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

A. To absorb oxygen
B. To remove carbon dioxide
C. To exchange gases
D. To regulate blood pressure

Correct answer: C

Rationale: The alveoli are tiny air sacs in the lungs responsible for the exchange of gases, specifically oxygen and carbon dioxide, during breathing. Oxygen is taken in and carbon dioxide is released through this process, enabling the body to receive oxygen and expel carbon dioxide. Choice A is incorrect because the alveoli do not absorb oxygen but facilitate the exchange of gases. Choice B is incorrect as the alveoli do not remove carbon dioxide but aid in the exchange of gases. Choice D is incorrect as the alveoli are not involved in regulating blood pressure but in gas exchange.

3. Which organ is responsible for the production of hormones during stress?

A. Parathyroid gland
B. Adrenal cortex
C. Posterior pituitary gland
D. Hypothalamus

Correct answer: B

Rationale: The adrenal cortex is the organ responsible for producing stress hormones like cortisol and aldosterone, which play a crucial role in the body's stress response. During stress, the adrenal cortex releases cortisol, a hormone that helps the body deal with stress by increasing blood sugar, suppressing the immune system, and aiding in metabolism. Parathyroid gland is responsible for calcium regulation, the posterior pituitary gland secretes hormones like oxytocin and vasopressin which are not directly related to the stress response, and the hypothalamus plays a role in regulating hormonal balance and various bodily functions but is not primarily responsible for producing stress hormones.

4. Which type of muscles are involved in peristalsis?

A. Smooth muscles
B. Cardiac muscles
C. Skeletal muscles
D. Epaxial muscles

Correct answer: A

Rationale: Peristalsis is a coordinated, wave-like muscular contraction that propels food and other materials through the digestive tract. Smooth muscles are responsible for this movement in the gastrointestinal tract, providing the involuntary contractions needed for peristalsis to occur. Skeletal muscles, cardiac muscles, and epaxial muscles are not directly involved in peristalsis. Cardiac muscles are found in the heart and are responsible for its contraction. Skeletal muscles are attached to bones and control voluntary movements. Epaxial muscles are located along the vertebral column and are involved in the movement and stabilization of the spine.

5. Which structure in the kidney is responsible for filtering blood?

A. Glomerulus
B. Bowman's capsule
C. Loop of Henle
D. Collecting duct

Correct answer: A

Rationale: The glomerulus is the correct answer. It is a vital structure in the kidney responsible for filtering blood. The glomerulus is a network of capillaries that filters waste products and excess substances from the blood to form urine. While the Bowman's capsule, Loop of Henle, and Collecting duct are also essential components of the nephron, the primary site of blood filtration occurs at the glomerulus. The Bowman's capsule surrounds the glomerulus and collects the filtered fluid, the Loop of Henle reabsorbs water and important ions, and the Collecting duct further concentrates the urine, but none of these structures are primarily responsible for filtering blood as the glomerulus is.