HESI A2
HESI A2 Anatomy and Physiology Quizlet
1. Which structure is responsible for carrying oxygen to the cells?
- A. Hemoglobin
- B. Plasma
- C. Platelets
- D. Red blood cells
Correct answer: A
Rationale: Hemoglobin, located in red blood cells, is responsible for binding to oxygen in the lungs and transporting it to tissues throughout the body. Red blood cells contain hemoglobin, making them the primary carrier of oxygen to cells. Hemoglobin is the correct answer because it is the protein within red blood cells that directly binds to oxygen for transport. Plasma is the liquid component of blood and does not carry oxygen. Platelets are responsible for blood clotting and have no role in oxygen transport. While red blood cells do carry oxygen, it is specifically the hemoglobin within them that performs this function.
2. Which cellular structure is responsible for protein synthesis?
- A. Nucleus
- B. Ribosome
- C. Endoplasmic reticulum
- D. Golgi apparatus
Correct answer: B
Rationale: The correct answer is B: Ribosome. Ribosomes, the cellular structures located in the cytoplasm or on the endoplasmic reticulum, are responsible for protein synthesis in the cell. They are the sites where mRNA is translated into proteins, making them essential for the synthesis of proteins in all living cells. The other choices, such as the nucleus (choice A), endoplasmic reticulum (choice C), and Golgi apparatus (choice D), are not directly involved in protein synthesis. The nucleus contains DNA and is responsible for housing the genetic material, the endoplasmic reticulum is involved in protein folding and transport, and the Golgi apparatus is responsible for modifying, sorting, and packaging proteins.
3. Which hormone regulates the sleep-wake cycle?
- A. Melatonin
- B. Insulin
- C. Cortisol
- D. Thyroxine
Correct answer: A
Rationale: Melatonin, produced by the pineal gland, is the hormone that regulates the sleep-wake cycle. Its secretion is influenced by light exposure, with levels typically rising in the evening to promote sleep and falling in the morning to encourage wakefulness. Insulin is involved in regulating blood sugar levels, not the sleep-wake cycle. Cortisol plays a role in the body's stress response and circadian rhythm but is not the primary hormone regulating sleep-wake cycles. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism, not the sleep-wake cycle.
4. 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).
5. Which vitamin is essential for blood clotting?
- A. Vitamin C
- B. Vitamin K
- C. Vitamin D
- D. Vitamin B12
Correct answer: B
Rationale: Vitamin K is essential for blood clotting as it is necessary for the synthesis of proteins involved in the coagulation process, such as clotting factors. Without sufficient Vitamin K, the blood may not clot properly, leading to excessive bleeding. Vitamin C is important for collagen synthesis and immune function, Vitamin D is essential for calcium absorption and bone health, and Vitamin B12 is crucial for red blood cell formation and neurological function. However, when it comes to blood clotting, Vitamin K plays a vital role.
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