Heart valves open and close in response to __________.
A. Electrical activity in the autorhythmic cells
B. Activity of papillary muscles
C. Pressure changes in heart chambers
D. Autonomic innervation
Answer: C. Pressure changes in heart chambers
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A ribosome exists as an association between different ribosomal protein subunits. The entire structure of the ribosome with its associations between subunits is considered the
A. primary structure. B. quaternary structure. C. tertiary structure. D. secondary structure.
Basically, what occurs in the countercurrent multiplier process?
A) Sodium is pumped into the blood while potassium is actively transported out of the blood back into the tissues. B) A higher sodium concentration is produced in the renal medulla that osmotically draws out water, reducing it within the tubules and the urine. C) Glucose and sodium are cotransported from urine back into blood. D) Creatinine is actively transported out of the blood into urine. E) Uric acid is excreted into the kidney tubules while urea is reabsorbed in the nephron loop.
This figure shows an example of regulation of hormone secretion by a negative feedback loop. The large box labeled 1 represents the initial stimulus. Which could be the initial stimulus for this pattern of regulation?
A. Low blood sugar level B. High WBC (white blood cell) count C. High blood calcium level D. Low body temperature E. Low RBC (red blood cell) count
Which of the following would be most associated with process of warming and humidifying inhaled air?
A) the paranasal sinuses B) the bones comprising the orbits C) the cranial bones D) hyoid bone