Anatomy HESI A2

Correct Answer: C

Rationale: The correct answer is C: peristalsis. Peristalsis is the coordinated contraction and relaxation of muscles that propels food along the digestive tract. This process helps move food from the esophagus to the stomach, then through the intestines for digestion and absorption. Defecation (A) is the elimination of waste, not the movement of food. Osmosis (B) is the movement of water across membranes, not the movement of food. Circulation (D) refers to the movement of blood, not food in the digestive system.

Correct Answer: D

Rationale: The correct answer is D: Simple columnar epithelium - secretion or absorption. Simple columnar epithelium is composed of a single layer of tall cells that are specialized for secretion and absorption due to their elongated shape and presence of microvilli. This type of epithelium is commonly found in the lining of the digestive tract where it secretes digestive enzymes and absorbs nutrients. A, B, and C are incorrect: A: Simple squamous epithelium is primarily involved in diffusion, not secretion or absorption. B: Stratified squamous epithelium is specialized for protection against mechanical stress and abrasion, not secretion or absorption. C: Stratified squamous epithelium is also not involved in secretion or absorption, its main function is protection.

Correct Answer: B

Rationale: The correct answer is B because the lymphatic system works with the circulatory system by drawing excess fluid from the cells and depositing it into the blood vessels. This process helps maintain fluid balance in the body. Lymphatic vessels collect the excess fluid, known as lymph, and transport it back to the bloodstream. This collaboration ensures that the body's tissues are not overloaded with fluid and helps with immune function. Choice A is incorrect because the circulatory system is responsible for producing red blood cells in the bone marrow, not the lymphatic system. Choice C is incorrect because the heart does not regulate the production of lymph; lymph is produced in lymphoid organs such as lymph nodes and the spleen. Choice D is incorrect because white blood cells from the lymphatic system play a role in the immune response, not in eliminating excess red blood cells.

Correct Answer: A

Rationale: The correct answer is A: To break down proteins. Pepsin is an enzyme produced in the stomach that specifically functions to break down proteins into smaller peptides. This process is crucial for the digestion and absorption of proteins in the body. Pepsin works optimally in the acidic environment of the stomach. Choices B, C, and D are incorrect because pepsin is not involved in breaking down starches, emulsifying fats and oils, or absorbing water and nutrients. Other enzymes like amylase are responsible for breaking down starches, bile helps emulsify fats, and various enzymes and mechanisms are involved in water and nutrient absorption in the digestive system.

Correct Answer: A

Rationale: The correct answer is A: Vitamin. Vitamins are essential nutrients that do not provide energy directly. They help the body perform various functions but do not contain calories. Carbohydrates, fats, and proteins are macronutrients that provide energy. Carbohydrates and fats provide 4 calories per gram, while protein provides 4 calories per gram as well. Vitamins are essential for overall health and proper bodily functions, but they do not contribute to energy production.