Physio/simple/cardio

Front 1

What is tetany?

Back 1

The action potential of skeletal muscle has a sharp rise and fall, as does an axon action potential. Thus rapid, successive discharges of a skeletal muscle fiber can result in tetany, which is the cumulation of multiple sustained contractions with no significant relaxation.

Front 2

Smooth muscle cells in blood vessels contract more slowly than cardiac muscle. TRUE/FALSE

Back 2

TRUE. They have as well a more prolonged action potential and plateau, and are more dependent upon calcium ion influx than are cardiac cells.

Front 3

parasympathetic innervation of the ventricles is minimal, whereas sympathetic fibers innervate all areas of the heart. TRUE/FALSE

Back 3

TRUE.

Front 4

Norepinephrine acts on which receptors?

Back 4

Norepi released by sympathetic fibers interacts with beta-1 receptors on cardiac muscle cells, leading to increased contractility by promoting increased Ca+ influx with each action potential.

Front 5

What does acetylcholine have in common with parasympathetic fibers?

Back 5

These fibers release acetylcholine and are more selective in their innervation.
Acetylcholine increases membrane permeability of the SA node to K+, therby hyperpolarizing the cell membranes and rendering them less susceptible to depolarization.