D313 Anatomy and Physiology II - Set 4 - Part 1

Correct Answer: Nitrogen

Option b is correct because bile stored in the gallbladder emulsifies dietary fats into smaller droplets in the duodenum, increasing surface area for pancreatic lipase to act upon. Option a is incorrect because beta-oxidation occurs inside mitochondria after absorption and is not a digestive step that would be directly affected by gallbladder removal. Option c is incorrect because glycerol conversion happens after triglycerides have already been digested and absorbed, placing it well beyond the point where bile is needed. Option d is incorrect because chylomicron assembly takes place inside intestinal epithelial cells after absorption, not during the digestion phase that bile supports.

Correct Answer: High-density lipoproteins

Option a is correct because high-density lipoproteins scour the bloodstream for excess cholesterol molecules and transport them back to the liver for processing or to steroid-producing glands. Option b is incorrect because chylomicrons transport absorbed dietary fats from the intestines into the lymphatic system and bloodstream, not cholesterol back to the liver. Option c is incorrect because very low-density lipoproteins carry triglycerides synthesized in the liver outward to tissues and are not responsible for cholesterol return. Option d is incorrect because low-density lipoproteins deliver fats and cholesterol to tissues and the liver but are not the primary scavenger removing excess cholesterol from blood.

Correct Answer: Pancreatic lipase

Option d is correct because pancreatic lipase acts in the duodenum to break triglycerides into their component fatty acids and monoglycerides, performing the majority of chemical fat digestion. Option a is incorrect because gastric lipase begins a small amount of fat digestion in the stomach, but it is not the primary enzyme responsible for triglyceride breakdown. Option b is incorrect because carbonic anhydrase catalyzes the conversion of carbon dioxide and water into carbonic acid, which is unrelated to lipid digestion entirely. Option c is incorrect because bile salts emulsify fats to increase the surface area available for enzymatic action but do not themselves chemically break down triglycerides.

Correct Answer: They have the lowest protein percentage

Option c is correct because chylomicrons are large lipoprotein particles that contain the lowest percentage of protein compared to all other lipoproteins, carrying mostly triglycerides. Option a is incorrect because chylomicrons actually contain the least protein of any lipoprotein class, making this statement the direct opposite of their known composition. Option b is incorrect because chylomicrons first enter the lymphatic system before reaching the bloodstream, and they travel through both veins and arteries afterward. Option d is incorrect because chylomicrons are assembled inside the epithelial cells of the small intestine, not produced by the pancreas, which secretes digestive enzymes instead.

Correct Answer: Low-density lipoproteins transporting excess dietary fats and glucose

Option b is correct because low-density lipoproteins are nicknamed bad cholesterol and transport excess dietary fats and glucose from the liver to adipose tissue and other sites. Option a is incorrect because high-density lipoproteins are considered good cholesterol since they remove excess molecules from the bloodstream and return them to the liver. Option c is incorrect because chylomicrons transport dietary fat from the intestines into the lymphatic system and blood, but they are not the lipoproteins called bad cholesterol. Option d is incorrect because albumin is a general plasma protein that may carry some fatty acids, but it is not classified as a lipoprotein and is not referred to as bad cholesterol.

Correct Answer: Beta-oxidation

Option d is correct because beta-oxidation is the mitochondrial process that breaks fatty acid chains into sequential two-carbon acetyl-CoA units, serving as a major ATP source during fasting. Option a is incorrect because lipogenesis is the opposite process, building up lipid molecules from acetyl-CoA rather than breaking fatty acids down into acetyl-CoA for energy. Option b is incorrect because glycogenolysis is the breakdown of glycogen into glucose and does not involve the conversion of fatty acid chains into acetyl-CoA units. Option c is incorrect because gluconeogenesis is the synthesis of new glucose molecules from non-carbohydrate sources and does not describe the mitochondrial breakdown of fatty acids.

Correct Answer: Lipolysis

Option a is correct because lipolysis refers specifically to the hydrolysis reaction that splits stored triglycerides into their components of glycerol and free fatty acids for further processing. Option b is incorrect because beta-oxidation is the step that follows lipolysis, occurring inside the mitochondria where fatty acids are chopped into two-carbon acetyl-CoA units. Option c is incorrect because ketogenesis is the production of ketone bodies from excess acetyl-CoA in the liver, not the initial splitting of triglycerides into components. Option d is incorrect because lipogenesis is the synthesis or building of new triglycerides from acetyl-CoA, which is the reverse direction of fat breakdown, not hydrolysis.

Correct Answer: Liver produces them and the brain uses them

Option b is correct because the liver generates ketone bodies from excess acetyl-CoA during prolonged fasting, and the brain can switch to using ketone bodies when glucose availability drops. Option a is incorrect because the kidneys do not produce ketone bodies during fasting, and while muscles can use various fuels, this pairing misidentifies the production site entirely. Option c is incorrect because adipose tissue releases fatty acids through lipolysis but does not produce ketone bodies, and the pancreas secretes hormones rather than consuming ketones for fuel. Option d is incorrect because the small intestine is involved in nutrient absorption and does not produce ketone bodies, though the heart does eventually use ketones during prolonged starvation.

Correct Answer: Acetoacetate

Option d is correct because acetoacetate is a well-recognized ketone body produced by the liver from excess acetyl-CoA when fatty acid breakdown outpaces the citric acid cycle capacity. Option a is incorrect because prothrombin is a blood clotting protein that is converted to thrombin during the coagulation cascade and has no connection to ketone body metabolism. Option b is incorrect because carbaminohemoglobin is a compound formed when carbon dioxide binds to hemoglobin for transport in blood and is unrelated to ketone production. Option c is incorrect because bicarbonate is an ion formed during carbon dioxide transport in the blood and plays a role in acid-base balance, not in ketone body metabolism.

Correct Answer: Lipogenesis

Option a is correct because lipogenesis converts excess glucose into acetyl-CoA and then into triglycerides, storing surplus energy as fat in adipose tissue when glycogen stores are full. Option b is incorrect because glycogenolysis is the breakdown of glycogen back into glucose for energy use, not a process that converts surplus glucose into stored triglycerides. Option c is incorrect because gluconeogenesis is the creation of new glucose from non-carbohydrate precursors during fasting, which is the opposite metabolic direction from fat storage. Option d is incorrect because beta-oxidation is the mitochondrial breakdown of fatty acids into acetyl-CoA for energy production, not a process that builds new fat from excess glucose.

Correct Answer: Insulin released from beta cells to move glucose into cells

Option d is correct because insulin is the dominant hormone during the absorptive state, produced by beta cells in the pancreatic islets, driving glucose from blood into cells for use or storage. Option a is incorrect because glucagon is the dominant hormone during the postabsorptive or fasting state, released by alpha cells to raise blood glucose, not lower it after eating. Option b is incorrect because cortisol plays a role in stress response and long-term glucose regulation but is not the primary hormone managing blood glucose during the absorptive state. Option c is incorrect because epinephrine is associated with the fight-or-flight response and stimulates quick energy release, not the routine storage of nutrients after a normal meal.

Correct Answer: Glucagon is released and stored glycogen is broken down

Option a is correct because during the postabsorptive state, alpha cells release glucagon, and the body begins glycogenolysis to break down stored glycogen and maintain blood glucose levels. Option b is incorrect because insulin levels fall during the fasting state and lipogenesis decreases since the body is mobilizing stored energy rather than creating new fat reserves. Option c is incorrect because beta cells produce insulin which dominates during the fed state, and glucose entry into adipose tissue slows down during fasting rather than increasing. Option d is incorrect because glycogenolysis actively increases during fasting as the body taps glycogen reserves, and protein synthesis does not accelerate when nutrients are scarce.

Correct Answer: Basal metabolic rate

Option b is correct because the basal metabolic rate represents the amount of energy the body expends each day to maintain basic life-sustaining functions such as breathing, circulation, and cell activity. Option a is incorrect because cardiac reserve refers to the difference between maximum cardiac output and resting cardiac output, which measures heart capacity rather than total daily energy expenditure. Option c is incorrect because cardiac output is the volume of blood the heart pumps per minute, a cardiovascular measurement that does not describe overall daily baseline energy consumption. Option d is incorrect because the respiratory quotient is a ratio comparing carbon dioxide produced to oxygen consumed during metabolism and does not define baseline daily energy requirements.

Correct Answer: Amino acids from muscle protein after fat stores deplete

Option a is correct because the body uses amino acids from muscle protein as its last resort fuel source once glycogen and fat stores are exhausted, directly causing muscle wasting and organ damage. Option b is incorrect because glycogen is actually the first energy source depleted during starvation, typically lasting only twelve to twenty-four hours before the body switches to fat mobilization. Option c is incorrect because the brain adapts well to using ketone bodies during extended fasting and does not reject them, making this an inaccurate description of starvation progression. Option d is incorrect because mitochondria continue performing beta-oxidation during starvation to generate energy from fats and do not simply stop functioning as fuel sources remain available.

Correct Answer: Glycogen first, then fat stores, then muscle protein

Option d is correct because the body depletes glycogen within roughly twelve to twenty-four hours, then mobilizes fat reserves producing ketone bodies, and finally catabolizes muscle protein as a last resort. Option a is incorrect because the body does not begin with fat stores during starvation; glycogen is the first and most immediately accessible energy reserve that gets used before fat mobilization begins. Option b is incorrect because muscle protein is the last energy source the body resorts to, not the first, since breaking down structural proteins causes serious damage to organs and tissues. Option c is incorrect because after glycogen depletion the body turns to fat stores next, not muscle protein, since fat reserves are a much larger and safer energy source to tap before sacrificing muscle.

Correct Answer: Pericardium with pericardial fluid

Option b is correct because the pericardium is the fibrous sac surrounding and anchoring the heart, and the pericardial cavity within it contains lubricating pericardial fluid that prevents friction. Option a is incorrect because the pleural membrane surrounds the lungs rather than the heart, and serous fluid in that space serves pulmonary function instead of cardiac protection. Option c is incorrect because the endocardium is the inner lining of the heart chambers and does not serve as an external protective sac anchoring the heart in position. Option d is incorrect because the myocardium is the muscular middle layer of the heart wall responsible for contraction, and cerebrospinal fluid surrounds the brain and spinal cord, not the heart.

Correct Answer: Bicuspid valve closing at the start of ventricular contraction

Option d is correct because the first heart sound is produced by the closing of the atrioventricular valves, and the bicuspid or mitral valve closing specifically corresponds to this first sound. Option a is incorrect because the aortic valve is a semilunar valve whose closure contributes to the second heart sound, not the first sound heard during the cardiac cycle. Option b is incorrect because the pulmonary valve is also a semilunar valve that closes to produce the second heart sound along with the aortic valve, not the first sound. Option c is incorrect because valve opening does not typically produce the heart sounds heard through a stethoscope; sounds are generated by the closing of valves, not their opening.

Correct Answer: Ventricular systole when ventricles contract and eject blood

Option a is correct because the QRS complex on an electrocardiogram represents ventricular depolarization, which triggers ventricular systole, the contraction phase when ventricles forcefully eject blood outward. Option b is incorrect because atrial depolarization is represented by the P wave on the electrocardiogram, not the QRS complex, and it occurs before the ventricles begin contracting. Option c is incorrect because ventricular repolarization is represented by the T wave on the electrocardiogram, which follows the QRS complex and represents the ventricles recovering and relaxing. Option d is incorrect because atrial systole corresponds to the P wave and the contraction of the atria, not the large QRS deflection that signals ventricular contraction on the tracing.

Correct Answer: Cardiac reserve

Option b is correct because cardiac reserve is defined as the difference between the maximum cardiac output a heart can achieve during exertion and the resting cardiac output at baseline. Option a is incorrect because stroke volume is the amount of blood ejected by one ventricle in a single beat, not the difference between maximum and resting cardiac output values. Option c is incorrect because blood pressure measures the force exerted by blood against arterial walls and does not describe the gap between maximum and resting heart pumping capacity. Option d is incorrect because ejection fraction is the percentage of blood in a ventricle that is pumped out during each contraction, not a measure of the reserve between maximum and resting output.

Correct Answer: Femoral artery

Option d is correct because the external iliac artery transitions into the femoral artery once it passes out of the body cavity and enters the lower limb at the thigh region. Option a is incorrect because the popliteal artery is found behind the knee and is a continuation further downstream in the leg, not the direct successor of the external iliac artery. Option b is incorrect because the tibial arteries branch off further down in the lower leg below the knee and are not the immediate continuation of the external iliac at the thigh. Option c is incorrect because the brachial artery is located in the upper arm and supplies the upper extremity, having no anatomical connection to the external iliac artery or the lower limb.