Quiz 2 - 13.3 questions

What is the difference in how contraction force is varied in multiunit and single-unit smooth muscle?

Multiunit smooth muscle increases force by recruiting additional muscle fibers; single-unit smooth muscle increases force by increasing Ca2+ entry

When the circular muscle layer of the intestine contracts, what happens to the shape of the tube? When the longitudinal layer contracts, what happens to the shape?

Contraction of the circular layer decreases the diameter of a tube. Contraction of the longitudinal layer shortens the tube.

Three weeks later, Paul had another attack of paralysis, this time at kindergarten after a game of tag. He was rushed to the hospital and given glucose by mouth. Within minutes, he was able to move his legs and arms and asked for his mother.

Q5: Explain why oral glucose might help bring Paul out of his paralysis.

Glucose stimulates insulin release, and insulin increases Na+/K+ ATPase activity. What happens to the extracellular K+ level when Na+/K+ ATPase is more active?

The dense bodies that anchor smooth muscle actin are analogous to what structure in a sarcomere?

Dense bodies are analogous to Z disks.

Name two ways smooth muscle myosin differs from skeletal muscle myosin.

Smooth muscle myosin is longer and has heads the entire length of the filament.

Name one way actin and its associated proteins differ in skeletal and smooth muscle.

Smooth muscle actin lacks troponin.

Graph A. Phosphorylation increases myosin ATPase activity and crossbridge formation.