primary peristalsis occurs in the

HESI A2

HESI A2 Anatomy and Physiology Practice Exam

1. Where does primary peristalsis occur?

A. Esophagus
B. Stomach
C. Nervous system
D. Small intestine

Correct answer: A

Rationale: Primary peristalsis occurs in the esophagus. Peristalsis is the coordinated muscular contractions that propel food through the digestive tract. In the esophagus, primary peristalsis is the involuntary wave-like contractions that push food from the mouth to the stomach. It is the natural and automatic process that occurs to facilitate the movement of food during digestion. The stomach (choice B), nervous system (choice C), and small intestine (choice D) are not the primary sites where peristalsis occurs in the digestive system.

2. Which vitamin is essential for the formation of red blood cells?

A. Vitamin A
B. Vitamin B12
C. Vitamin C
D. Vitamin D

Correct answer: B

Rationale: Vitamin B12 is the correct answer. It is crucial for the formation and maturation of red blood cells, playing a vital role in preventing megaloblastic anemia. Additionally, Vitamin B12 is essential for maintaining nerve function. Vitamin A is important for vision and immune function, Vitamin C is necessary for collagen synthesis and immune health, and Vitamin D is crucial for bone health and immune function. Therefore, options A, C, and D are incorrect as they do not play a direct role in the formation of red blood cells.

3. What is the primary function of platelets?

A. To fight infections
B. To clot blood
C. To carry oxygen
D. To transport nutrients

Correct answer: B

Rationale: The primary function of platelets, or thrombocytes, is to clot blood. Platelets play a crucial role in hemostasis by forming clots to prevent excessive bleeding when injuries occur. They are not directly involved in fighting infections, carrying oxygen, or transporting nutrients. Therefore, the correct answer is B.

4. Why might certain young people be underweight?

A. They are growing in height faster than they are gaining weight.
B. They eat little protein and too much fat and sugar.
C. They eat several meals a day and fail to exercise enough.
D. They seldom eat a meal that contains foods from all food groups.

Correct answer: A

Rationale: Certain young people might be underweight because they are growing in height faster than they are gaining weight. During periods of rapid growth, the body's energy requirements are primarily directed towards height growth rather than weight gain, resulting in some individuals being underweight despite consuming sufficient calories. Choice B is incorrect because the question focuses on reasons related to growth rather than diet composition. Choice C is incorrect as it suggests overeating rather than the specific growth-related issue of height surpassing weight gain. Choice D is incorrect as it addresses nutritional variety rather than the growth dynamics affecting weight.

5. Which hormone is involved in the regulation of water balance in the body?

A. ADH
B. Insulin
C. Cortisol
D. Thyroxine

Correct answer: A

Rationale: The correct answer is ADH (antidiuretic hormone), also known as vasopressin. ADH helps regulate water balance in the body by controlling the amount of water reabsorbed by the kidneys. When there is a need to conserve water, ADH levels increase, leading to more water reabsorption and concentration of urine. Insulin is involved in regulating blood sugar levels, not water balance. Cortisol is a stress hormone that helps regulate metabolism and immune response, not water balance. Thyroxine is a thyroid hormone that regulates metabolism, growth, and development, not water balance.