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Flashcards in MSK phys Deck (90)
1

toxin in puffer fish

tetrodoxin

2

what is given to Tx tetrodoxin poisoning

activated charcoal to bind it up

3

how does tetrodoxin work

block V Na Channels
inhibits depolarization
AP generation/propagation inhibited

4

blockage of K leak channels would do what

hypopolarize RMP

5

what toxin is in mamba snakes

dendrotoxin

6

how does dendrotoxin work

blocks V K channels so blocks hypopolarization

7

effects of dendrotoxin on Ach release

inhibit repolarization
prolonging AP
prolonged Ca influx at nerve terminal
enhanced ACh release
hyperexcitability and convulsive Sx

8

inheritance of malignant hyperthermia

autosomal dominant

9

what can trigger malignant hyperthermia

volatile anesthetics and some muscle relaxers

10

what causes malignant hyperthermia

uncontrolled release of Ca from SR leading to tachy, rigidity, hyperventilation and hyperthermia
acute hypermetabolic state in muscle tissue leading to prolonged contraction

11

what R is affected in malignant hyperthermia

RYR1
also could be dihydropyridine R

12

where is RYR located

SR membrane

13

what are the L type Ca channels and where are they located

DHPR
T tubule membrane

14

role of DHPR

voltage sensor

15

role of Ca in skel mm tension

removes regulatory protein tropomyosin from actin so there can be cross bridge formation

16

what is directly proportional to tension production in skel mm

number of cross bridges

17

what is required for muscle relaxation to occur

removal of Ca from sarcoplasm

18

is ATP needed for muscle relaxation or contraction

relaxation

19

where is the ATPase binding site

on myosin head

20

what is the pump to remove Ca from sarcoplams for skel mm relaxation to occur

SERCA the sarcoplasmic and endoplasmic reticulum Ca ATPase

21

AutoAb are against what in myasthenia gravis

nAChrR

22

initial mm affected in myasthenia gravis

extraocular mm
bulbar (speech swallowing)
neck
proximal limb muscles

23

Ach binding to R on motor end plate cause what

opening of ligant gated ion channels
depolarization end plate between Na and K

24

effect of EPP on adjacent sarcolemma of skel m

V Na Channels open and AP generated

25

enzyme that degrades Ach in NMJ

acetylcholinesterase

26

what enzyme synthesizes Ach

choline acetyltransferase

27

what drives Ach uptake into vesicle

vesicular proton elctrochemical gradient (+ voltage and low pH inside)

28

Where is Ach made

nerve terminal

29

what allows for Ach uptake by vescile

ACh- H+ exchanger
in ACh
out H+

30

endrophonium (tensilon) test

give AChEI and see if improve Sx

31

why does an ice pack help in myasthenia gravis

inhibits AChE activity

32

two major clinical forms of myasthenia gravis in eyes

ocular MG: only ocular Sx
general MG: generalized weakness

33

why does MG attack eyes frist

fewer ACh R in eye muscles
high rate firing in eye motor neurons
lower quantal release ACh per event

34

+ SCC
EMG increase uppon repeated activation
autoAb found against V Ca Ch
Dx

lambert eaton myasthenic syndrome
paraneoplastic

35

where does LEMS attack

presynaptic VCaCh
decrease ACh vesicle fusion and exocytosis

36

Which vesicle protein is a Ca sensor

synpatotagmin

37

conotoxin is from what

marine cone snail

38

how does conotoxin work

blocks N type VCa ch
analgesic

39

botulism affects what in NMJ

impaired ACh vesicle fusion

40

what other toxin (not botulinum) blocks the ACh release

tetanus toxin

41

why does botulinum toxicity take a while to reverse after given anti toxin

need synaptobrevin (v SNARE)
and sNAP 25 (t SNARE) to be newly synthesized

42

which botulinum attack SNAP 25

A and E

43

which botulinum attack synaptobrevin

B D F G

44

what causes spastic paralysis seen in tetanus

central effects bind NMJ presynaptic membrane and retroaxonally transported to SC
NT release is blocked
impact spinal INHIBITORY interneurons

45

what type of paralysis does botulinum toxin cause

flaccid

46

RMP

-70mV

47

what medications promote cellular uptake of K

epinephrine, insulinm, aldosterone

48

cell death can result in what metabolic state

hyperkalemia

49

what occurs to membrane with highger K efflux

hyperpolarization

50

what occurs with a decrease in ECF K

more K efflux, hypokalemia

51

what occurs with an increase in ECF K

dec K efflux, hyperkalmia
membrane potential less negative aka depolarized

52

RMP most sensitive to what ion [ ]

K

53

When is K permeability the highest

relative refractory period of Na channels

54

methods of removal of NT from synaptic cleft

enzymatic breakdown, cellular uptake, diffusion

55

NMJ are excitatory/inhbitory or both

always excitatory EPP

56

how is inhibition of skel mm achieved

CNS through IPSPs at dendrites and cell body of motor neuron

57

what are the active zones of NMJ

dense spots where synaptic vesicles are clustered
oriented over postjunctional folds

58

what are postjunctional folds

extensive invaginations on postsynaptic membranes under nerve terminal
increase SA of muscle plasma membrane

59

what is time delay in impulse transmission with Ach diffusion

50 nm

60

What is synaptotagmin

Ca R of synaptic vesicles
detect rise in Ca and trigger exocytosis of docked vesicles

61

synaptobrevin forms a complx with what

SNAP 25 and syntaxin

62

botulinum toxin C1 blocks what

cleaves syntaxin

63

what are sarcomeres

actin and myosin units
Z line to Z line

64

What is the A band

myosin (thick filament)

65

What is the H zone

middle of A band (part where does not overlap with thin actin)

66

what is the M line

center of A band

67

what is the I band

part of ACtin not overlapping with myosin

68

what is the Z line

thin filament attachment

69

what is a thick filament

2 myosin heavy chains and 4 light chains

70

what are the regions of the myosin heavy chains

rod (tail)
hinge (arm)
head (cross bridges)

71

what are the 4 light chains in thick filament

2 alkali (essential)
2 regulatory

72

What are the binding sites on myosine heavy chains

actin binding site for cross bridge formation
myosin ATPase site for hydrolyzing ATP

73

What is F actin

filamentous- backbone
double stranded alpha helical polymer of actin molecules

74

what are the actin binding proteins

tropomyosin
troponin

75

tropomyosin blocks what at rest

myosin binding site on actin

76

tropomyosin interacts with how many actin monomers

7

77

tropinin interacts with what

1 tropomyosin molecule and actin

78

torponin T

binds single tropomyosin molecule

79

troponin C

binds Ca

80

troponin I

binds actin and inhibits contraction

81

what happens when Ca binds troponin

tropomysoin slips away from blocking position allowing for cross bridging to occur

82

how do AP propagate from sarcolemma to interior of muscle fibers

transverse tubules

83

What is the triad in skel mm propagation

SR cisternae on 2 sides of T tubule that allow for propagation of AP

84

Channels needed to propagate AP

DHPR- t tubule
RYR- SR

85

DHPR are found in clusters of how man

4 needed for conformational change allowing Ca release

86

do you need Ca release to activate RYR

no, mechanical from DHPR

87

high Ca in SR causes what

inhibits activity of SERCA

88

what delay inhibition of Ca pump activity

Ca binding proteins in SR lumen (increase Ca amount in SR)

89

what are the Ca binding proteins in SR

calsequestrin
localized in SR at triad junction
complexes with RYR

90

what is calreticulin

Ca binding protein in smooth muscle