What prevents an action potential from moving backward along the axon? In other words, why do action potentials move in one direction only, down the axon away from the cell body?
A. The refractory period prevents the action potential from moving backward.
B. Myelin sheaths prevent the action potential from moving backward.
C. In some axons, action potentials do move backward.
Answer: A
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The diameter of the airways in normal lungs is generally great enough that little resistance is offered to airflow.
Answer the following statement true (T) or false (F)
As a person ages,
A) the skin becomes more elastic. B) lung tissue becomes more elastic. C) peristalsis and muscle tone decrease. D) all hormone levels decrease. E) peristalsis and muscle tone decrease and some hormone levels decrease.
Which vessel type typically has an internal diameter of about 30 ?m and has a tunica media comprised of 1-2 layers of smooth muscle cells?
A) capillaries B) muscular arteries C) arterioles D) venules E) elastic arteries
The entire cardiovascular system is lined internally with a special type of epithelial tissue called _______
Fill in the blank(s) with correct word