HESI A2
HESI A2 Anatomy and Physiology 2023
1. What is the most visible part of the ear called?
- A. Cochlea
- B. Pinna
- C. Ear canal
- D. Organ of Corti
Correct answer: B
Rationale: The pinna, also known as the auricle, is the most visible part of the ear. It is responsible for capturing sound waves and directing them into the ear canal, where the process of hearing begins. The other structures mentioned, such as the cochlea, ear canal, and organ of Corti, play crucial roles in the auditory system but are not the most visible parts of the ear. The cochlea is a spiral-shaped cavity responsible for converting sound vibrations into neural signals. The ear canal is a tube that connects the outer ear to the eardrum. The organ of Corti is the actual sensory organ of hearing located in the cochlea.
2. What is the name of the structure that prevents food from entering the airway?
- A. trachea
- B. esophagus
- C. diaphragm
- D. epiglottis
Correct answer: D
Rationale: The epiglottis is the structure that prevents food from entering the airway. It acts as a lid over the trachea during swallowing, directing food to the esophagus instead of the windpipe (trachea). The trachea (Choice A) is the windpipe that allows air to pass into the lungs, the esophagus (Choice B) is the tube that carries food from the mouth to the stomach, and the diaphragm (Choice C) is a muscle involved in breathing and not in preventing food passage.
3. What is the main component of the cell membrane?
- A. Proteins
- B. Carbohydrates
- C. Lipids
- D. Nucleic acids
Correct answer: C
Rationale: The main component of the cell membrane is the phospholipid bilayer, which is primarily composed of lipids. Lipids form a barrier that separates the interior of the cell from the external environment, providing structural integrity and regulating the passage of substances in and out of the cell. Proteins are also essential components of the cell membrane, serving various functions such as transport, signaling, and cell recognition. Carbohydrates are present in the form of glycoproteins and glycolipids on the cell membrane surface, contributing to cell-cell recognition. Nucleic acids are not a primary component of the cell membrane.
4. What is the primary function of the kidneys in the urinary system?
- A. To filter waste from the blood
- B. To produce urine
- C. To regulate blood pressure
- D. To absorb nutrients
Correct answer: A
Rationale: The correct answer is A: 'To filter waste from the blood.' The primary function of the kidneys in the urinary system is to filter waste products and excess substances from the blood, forming urine, which is then excreted from the body. Kidneys play a crucial role in maintaining the body's overall balance by filtering out waste, regulating fluid levels, and helping in the elimination of toxins. Choices B, C, and D are incorrect because while the kidneys do produce urine, regulate blood pressure, and help in nutrient absorption indirectly, their primary function is the filtration of waste from the blood.
5. Which hormone is responsible for the regulation of calcium levels in the blood?
- A. Insulin
- B. Parathyroid hormone
- C. Cortisol
- D. Melatonin
Correct answer: B
Rationale: Parathyroid hormone, produced by the parathyroid glands, is responsible for regulating calcium levels in the blood. It achieves this by increasing calcium absorption in the intestines and kidneys, thus maintaining appropriate calcium levels in the bloodstream. Insulin is involved in glucose metabolism, not calcium regulation. Cortisol is a stress hormone that affects various body functions but not calcium levels. Melatonin is responsible for regulating the sleep-wake cycle, not calcium levels.
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