A neuromodulator
A. inactivates neurotransmitters.
B. acts as a neurotransmitter.
C. is a receptor site for a neurotransmitter.
D. is a substance released from neurons that influences the sensitivity of neurons to neurotransmitters.
E. has no influence on the amount of neurotransmitter released.
Answer: D
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The center cavity of the diaphysis of a long bone is called the __________.
A. marrow cavity B. central canal C. nutrient foramen D. canaliculus E. epiphysis
Which statement is incorrect?
a. Juxtamedullary nephrons establish a vertical osmotic gradient in the medulla. b. NaCl pumps of the ascending limb of the loop of Henle can establish a 1,200 mOsm/liter difference between ascending and descending limbs at any given location. c. Countercurrent exchange allows the vasa recta to preserve the vertical osmotic gradient while supplying blood to the medullary tissue. d. Collecting tubules of all nephrons utilize the driving force of the vertical osmotic gradient to accomplish variable H2O reabsorption under the control of vasopressin. e. The filtrate is isotonic as it enters the loop of Henle, hypertonic at the tip of the loop of Henle, and hypotonic as it leaves the loop of Henle.
Broca's area is located on the cerebral cortex of the ____ lobe
a. frontal. b. occipital. c. parietal. d. temporal. e. insula.
After her last check-up, Harriet was informed that her active Vitamin D levels were low. Which of the following conditions may explain why this is so?
A. Melanin production has increased due to sun exposure, reducing Vitamin D activation. B. An increase in Vitamin D absorption at the intestines has overwhelmed the homeostasis of vitamin production at the kidneys. C. Liver dysfunction has reduced the conversion of cholecalciferol to the intermediate for calcitriol production.