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MSK > Conductive tissue/NMJ Junction > Flashcards

Conductive tissue/NMJ Junction Flashcards

1
Q

Give 2 examples of location for electrical synapse

A

cardiac and some types of smooth muscle

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2
Q

are “many to one” synapses common?

A

yes

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3
Q

EPSPs do what to a post synaptic cell?

i. Name examples of neurotransmitters

A

Depolarize and bring closer to threshold potential
i. purines, acetylcholine (ACh), norepinephrine,
epinephrine, dopamine, glutamate, aspartate

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4
Q

IPSPs do what to a post synaptic cell?

i. Name examples of neurotransmitters

A

Hyperpolarize and bring further from threshold potential

ii. γ-aminobutyric acid (GABA), glycine, serotonin, and nitric oxide

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5
Q

overlapping of multiple presynaptic inputs in rapid succession from THE SAME presynaptic neuron is an example of …..

A

temporal summation

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6
Q

multiple presynaptic inputs arriving simultaneously is an example of …..

A

spatial summation

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7
Q

name location of a presynaptic input that would have the largest effect on whether or not an AP is fired in the POSTsynaptic cell.

A

received by a dendrite near the axon hillock

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8
Q

main mechanism for synaptic fatigue

A

ready neurotransmitter supply is exhausted

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9
Q

list steps of neurotransmitter transmission to NMJ from
(first step) AP in neuron → depolarize presynaptic terminal

….

(last step) Choline taken up by presynaptic terminal via Na+/choline cotransporter

A
  1. AP in neuron depolarize presynaptic terminal
  2. Calcium channels in presynaptic terminal open
  3. Calcium causes vesicles to fuse with presynaptic membrane and release ACH into synaptic cleft
  4. ACH binds motor end plate where there is nicotinic receptor that opens cation channel
  5. Na flows in; K flows out. Cell gets depolarized to EPP (-50 mV)
  6. EPP spreads and causes AP generation in muscle fibers
  7. ACH broken down by ACH esterase
  8. Choline taken up by presynaptic terminal via Na+/choline contransporter
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10
Q

Where do EPP and AP occur respectively?

A

EPP–motor end plate

AP-muscle fibers (not end plate)

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11
Q

what is a quantum and how is it related to mini EPP?

A

quantum is amount of neurotransmitter in one vesicle. it depolarizes end plate in a quantal fashion, so one vesicle contents equate to a mini epp.

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12
Q

MOA of botulinum

i. <3 word clinical finding after botulinum toxicity

A

blocks release of ACH from presynaptic cell (blocks vesicle fusion)
i. flaccid paralysis

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13
Q

MOA of curare

i. what does it do to EPSP?

A

competes with ACH for nicotinic receptors

i. decreases size of EPSP

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14
Q

uses of curare

A

skeletal muscle relaxation during anesthesia

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15
Q

uses of botox

A 
upper motor neuron disorders
chewing swallowing disorders
hair loss
muscle spasms
excessive sweating
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16
Q

MOA of ach esterase inhibitors

A

prevent degradation of ach in synaptic cleft

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17
Q

uses of ach esterase inhibitors

A

myasthenia gravis, alzheimers, parkinsons

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18
Q

where is the dihydropyridine (dhp) receptor located?

A

dhp receptor is located on the t-tubule and is sensitive to voltage

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19
Q

where is the ryanodine receptor located?

A

ryanodine receptor is on the terminal cisternae of SR

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20
Q

how do the dhp and ryanodine receptor interact

A

dhp and ryanodine are touching. dhp receptor is responsive to voltage from AP. dhp then conformational changes and activates ryanodine receptor which lets calcium out of SR

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21
Q

explain calcium binding to …. protein in short filament complex

A

calcium binds to troponin c, cooperatively. causes tropomyosin to move and reveal binding sites for myosin.

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22
Q

is serca active constitutively yes or no?

A

yes

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23
Q

recocking of the myosin head is initiated by what

A

hydrolysis of atp to adp and pi

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24
Q

what causes conformational change resulting in decreased affinity of myosin for actin?

A

atp binding to myosin

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25
Q

what causes power stroke?

A

pi release

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26
Q

what is tetanus?

A

sustained muscle contraction due to temporal summation of APs

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27
Q

does smooth muscle have troponin?

A

no so always free binding sites

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28
Q

sources of Ca+ for skeletal and smooth muscles

A

skeletal: only from SR
smooth: from SR (IP3) and voltage+ ligand Ca+ channels on PM (sarcolemmel membrane)

29
Q

effect of calcium concentration on skeletal and smooth muscles

A

skeletal muscle: all or nothing

smooth: calcium gradient

30
Q

regulation of calcium in skeletal and smooth muscle

A

Skeletal: SERCA: removes calcium from skeletal muscle causing relaxation
Smooth: lowering calcium or activating myosin phosphotase which inhibits myosin atpase activity

31
Q

describe calmodulin and MLCK interaction

A

in smooth muscle, ca binds calmodulin. this activates mlck. mlck then phosphorylates myosin head, greatly increasing its atpase activity (myosin is always high atpase activity for skeletal)

32
Q

how can calcium be lowered in smooth muscle?

4 ways

A
  1. Hyperpolarization closes voltage-gated Ca channels
  2. Direct inhibition of Ca channels by ligands like cAMP and cGMP
  3. Inhibition of IP3 production
  4. Increase in Ca/ATPase activity
33
Q

local anesthetics block ….

A

Sodium channels

34
Q

potency of local anesthetics is directly proportional to

A

lipid solubility (e.g not good if acidosis which charges basic part of drug)

35
Q

what functional group class is: procaine?

A

ester

36
Q

what functional group class is: tetracaine?

A

ester

37
Q

what functional group class is: lidocaine?

A

amide

38
Q

what functional group class is: mepivacaine

A

amide

39
Q

what functional group class is: bupivacaine

A

amide

40
Q

best drug for old ppl with heart issues

i. why

A

mepivacaine (carbocain)

i. no coadmin of epi needed

41
Q

local anesthetic fxn group class metabolized by liver

A

amide

42
Q

local anesthetic fxn group class metabolized in serum quickly

A

ester

43
Q

which is more sensitive to anesthetics? large or small nerve fibers?

A

small fibers more sensitive bc have no or less myelination

44
Q

rank nerve classes in terms of sensitivity from LEAST to most sensitive.

A

A-alpha, A-beta, A-gamma, A-delta, B, C.

45
Q

C type neurons are

A

nociceptor and sympathetic efferents

46
Q

alpha type neurons are

A

motor

47
Q

list 2 disadvantages to epi coadmin

A

ischemia

cardiovasc effects

48
Q

list two systems in body affected by LA spillage into circulation

A

CV (arrythmia) and CNS (initially depression then excitation/seizure)

49
Q

selectivity of ion channels (list 2 things)

A

charge and size of pore

50
Q

conductance of ion synonym

A

permeability

51
Q

V=

A

IR

52
Q

typical resting potential of a cell is

A

-75mV

53
Q

equilibrium potential for an ion is

A

potential at which ion flow is in equilibrium across a membrane (balanced with concentration gradient flow)

54
Q

Sort Na+ Ca+ K+ and Cl- as higher concentration in cell or outside cell

A

Na–outside cell higher
Ca–outside cell higher
K–inside cell higher
Cl–outside cell higher

55
Q

what is a way you could change the resting membrane potential of a cell in lab?

A

changing extracellular potassium concentration, since the cell is most permeable to potassium

56
Q

what pump maintains membrane potential?

A

Na/K atp pump

57
Q

at rest, which conductance is higher, Na or K?

A

K

58
Q

what is lvl for threshold potential usually

A

-55mV

59
Q

all or none principle of APs

A

All AP’s of a cell will cause the same voltage changes.

60
Q

describe permeability changes of Na and K ions during phases of excitation

A

see doc

61
Q

basis for absolute refractory period

A

closure of sodium inactivation gates in RESPONSE to depolarization

62
Q

basis for relative refractory period

A

higher potassium conductance (mostly hyperpolarization)

Na channels are closed but available

63
Q

Accomodation

A

slow depolarization closes inactivation gates (bc it is slow allows the gates to close before an AP can ever be fire), even tho activation gate is open the inactivation one is closed.

64
Q

internal diameter is ….. proportional to rate of conduction and …. to internal resistance

A

directly….inversely

65
Q

membrane resistance is …. proportional to conduction velocity

A

directly

66
Q

capacitance is …. proportional to conduction velocity

more myelin causes ….. capacitance

A

inversly

less

67
Q

C and IV neuron types

A

slow pain

68
Q

Rank the following nerve classes as fastest, medium, or slowest: Ia, Ib, A alpha A beta, A gamma, A delta, B, C.

A

Fastest: A alpha, Ia, Ib
Slowest: C

69
Q

name two nerve fiber types/classes that are not myelinated

A

C and IV

MSK (9 decks)

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