The pacemaker potential produced in autorhythmic cells is due to the presence of
a. a continuously depolarizing membrane that slowly reaches threshold.
b. intercalated discs at cell junctions.
c. desmosomes.
d. many large mitochondria in the cytoplasm.
Answer: a. a continuously depolarizing membrane that slowly reaches threshold.
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When the tidal volume is large, as during exercise, the Bohr reflex is triggered to prevent over-inflation of the lungs
a. True b. False Indicate whether the statement is true or false
Platelets are continually produced in the red bone marrow by cells called ________.
Fill in the blank(s) with the appropriate word(s).
Air flows out of the body during expiration because
A. intrapulmonary pressure is greater than atmospheric pressure. B. intrapleural pressure is greater than intrapulmonary pressure. C. intrapleural pressure is greater than atmospheric pressure. D. atmospheric pressure is greater than intrapulmonary pressure.
Match each of the terms with its definition or description.
a. pia mater b. dura mater c. cranial nerves d. spinal nerves e. arachnoid mater f. dermatome g. parasympathetic nervous system h. sympathetic nervous system i. acetylcholine j. norepinephrine 1. _____ Skin surface that is supplied by a single spinal nerve 2. _____ Outermost and toughest of the meninges 3. _____ 31 pairs of these make up part of the peripheral nervous system 4. _____ “Cobweb”–like part of the meninges 5. _____ Regulates the “fight or flight” response 6. _____ Thin innermost layer of the meninges 7. _____ 12 pairs of these make up part of the peripheral nervous system 8. _____ Neurotransmitter that is released from the postganglionic axons of the parasympathetic nervous system 9. _____ Sometimes called the craniosacral nervous system 10. _____ Neurotransmitter that is released from the postganglionic axon or the sympathetic nervous system