Smooth Muscle Physiology

Question 1

What factors affect striated muscle?

Answer 1

• Increased intracellular Ca2+

- stretch

Question 2

Factors affecting smooth muscle

Answer 2

increased intracellular Ca2+
phosphorylation of myosin light chain kinase
inhibition of myosin light chain kinase

Question 3

What causes muscle relaxation?

Answer 3

• drop in Ca2+: returns Ca2+ to pre-excitation levels

- dephosphorylation: myosin light chain phosphatase

Question 4

What are the two types of smooth muscle?

Answer 4

• Multiunit/tonic

- unitary/phasic

Question 5

What is calmodulin?

Answer 5

a Ca2+ binding protein found in cytoplasm of all eukaryotic cells.

Question 6

Describe smooth muscle contraction (E-C coupling).

Answer 6

• Pharmacomechanical coupling: processes by which an agent causes a change in smooth muscle tone without a change in membrane potential.
• Electromechanical coupling: refers primarily to the opening of plasma membrane voltage-activated L-type Ca2+ channels in response to depolarisation
  with, or without, action potential generation