Anatomy & Physiology NCLEX-PN Practice Quiz

Systole begins with ventricular contraction. During this phase, the mitral and tricuspid valves close (producing S1, the 'lub' sound), and blood is ejected through the aortic and pulmonic valves into the great vessels. The atria fill during ventricular systole.

The alveoli are tiny air sacs at the end of the bronchial tree where gas exchange occurs. Oxygen diffuses from the alveoli into the pulmonary capillaries, and carbon dioxide diffuses from the blood into the alveoli to be exhaled. The alveoli are surrounded by a dense network of capillaries to maximize surface area for exchange.

Bile is produced by the liver, stored in the gallbladder, and released into the duodenum when fatty food is present. Bile emulsifies fat -- breaking large fat globules into smaller droplets so that pancreatic lipase can more effectively digest them. Without bile, fat-soluble vitamins (A, D, E, K) cannot be absorbed.

The medulla oblongata, located in the brainstem, controls vital involuntary functions including respiratory rate, heart rate, blood pressure, and reflexes such as coughing, sneezing, swallowing, and vomiting. Damage to the medulla is often incompatible with life because these automatic functions cease.

The liver makes clotting factors (fewer factors -> bleeding risk), clears ammonia (buildup -> confusion and hepatic encephalopathy), and processes bilirubin (buildup -> jaundice). It also makes albumin, and in failure albumin FALLS rather than rises -- the low albumin is exactly what pulls fluid into the tissues and abdomen, producing edema and ascites. The liver produces FEWER clotting factors in failure, and with no bile reaching the gut fat absorption WORSENS (fatty, clay-colored stools).