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6
Q

Motor nervous system

A

initiates and transmits information from the CNS to effectors

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7
Q

The 2 components of the sensory nervous system

A

somatic sensory and visceral sensory

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8
Q

Somatic sensory

A

sensory input from the receptors of the five senses and proprioceptors; senses we consciously perceive

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9
Q

Visceral sensory

A

sensory input from receptors of internal organs and blood vessels; senses we are unaware of

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10
Q

The 2 components of the motor nervous system

A

somatic motor and autonomic motor

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11
Q

Somatic motor

A

motor output to skeletal muscle; voluntary

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12
Q

Autonomic motor

A

motor output to cardiac muscle, smooth muscle, and glands; involuntary

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13
Q

What is a nerve composed of?

A

cable like bundle of axons, connective tissue layers, and blood vessels, and it is a component of the PNS

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14
Q

Epineurium

A

a thick layer of dense irregular connective tissue that encloses the nerve

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15
Q

Perineurium

A

a layer of dense irregular connective tissue that wraps each fascicle

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16
Q

Endoneurium

A

a delicate layer of areolar connective tissue that surrounds each axon

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17
Q

Know the structure of a nerve and ganglion

A
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18
Q

Are nerves vascularized?

A

yes

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18
Q

Neurotransmitters

A

are molecules stored in vesicles and when released, bind to an excitable cell to cause either an excitatory or inhibitory effect on these target cells

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19
Q

Know the structures in a typical neuron

A
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19
Q

General characteristics of a neuron

A
  • excitability
  • conductivity
  • secretion
  • extreme longevity
  • amitotic
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20
Q

Ganglion

A

a cluster of neuron cell bodies within the PNS

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21
Q

Anterograde transport

A

the movement of materials from the cell body toward synaptic knobs

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22
Q

Retrograde transport

A

the movement of materials from synaptic knobs toward the cell body

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23
Q

Fast axonal transport

A

occurs at approximately 400 millimeters per day; involves movement along microtubules towards either direction (anterograde or retrograde)

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24
Q

Slow axonal transport

A

occurs at approximately 0.1 to 3 millimeters per day; results from the flow of axoplasm; only allows movement to the synaptic knob (anterograde)

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25
Q

Multipolar neurons

A

have many dendrites and a single axon that extends from the cell body; these are the most common types of neurons in the human body

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26
Q

Bipolar neuron

A

have two processes that extend from the cell body- one dendrite and one axon; the location of these neurons is relatively limited to humans

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27
Q

Unipolar neurons

A

have a single, short neuron process that emerges from the cell body and branches like a T

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28
Q

Anaxonic neurons

A

have only dendrites and no axons; they produce graded potentials, but not action potentials

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29
Q

Sensory neurons

A

responsible for conducting sensory input from both somatic sensory and visceral sensory receptors TOWARD the CNS; most are unipolar but some somatic sensory neurons are bipolar

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30
Q

Motor neurons

A

conducting motor output AWAY FROM the CNS to both somatic effectors and autonomic effectors; all motor neurons are multipolar

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31
Q

Interneurons

A

lie entirely within the CNS; receive, process, and store information and “decide” how the body responds to stimuli

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32
Q

Synapse

A

the specific location where a neuron is functionally connected to either another neuron or an effector

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33
Q

Chemical synapse

A

between two neurons; is composed of a presynaptic neuron and a postsynaptic neuron with a narrow fluid-filled gap

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34
Q

Presynaptic neuron

A

the signal producer

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35
Q

Postsynaptic neuron

A

the signal receiver

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36
Q

Synaptic cleft

A

an extremely narrow, fluid-filled gap between two neurons

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37
Q

Transmission

A

occurs between a presynaptic and postsynaptic neuron when neurotransmitter molecules stored in synaptic vesicles are released from the synaptic knob of a presynaptic neuron into the synaptic cleft

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38
Q

Synaptic delay

A

the time between the neurotransmitter release from the presynaptic cell, its diffusion across the synaptic cleft, and neurotransmitter binding to receptors in the postsynaptic neuron plasma membrane

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39
Q

Electrical synapse

A

composed of a presynaptic neuron and a postsynaptic neuron physically bound together

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40
Q

Glial cells

A

found both in the CNS and PNS; have mitotic ability; smaller than neurons; they do not transmit electrical signals, but they do assist neurons with their functions

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41
Q

4 types of glial cells found in the CNS

A

1- astrocytes
2- ependymal cells
3- microglia
4- oligodendrocytes

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42
Q

Astrocytes

A

exhibit a starlike shape due to projections from their surface; most abundant glial cells in the CNS

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43
Q

Astrocyte functions

A
  • help form the blood-brain barrier (BBB)
  • regulate interstitial fluid composition
  • form structural support
  • assist neuronal development
  • alter synaptic activity
  • occupy the space of dying neurons
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44
Q

The blood-brain barrier (BBB)

A

strictly controls the movement of substances from exiting the blood and entering the nervous tissue in the brain

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45
Q

Ependymal cells

A

ciliated simple cuboidal or simple columnar epithelial cells that line the internal cavities of the brain and the central canal of the spinal cord

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46
Q

Choroid plexus

A

helps produce cerebrospinal fluid, a clear liquid that bathes the external surfaces of the CNS and fills its internal cavities

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47
Q

Microglia

A

typically small cells that have slender branches extending from the main portion of the cell; they represent the smallest portion of CNS glial cells; classified as phagocytotic cells of the immune system

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48
Q

Oligodendrocytes

A

are large cells with a bulbous body and slender cytoplasmic extensions or processes; insulate axons within the CNS to form a myelin sheath through a process called myelination

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49
Q

2 types of glial cells in the PNS

A

1- satellite cells
2- neurolemmocytes

50
Q

Satellite cells

A

are flattened cells arranged around neuronal cell bodies in a ganglion; physically separating cell bodies from their surrounding interstitial fluid; they electrically insulate the cell body and regulate the continuous exchange of nutrients and waste products between neuron cell bodies and their environment

51
Q

Neurolemmocytes

A

elongated and flattened cells wrap around and insulate axons within the PNS to form a myelin sheath through myelination

52
Q

Myelination

A

the process by which part of an axon is wrapped with myelin

53
Q

Myelin

A

the insulating covering around the axon that consists of repeating concentric layers of plasma membrane of glial cells

54
Q

Neurilemma

A

the periphery of the neurolemmocyte contains the cytoplasm and nucleus

55
Q

Neurofibril nodes (nodes of Ranvier)

A

gaps in between the neurolemmocytes

56
Q

Unmyelinated axons

A

no myelin covers them; in the PNS are also associated with neurolemmocytes, which help to protect and support the axon

57
Q

Axon regeneration process

A
58
Q

Pumps

A

maintain specific concentration gradients by moving substances against a concentration gradient, a process that requires cellular energy

59
Q

Channels

A

provide the means for a substance to move with a concentration gradient

60
Q

Major types of channels

A
  • leak channels
  • chemically-gated channels
  • voltage-gated channels
61
Q

Leak channels

A

always open, allowing continuous diffusion of a specific type of ion from a region of high concentration to a region of low concentration

EXAMPLES:
- Na+ leak channels
- K+ leak channels

62
Q

Chemically gated channels

A

normally closed; they temporarily open in response to the binding of a neurotransmitter; when open, they allow a specific type of ion to diffuse across the plasma membrane

EXAMPLES:
- Chemically gated K+ channels
- Chemically gated Cl- channels

63
Q

Voltage-gated channels

A

normally closed, but they temporarily open in response to changes in electrical charge across the plasma membrane; when open, they allow a specific type of ion to diffuse across the membrane

EXAMPLES:
- Voltage-gated Na+ channels
- Voltage-gated K+ channels
- Voltage-gated Ca2+ channels

64
Q

Voltage-gated Na+ gates

A

1- activation gate
2- inactivation gate

65
Q

The 3 stages of voltage-gated Na+ channels

A

1- resting state
2- activation state
3- inactivation state

66
Q

Stages of voltage-gated Na+ channels

A
67
Q

Modality-gated channel

A

normally closed, but open in response to specific type of sensory stimulus

68
Q

Know the distribution of pumps and channels in the plasma membrane of a neuron

A
69
Q

Electrical energy

A

the movement of charged particles, and that all usable forms of energy are available to do work

70
Q

Voltage

A

amount of difference in electrical charge

71
Q

Current

A

movement of charged particles across plasma membrane through open channels

72
Q

Resistance

A

opposition to movement of charged particles

73
Q

Ohm’s Law

A

current= voltage/resistance

74
Q

Know neurons and Ohm’s law

A
75
Q

Neuron at rest

A
76
Q

Neurons at rest characteristics

A

-ion concentration gradients exist for K+, Na+, and Cl- across the plasma membrane along the entire neuron
- a Ca2+ concentration gradient exists at the synaptic knob
- gated channels are CLOSED
- there is an electrical charge difference across the plasma membrane

77
Q

Resting Membrane Potential (RMP)

A

the neuron is at rest, the membrane potential is at RMP; -70 mV

78
Q

Role of Na+/K+ pumps

A

push 3 Na+ out and pulls K+ in; maintains the concentration gradients for these ions

79
Q

Graded potentials

A

are relatively small, short-lived changes in the resting membrane potential that are caused by the movement of small amounts of ions across the plasma membrane

80
Q

Characteristics of graded potentials

A
  • established in the receptive segment by the opening of chemically gated channels
  • local currents associated with the graded potentials are short-lived because the flow or current of ions along the plasma membrane experiences resistance
  • they vary in both the degree of change and the direction of change of the RMP
81
Q

Know the events in each neuron segment

A
82
Q

Postsynaptic potentials

A

graded potentials that occur in postsynaptic neurons

83
Q

Excitatory postsynaptic potentials (EPSP)

A

postsynaptic potentials that result in the neuron becoming more positive

84
Q

Inhibitory postsynaptic potentials (IPSP)

A

postsynaptic potentials resulting in the neuron becoming more negative

85
Q

Generation of an EPSP

A
86
Q

Generation of an IPSP

A
87
Q

Summation

A

the changes in the membrane potential associated with these graded postsynaptic potentials are “added” in the initial segment to determine if an action potential is initiated

88
Q

Threshold membrane potential

A

the minimum voltage change

89
Q

Spatial summation

A

multiple locations on the cell’s receptive regions receive neurotransmitter simultaneously and generate postsynaptic potentials

90
Q

Temporal summation

A

a single presynaptic neuron repeatedly releases neurotransmitter and produces multiple EPSPs within a very short period of time

91
Q

All-or-none law

A

if threshold is reached, action potential generated and propagated down the axon without any loss in intensity; if threshold not reached, voltage-gated channels stay closed, no action potential

92
Q

Action potential

A

involves depolarization and repolarization

93
Q

Depolarization

A

gain of positive charge as Na+ enters through voltage gated Na+ channels

94
Q

Repolarization

A

return to negative potential as K+ exits through voltage gated K+ channels

95
Q

Nerve signal

A

propagation of of an action potential

96
Q

Generation of an Action Potential: Depolarization and its Activation

A
97
Q

Generation of an Action Potential: Repolarization and its Propagation

A
98
Q

Refractory period

A

period of time after start of action potential when it is impossible or difficult to fire another action potential

99
Q

Absolute refractory period

A

no stimulus can initiate another action potential

100
Q

Relative refractory period

A

another action potential is possible but the minimum stimulus strength is now greater; some K+ channels are still open and cell is slightly hyperpolarized and further from threshold

101
Q

Continuous conduction

A

occurs in unmyelinated axons and involves the sequential opening of voltage-gated Na+ channels and voltage-gated K+ channels located within the axon plasma membrane along the entire length of the axon

102
Q

Saltatory conduction

A

occurs in myelinated axons; action potential only occurs ate neurofibril nodes ; much faster than continuous conduction and myelinated cells use less ATP to maintain resting membrane potential

103
Q

Propagation of an action potential (continuous and saltatory conduction)

A
104
Q

Steps involved when a nerve signal reaches the transmissive segment

A
105
Q

Know the difference between a graded potential and an action potential

A

Shown on table 12.2

106
Q

Velocity of action potential propagation is influenced by what two factors

A

1- diameter of the axon
2- myelination of the axon

107
Q

Nerve fiber

A

an axon and its myelin sheath

108
Q

Neurotransmitters

A

small, organic molecules that are:
- synthesized by neurons and stored within vesicles in synaptic knobs
- released from the vesicles when action potential triggers calcium entry into the synaptic knob
- bind to a specific receptor in a target cell
- trigger a physiologic response in the target cell

109
Q

4 categories of neurotransmitters based on chemical structure

A

1- acetylcholine (ACh)
2- biogenic amines
3- amino acids
4- neuropeptides

110
Q

Acetylcholine

A

structure differs substantially from other transmitters

111
Q

Biogenic amines

A

an amino acid is slightly modified to synthesize the transmitter
Catecholamines (dopamine)- are made from tyrosine
Indoleamines (serotonin)- are made from histidine or tryptophan

112
Q

Amino acids

A

include common transmitters glutamate, glycine, GABA

113
Q

Neuropeptides

A

chains of amino acids including endorphins, substance P, enkephalin, somatostatin

114
Q

Neurotransmitters are also classified by function:

A

1) excitatory- transmitters cause EPSPs
2) inhibitory- transmitters cause IPSPs

115
Q

Neurotransmitters are also classified by action:

A

1) direct- transmitters bind to receptors that are chemically gated channels
2) indirect- transmitters bind to receptors that involve G-proteins and second messengers

116
Q

Acetylcholine release, removal from synaptic cleft, and action

A
117
Q

Acetylcholinesterase

A

an enzyme that resides in the synaptic cleft

118
Q

Neuromodulators

A

chemicals that alter responses of local neurons; modify neurotransmitters

119
Q

Facilitation

A

modulation that causes greater response in postsynaptic neurons; may increase the amount of neurotransmitter in cleft or number of postsynaptic receptors

120
Q

Inhibitation

A

modulation that causes weaker response; may decrease the amount of neurotransmitter in cleft or number of postsynaptic receptors

121
Q

Nitric oxide

A

might be a neurotransmitter or a modulator; a short-lived, nonpolar gas; made and released by postsynaptic neurons in the brain where it is believed to strengthen memory by affecting presynaptic cells; effects in the PNS include blood vessel dilation

122
Q

Endocannabinoids

A

influence same receptors; small, nonpolar molecules; made and released by postsynaptic neurons; have effects on presynaptic neurotransmitter release; influence memory and appetite

123
Q

Subthreshold

A

any change in voltage below the threshold value is not sufficient to open voltage-gated channels

Anatomy and Physiology 210 (13 decks)

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