Nokea
Peripheral vasodilation results in heat loss through which of the following processes?
- A. conduction
- B. convection
- C. radiation
- D. evaporation
Correct Answer: C
Rationale: Peripheral vasodilation is the widening of blood vessels near the surface of the skin, allowing more blood to flow near the skin's surface. This process enhances heat loss primarily through radiation. Radiation is the transfer of heat energy in the form of electromagnetic waves. Conduction involves direct contact between objects, convection involves the transfer of heat through fluid or gas, and evaporation involves the phase change of a liquid to a gas, which cools the surface.
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Lowering the hand by straightening the elbow affects which of the following muscles?
- A. biceps brachii
- B. triceps brachii
- C. brachialis
- D. brachioradialis
Correct Answer: B
Rationale: Lowering the hand by straightening the elbow is the action of extending the forearm, which is primarily done by the triceps brachii muscle. The triceps brachii is the main extensor muscle of the elbow joint. The biceps brachii is responsible for flexing the elbow, not extending it, making it an incorrect choice. Brachialis is a strong elbow flexor, and brachioradialis helps in flexing the elbow and pronating the forearm, so they are not the primary muscles involved in straightening the elbow.
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.
Which of the following types of cells is primarily responsible for the destruction of old cells and invasive micro-organisms?
- A. Basophils
- B. Eosinophils
- C. B-cells
- D. Macrophages
Correct Answer: D
Rationale: Macrophages are a type of white blood cell that plays a crucial role in the immune system by engulfing and digesting cellular debris, foreign substances, microbes, cancer cells, and old or damaged cells. Basophils are primarily involved in allergic reactions and parasitic infections, eosinophils combat multicellular parasites and have a role in allergic reactions, and B-cells are responsible for producing antibodies. Therefore, the correct answer is macrophages as they are specialized in phagocytosis and removal of unwanted cells and microorganisms.
Which of the following is a result of stimulation of the sympathetic nervous system?
- A. decreased blood flow to the skeletal muscles
- B. increased cardiac output
- C. decreased respiratory rate
- D. increased urinary output
Correct Answer: B
Rationale: Stimulation of the sympathetic nervous system leads to an increase in cardiac output. When the sympathetic nervous system is activated, it causes the heart to beat faster and with more force, leading to an increased cardiac output. Choices A, C, and D are incorrect because the sympathetic nervous system does not cause decreased blood flow to the skeletal muscles, decreased respiratory rate, or increased urinary output.
Which of the following ions is most abundant in extracellular fluid?
- A. Calcium
- B. Chloride
- C. Sodium
- D. Potassium
Correct Answer: C
Rationale: Sodium is the most abundant ion in extracellular fluid. It plays a crucial role in maintaining fluid balance, nerve function, and muscle contraction. Calcium (Choice A) is mainly found in bones and teeth, Chloride (Choice B) is the major anion in extracellular fluid but not the most abundant ion, and Potassium (Choice D) is found predominantly inside cells.