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Phys 208 > Muscles--Cardiac/Smooth > Flashcards

Muscles--Cardiac/Smooth Flashcards

1
Q

___ disks contain ___ link myocytes

A

intercalated; desmosomes

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2
Q

___ link electrically

A

gap junctions

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3
Q

have ____ T tubules

A

wider, less abundant (NEED xtracell Ca)

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4
Q

1/3 of cell vol is ___

A

mitochondria

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5
Q

approx. 1% myocardial cells are ____ that gen. AP

A

autorhythmic (pacemaker)

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6
Q

AP gen by ___

A

HCN channels

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7
Q

spontaneous AP mechanism:

A

-60mV the funny channels open–>T type open, funny close–>L type open, depolarize–>L type close and K channel open, hyperpolarize

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8
Q

why can’t depolarization just go thru atria to ventricle>

A

connective tissue

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9
Q

how is AP diff in contractile cells?

A

volt gated Na/K channels, Ca channels slower and create plateau

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10
Q

why is Ca induced ca release necessary?

A

L-type Ca channel NOT mech coupled to RYR

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11
Q

cardiac muscle capable of ___ contractions; ^ in ___ entry enhances force

A

graded; Ca

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12
Q

membrane bound receptor that is linked to 3-part membrane transducer

A

G-protein

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13
Q

2 things happen with ligand binding to G-pro receptor :

A

1) interact w/ ion channel (G protein dissociates or direct contact)
2) alter enzyme activity on cyto side

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14
Q

mechanism of signal transduction/amplification:

A

G protein–>adenyl syclase–>cAMP–>protein kinase A–>phosphorylate protein–>response

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15
Q

functions of protein kinase:

A

phosphorylate Ca channel remain open longer, phosphorylate RyR to ^ Ca release from SR, sensitize trop C to Ca, phosphorylate SERCA, ^ myosin ATPase

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16
Q

SERCA inhibited by dephosphorylated ___

A

PLN (phospholamban)

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17
Q

___ channels cause hyperpolarization of autorhytmic cells , ____ channels cause + shift in threshold, ___ cause decreased rate of depolarzation

A

GIRK; T-type Ca; funny channels

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18
Q

___ released from symp neurons ^ pacemaker activity thru these 2 mechs:

A

catecholamines; 1) beta 1 adrenergic activation–>activation HCN–>^ AP generation
2) beta adrenergic activation ^ Ca current in myo cells–>rapid, shorter AP

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19
Q

why cardiac cells like stretch?

A

^ Ca sensitivity of myofilaments, v diffusion distance, additional tension on stretch activated Ca channels (^ Ca induced Ca release)

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20
Q

cardiac muscle cells have more ___ charge, and have a long contractile AP because:

A

negative; prevent summation, contract/relax in unison

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21
Q

____ is absent in smooth muscle

A

troponin (have calmodulin), T tubules

22
Q

thin filaments are anchored to cell mem/cyto structures called ____

A

dense bodies (like z lines)

23
Q

actin:myosin ratio is ____

A

15:1

24
Q

4 types of smoooth muscle contraction:

A

phasic usually relaxed (esophagus), phasic cycling relax/contract (intestine), tonic usually contract (sphincter); tonic contraction varied (vascular)

25
Q

2 types of communication in smooth muscle:

A

single-unit (cells act as single unit via gap junctions), multi-unit (not electrically linked, stim independently)

26
Q

Gi constriction by ___ receptors, airway dilation by ____

A

alpha adrenergic; beta adrenergic

27
Q

examples of multi unit:

A

iris and ciliary body, male repro tract and in uterus (up until labor)

28
Q

examples of unitary:

A

viscera

29
Q

why are upstroke and repolarization slower?

A

L-type Ca channels slower than Na channels , delayed activation of K channels

30
Q

___ potential sometimes reach threshold, __ potential always reach threshold

A

slow wave; pacemaker

31
Q

example of slow wave:

A

ICCs

32
Q

what cause slow wave?

A

possibly voltage gated Ca channel active at rest

33
Q

AP usually don’t occur in ____

A

multi unit smooth muscle

34
Q

instead of AP, multiunit use _____

A

tonic contractions (graded fashion)

35
Q

3 mech of Ca release:

A

1) Ca thru volt gate L-type channels
2) Ca release from SR
3) Ca etry thry volt independent channels (store and stretch)

36
Q

type of Ca release from SR in smooth muscle?

A

IP3 Ca release from IP3R (less RyR)–> A1 adrenergic

37
Q

smooth muscle have __ instead of T tubules

A

calveoli

38
Q

smooth muscle has ___ SR than skel and cardiac

A

less

39
Q

v Ca in SR activates ____ on SR and communicates with ____

A

STIM1; store operated channels (cause Ca come thru membrane)

40
Q

Ca channel made up of ___ proteins

A

Orai-1

41
Q

IP3 path+store operated channels =

A

pharmacomechanical coupling (no need for AP)

42
Q

ex. of stretch activated channel

A

TRPV 4 (non specific)

43
Q

stretch of smooth muscle cause _____

A

1) internal release Ca from SR through RyR

2) stretch cause phosphorylation of myosin light chain

44
Q

why do we need to phosphorylate regulatory light chain in smooth muscle?

A

Myosin ATPase pretty much turned off , unlike cardiac and skel

45
Q

explain cross bridge cycling in smooth muscle

A

4 Ca bind calmodulin–>Ca-calmodulin activate MLCK–>MLCK phosphorylate regulatory light chain–>^ ATPase activity and can now interact w/ actin (activation of thick fil)

46
Q

how to relax in smooth muscle?

A

reg light chain dephosphorylated by myosin light chain phosphatase, which is mod. by hormones, paracrines, neurotrans (lvl Ca, Ca-CaM)

47
Q

inhibiting ___ or activating ____ can modiy contraction in sm muscle independent of Ca [ ]

A

MLCP; MLCK

48
Q

what is an inhbitor of MLCP?

A

DAG (result of PLC signal path)

49
Q

MLCK is more sensitive to Ca when _____

A

dephosphorylated

50
Q

low energy consumtion/high tension state is referred to as:

A

latch state

51
Q

in cardiac, only ___ can modify contraction

A

symp

Phys 208 (10 decks)

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