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. What type of tissue forms the outer layer of the skin?

A. Connective tissue
B. Epithelial tissue
C. Muscle tissue
D. Nervous tissue

Correct answer: B

Rationale: Epithelial tissue is the correct answer. It forms the outer layer of the skin, serving as a protective barrier against pathogens and environmental damage. This tissue type is essential for maintaining skin integrity and plays a crucial role in skin function. Connective tissue (Choice A), although important for providing support and structure, does not form the outer layer of the skin. Muscle tissue (Choice C) is responsible for movement and is not the primary tissue in the skin. Nervous tissue (Choice D) is involved in transmitting signals but is not the main component of the skin's outer layer.

3. 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.

4. Where are B-lymphocytes produced?

A. Thymus
B. Red bone marrow
C. Lymph nodes
D. Spleen

Correct answer: B

Rationale: B-lymphocytes are produced in the red bone marrow. The red bone marrow is the primary site for B-cell development, where they mature before entering the circulation. The thymus is responsible for T-lymphocyte maturation, not B-lymphocytes. Lymph nodes and spleen play roles in immune responses but are not the primary sites for B-lymphocyte production.

5. What is the function of platelets in the blood?

A. Transporting oxygen
B. Clotting blood
C. Fighting infection
D. Transporting nutrients

Correct answer: B

Rationale: Platelets, also known as thrombocytes, are responsible for clotting blood. When there is an injury, platelets help form blood clots to prevent excessive bleeding. This function is crucial in maintaining hemostasis and preventing hemorrhage. Choices A, C, and D are incorrect. Platelets do not transport oxygen, fight infection, or transport nutrients in the blood.