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PHYSL 200 > Nerve, Muscle, Synapse > Flashcards

Nerve, Muscle, Synapse Flashcards

1
Q

true or false - the withdrawal reflex is an autonomic behavior

A

true

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2
Q

what are the structures of the central nervous system

A

cerebral cortex, cerebellum, brainstem and spinal cord

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3
Q

what is the difference between the efferent and afferent neurons

A

afferent neurons - carry information from the outside to the spinal cords via the DORSAL roots
efferent neurons - carry information from the spinal cord to the outside via the VENTRAL roots

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4
Q

what are the name of the cells that are the most in number of the central nervous system

A

glia cells

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5
Q

what are the four functions of the different types of glia cells

A
  1. satellite cells provide structure/support neurons
  2. produce myelin
  3. radial glia guide neurons and development of axon’s outgrowth
  4. astrocytes form blood brain barrier
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6
Q

what are the cells in the PNS and CNS that make myelin

A

oligodendrocytes in CNS; Schwann cells in PNS

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7
Q

describe the stretch reflex

A
  1. patellar tendon is tapped
  2. makes the quadricep muscle stretch
  3. activates the afferent neuron
  4. then interneurons inhibit the efferent neuron
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8
Q

true or false - the synaptic terminals is the start/initial segment of the neuron

A

false - it is the axon hillock

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9
Q

what are the three different types of neurons

A

bipolar, pseudo-unipolar and multipolar

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10
Q

a motor neuron is

a) afferent
b) efferent

A

efferent

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11
Q

where is the bipolar neuron usually found

A

in the visual system (retina)

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12
Q

what is an example of a electrogenic transporter

A

Na/K pump

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13
Q

___ Na molecules move ___ of cell and ___ K meolcules move ___ cell

A

3, out, 2, in

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14
Q

is there a net positive or negative charge inside the cell

A

negative

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15
Q

true or false - leak channels are not always open

A

false they are always open

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16
Q

briefly describe leak channels

A
  • they passively allow ions in and out but they are very selective in which each ion has its own leak channel
  • two forces involved ; chemical and electrical gradient
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17
Q

what is the equilibrium potential for K and Na

A

K is -90mV
Na is +60mV

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18
Q

if there are both Na and K present in nerve cells, what happens to the resting membrane potential

A

the ion that has the most permeability to the membrane will impact the EM the most

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19
Q

if the RMP was +75, would there be more Na or k leak channels and why

A

there would be a lot more Na channels because its RMP on its own is about +60 so it is close to +75, therefore there is greater permeability to Na

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20
Q

choose the factors that do not play a role in setting RMP

Na, Cl-, K, and anions

A

Cl- and anions do not play a role because
1. Cl’s equilibrium potential = RMP
2. anions are too big

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21
Q

true or false - the cell can sometimes be at rest/quiet

A

false it is never quiet because either one of the ions is never happy until it has reached its preferable EP and when the cell is at -70mV, neither of the ions are happy

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22
Q

what is the definition of action potential

A

a change in membrane potential from -70mV to +30mV and then back to rest

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23
Q

at rest, the voltage gated channels are open/closed

A

closed

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24
Q

what is the difference between absolute and refractory period

A

absolute - not able to generate another AP
refractory - possibly able to generate another AP

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25
Q

what is a major factor in keeping the signal flow in one direction

A

refractory period

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26
Q

what is the steps of an action potential being generated in terms of channels and gates

A

activated stimulus -> increase in permeability to Na ions -> Na flows in -> Na gate deactivates and K opens -> K rushes in -> so much rushes out that the membrane potential reaches below resting potential -> back to rest

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27
Q

which of the ions are associated with depolarizing and repolarizing phases

A

Na - depolarizing
K - repolarizing

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28
Q

what is the term given to the spread of current inside an axon

A

electric conduction

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29
Q

what are the three types of neurons

A

inter/afferent/efferent neurons

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30
Q

true or false - afferent and efferent neurons can be inhibitory

A

false - only excitatory

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31
Q

what is myelin made of

A

80% lipid and 20% protein

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32
Q

complete the following scenarios
if myelin is there….
if myelin is not there

A

if myelin is there, there is no need for regeneration of AP and so it is one smooth current

if myelin is not there, the AP would leak out the nerve fibres

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33
Q

true or false - oligodendrocytes are found in the PNS

A

false - they are found in the CNS

34
Q

what is the only place in the neuron that has myelin

A

axon

35
Q

why is the myelin not continuous

A

because of nodes of ranvier

36
Q

true or false - one oligodendrocytes ensheath many axons

A

true

37
Q

many schwann cells ensheath many/1 axon

A

1 axon

38
Q

does saltatory conduction occur with or without myelin

A

only when there is myelinated fibre

39
Q

what happens with multiple sclerosis

A

the myelinated nerve fibres become degenerated therefore, the pattern of node ranvier and axons are abnormal -> AP is not generated at the speed its supposed to so there is inappropriate pain responses

40
Q

define proprioceptor

A

occurs in muscle and allows us to know where our muscles are in space without looking

41
Q

order the fibre types from lowest AP frequency to highest

A

Group 4, group 3, group 2, group 1

42
Q

what are the associated sensory receptors with the fibre types

A

group 1 - skeletal muscle and proprioceptor
group 2 - skin mechanoreceptor
group 3 - pain and temperature
group 4 - pain, itch and temperature

43
Q

what is the direction of the AP

A

it arrives at the axon from left to right

44
Q

true or false - synaptic transmission is only electrical

A

false - it is electrical or chemical

45
Q

what is the significance of electrical synapses

A

it is fast and bidirectional

46
Q

what is an important structure of electrical synapses

A

connexons - work to fuse two cells together

47
Q

how does directly gated chemical synapses work

A

transmitter binds -> channel opens -> excitatory ions pass through (K and/or Na) -> for inhibition, Cl- or K will pass through

48
Q

how does indirectly gated chemical synapses work

A

transmitter binds -> activation of 2nd messenger system -> causes cAMP to activate protein kinases to phosphorylate channels -> channels open/close -> ions flow in/out

49
Q

how does the 2nd messenger system become activated

A

via G proteins - GTP activates adenylyl cyclase which then converts ATP to cAMP

50
Q

what is the name of the 2nd messenger system

A

cAMP

51
Q

true or false - receptor and effector(ion channel) are different molecules in indirectly gated chemical synaptic transmission

A

true

52
Q

provide the differences between electrical and chemical synapses

A

chemical - flexibility, inhibition, plastic, complex
electrical - inflexible, difficult to change, great for stereotypical behaviors

53
Q

what is the course of events for synaptic transmission

A
  1. action potential starts at the pre synaptic terminal
  2. depolarization of pre synaptic terminal
  3. Ca voltage gated channels open and influx of Ca
  4. this influx of calcium allows the synaptic vessicles to fuse with the presynaptic membrane
  5. transmitter is released by exocytosis and binds to ligan gated ion channels
  6. ions flow across membrane by their concentration gradient
  7. the postsynaptic cell can either be hyperpolarized or depolarized
  8. once the channel closes, the transmitter is then recycled
54
Q

how can a presynaptic neuron be excitatory

A

it can release the excitatory neurotransmitter glutamate
- glutamate binds and opens the Na ligand gated channels
- Na enters and causes depolarization aka EPSPs

55
Q

how can a presynaptic neuron be inhibitory

A

it can release glycine or GABA
- inhibitory transmitter binds and opens ligand gated Cl channels
- Cl enters and causes hyperpolarization aka IPSPs
- no more generation of APs

56
Q

true or false - the synpatic potentials travel away from cell body

A

true

57
Q

true or false - as the synpatic potentials travel, it gets stronger and stronger

A

false - it decays with distance

58
Q

describe temporal summation

A

PSPs from a single presynaptic axon will overlap in time and add together
- this happens when EPSPs are too small on their own so they are able to sum together to get to threshold and trigger an AP

59
Q

describe spatial summation

A

PSPs in different regions of the postsynaptic neuron are added together
- this happens when EPSPs from different areas on their own are too small on their own so they are able to sum together to get to threshold and trigger an AP

60
Q

a neuron sits at -70mV and has a threshold of -50mV, it then receives 10 IPSPs of 0.5mV each and 20 EPSPs of 1mV each. does the cell fire an AP

A

first, the cell needs 20mV to fire an AP (50-70)
- 10IPSPs x 0.5mV = -5 because it is hyperpolarized
- 20 EPSPs x 1mV = +20
in total that is +15mV which is less than what it needed, therefore no AP is generated

61
Q

compare PSP and AP in areas of amplitude, duration, location, conduction and function

A

PSP
amplitude - depolarization or hyperpolarization
duration - long
location - dendrites and soma
conduction - short distances
function - moves the postsynaptic neuron closer to or further from threshold

AP
amplitude - all or none
duration - short
location - start at axon hillock to terminal
conduction - long distances
function - AP is conducted to the terminal where it causes a PSP in the post synaptic neuron

62
Q

name the three types of muscle

A

smooth, cardiac and skeletal

63
Q

of the three types of muscles, which are involuntary and voluntary

A

cardiac and smooth are involuntary
skeletal is voluntary

64
Q

where is smooth muscle found and what is its function

A

it is found in hollow organs
functions :
1. regulates blood flow in arteries
2. moves food through GI tract
3. expels urine
4. regulates flow of air in lungs

65
Q

what is the main function of cardiac muscle

A

found in the heart walls where it propels blood into the heart and through the circulatory system

66
Q

true or false - skeletal muscle is non striated

A

false - it is striated

67
Q

name 2 differences between synaptic transmission at a central synapse and a neuromuscular junction

A
  1. one action potential in a motorneuron initiates one AP in a muscle cell
  2. there are no inhibitory neurotransmitters that are released to stop the activity
68
Q

how is muscle action stopped if there are no inhibitory neurotransmitters

A

lack of neurotransmitter, which means lack of activity = inhibition

69
Q

how is acetycholine released and what happens when it is

A

it is contained in vesicles and it is released through exocytosis and into the synaptic cleft
- when this happens, calcium ions are pumped out

70
Q

what is a major role of calcium

A

it triggers contraction of muscles

71
Q

what part of the sarcomere does not change during contraction and relaxation

A

the H zone

72
Q

what are the steps of cross bridge cycling

A
  1. influx of calcium allows the binding of site on actin to be available
  2. myosin binds to actin
  3. power stroke of cross bridge allows the sliding of the thin filaments
  4. the cross bridge disconnects when ATP is bound to it
  5. the cross bridge will reposition itself once ATP goes through hydrolysis
  6. calcium ions travel back to the. sarcoplasmic reticulum
73
Q

explain the three roles of ATP in muscle cells

A
  1. energized the power stroke
  2. disconnects the myosin cross bridge from actin binding site
  3. helps transport Ca back into the sarcoplasmic reticulum
74
Q

what are the two types of muscle fibres

A

red and white

75
Q

list the features of red muscle fibres

A
  1. shorter than white fibres
  2. lots of myoglobin so very red
  3. lots of mitochondria
  4. low glycogen content
76
Q

list the features of white muscle fibres

A
  1. larger than red fibres
  2. not so much myoglobin so light in color
  3. few mitochondria
  4. high glycogen content
77
Q

how do white muscle fibres synthesize ATP

A

through glycolysis because they have a high glyocgen content

78
Q

how do red muscle fibres synthesize ATP

A

using Krebs cycle and oxidative phosphorylation

79
Q

what is another name for white muscle fibres

A

fast twitch glycolytic fibres

80
Q

true or false - white muscle fibres are suited for activities requiring power and speed for a long period of time

A

false - it is only suitable for a short amount of time

81
Q

true or false - red muscle fibres are fatigue resistant and have high endurance

A

true

PHYSL 200 (17 decks)

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