Lec 16: Smooth muscle: structure and activation

Question 1

What does smooth muscle do?

Answer 1

Squeezes our pipes: vascular tone - blood pressure, airway diametre - regulation of ventilation, GI transit (peristalsis) - movement of food, Sphincters - control of bladder, glandular secretions

Question 2

Describe the structure of smooth muscle

Answer 2

single nucleus, able to proliferate, arranged in sheets for form muscle, not striated but rely upon myosin and actin filaments, no troponin

Question 3

Describe how muscle contraction works in smooth cells

Answer 3

Actin and myosin are losely arraged around the periphery of the cell, held in place by protein dense bodies, the arrangement of the fibres causes the cell to become globular when is contracts, myosin can slide along actin for long distances without encountering the end of a sarcomere.

Question 4

What control smooth muscle?

Answer 4

Autonomic nervous system: sympathetic (fight or flight) and parasympathetic (rest/digest), hormonal secretions, spontaneous electrical activity - peristalsis