Myometrium Physiology: Smooth Muscle: Young

Question 1

Life is the maintenance of an ionic gradient. What is the dominant ion on the inside of the cell?

Answer 1

K

Question 2

How does K get into the cell?

Answer 2

Na/K exchanger ATPase

Question 3

What is the dominant member of a membrane?

Answer 3

Lipid

Question 4

How thick is the membrane relative to the cell?

Answer 4

Like a basketball rubber thickness relative to cell

Question 5

What causes shortening of the cell?

Answer 5

Actin and myosin shortening

Question 6

What ion causes actin and myosin to shorten?

Answer 6

Ca+2

Question 7

What is concentration of Ca+2 within the cell?

Answer 7

100 nanomolar Ca+2

Question 8

What goes over the actin and interacts with Ca?

Answer 8

Calmodulin

Question 9

Where does Ca come from to flood the cell?

Answer 9

Sarcoplasmic reticulum

Question 10

What other mechanism raises intracellular calcium?

Answer 10

L type Dihydropyrodine Ca Channel: Ca Channel on membrane

Question 11

What clinical drug inhibits L type Dihydropyridine Ca channel?

Answer 11

NIfedipine: Dihydropyridine blocker

Question 12

What agonist modulates the 7 transmembrane receptor of the myometrial smooth muscle cell?

Answer 12

1. Epi

2. Oxytocin

Question 13

What is the 7 TM receptor coupled to?

Answer 13

G protein on inside

Question 14

What is the name of the signaling compound activated by G protein?

Answer 14

IP3

Question 15

Where does IP3 act?

Answer 15

Sarcoplasmic reticulum

Question 16

What receptor does IP3 act on in SR?

Answer 16

IP3 receptor

Question 17

What is the resting potential of a smooth muscle cell?

Answer 17

-40

Question 18

What is the maximum voltage of a smooth muscle cell?

Answer 18

+10

Question 19

Where does Ca begin to enter cell in action potential curve?

Answer 19

Phase 2

Question 20

How does Ca get removed from cytoplasm?

Answer 20

1. (SCRCA pump) ScR Ca ATPase pumps it back into SR
2. Pumped out of cell by CaATPase on membrane
3. Na/Ca Exchanger on membrane

Question 21

How does cell A communicate with cell B?

Answer 21

CONNEXIN 43: gap junction for electrical communication

Question 22

What is the stretch activated K channel?

Answer 22

When you stretch a cell, K leaves

Question 23

What happens with K leaves the cell?

Answer 23

Hyperpolarizes cell

Cell naturally depolarizes to threshold

Question 24

What is the threshold of the AP in the smooth muscle cell?

Answer 24

-35

Question 25

What happens when AP reaches threshold in sm cell?

Answer 25

Ca rushes in

Question 26

What is activated to release Ca from SR?

Answer 26

Ryanodine receptor

Question 27

How high does the Ca concentration increase from 100 nm resting concentration?

Answer 27

700-800 nm

Question 28

What happens when Ca concentration increases in cell?

Answer 28

Binds calmodulin | Reveals actin binding site, myosin slides across with ATP binding: CONTRACTION

Question 29

What pumps Ca back into the SR?

Answer 29

SRCA

Question 30

What allows Ca to exit cell?

Answer 30

Ca ATPase | Na/Ca exchanger

Question 31

How does smooth muscle relax?

Answer 31

Ca is pumped out of cell

Question 32

What causes tissue to contract?

Answer 32

Stretching

Question 33

How do you maintain membrane potential?

Answer 33

Leak and pumps

Question 34

Is there a DK channel in the uterine smooth muscle to allow Ca in and out of cell?

Answer 34

No... must be another one

Question 35

What is ROMK?

Answer 35

Volatage activated K channel

Question 36

What depolarizes membrane potential?

Answer 36

K channel: DK channel (delayed

Question 37

What starts all of these contractions?

Answer 37

Oxytocin!

Question 38

Does the uterine sm act as a syncytium?

Answer 38

Yes! Gap junctions: CONNEXIN 43

Question 39

What has to happen for myometrium to be ready to contract?

Answer 39

Make CONNEXIN 43 Make Calmodulin etx... make the players

Question 40

How long does it take for myometrium to be activated?

Answer 40

7-10 days

Question 41

What from the baby goes to the myometrium of the mother to start activation of structural proteins there?

Answer 41

Protein A from surfactant | increases sex hormones in myometrium

Question 42

The relationship of the funduus to the cervix is almost exclusively due to?

Answer 42

Prostaglandins Inflammation (oxytocin in labor)

Question 43

This stuff is important... will you know it in your 3rd year?

Answer 43

Yes. Memorize it. Especially the attack points. And that it is redundant. There are 3 ways for Ca get out . Why? So that if one breaks, the others continue life on.