Which of the following statements correctly describes why a series of closely spaced action potentials causes a sustained contraction rather than a series of closely spaced twitches?
When a series of action potentials is closely spaced, there is not sufficient time for Ca2+ uptake into the sarcoplasmic reticulum between action potentials, and Ca2+ remains bound to troponin throughout the series.
During inhalation, the diaphragm and rib muscles ________, causing the volume of the lungs to __________.
Select the order that air enters the lungs, starting with entering the nose or mouth. 1. bronchioles 2. trachea 3. alveoli 4. bronchi
2, 4, 1, 3
Oxygen diffuses from the _______ to ___________ in the lungs.
Carbon dioxide diffuses from _______ to ______, while oxygen diffuses from _____ to _______.
body tissues to blood.... blood to body tissues.
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