Smooth Muscle

Question 1

Calcium is required in smooth muscle to initiate contraction. What are the 2 sources of calcium to start this

Answer 1

Sarcoplasmic reticulum (calcium storage inside the cell)
Extracellular calcium (into cells through channels)

Question 2

Relaxation of smooth muscle requires calcium to return to pre-contraction levels. What are the 3 mechanisms that lower calcium levels of smooth muscle cells

Answer 2

SERCA, Na+/Ca++ antiporter, Ca++ ATPase
Calcium pumps

Question 3

What property of smooth muscle found in sphincters allows for tonic contractions that exhibit high levels of contraction for a prolonged period of time

Answer 3

Cells produce a latch state that is a low energy contractile state

Question 4

Function of gap junctions

Answer 4

Allow spread of excitation therefore providing synchronous contraction of linked muscle cells

Question 5

What happens to flow rates in airways and arteries when there is contraction of smooth muscle cells

Answer 5

Flow of airways or arteries decreases

Question 6

An influx of which ions into a smooth muscle cell can result in a pacemaker potential

Answer 6

Sodium and calcium