D313 Anatomy and Physiology II - Set 4 - Part 2

Correct Answer: Hemoglobin

Option c is correct because hemoglobin is the iron-containing protein inside erythrocytes that binds oxygen molecules in the lungs and releases them to tissues throughout the body. Option a is incorrect because prothrombin is a clotting protein in the coagulation cascade that gets converted to thrombin and plays no role in oxygen binding or transport. Option b is incorrect because fibrinogen is another blood clotting protein that is converted to fibrin to form clots and is not involved in oxygen transport within red blood cells. Option d is incorrect because albumin is a plasma protein involved in maintaining osmotic pressure and transporting various substances, but it does not bind oxygen inside erythrocytes.

Correct Answer: Converted to bicarbonate ions in plasma

Option a is correct because the majority of carbon dioxide in blood is transported as bicarbonate ions in plasma, formed after carbonic anhydrase catalyzes the reaction inside red blood cells. Option b is incorrect because only a small percentage of carbon dioxide dissolves directly in plasma as a gas, making it the least significant transport method for carbon dioxide. Option c is incorrect because albumin does not serve as a carrier molecule for carbon dioxide transport, and this mechanism does not exist as a recognized pathway for carbon dioxide carriage. Option d is incorrect because binding to hemoglobin as carbaminohemoglobin accounts for a moderate portion of carbon dioxide transport but is not the most common method overall.

Correct Answer: Chloride ions move into the red blood cell

Option c is correct because for every bicarbonate ion that moves out of a red blood cell into plasma, one chloride ion moves in from the plasma to maintain electrical neutrality in the chloride shift. Option a is incorrect because sodium ion movement into red blood cells is not the compensatory exchange mechanism that occurs when bicarbonate ions exit during carbon dioxide transport. Option b is incorrect because potassium ions exiting the cell would worsen the charge imbalance rather than correct it, and this is not part of the chloride shift mechanism. Option d is incorrect because calcium ions do not participate in the chloride shift, and their movement into red blood cells is not the compensatory response to bicarbonate ion departure.

Correct Answer: Hemoglobin releases oxygen more readily in warm acidic conditions

Option d is correct because higher temperature and lower pH reduce hemoglobin's affinity for oxygen, promoting oxygen release to actively working tissues where it is most needed, described by the Bohr effect. Option a is incorrect because warmer and more acidic conditions cause hemoglobin to release oxygen more easily, not bind it more tightly, which would be counterproductive for active tissues. Option b is incorrect because hemoglobin's oxygen affinity is significantly influenced by both temperature and pH changes, and these factors are central to the Bohr effect mechanism. Option c is incorrect because hemoglobin does not denature under the normal physiological temperature and pH changes that occur during exercise, so oxygen transport continues functioning properly.

Correct Answer: Monocytes and lymphocytes

Option b is correct because monocytes and lymphocytes are the two white blood cell types classified as agranulocytes, meaning they lack the prominent visible granules seen in granulocyte cells. Option a is incorrect because both neutrophils and basophils are granulocytes that contain clearly visible granules in their cytoplasm when examined under a microscope. Option c is incorrect because eosinophils and neutrophils are both granulocytes with distinct granules, and neither belongs to the agranulocyte category of white blood cells. Option d is incorrect because basophils are granulocytes with visible granules, so pairing them with monocytes creates an inconsistent grouping that mixes granulocyte and agranulocyte classifications.

Correct Answer: Beta cells of the pancreatic islets

Option c is correct because beta cells in the pancreatic islets produce insulin, the hormone responsible for moving glucose out of the blood and into cells during the absorptive fed state. Option a is incorrect because alpha cells in the pancreatic islets produce glucagon, the hormone that raises blood glucose during fasting, performing the opposite function of insulin in metabolism. Option b is incorrect because delta cells produce somatostatin, a regulatory hormone that modulates the release of other pancreatic hormones rather than directly controlling glucose uptake into cells. Option d is incorrect because acinar cells belong to the exocrine portion of the pancreas and secrete digestive enzymes into the small intestine rather than producing hormones for blood glucose regulation.

Correct Answer: Glucagon triggers glycogenolysis

Option a is correct because glucagon is released from alpha cells during fasting and stimulates glycogenolysis, the breakdown of stored glycogen in the liver to release glucose into the bloodstream. Option b is incorrect because insulin is the dominant hormone during the fed state and promotes glucose storage rather than breakdown, and gluconeogenesis makes new glucose from non-carbohydrate sources. Option c is incorrect because cortisol is a stress hormone and lipogenesis is the synthesis of new fat, which is not the process used to raise blood glucose when glycogen stores are available. Option d is incorrect because while epinephrine can stimulate energy release during stress, lipolysis is the breakdown of triglycerides into fatty acids and is not the initial glycogen breakdown response.

Correct Answer: Insulin dominates after eating and glucagon dominates when the intestines are empty

Option c is correct because insulin is the dominant hormone during the absorptive state after eating, while glucagon takes over during the postabsorptive state when the intestines are empty. Option a is incorrect because insulin and glucagon do not operate at equal levels simultaneously; their relationship is reciprocal, with one rising as the other falls depending on nutrient availability. Option b is incorrect because this reverses the correct relationship; insulin dominates during the fed state after eating, not glucagon, and glucagon dominates during fasting, not insulin. Option d is incorrect because the primary trigger for insulin and glucagon release is nutrient availability in the blood, not whether the person is exercising or sleeping.

Correct Answer: Gluconeogenesis

Option d is correct because gluconeogenesis is the metabolic pathway that synthesizes new glucose from non-carbohydrate sources such as amino acids and glycerol once glycogen reserves have been depleted. Option a is incorrect because glycogenolysis is the breakdown of existing glycogen into glucose, not the creation of new glucose molecules from non-carbohydrate precursors during extended fasting. Option b is incorrect because beta-oxidation breaks down fatty acids into acetyl-CoA for energy production in mitochondria and does not directly produce new glucose molecules for the body. Option c is incorrect because lipogenesis is the process of building new triglycerides from acetyl-CoA for fat storage, which is the opposite metabolic direction from producing glucose during fasting.

Correct Answer: Glucagon is produced by alpha cells

Option a is correct because glucagon is produced specifically by the alpha cells of the pancreatic islets and is released into the bloodstream during fasting to raise blood glucose levels. Option b is incorrect because beta cells produce insulin, the hormone that lowers blood glucose by moving it into cells, which is the opposing hormone to glucagon in metabolic regulation. Option c is incorrect because delta cells produce somatostatin, a regulatory hormone that helps modulate the activity of other hormone-producing cells rather than directly raising blood glucose. Option d is incorrect because acinar cells are part of the exocrine pancreas and produce digestive enzymes that are secreted into the small intestine, not hormones released into the blood.

Correct Answer: Aortic and pulmonary valves

Option b is correct because the second heart sound is produced by the closing of the semilunar valves, which are the aortic valve and the pulmonary valve, after blood has been ejected from the ventricles. Option a is incorrect because the mitral and tricuspid valves are the atrioventricular valves whose closure produces the first heart sound, not the second sound heard during the cardiac cycle. Option c is incorrect because this mixes one atrioventricular valve with one semilunar valve, and the second heart sound requires both semilunar valves closing together, not this combination. Option d is incorrect because while the pulmonary valve is correct, the tricuspid valve is an atrioventricular valve that contributes to the first heart sound rather than the second sound.

Correct Answer: Mitral valve

Option d is correct because the mitral valve, also called the bicuspid valve, is the atrioventricular valve located between the left atrium and left ventricle, and its closure contributes to the first heart sound. Option a is incorrect because the pulmonary valve is a semilunar valve located between the right ventricle and the pulmonary artery, not between the left atrium and left ventricle. Option b is incorrect because the aortic valve is a semilunar valve positioned between the left ventricle and the aorta, controlling blood flow out of the heart rather than between chambers. Option c is incorrect because the tricuspid valve is the atrioventricular valve on the right side of the heart, sitting between the right atrium and right ventricle, not the left side.

Correct Answer: An atrioventricular valve failing to close completely

Option b is correct because an abnormal sound occurring right after the first heart sound during ventricular systole suggests blood is leaking back through an incompletely closed atrioventricular valve. Option a is incorrect because semilunar valve dysfunction would more likely produce abnormalities associated with the second heart sound when those valves close at the end of ventricular ejection. Option c is incorrect because the pulmonary valve opening too early would not typically produce a murmur immediately following the first heart sound, as this is a semilunar valve issue. Option d is incorrect because the aortic valve closing before ejection completes would affect the second heart sound timing, not create an abnormal sound right after the first sound.

Correct Answer: Sixty to one hundred ten beats per minute

Option c is correct because the normal resting heart rate for an adult falls between sixty and one hundred ten beats per minute, and values outside this range may indicate a cardiac condition. Option a is incorrect because forty to fifty-five beats per minute falls below the normal resting range for most adults and could indicate bradycardia unless the person is a trained endurance athlete. Option b is incorrect because one hundred twenty to one hundred fifty beats per minute is well above the normal resting range and would suggest tachycardia or that the person is actively exercising. Option d is incorrect because twenty to forty beats per minute is dangerously low and would be considered a medical emergency requiring immediate evaluation and likely intervention for most adults.

Correct Answer: Right ulnar artery

Option d is correct because the right brachial artery gives rise to the right ulnar artery, which travels along the medial side of the forearm to supply blood to that region. Option a is incorrect because the femoral artery is located in the lower limb and supplies the thigh region, having no anatomical connection to the brachial artery of the upper extremity. Option b is incorrect because while the radial artery does branch from the brachial artery, the question asks specifically about the ulnar side, and the radial artery supplies the lateral forearm instead. Option c is incorrect because the external iliac artery is in the pelvic region and transitions into the femoral artery, placing it entirely in the lower body with no connection to the arm.

Correct Answer: Erythrocytes because iron is part of hemoglobin that carries oxygen

Option c is correct because erythrocytes contain the highest concentration of iron of any cell in the body, since iron is a central component of hemoglobin needed for oxygen binding and transport. Option a is incorrect because white blood cells function in immune defense and do not require large amounts of iron for their pathogen-fighting role compared to red blood cells. Option b is incorrect because platelets are cell fragments involved in clotting and do not contain significant amounts of iron, as their function does not depend on iron-containing proteins. Option d is incorrect because plasma cells produce antibodies as part of the immune response and do not accumulate iron at levels anywhere near those found in red blood cells.

Correct Answer: Prothrombin

Option b is correct because prothrombin is a blood clotting protein that is converted to its active form thrombin during the coagulation cascade, playing a direct role in clot formation. Option a is incorrect because hemoglobin is the oxygen-carrying protein found inside red blood cells and does not participate in the blood clotting cascade or clot formation process. Option c is incorrect because albumin is a plasma protein responsible for maintaining osmotic pressure and transporting various molecules, not for participating in the coagulation cascade. Option d is incorrect because carbonic anhydrase is an enzyme involved in carbon dioxide transport within red blood cells and has no function in the blood clotting process.

Correct Answer: Neutrophils, eosinophils, and basophils

Option d is correct because neutrophils, eosinophils, and basophils are the three types of granulocytes, each containing prominent visible granules in their cytoplasm when viewed under a microscope. Option a is incorrect because monocytes and lymphocytes are both agranulocytes that lack visible granules, so grouping them with the granulocyte basophils creates an incorrect mixed classification. Option b is incorrect because lymphocytes and monocytes are agranulocytes without visible granules, making this grouping inaccurate despite correctly including neutrophils as a granulocyte member. Option c is incorrect because monocytes are agranulocytes lacking visible granules, so including them alongside the granulocytes eosinophils and neutrophils produces an incorrect classification set.

Correct Answer: Its iron-containing structure within each molecule

Option a is correct because hemoglobin contains iron atoms at its core that directly bind oxygen molecules, making iron the essential structural element that enables hemoglobin to carry oxygen. Option b is incorrect because hemoglobin does not rely on calcium-dependent binding sites for oxygen transport, as it is the iron within the heme group that performs the oxygen binding. Option c is incorrect because sodium channels are membrane transport proteins involved in nerve signaling and fluid balance, not structural components of hemoglobin that participate in oxygen binding. Option d is incorrect because potassium-activated transport mechanisms are unrelated to hemoglobin function, as oxygen binding depends on the iron atoms within the heme groups of the molecule.

Correct Answer: Fewer erythrocytes means less hemoglobin and reduced oxygen delivery to tissues

Option c is correct because anemia reduces the number of erythrocytes available, which decreases total hemoglobin and therefore limits the amount of oxygen delivered to tissues, causing fatigue and breathlessness. Option a is incorrect because prothrombin is a clotting protein found in plasma, not inside erythrocytes, so a reduction in red blood cells would not directly reduce prothrombin levels or impair clotting. Option b is incorrect because while carbonic anhydrase exists in red blood cells, the primary symptom-causing problem in anemia is reduced oxygen delivery through hemoglobin, not carbon dioxide buildup. Option d is incorrect because albumin is a plasma protein produced by the liver, not a component of erythrocytes, so red blood cell reduction does not directly affect albumin levels or cause fluid leakage.