The umbilical cord is a blood vessel-containing stalk of tissue that connects the embryo to the placenta
Indicate whether the statement is true or false
TRUE
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Twitch summation
a. results from increases in cytosolic calcium levels b. results from pumping of calcium into the sarcoplasmic reticulum c. can be enhanced by allowing a cell to completely relax d. rarely results in tetany e. is not characterized by any of the above
Which of these is a major difference between smooth muscle and skeletal muscle?
A. Only skeletal muscle requires increased calcium ion concentration in the cytosol for contraction. B. Only skeletal muscle has both actin and myosin. C. Myosin is the main regulatory protein in smooth muscle. D. Myosin is the main regulatory protein in skeletal muscle. E. Skeletal muscle usually exhibits spontaneous activity, while smooth muscle cannot contract spontaneously.
If acetylcholine binds to muscarinic receptors,
A. Na+ channels open. B. Ca2+ channels open. C. adrenaline is released. D. G proteins mediate the cell's response. E. the response is neither excitatory nor inhibitory.
Imagine a patient who loses lots of blood and therefore has less stretch of their aorta with each heartbeat. What reflex will result?
A. Baroreceptors increase firing, the vasomotor center increases firing, and skin blood vessels will dilate to cause a compensatory increase in flow. B. Baroreceptors decrease firing, the cardioacceleratory center increases firing, and cardiac output will exhibit a compensatory increase. C. Baroreceptors increase firing, the cardioinhibitory center increases firing, and the heart slows significantly to prevent further bleeding. D. Baroreceptors decrease firing, the cardioinhibitory center and vasomotor centers increase firing, the heart slows, and