HESI A2
Anatomy HESI A2
1. Which parts of the heart are separated by the mitral valve?
- A. Left atrium and right atrium
- B. Right atrium and right ventricle
- C. Left ventricle and right ventricle
- D. Left atrium and left ventricle
Correct answer: D
Rationale: The mitral valve, also known as the bicuspid valve, separates the left atrium and the left ventricle of the heart. Its primary function is to prevent the backflow of blood from the left ventricle to the left atrium during the heart's contraction. Therefore, option D, 'Left atrium and left ventricle,' is the correct answer. Choices A, B, and C are incorrect because they do not represent the parts separated by the mitral valve.
2. Which hormone is involved in regulating the sleep-wake cycle?
- A. Insulin
- B. Melatonin
- C. Cortisol
- D. Thyroxine
Correct answer: B
Rationale: The correct answer is B: Melatonin. Melatonin, produced by the pineal gland, is the hormone involved in regulating the sleep-wake cycle. It plays a crucial role in signaling the body that it is time to sleep and is influenced by light exposure. Melatonin levels typically rise in the evening, promoting sleep, and decrease in the morning, helping in waking up. Choice A, Insulin, is involved in regulating blood sugar levels, not the sleep-wake cycle. Choice C, Cortisol, is a stress hormone that helps regulate metabolism and immune response but is not primarily involved in the sleep-wake cycle. Choice D, Thyroxine, is a hormone produced by the thyroid gland that regulates metabolism, growth, and development, but it is not directly involved in regulating the sleep-wake cycle.
3. What is the primary function of the respiratory system?
- A. To absorb oxygen
- B. To transport nutrients
- C. To produce sound and speech
- D. To regulate blood pressure
Correct answer: A
Rationale: The primary function of the respiratory system is to absorb oxygen from the air into the bloodstream and expel carbon dioxide from the body. This process is essential for cellular respiration and the production of energy in the body. Option A, 'To absorb oxygen,' aligns with this crucial function, making it the correct choice. Choices B, C, and D are incorrect as they do not represent the primary function of the respiratory system. The respiratory system is not responsible for transporting nutrients (choice B), producing sound and speech (choice C), or regulating blood pressure (choice D).
4. How many different types of tissues are there in the human body?
- A. four
- B. six
- C. eight
- D. ten
Correct answer: A
Rationale: There are four major types of tissues in the human body: epithelial, connective, muscle, and nervous tissues. Epithelial tissue covers body surfaces, connective tissue supports and binds other tissues together, muscle tissue enables movement, and nervous tissue allows for communication between different parts of the body. Choices B, C, and D are incorrect because the human body has four main types of tissues, not six, eight, or ten.
5. Which of the following is not an example of a nonspecific immune response?
- A. Inflammation
- B. Vasodilation
- C. Release of histamine
- D. Production of antibodies
Correct answer: D
Rationale: The correct answer is D, 'Production of antibodies.' Antibodies are generated as part of the specific immune response, which targets specific antigens. Nonspecific immune responses, such as inflammation, vasodilation, and histamine release, are general defense mechanisms aimed at combating various pathogens. Inflammation is a localized response to infection or injury, vasodilation increases blood flow to the affected area, and histamine release triggers inflammatory responses. It's vital to differentiate between nonspecific responses that provide immediate, general protection and specific responses designed to tackle particular threats.
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