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OBMP Exam 3 > Neurophysiology of Nerve Conduction > Flashcards

Neurophysiology of Nerve Conduction Flashcards

1
Q

The functional/structural unit of the nervous system is a

A

neuron

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2
Q

Depending on the structures and functions, neurons take

A

different forms and classifications

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3
Q

Cell body (soma)

A

keeps the cell running

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4
Q

Dendrite

A

receives info from another neuron via nerve terminal and send impulse to cell body

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5
Q

Axon

A

sends impulses away from cell body

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6
Q

Nerve and muscle are _____ tissues but the properties of nerves also include _______.

A

excitable, conductivity

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7
Q

_____ can initiate action potentials and conduct/transmit impulses/signals

A

nerves

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8
Q

Cell membrane is composed mainly of a

A

lipid bilayer of phospholipids

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9
Q

______ are found in the lipid bilayer that have different functions that protrude through

A

protein molecules

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10
Q

______ moieties are also attached to the protein molecules. (glycoprotein)

A

carbohydrate

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11
Q

There are _____ differences between the EC & IC fluids

A

concentration

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12
Q

The cell membrane has _____

A

selective permeability

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13
Q

Ionic charge between the 2 sides create an _________

A

electrical potential difference

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14
Q

The _____ of the cell is more _______ during resting electrical membrane potential

A

outside, more positive

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15
Q

The diffusion of Na and K ions, and the pumping function of the Na/K ATPase largely contribute to

A

Resting membrane potential

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16
Q

Nerves are also able to

A

self propagate

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17
Q

__ can be used for direct measurement of the membrane potential

A

Microelectrode

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18
Q

The _____ in the cell membrane serve as components of the transport process for molecules and ions across the cell membrane.

A

protein molecules

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19
Q

provide watery pathways

A

channel/pore proteins

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20
Q

bind specific substances to be transported

A

carrier proteins

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21
Q

Can cross cell membrane without transporters or ion channels by simple diffusion

A

lipid soluble substances

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22
Q

Substances can leave and enter cells using

A

simple diffusion, facilitated diffusion, active transport

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23
Q

Membrane conductance refers to # of

A

channels that are open in a membrane

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24
Q

The rate at which ions move across a membrane depends on

A

1) # of open channels and 2) net force

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25
Q

Channels are divided into 3 groups

A

1) ungated channels
2) voltage-gated channels
3) ligand-gated channels

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26
Q

Have no gates and are always open

A

ungated channels

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27
Q

Gates open and/or close in response to a membrane voltage change

A

voltage-gated channel

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28
Q

Example of a voltage-gated channel

A

Na channels in excitable cells

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29
Q

_____ are part of protein conformation forms/shapes in the cell membrane.

A

Channels

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30
Q

Conformational changes in channel molecules ________ gates guarding them

A

open and close

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31
Q

Two types of gating

A

1) Voltage-gating

2) Ligand-gating (chemical gating)

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32
Q

Upon opening of gates, ions move down concentration gradients which means

A

from high to low concentrations

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33
Q

3 ways substances can leave cells

A

1) simple diffusion
2) Facilitated diffusion (carrier mediated)
3) Active transport (both carrier-mediated and energy-dependent)

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34
Q

This process is carrier mediated

A

Facilitated disffusion

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35
Q

Molecule binds to ____ to be transported in facilitated diffusion and involves a conformational change

A

carrier protein

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36
Q

The molecule is released ____ in facilitated diffusion

A

inside

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37
Q

Examples of facilitated diffusion

A

transport of glucose and most amino acids

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38
Q

_____ involves diffusion of substances against electromechanical gradient “uphill movement”

A

active transport

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39
Q

Active transport needs ____ and a _____

A

ATP, carrier protein

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40
Q

Examples of primary active transport

A

1) sodium potassium pump for transport of Na and K ions outward and inward
2) calcium pump in SR of skeletal muscle

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41
Q

NA-K/ATP pump

A

3Na from inside to outside, 2 K from outside to inside, + ATP used

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42
Q

The Na-K/ATP pump is present in ___ cells

A

all

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43
Q

The voltage (charge) difference across cell membrane when the cell is at rest

A

Resting membrane potential

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44
Q

Resting membrane potential is due to

A

unequal distribution of charged particles (ions).

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45
Q

Resting membrane potential exists in ____ cells

A

all

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46
Q

The outside of the cell contains excess ____ and is relatively _____

A

Na, positive

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47
Q

The inside of the cell contains excess ______ and is relatively ________

A

K, negative

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48
Q

With excess Na outside and K inside, the cell is said to be ______ but with no impulse transmission

A

polarized

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49
Q

Na/k ATPase pump maintains high NA outside and K inside the cell by pumping

A

3 Na and 2 K against their concentration gradients

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50
Q

___ leaks back outside the cell more easily than ___ leaks in, further contributing the electrical potential difference

A

K, Na

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51
Q

The magnitude of membrane potential mostly depends on the distribution and permeability of ions like Na and L being at _____ in most nerves and ___ in muscle

A

-70 mV, -90 mV

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52
Q

Establishment of resting membrane potential in nerve fibers occurs when

A

1) the membrane potential is caused entirely by K+ diffusion alone
2) When the membrane potential is caused by diffusion of both sodium and potassium
3) When the membrane potential is caused by diffusion of both sodium and potassium ions plus pumping of both ions by the Na/K pump

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53
Q

There is also additional contribution of _____ to the potentials

A

ion leak

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54
Q

Resting membrane potential

A

-90 mv

55
Q

Nerve action potential generated in ____ tissues and is stimulated by

A

excitable tissues, electrical, chemical or physical stimuli.

56
Q

Polarized state of the membrane becomes _________ as Na channels open, and Na ions enter the cell.

A

depolarizes

57
Q

The membrane potential decreases with ______ conductance of Na

A

increased

58
Q

When potential decreases with Na entering the cell the potential becomes ____ at which point the Na channel is inactivated

A

+40 mv

59
Q

K channel gets activates to stop the influx of NA and allow the exit of K. This efflux causes

A

repolarization

60
Q

K exiting slows down after depolarization followed by a faster K exit which makes the membrane more negative, which is called

A

hyperpolarisation

61
Q

The axon develops an AP of the stimulus is at the threshold or above

A

all or none law

62
Q

Any ___ of stimulus above threshold does not alter pattern of response.

A

increase

63
Q

The time interval during which the nerve fiber does not respond to a second stimulus is known as

A

absolute refractory (nerve is still in excitatory phase)

64
Q

When a stronger stimulus can produce a response close to the end

A

relative refractory period

65
Q

If not interrupted, this phase leads to the return of normal excitability or polarized state/RMP.

A

relative refractory period

66
Q

Due to the inability of many negatively charged molecules to pass through the membranes, the deficit of positive ions (K) on the inside of the membrane leaves an excess of impermeant negative ions. These are responsible for the negative charge inside the cell.

A

Non-diffusible anions

67
Q

This pump behaves like the Na-K pump and regulates the IC concentration of calcium in many cells.

A

Calcium pump

68
Q

Voltage gated calcium channels are usually involved in

A

smooth and cardiac muscle

69
Q

The initial spike of a cardiac AP is

A

Na channel activation (fast channels)

70
Q

The plateau in a cardiac ap is due to

A

1) slow opening of the voltage gated calcium channels

2) slowed/delayed activation of voltage-gated potassium channels

71
Q

Rhythmical AP in intestinal smooth muscle is similar to those recorded int he rhythmical control od the

A

heart

72
Q

When stimuli are below threshold required for eliciting an AP

A

acute subthreshold potentials

73
Q

Velocity of conduction in nerve fibers varies from

A

0.25 m/sec to 100 m/sec

74
Q

Approximate rate of conduction for most fibers

A

1 m/s for unmyelinated, 10-100 m/sec for myelinated

75
Q

impulses travel by self-excitation and propagation

A

unmyelinated fiber

76
Q

directly related to the square roots of diameter of the nerve fiber

A

conduction of velocity

77
Q

____ fibers are myelinated

A

large fibers

78
Q

Factors causing ______ sufficiently can set off automatic regenerative opening f the channels

A

N ions to diffuse inward

79
Q

The functional significance of the schwann cell is to form

A

myelin

80
Q

Myelin serves as support for the axon and

A

a tube for nerve regeneration in the event of damage or degeneration.

81
Q

General structure of LA molecules

A

aromatic group, ester/amide, and amine group

82
Q

LA block and close ______ bu interacting with an intracellular domain of the channels.

A

Na channels

83
Q

By blocking impulse transmission along sensory nerve fibers, LAs ____ pain

A

reduce/block

84
Q

T or F: LA are analgesics

A

F-They are not analgesics, they only block pain.

85
Q

Other membrane stabilizers that decrease nerve excitability include

A

high extracellular calcium ions and some other drugs

86
Q

The _____ form binds to the sodium channel in the open state which prolongs the sodium channel inactivation state

A

ionized form

87
Q

Sodium entry is blocked during

A

Sodium inactivation state

88
Q

As anesthetic progressively develops in a nerve, the…

A

1) threshold for electrical excitability gradually increases
2) the rate of rise of the action potential declines
3) impulse conduction slows

all leads to nerve conduction

89
Q

nerve fibers with _______ diameters are affected first

A

smaller

90
Q

Transient and reversible in the following order

A

autonomic function, temperature, blocking of pain, touch, pressure, motor function.

91
Q

Loss of autonomic function causes

A

vasodilation

92
Q

Depending on the local tissue concentrations of LA, there may be ________ or_________

A

inhibitory (lower doses) or excitatory (higher doses)

93
Q

____________ is used as a desensitizing agent for tooth pain.

A

potassium nitrate

94
Q

Potassium nitrate provides protection against

A

painful sensitivity like cold, heat, acids, sweets, or contact

95
Q

Potassium nitrate works by

A
  • decreasing the ability of the nerve fibers in the dental pulp to re-polarize
  • decreasing the fluid flow decreasing the level of the activity of dental sensory nerves and preventing or reducing the sensation signals from reaching the brain
96
Q

Synaptic transmission is ____ in nature

A

chemical

97
Q

Neurotransmitters can be

A

excitatory or inhibitory

98
Q

Synaptic transmission is initiated by entry of ___ in to the nerve terminal

A

Ca

99
Q

Ca ions coming into the nerve channel helps release of

A

neurotransmitters from the presynaptic vesicles

100
Q

The neurotransmitters released from the presynaptic terminal are released via

A

exocytosis

101
Q

The presynaptic nerve terminal is rich in ____ which is needed for synthesis of the neurotransmitter.

A

mitochondria

102
Q

The event following the interaction of the NT on the ______ receptor depends on the nature of the NT.

A

postsynaptic

103
Q

Synthesis of acetylcholine starts with acetyl CoA+ choline, involving the enzyme

A

choline actyltransferase

104
Q

Ach is stored in vesicles released by exocytosis and broken-down by

A

acetylcholinesterase

105
Q

Ach acts on M receptors on effector tissue to produce response. An example is

A

saliva secretion

106
Q

Ach involved with

A

autonomic cholinergic

107
Q

Autonomic adrenergic involves

A

NE

108
Q

Synthesis of for autonomic adrenergic starts with the uptake of

A

tyrosine and phenylalanine

109
Q

NE is stored in vesicles, released by exocytosis, and broken-down by enzymes…

A

MAO and COMT

110
Q

____ is a major terminating mechanism for NEs action (about 80%)

A

Uptake1 (U1)

111
Q

NE acts on the receptors __ and ___ at the effector site

A

alpha and beta

112
Q

alpha activation causes _____ by an agonist like EP

A

vasoconstriction

113
Q

At the NMJ, the arrival of the AP at the somatic nerve terminal causes Ca influx into the nerve. This is followed by the release of ____ from its vesicle into the synaptic space/cleft.

A

Ach

114
Q

The Ach by activating its receptors on muscle fibers across the synapse, leads to

A

muscle contraction

115
Q

On the inside surface of the neural membranes are linear

A

dense bars.

116
Q

Each side of the protein bars are ____ that penetrate the membrane as voltage gated calcium channels.

A

protein particles

117
Q

Voltage gated calcium channels allow for the _____ into the nerve ending for the release of ______-

A

influx of Ca, Ach

118
Q

Events of NMJ for muscle contractino

A

1) Nerve AP
2) Release of Ach
3) binding of Ach with receptor
4) Activation of receptor
5) sodium influx into SKM fibers
6) muscle AP and SR channel opening
7) Ca2+ release
8) contraction

119
Q

Examples of other sensory receptor mediated responses

A

muscle spindle, golgi tendon organ, baroreceptor, chemoreceptors

120
Q

Excitation from anterior motor nucleus and ____ help with proper function of muscles.

A

continuous sensory feedback to the nervous system

121
Q

_____ are located in the muscle and sense changes in muscle length and rate of change of length

A

muscle spindles

122
Q

_____ are located in tendons and give information about tension

A

golgi tendon organs

123
Q

______ give rise to axons that exit the cord via the ventral roots and pass in peripheral nerves to innervates skeletal muscle

A

anterior horn motor neurons

124
Q

Spinal cord ventral horn ____ neurons are alpha or gamma neurons

A

motor

125
Q

____ large, give rise to myelinated axons, conduct AP rapidly

A

alpha

126
Q

____ smaller, give rise to small axons, conduct slowly

A

gamma

127
Q

Interneuron cells contribute to ____ and _____ in the spinal cord

A

motor and sensory

128
Q

There are ___ interneuron than motor neurons

A

30x more

129
Q

Interneurons have relatively high excitability and receive inputs as incoming

A

sensory info or as signal descending from higher centers in the brain and help processing info.

130
Q

Interneuron cells connect adjacent segments of the cord and help

A

modulate signals

131
Q

Large skeletal muscle fibers called extrafusal fibers

A

alpha motor neurons

132
Q

very small intrafusal muscle fibers in muscle spindles

A

gamma motor neurons

133
Q

Muscle spindles detect muscle ____, while tendon organ detects muscle _____

A

length, tension and also stabilizes contractile forces

OBMP Exam 3 (6 decks)

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