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. What is the primary hormone secreted by the thyroid gland?

A. Oxytocin
B. TSH
C. Adrenaline
D. T4

Correct answer: D

Rationale: The correct answer is D: T4. The primary hormone secreted by the thyroid gland is thyroxine, also known as T4. T4 plays a crucial role in regulating metabolism, growth, and energy levels in the body. It is converted into the more active form, triiodothyronine (T3), which exerts most of the biological effects of thyroid hormones. Choices A, B, and C are incorrect. Oxytocin is not produced by the thyroid gland but by the pituitary gland, TSH (thyroid-stimulating hormone) is secreted by the pituitary gland to stimulate the thyroid gland, and adrenaline is produced by the adrenal glands, not the thyroid gland.

3. How does the nervous system work with the muscular system?

A. The muscles of the body produce chemicals that feed the nerves.
B. The nervous system tells the muscles how to respond to the environment.
C. The nervous system releases chemicals that remove excess waste from the muscles.
D. The muscular system provides input that allows the nerves to make decisions.

Correct answer: B

Rationale: The correct answer is B because the nervous system communicates with the muscular system to control voluntary and involuntary muscle movements. The nervous system sends signals to the muscles, instructing them on how to respond to various stimuli in the environment. This communication allows for coordinated movement and responses to external and internal changes. Choice A is incorrect because muscles do not produce chemicals to feed the nerves. Choice C is incorrect because the nervous system does not release chemicals to remove waste from the muscles. Choice D is incorrect because the muscular system does not provide input for the nerves to make decisions.

4. A person who has damage to their ulnar nerve will have decreased sensation in which part of the body?

A. Hand
B. Arm
C. Leg
D. Foot

Correct answer: A

Rationale: Corrected Rationale: Damage to the ulnar nerve typically results in decreased sensation in the hand, particularly affecting the little finger and half of the ring finger. The ulnar nerve innervates the hand and is responsible for providing sensation to these areas. This nerve does not extend to the leg or foot, so choices C and D are incorrect. While the ulnar nerve travels through the arm, its primary sensory impact is felt in the hand, making choice B less specific and therefore not the best answer.

5. 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.