what is the primary function of the alveoli in the lungs

HESI A2

Anatomy HESI A2 Practice Test

1. What is the primary function of the alveoli in the lungs?

A. Removing carbon dioxide from the blood
B. Exchanging oxygen and carbon dioxide
C. Transporting oxygen to the bloodstream
D. Filtering blood

Correct answer: B

Rationale: The primary function of the alveoli in the lungs is to exchange oxygen and carbon dioxide. The alveoli are tiny air sacs in the lungs responsible for this gas exchange during breathing. Oxygen diffuses from the inhaled air into the blood in the capillaries surrounding the alveoli, while carbon dioxide diffuses from the blood into the alveoli to be exhaled out of the body. Choice A is incorrect because the alveoli primarily facilitate the exchange of gases, not just the removal of carbon dioxide. Choice C is incorrect as the alveoli do not transport oxygen to the bloodstream but rather facilitate the exchange of gases. Choice D is incorrect as the alveoli are not involved in filtering blood but in gas exchange to ensure proper oxygenation and removal of carbon dioxide in the respiratory process.

2. Which hormone is secreted by the pancreas to lower blood glucose levels?

A. Insulin
B. Glucagon
C. Somatostatin
D. Cortisol

Correct answer: A

Rationale: Insulin is secreted by the pancreas to lower blood glucose levels by facilitating the uptake of glucose into cells. It promotes the storage of glucose as glycogen in the liver and muscles, reducing blood sugar levels. Glucagon, on the other hand, works to raise blood glucose levels by stimulating the breakdown of glycogen into glucose and releasing it into the bloodstream. Somatostatin regulates the endocrine system and inhibits the release of insulin and glucagon. Cortisol is a hormone produced by the adrenal glands, not the pancreas, and it plays a role in stress response and metabolism, but it does not directly lower blood glucose levels.

3. Which vitamin is essential for the maintenance of healthy skin?

A. Vitamin A
B. Vitamin C
C. Vitamin D
D. Vitamin K

Correct answer: A

Rationale: Vitamin A is the correct answer. It is crucial for maintaining healthy skin as it supports skin cell growth, repair, and overall skin health. Additionally, vitamin A plays a role in vision and immune function. Deficiency in vitamin A can lead to skin issues such as dryness and poor wound healing. Vitamin C is known for its role in collagen synthesis and antioxidant properties, while Vitamin D is important for bone health and immunity. Vitamin K is essential for blood clotting, but it is not primarily associated with skin health.

4. Which part of the brain is responsible for balance and coordination?

A. Cerebellum
B. Cerebrum
C. Medulla oblongata
D. Hypothalamus

Correct answer: A

Rationale: The correct answer is the cerebellum. The cerebellum, situated at the back of the brain, is responsible for coordinating voluntary movements and maintaining balance and posture. It receives information from the sensory systems, the spinal cord, and other parts of the brain to regulate motor movements. The cerebrum (choice B) is responsible for higher brain functions such as thinking and decision-making, the medulla oblongata (choice C) controls vital autonomic functions like breathing and heart rate, and the hypothalamus (choice D) is involved in regulating basic biological needs like hunger, thirst, and body temperature.

5. 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.