Lecture 8: Vascular Excitation-Contraction Coupling

Question 1

Which ion is ultimately responsible for cellular contraction?

Answer 1

Calcium. (Ca2+)

Question 2

Vascular tone refers to the fact that vascular smooth muscle is continuously what?

Answer 2

Continuously active. So can be contracted more or relaxed but it is constantly active.

Question 3

Does the majority of calcium come from inside or outside the cell?

Answer 3

Outside!

Question 4

How does calcium result in contraction?

Answer 4

Intracellular calcium increases -> it binds to and activates Calmodulin -> calmodulin activates MLCK -> MLCK phosphorylates Myosin using an ATP molecule -> actin and myosin can now interact and generate force (contraction!) and this also uses an ATP molecule.