Muscles--Cardiac/Smooth

Question 1

___ disks contain ___ link myocytes

Answer 1

intercalated; desmosomes

Question 2

___ link electrically

Answer 2

gap junctions

Question 3

have ____ T tubules

Answer 3

wider, less abundant (NEED xtracell Ca)

Question 4

1/3 of cell vol is ___

Answer 4

mitochondria

Question 5

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

Answer 5

autorhythmic (pacemaker)

Question 6

AP gen by ___

Answer 6

HCN channels

Question 7

spontaneous AP mechanism:

Answer 7

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

Question 8

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

Answer 8

connective tissue

Question 9

how is AP diff in contractile cells?

Answer 9

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

Question 10

why is Ca induced ca release necessary?

Answer 10

L-type Ca channel NOT mech coupled to RYR

Question 11

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

Answer 11

graded; Ca

Question 12

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

Answer 12

G-protein

Question 13

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

Answer 13

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

Question 14

mechanism of signal transduction/amplification:

Answer 14

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

Question 15

functions of protein kinase:

Answer 15

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

Question 16

SERCA inhibited by dephosphorylated ___

Answer 16

PLN (phospholamban)

Question 17

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

Answer 17

GIRK; T-type Ca; funny channels

Question 18

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

Answer 18

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

Question 19

why cardiac cells like stretch?

Answer 19

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

Question 20

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

Answer 20

negative; prevent summation, contract/relax in unison

Question 21

____ is absent in smooth muscle

Answer 21

troponin (have calmodulin), T tubules

Question 22

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

Answer 22

dense bodies (like z lines)

Question 23

actin:myosin ratio is ____

Answer 23

15:1

Question 24

4 types of smoooth muscle contraction:

Answer 24

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

Question 25

2 types of communication in smooth muscle:

Answer 25

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

Question 26

Gi constriction by ___ receptors, airway dilation by ____

Answer 26

alpha adrenergic; beta adrenergic

Question 27

examples of multi unit:

Answer 27

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

Question 28

examples of unitary:

Answer 28

viscera

Question 29

why are upstroke and repolarization slower?

Answer 29

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

Question 30

___ potential sometimes reach threshold, __ potential always reach threshold

Answer 30

slow wave; pacemaker

Question 31

example of slow wave:

Answer 31

ICCs

Question 32

what cause slow wave?

Answer 32

possibly voltage gated Ca channel active at rest

Question 33

AP usually don't occur in ____

Answer 33

multi unit smooth muscle

Question 34

instead of AP, multiunit use _____

Answer 34

tonic contractions (graded fashion)

Question 35

3 mech of Ca release:

Answer 35

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

Question 36

type of Ca release from SR in smooth muscle?

Answer 36

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

Question 37

smooth muscle have __ instead of T tubules

Answer 37

calveoli

Question 38

smooth muscle has ___ SR than skel and cardiac

Answer 38

less

Question 39

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

Answer 39

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

Question 40

Ca channel made up of ___ proteins

Answer 40

Orai-1

Question 41

IP3 path+store operated channels =

Answer 41

pharmacomechanical coupling (no need for AP)

Question 42

ex. of stretch activated channel

Answer 42

TRPV 4 (non specific)

Question 43

stretch of smooth muscle cause _____

Answer 43

1) internal release Ca from SR through RyR | 2) stretch cause phosphorylation of myosin light chain

Question 44

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

Answer 44

Myosin ATPase pretty much turned off , unlike cardiac and skel

Question 45

explain cross bridge cycling in smooth muscle

Answer 45

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)

Question 46

how to relax in smooth muscle?

Answer 46

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

Question 47

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

Answer 47

MLCP; MLCK

Question 48

what is an inhbitor of MLCP?

Answer 48

DAG (result of PLC signal path)

Question 49

MLCK is more sensitive to Ca when _____

Answer 49

dephosphorylated

Question 50

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

Answer 50

latch state

Question 51

in cardiac, only ___ can modify contraction

Answer 51

symp