which structure in the ear is responsible for hearing

HESI A2

Anatomy and Physiology Hesi A2 Practice Test

1. 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.

2. Which of the following statements best describes endocrine glands?

A. They absorb chemicals from the blood
B. They secrete chemicals into the blood
C. They filter chemicals from the blood
D. They absorb chemicals from the lymphatic system

Correct answer: B

Rationale: The correct answer is B: 'They secrete chemicals into the blood.' Endocrine glands release hormones directly into the bloodstream to regulate various body functions. This process helps in maintaining homeostasis and coordinating different physiological processes within the body. Choice A is incorrect as endocrine glands do not absorb chemicals from the blood; instead, they release hormones. Choice C is incorrect as endocrine glands do not filter chemicals from the blood; they secrete hormones. Choice D is incorrect as endocrine glands do not absorb chemicals from the lymphatic system; they release hormones into the bloodstream.

3. Which of the following is not part of the body’s secondary defense system?

A. Macrophages
B. Leukocytes
C. T cells
D. Cilia

Correct answer: D

Rationale: Cilia are not part of the body's secondary defense system. They are hair-like structures primarily involved in movement and transporting substances across cell surfaces, such as in the respiratory tract for debris and pathogen removal. However, cilia do not play a direct role in the immune response mechanisms characteristic of the body's secondary defense system. Macrophages, leukocytes, and T cells are immune cells that actively participate in the secondary defense system by targeting and eliminating pathogens.

4. What is the primary function of the kidneys in the urinary system?

A. Regulating blood pressure
B. Filtering blood to remove waste
C. Producing red blood cells
D. Regulating electrolyte balance

Correct answer: B

Rationale: The primary function of the kidneys in the urinary system is to filter blood to remove waste products and excess fluids, which are then excreted as urine. Kidneys act as a filtration system, removing waste like urea, excess salts, and toxins. While the kidneys do play a role in regulating blood pressure by secreting renin and maintaining electrolyte balance by adjusting the levels of sodium, potassium, and other ions in the blood, their main and essential function is filtration and waste removal, making choice B the correct answer.

5. What is the function of the skin in protecting the body?

A. To produce vitamin D
B. To protect against pathogens
C. To store nutrients
D. To regulate body temperature

Correct answer: B

Rationale: The skin serves several crucial functions in protecting the body. One of its primary roles is to act as a physical barrier against pathogens, preventing harmful microorganisms from entering the body. Choice A, 'To produce vitamin D,' is incorrect because while the skin is involved in vitamin D synthesis upon exposure to sunlight, its primary protective role is against pathogens. Choice C, 'To store nutrients,' is incorrect as the skin is not a primary organ for nutrient storage. Choice D, 'To regulate body temperature,' is a function of the skin, but the primary role in protecting the body is to act as a barrier against pathogens.