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Bio 472 > Velocity of Nerve Signal Conduction, Physiology of Synapses > Flashcards

Velocity of Nerve Signal Conduction, Physiology of Synapses Flashcards

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Biology 101 flashcards
1
Q

What causes Conduction Velocity to change?

A
  1. Resistance of Membrane (Rm)
  2. Capacitance of Membrane (Cm)
  3. Resistance of Interior (Ri)
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2
Q

Resistance is …

A

resistance to flow

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3
Q

Capacitance is

A

stored electrical charge

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4
Q

capacitance =

A

1 / resistance

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5
Q

smaller effective resistance =

A

faster velocity

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6
Q

Effective resistance is proportional to

A

SQRT(RmRi)(Cm)

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7
Q

membrane capacitance increases when

A

the membrane area increases

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8
Q

membrane capacitance decreases when

A

the membrane area decreases

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9
Q

Effective Resistance Equation

A

ER is proportional to SQRT((2/pirl)(1/pirSQ))(2pirl)

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10
Q

Causes Rm decrease x2, Ri decreases x4, Cm increase x2

A

doubling the radius of a nerve

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11
Q

larger diameter fibers

A

faster conduction velocities

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12
Q

Myelin results in

A

faster velocity

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13
Q

Why does myelin increase conduction velocity?

A
  1. Schwann cell membranes (decrease capacitance, increase Rm)
  2. Saltatory conduction (impulse jumps from one Node of Ranvier to another, less Na+/K+ ATPase and energy required)
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14
Q

Schwann cell wrap of 25

A

Lowers Capacitance 50 fold, increases Rm 50 fold.
Always doubled

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15
Q

Autoimmune demyelinating diseases

A

Multiple Sclerosis
ALS (Amyelotropic Lateral Sclerosis)

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16
Q

close (2-3 nm), gap junction, electrical current crosses without chemicals, common in the heart

A

Electrical Synapses

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17
Q

wider (30-50 nm), begins with arrival of action potential, accounts for most of delay in signal transduction (0.5 msec)

A

Chemical Synapses

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18
Q

Synapses Steps

A
  1. Action potential impulse
  2. Voltage gated calcium channels open
  3. Calcium enters the Presynaptic Ending (down the concentration gradient)
  4. Release of Neurotransmitter (exocytosis)
  5. Neurotransmitter moves across synapse and binds to a receptor
  6. Transient change in postsynaptic membrane ion permeability
  7. breakdown of neurotransmitter by specific enzyme, recycling of products
  8. Membrane potential altered in Postsynaptic cell
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19
Q

Causes the synapse stimulation to cease

A
  1. negative feedback from the Neurotransmitter at Presynapse
  2. degradation of neurotransmitter at receptor
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20
Q

cell body to axon flow impulse 99.9% of the time

A

orthodromic

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21
Q

axon to cell body flow of impulse

A

antidromic

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22
Q

3 causes of synaptic delay

A
  1. release of the neurotransmitter
  2. travel of the neurotransmitter across synapse
  3. binding of the neurotransmitter to the post synaptic receptor
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23
Q

activates neurons to fire

A

Excitatory Post-Synaptic Potential (EPSP)

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24
Q

EPSP fast

A

increase in Na+ conductance

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25
Q

EPSP slow

A

decrease in K+ conductance

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26
Q

stops neurons from firing

A

Inhibitory Post-Synaptic Potential (IPSP)

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27
Q

IPSP fast

A

increase in Cl- conductance, hyperpolarizes cell, harder to depolarize

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28
Q

IPSP slow

A

increase in K+ conductance

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29
Q

2 impulses at the same time that total threshold

A

Spatial Summation

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30
Q

2 impulses in rapid succession that total threshold,
second comes before the first degrades

A

temporal summation

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31
Q

Presynaptic facilitation

A

simulation of Ca++ channel opening,
more neurotransmitter released

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32
Q

inhibition of Ca++ channel opening, reduces amount of neurotransmitter released

A

presynaptic inhibition

33
Q

multiple nerve impulses work toward one result

A

Convergent neural network

34
Q

one neural impulse works to make multiple results

A

Divergent neural network

35
Q

mediated by acetyltransferase
Choline + acetyl Co A

A

Acetyl choline (ACh)

36
Q

General Action of Acetyl Choline

A

parasympathetic stimulation (low HR, low BP, fast GI)
neurotransmitter for neuromuscular junction (nerve to muscle)

37
Q

cholinergic receptor that is stimulated by acetylcholine located on smooth muscle, cardiac muscle, glands, and brain and stimulates the parasympathetic nervous system when activated

A

Muscarinic Cholinergic receptor

38
Q

stimulated by Muscarine, blocked by atropine

A

Muscarinic Cholinergic receptor

39
Q

located at neurons, skeletal muscle, and on the brain
stimulates the sympathetic nervous system when activated

A

Nicotinic Cholinergic receptor

40
Q

stimulated by nicotine, blocked by curare

A

Nicotinic Cholinergic receptor

41
Q

prevents degradation of ACh message, causes synapses to get stuck
1 mg is lethal

A

Sarin, VX Nerve Gas (AChe inhibitor, Organophosphate)

42
Q

breaks down Acetylcholine

A

Acetylcholinesterase (AChe)

43
Q

reverses Sarin, VX Nerve Gas effects

A

Atropine + Pralidoxime autoinjectors

43
Q

few ACh receptors due to autoimmune degradation

A

Myasthenia gravis

44
Q

decreased ACh synthesis in brain

A

Alzheimer’s disease

45
Q

anti-smoking drugs

A

nicotrol - nicotine replacement therapy
chantix - ACh agonist/antagonist
zyban - Dopamine reuptake inhibitor

46
Q

Catecholamines
Serotonin
Histamine

A

Biogenic Amines

47
Q

Norepinephrine
Epinephrine
Dopamine

A

Catecholamines

48
Q

Amine synthesis

A

Dietary Tyrosine + Tyrosine hydroxylase = Dopa
Dopa + Dopa decarboxylase = Dopamine
Dopamine + Dopamine B- Hydroxylase = Norepinephrine
Norepinephrine + N-methyltransferase = Epinephrine

49
Q

Norepinephrine deactivation methods

A

Monoamine Oxidase (MAO, in many Anti Depressants)
Catechol-O-Methyltransferase (COMT, peripheral tissues, liver, kidney, etc)

50
Q

Nerve tracts using Epinephrine, Norepinephrine

A

Adrenergic Fibers

51
Q

General Action of Epinephrine and Norepinephrine

A

sympathetic stimulation (HR up, BP up, GI tact slow)
E and NE have different actions depending on Receptor Types

52
Q

Alpha Receptor
Beta Receptors

A

Adrenergic Receptors

53
Q

Adrenergic Receptor with a greater affinity for NE

A

Alpha receptors

54
Q

Adrenergic Receptor with a greater affinity for E

A

Beta receptors

55
Q

stimulates contraction of smooth muscle, (vasoconstriction)
in vessels and the sympathetic nerve tract
IP3

A

Alpha 1 receptor

56
Q

inhibition of smooth muscle contraction in GI tract
common in GI tract + pancreas
decreases cAMP

A

Alpha 2 receptor

57
Q

stimulates heart rate, contractility, Kidney, fat lipolysis, increases cAMP

A

Beta 1 receptor

58
Q

inhibits smooth muscle, increases cAMP
in lungs, heart, skeletal muscle blood vessels

A

Beta 2 receptors

59
Q

fat exclusively, lipolysis, increases cAMP

A

Beta 3 receptors

60
Q

ACh AND nicotinic receptors are present in which nervous system?

A

Somatic Nervous system

61
Q

sympathetic pathways distribution

A

distributed in thoracolumbar area of spinal cord
ventral roots of the spinal nerves, system runs parallel to the spinal cord

62
Q

short fibers in the ANS, use ACh as their neurotransmitter
sympathetic pathways

A

Preganglionic fibers

63
Q

long fibers in the ANS, use NE as a neurotransmitter
sympathetic pathways,
adrenergic receptors on target tissue

A

Postganglionic fibers

64
Q

parasympathetic pathways distribution

A

distribution via cranial nerves and pelvic nerves from the sacral region
cranial nerves, 3, 7, 9, and 10 have 90^ of the body’s parasympathetic fibers

65
Q

long in length use ACh as their neurotransmitter
parasympathetic pathways

A

preganglionic fibers

66
Q

short in length, on target tissue, use ACh as their neurotransmitter, cholinergic muscarinic receptors are on the target tissue

A

postganglionic fibers

67
Q

CNS neurotransmitter, pleasure pathways

A

Dopamine

68
Q

Methamphetamine and Cocaine affect this neurotransmitter …

A

Dopamine

69
Q

Parkinsons disease in caused by a lack of this neurotransmitter …
and is treated with this therapy …

A

Dopamine
L-Dopa therapy

70
Q

derived from Tryptophan (milk, turkey)
catabolized by MAO
excitatory for muscle
inhibitory for sensation

A

seratonin

71
Q

amino acid neurotransmitters

A

glutamate, aspartate, glycine, GABA (Gama Amino Butyric Acid)

72
Q

excitatory in CNS, important for learning and memory

A

glutamate and aspartate

73
Q

inhibitory in CNS, anesthetic action

A

Glycine and GABA

74
Q

4 modes of action for alcohol

A
  1. Activates GABA pathways (inhibitory)
  2. Activates Adenosine receptors (inhibitory)
  3. Blocks Glutamate pathways (stimulatory path, inhibited)
  4. Membrane soluble (inhibits/slows down second messenger pathways)
75
Q

Neuropeptide Examples

A

Endogenous Opioids
Morphine (Codeine, Oxycodone, Ketamine)
Substance P

76
Q

released in the presence of a stressor
stress, defense, repair, survival system
Vasodilator

A

Substance P

77
Q

Action of Endogenous Opioids

A

Analgesic
Reduces Pain

78
Q

Assists in memory and learning
Possibly protects the brain from neuronal damage in a stroke

A

Nitric Oxide

Bio 472 (23 decks)

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