calciferol is controlled by

HESI A2

Anatomy HESI A2

1. Which gland controls Calciferol?

A. Thyroid
B. Pituitary
C. Parathyroid
D. Hypothalamus

Correct answer: C

Rationale: Calciferol, commonly known as Vitamin D, is regulated by the parathyroid gland, not the thyroid, pituitary, or hypothalamus. The parathyroid gland plays a crucial role in maintaining calcium and phosphorus balance in the body by regulating the production of calcitriol, the active form of Vitamin D. This hormone helps in the absorption of calcium from the intestines and its reabsorption in the kidneys to maintain proper calcium levels in the blood. Therefore, the correct answer is the Parathyroid gland (Choice C). Choices A, B, and D are incorrect as they do not have a direct role in controlling Calciferol.

2. Which of the following is true about skeletal muscle?

A. Skeletal muscle makes up 40% of the body's weight.
B. Skeletal muscle attaches to bones by tendons.
C. Muscle contraction is not involved in temperature regulation.
D. Skeletal muscles contract only when in use.

Correct answer: B

Rationale: The correct statement is that skeletal muscle attaches to bones through tendons, enabling movement. Tendons connect muscles to bones and allow the force generated by muscle contraction to be transmitted to the bones, facilitating voluntary movements. Choice A is incorrect because skeletal muscle typically makes up around 40-50% of an individual's body weight, not a fixed 40%. Choice C is incorrect as muscle contraction plays a vital role in temperature regulation by generating heat. Choice D is incorrect as skeletal muscles may have constant low-level contractions even at rest, known as muscle tone.

3. What is the name of the structure that prevents food from entering the airway?

A. trachea
B. esophagus
C. diaphragm
D. epiglottis

Correct answer: D

Rationale: The epiglottis is the structure that prevents food from entering the airway. It acts as a lid over the trachea during swallowing, directing food to the esophagus instead of the windpipe (trachea). The trachea (Choice A) is the windpipe that allows air to pass into the lungs, the esophagus (Choice B) is the tube that carries food from the mouth to the stomach, and the diaphragm (Choice C) is a muscle involved in breathing and not in preventing food passage.

4. Which of the following locations is not involved in the release of hormones during stress?

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

Correct answer: A

Rationale: The parathyroid gland is not involved in the release of hormones during stress. It is responsible for regulating calcium levels in the blood by secreting parathyroid hormone. During stress, the adrenal cortex, posterior pituitary, and hypothalamus play crucial roles in releasing stress hormones like cortisol, adrenaline, and oxytocin. Therefore, the correct answer is the parathyroid gland, as it is not directly associated with the release of stress-related hormones.

5. Which cellular structure is responsible for protein synthesis?

A. Nucleus
B. Ribosome
C. Endoplasmic reticulum
D. Golgi apparatus

Correct answer: B

Rationale: The correct answer is B: Ribosome. Ribosomes, the cellular structures located in the cytoplasm or on the endoplasmic reticulum, are responsible for protein synthesis in the cell. They are the sites where mRNA is translated into proteins, making them essential for the synthesis of proteins in all living cells. The other choices, such as the nucleus (choice A), endoplasmic reticulum (choice C), and Golgi apparatus (choice D), are not directly involved in protein synthesis. The nucleus contains DNA and is responsible for housing the genetic material, the endoplasmic reticulum is involved in protein folding and transport, and the Golgi apparatus is responsible for modifying, sorting, and packaging proteins.