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. To which two systems does the urethra belong?

A. Reproductive and endocrine
B. Urinary and reproductive
C. Endocrine and urinary
D. Digestive and cardiovascular

Correct answer: B

Rationale: The urethra belongs to both the urinary and reproductive systems. In the urinary system, it functions as a passage for urine from the bladder to exit the body. In the reproductive system, it serves as a conduit for the expulsion of semen during ejaculation. Choice A is incorrect because the urethra is not part of the endocrine system. Choice C is also incorrect because the urethra is not primarily associated with the endocrine system. Choice D is incorrect as the urethra is not part of the digestive or cardiovascular systems.

3. How does a transverse section divide the body?

A. Into right and left regions
B. Into upper and lower regions
C. Into front and back regions
D. Between the dorsal and ventral cavities

Correct answer: B

Rationale: A transverse section, also known as a cross-section, divides the body into upper and lower regions. This type of section cuts across the body horizontally, creating a division between the superior (upper) and inferior (lower) portions of the body. Choice A is incorrect as dividing the body into right and left regions is typically done by a sagittal section. Choice C is incorrect as dividing the body into front and back regions is usually achieved by a frontal section. Choice D is incorrect as it refers more to the relationship between dorsal and ventral cavities rather than the actual division of the body.

4. What is the main function of the urinary bladder?

A. To filter blood
B. To store and concentrate bile
C. To store urine
D. To absorb nutrients

Correct answer: C

Rationale: The correct answer is C: To store urine. The main function of the urinary bladder is to store urine produced by the kidneys before it is excreted from the body. It acts as a reservoir for urine until it is expelled during urination. Choices A, B, and D are incorrect because the urinary bladder does not filter blood, store or concentrate bile, or absorb nutrients. It is solely responsible for storing and releasing urine.

5. Which hormone is involved in the fight or flight response?

A. Cortisol
B. Adrenaline
C. Thyroxine
D. Melatonin

Correct answer: B

Rationale: The correct answer is B: Adrenaline. Adrenaline, also known as epinephrine, is the hormone involved in the fight or flight response. It is released by the adrenal glands, preparing the body for action by increasing heart rate, dilating airways, and mobilizing energy stores. Choice A, Cortisol, is a hormone released in response to stress but is not directly involved in the fight or flight response. Choice C, Thyroxine, is a hormone produced by the thyroid gland that regulates metabolism and growth, not specifically associated with the fight or flight response. Choice D, Melatonin, is a hormone that regulates sleep-wake cycles and is not involved in the fight or flight response.