HESI A2
HESI A2 Anatomy and Physiology 2023
1. Which gland is responsible for regulating metabolism and calcium levels?
- A. Pituitary gland
- B. Adrenal gland
- C. Thyroid gland
- D. Pineal gland
Correct answer: C
Rationale: The correct answer is the thyroid gland (Choice C). The thyroid gland plays a crucial role in regulating metabolism by producing hormones like thyroxine, which control the body's metabolic rate. It also helps in controlling calcium levels in the blood through the release of calcitonin. The pituitary gland (Choice A) is known as the 'master gland' as it controls other glands but is not primarily responsible for regulating metabolism and calcium levels. The adrenal gland (Choice B) produces hormones like cortisol and adrenaline, which are involved in the stress response and metabolism, but they do not specifically regulate calcium levels. The pineal gland (Choice D) mainly produces melatonin, a hormone that helps in regulating sleep-wake cycles and has no direct role in metabolism or calcium level regulation.
2. Which structure in the ear is responsible for hearing?
- A. Cochlea
- B. Semicircular canals
- C. Ossicles
- D. Eustachian tube
Correct answer: A
Rationale: The cochlea, located in the inner ear, is responsible for detecting sound waves and converting them into neural signals that are sent to the brain for processing. It plays a crucial role in the process of hearing by translating mechanical vibrations into electrical signals that the brain can interpret as sound. The semicircular canals (Choice B) are responsible for balance and detecting head movements, not hearing. The ossicles (Choice C) are three tiny bones in the middle ear that transmit sound vibrations from the eardrum to the cochlea. The Eustachian tube (Choice D) helps equalize pressure between the middle ear and the atmosphere, but it is not directly involved in the process of hearing.
3. Which of the following processes represents a different level of defense compared to the others?
- A. A low pH in the stomach
- B. Cilia present in the trachea
- C. Body cells recognizing a pathogen
- D. Mucus present in the nasal cavity
Correct answer: C
Rationale: Among the listed processes, low pH in the stomach, cilia in the trachea, and mucus in the nasal cavity serve as physical barriers that form the first line of defense against pathogens. These barriers work to block pathogens from entering the body. On the other hand, body cells recognizing a pathogen involves the immune response, which operates at a different level of defense. This process is part of the adaptive immune response, where the body's immune cells identify, target, and eliminate specific pathogens to provide a specialized defense after the pathogens have breached the physical barriers. Therefore, body cells recognizing a pathogen represent a different level of defense compared to the other listed processes.
4. 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.
5. Which hormone stimulates the production of red blood cells?
- A. Insulin
- B. Erythropoietin
- C. Glucagon
- D. Thyroxine
Correct answer: B
Rationale: Erythropoietin is the correct answer. It is the hormone responsible for stimulating the production of red blood cells. Erythropoietin is produced by the kidneys in response to low oxygen levels in the blood. This hormone promotes the generation of more red blood cells to increase the blood's oxygen-carrying capacity. Insulin (Choice A), Glucagon (Choice C), and Thyroxine (Choice D) do not stimulate the production of red blood cells. Insulin regulates blood sugar levels, Glucagon increases blood sugar levels, and Thyroxine regulates metabolism.
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