13 Smooth Muscle Physiology

Question 1

Do we see more actin in smooth muscle or skeletal muscle?

Answer 1

Much more actin in smooth muscle

(There is a lot more myosin in skeletal muscle)

Question 2

Where does most of the calcium for contraction of a smooth muscle cell come from?

Answer 2

Outside the cell (not the sarcoplasmic reticulum)

Question 3

What are the three methods for getting calcium out of a smooth muscle cell (that were covered in class)?

Answer 3

SERCA

Sodium / Calcium antiporters

Sarcolemmal Ca2+ ATPase

Question 4

What does calcium bind to in smooth muscle cells to initiate a contraction?

Answer 4

Calmodulin

Question 5

What is activated by Calmodulin after it binds to calcium?

Answer 5

Myosin light chain kinase

(Phosphorylates myosin light chains)

Question 6

What are the functions of angiotensin II, vasopressin, and endothelin I?

Answer 6

They contract smooth muscle

Question 7

What is the function of adenosine on smooth muscle?

Answer 7

Relaxes smooth muscle

Question 8

What ion is primarily responsible for generating action potential in smooth muscle?

Answer 8

Calcium

Question 9

What is different about the length tension curve between skeletal and smooth muscle?

Answer 9

Smooth muscle can adjust its length tension curve in order to maintain closer to the ideal.