15. Smooth muscle contraction Flashcards Preview

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Flashcards in 15. Smooth muscle contraction Deck (15)
1

MLCK

myosin - light chain kinase

2

MLCK ( myosin - light chain kinase ) action

myosin + actin --> myosin - P + actin

3

Smooth muscle cell - vasodilator

Nitric oxide ( NO)

4

Ca2+ vs No on smooth muscle contraction

Ca2+ --> contraction
NO --> relaxation

5

NO associated relaxation of smooth muscles - process

No --> activation of Guanylate cyclase --> increased cGMP ( from GTP ) --> activation of MLCP --> Myosin +actin ( no Pi) --> relaxation

6

MLCP

mysoin - lught - chain - phosphatase

7

mLCP ( myosin - light -chain - phosphatase ) action

Myosin - P + actin --> Myosin + actin

8

MLCP vs MLCK according action and results

MLCP --> MYosin -P actin ---> Myosin +actin --> relaxation
MLCK --> myosin +actin --> myosin -P +actin --> contraction

9

NO synthase - action

L-argirinine --> NO

10

• In skeletal muscle, calcium binds ___; in smooth muscle, calcium binds ___

Troponin; calmodulin

11

• What are the steps in smooth muscle contraction following calmodulin binding Ca2+?

MLCK is activated, phosphorylating myosin and leading to contraction (relaxation involves MLCP and dephosphorylation of myosin)

12

• What are the steps to relax smooth muscle after contraction?

NO enters cell, guanylate cyclase stimulated, cGMP increases, cGMP actives MLCP, myosin/actin complex dephosphorylated, unbinding/relaxation

13

• Calcium leads to muscle ___ (contraction/relaxation). Nitric oxide leads to muscle ___ (contraction/relaxation).

Contraction (Ca2+ = Contraction); relaxation (nitric oxide = relaxation)

14

• An action potential reaching a smooth muscle cell must activate what type of channel to promote calcium influx into the cell?

L-type voltage gated calcium channels

15

• Myosin-light-chain ____ (kinase/phosphatase) promotes contraction. Myosin-light-chain ____ (kinase/phosphatase) promotes relaxation.

Kinase; phosphorylase

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