Nokea
Which of the following is a role of platelets in hemostasis?
- A. formation of plugs
- B. promotion of vasodilation
- C. conversion of prothrombin to thrombin
- D. activation of calcium
Correct Answer: A
Rationale: Platelets play a crucial role in hemostasis by forming plugs to stop bleeding. Choice B is incorrect because platelets do not promote vasodilation; instead, they help in vasoconstriction. Choice C is incorrect as the conversion of prothrombin to thrombin is a function of the coagulation cascade involving various clotting factors, not platelets. Choice D is incorrect as platelets do not directly activate calcium; instead, they play a role in the activation of other clotting factors.
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What is the maximum capacity of a normal adult bladder before involuntary micturition is likely to occur?
- A. 800-900ml
- B. 300-600ml
- C. 1000-2000ml
- D. 400-700ml
Correct Answer: B
Rationale: The correct answer is B: 300-600ml. A normal adult bladder can hold approximately 300-600ml of urine before the urge to urinate becomes strong and involuntary micturition is likely to occur. Choice A (800-900ml), Choice C (1000-2000ml), and Choice D (400-700ml) all exceed the typical capacity of a normal adult bladder and would generally not be accurate in the context of involuntary micturition.
Which of the following bones is a component of the appendicular skeleton?
- A. Xiphoid process
- B. Symphysis pubis
- C. Sacrum
- D. Sternum
Correct Answer: B
Rationale: The correct answer is B: Symphysis pubis. The symphysis pubis is a component of the appendicular skeleton, specifically part of the pelvic girdle. The xiphoid process (Choice A) is part of the axial skeleton, located at the lower end of the sternum. The sacrum (Choice C) is also part of the axial skeleton, forming the posterior part of the pelvis. The sternum (Choice D) is part of the axial skeleton, located in the center of the chest.
Which part of the nephron is closest to the collecting duct?
- A. Distal convoluted tubule (DCT)
- B. Bowman's Capsule
- C. Afferent Arteriole
- D. Proximal Convoluted Tubule (PCT)
Correct Answer: A
Rationale: The correct answer is the Distal convoluted tubule (DCT). The DCT is the part of the nephron closest to the collecting duct, where the final adjustments to electrolyte and fluid balance are made. Bowman's Capsule is located at the beginning of the nephron, where filtration of blood occurs. The Afferent Arteriole brings blood to the glomerulus for filtration. The Proximal Convoluted Tubule (PCT) is situated after the Bowman's Capsule and is not the part closest to the collecting duct.
What effect does aldosterone secretion have on electrolyte levels?
- A. Calcium levels are decreased
- B. Sodium levels are increased
- C. Potassium levels are increased
- D. Magnesium levels are decreased
Correct Answer: B
Rationale: Aldosterone is a hormone that primarily acts on the kidneys to increase the reabsorption of sodium and water into the bloodstream. As a result, sodium levels are increased. Choices A, C, and D are incorrect. Aldosterone does not significantly affect calcium, potassium, or magnesium levels.
Which of the following valves prevents backflow of blood from the right ventricle into the right atrium of the heart?
- A. Aortic
- B. Tricuspid valve
- C. Pulmonic
- D. Mitral valve
Correct Answer: B
Rationale: The correct answer is the tricuspid valve. The tricuspid valve is located between the right atrium and the right ventricle of the heart. Its main function is to prevent the backflow of blood from the right ventricle into the right atrium during the heart's pumping cycle. Choice A, the aortic valve, is responsible for preventing backflow from the aorta into the left ventricle. Choice C, the pulmonic valve, prevents backflow from the pulmonary artery into the right ventricle. Choice D, the mitral valve, prevents backflow from the left ventricle into the left atrium.