which structure in the ear is responsible for balance

HESI A2

Anatomy HESI A2 Practice Test

1. Which structure in the ear is responsible for balance?

A. Cochlea
B. Semicircular canals
C. Ossicles
D. Eustachian tube

Correct answer: B

Rationale: The semicircular canals in the inner ear are responsible for maintaining balance by detecting changes in head position and movement. These structures contain fluid and hair cells that send signals to the brain regarding the body's orientation in space, helping us stay balanced and navigate our surroundings. The cochlea is responsible for hearing, the ossicles are involved in sound transmission, and the Eustachian tube helps equalize pressure in the middle ear, but they are not directly related to balance.

2. The skull is positioned ________ to the spinal cord.

A. anterior
B. posterior
C. lateral
D. superior

Correct answer: D

Rationale: The correct answer is D. The skull is superior to the spinal cord, meaning it is located above the spinal cord in anatomical position. Superior in anatomy refers to a structure being positioned higher or above another structure in the body. Choices A, B, and C are incorrect because they refer to different directional relationships. Anterior means in front of, posterior means behind, and lateral means to the side. In this case, the relationship between the skull and the spinal cord is based on a superior-inferior orientation.

3. Which might be a result of stenosis, or narrowing of a heart valve?

A. Abdominal pain
B. Blood clots
C. Edema (swelling) in organs
D. Irregular heartbeat

Correct answer: D

Rationale: Stenosis, or narrowing of a heart valve, restricts blood flow through the valve, leading to changes in the heart's normal rhythm. This alteration can result in an irregular heartbeat, making it a common consequence of heart valve stenosis. Abdominal pain, blood clots, and organ swelling are not typically associated with stenosis of a heart valve.

4. Which muscle is responsible for the extension of the elbow?

A. Biceps brachii
B. Triceps brachii
C. Deltoid
D. Pectoralis major

Correct answer: B

Rationale: The correct answer is B: Triceps brachii. The triceps brachii muscle is responsible for extending the elbow joint. It is located on the back of the upper arm and acts in opposition to the biceps brachii, which is responsible for elbow flexion. The deltoid muscle is primarily responsible for shoulder abduction, not elbow extension. The pectoralis major muscle is involved in movements of the shoulder joint, not the elbow.

5. What is the function of the lungs in the respiratory system?

A. To filter blood
B. To exchange gases
C. To produce energy
D. To remove waste products

Correct answer: B

Rationale: The correct function of the lungs in the respiratory system is to exchange gases. The lungs facilitate the exchange of oxygen and carbon dioxide between the air we breathe in and the blood, ensuring oxygen is absorbed and carbon dioxide is removed during respiration. Choice A is incorrect as the kidneys, not the lungs, filter blood. Choice C is incorrect as energy production primarily occurs in cells, not in the lungs. Choice D is incorrect as waste removal, such as the excretion of carbon dioxide, is a function of the lungs, but the primary function is the exchange of gases.