HESI A2
HESI A2 Anatomy and Physiology 2023
1. Which vitamin is essential for the formation of red blood cells?
- A. Vitamin A
- B. Vitamin B12
- C. Vitamin C
- D. Vitamin D
Correct answer: B
Rationale: Vitamin B12 is the correct answer. It is crucial for the formation and maturation of red blood cells, playing a vital role in preventing megaloblastic anemia. Additionally, Vitamin B12 is essential for maintaining nerve function. Vitamin A is important for vision and immune function, Vitamin C is necessary for collagen synthesis and immune health, and Vitamin D is crucial for bone health and immune function. Therefore, options A, C, and D are incorrect as they do not play a direct role in the formation of red blood cells.
2. What is the primary function of the hypothalamus?
- A. Regulates body balance and thermoregulation
- B. Controls hunger and thirst
- C. Regulates sleep and circadian rhythms
- D. Controls voluntary movements
Correct answer: A
Rationale: The primary function of the hypothalamus is to regulate body balance and thermoregulation. It plays a crucial role in maintaining overall body equilibrium by controlling functions such as body temperature and water balance. While the hypothalamus is also involved in hunger and thirst regulation, its main role is to ensure homeostasis by monitoring and adjusting body balance and temperature. Choices B, C, and D are incorrect because hunger and thirst regulation, sleep and circadian rhythm regulation, and control of voluntary movements are secondary functions of the hypothalamus compared to its primary role in maintaining body balance and thermoregulation.
3. Which hormone is responsible for regulating blood sugar levels?
- A. Insulin
- B. Glucagon
- C. Thyroxine
- D. Melatonin
Correct answer: A
Rationale: Insulin, produced by the pancreas, is the hormone responsible for regulating blood sugar levels. It works by facilitating the uptake of glucose into cells, helping to lower blood sugar levels. Glucagon, on the other hand, works to increase blood sugar levels by promoting the release of glucose from the liver. Thyroxine is a hormone produced by the thyroid gland that regulates metabolism. Melatonin, a hormone that helps regulate sleep-wake cycles, is not responsible for regulating blood sugar levels. Therefore, the correct answer is insulin.
4. What is the primary function of the immune system?
- A. To transport oxygen
- B. To fight infections
- C. To produce energy
- D. To regulate body temperature
Correct answer: B
Rationale: The primary function of the immune system is to fight infections. It identifies and destroys pathogens like bacteria and viruses, protecting the body from harmful substances. While oxygen transportation is carried out by the respiratory system, energy production is mainly the role of the metabolic system, and body temperature regulation is managed by the thermoregulatory system. These functions are separate from the immune system's primary role of defending the body against infections.
5. Which muscle is responsible for breathing?
- A. Diaphragm
- B. Intercostal muscles
- C. Rectus abdominis
- D. Pectoralis major
Correct answer: A
Rationale: The diaphragm is the primary muscle responsible for breathing. It is a large, dome-shaped muscle located at the base of the chest cavity. When it contracts, it flattens, increasing the volume of the chest cavity and causing inhalation. When it relaxes, it returns to its dome shape, decreasing the volume of the chest cavity and causing exhalation. The intercostal muscles, located between the ribs, assist the diaphragm in breathing by expanding and contracting the chest cavity. The rectus abdominis and pectoralis major are not directly involved in the process of breathing.
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