Smooth muscle regulation

Question 1

where is smooth muscle present

Answer 1

in walls of hollow organs (GI, bladder, uterus)

Question 2

where is smooth muscle present

Answer 2

in walls of hollow organs (GI, bladder, uterus)

Question 3

smooth muscle contraction and relaxation is

Answer 3

involuntary

Question 4

structure of smooth muscle

Answer 4

no sarcomere, single nucleated, no myofibrils, allows slow sustained contraction

Question 5

there is no… in smooth muscle

Answer 5

troponin

Question 6

what replaces troponin

Answer 6

calmodulin

Question 7

how an increase in calcium concentration results in contraction

Answer 7

1) free calcium binds to calmodulin
2) calcium/calmodulin activates MLCK
3) MLC is phosphorylated by ATP
4) cross bridge formation between myosin head and actin
5) contraction initiated
6) smooth muscle relaxation occurs when MLC phosphorylation is reduced

Question 8

Gq

Answer 8

stimulates contraction

Question 9

Gs

Answer 9

inhibits contraction

Question 10

Gi

Answer 10

elicits contraction

Question 11

Gq are activated by

Answer 11

• angiotensin II (AT2)
• endothelin 1 (ETA)
• vasopressin (V1)

Question 12

Gq pathway

Answer 12

• stimulates Ca2+ release (IP3)
• activates RHO-kinase, which inhibits MLCP
• enhances contraction

Question 13

Gs are activated by

Answer 13

• adrenaline (B2)
• adenosine ((A2)
• prostacyclin (IP)

Question 14

Gs pathway

Answer 14

• increases cAMP
• cAMP inhibits MLCK- reducing MLC phosphorylation
• relaxes SM

Question 15

Gi activated by

Answer 15

noradrenaline (alpha 2)

Question 16

Gi pathway

Answer 16

• cAMP levels reduce
• increasing activity of MLCK
• contraction via MLC

Question 17

cAMP inhibits

Answer 17

MLCK

Question 18

MLCP

Answer 18

inhibits contraction

Question 19

NO causes

Answer 19

vasodilation by activating cGMP which activates MLCP

Question 20

Rho kinase is activated by

Answer 20

Gq- Rho inhibits MLCP

Question 21

smooth muscle contraction and relaxation is

Answer 21

involuntary

Question 22

structure of smooth muscle

Answer 22

no sarcomere, single nucleated, no myofibrils, allows slow sustained contraction

Question 23

there is no… in smooth muscle

Answer 23

troponin

Question 24

what replaces troponin

Answer 24

calmodulin

Question 25

how an increase in calcium concentration results in contraction

Answer 25

1) free calcium binds to calmodulin 2) calcium/calmodulin activates MLCK 3) MLC is phosphorylated by ATP 4) cross bridge formation between myosin head and actin 5) contraction initiated 6) smooth muscle relaxation occurs when MLC phosphorylation is reduced

Question 26

Gq

Answer 26

stimulates contraction

Question 27

Gs

Answer 27

inhibits contraction

Question 28

Gi

Answer 28

elicits contraction

Question 29

Gq are activated by

Answer 29

- angiotensin II (AT2) - endothelin 1 (ETA) - vasopressin (V1)

Question 30

Gq pathway

Answer 30

- stimulates Ca2+ release (IP3) - activates RHO-kinase, which inhibits MLCP - enhances contraction

Question 31

Gs are activated by

Answer 31

- adrenaline (B2) - adenosine ((A2) - prostacyclin (IP)

Question 32

Gs pathway

Answer 32

- increases cAMP - cAMP inhibits MLCK- reducing MLC phosphorylation - relaxes SM

Question 33

Gi activated by

Answer 33

noradrenaline (alpha 2)

Question 34

Gi pathway

Answer 34

- cAMP levels reduce - increasing activity of MLCK - contraction via MLC

Question 35

cAMP inhibits

Answer 35

MLCK

Question 36

MLCP

Answer 36

inhibits contraction

Question 37

NO causes

Answer 37

vasodilation by activating cGMP which activates MLCP

Question 38

Rho kinase is activated by

Answer 38

Gq- Rho inhibits MLCP