What is the primary function of the integumentary system?

Correct Answer: A

Rationale: The correct answer is A: Protecting the body from external damage. The primary function of the integumentary system, which includes the skin, hair, and nails, is to act as a physical barrier that protects the body from external damage such as pathogens, UV radiation, and mechanical injuries. While the integumentary system does play roles in regulating body temperature and producing vitamin D, its main and most crucial function is to provide a protective shield for the body. Choices B, C, and D are incorrect because although the integumentary system contributes to regulating body temperature and producing vitamin D, as well as housing cells involved in the immune response, its primary role is protection.

Correct Answer: B

Rationale: The small intestine is the primary site for nutrient absorption in the digestive system. It plays a crucial role in absorbing digested food into the bloodstream, where the nutrients are then circulated to the body's cells for energy and other functions. The stomach primarily breaks down food through the action of acids and enzymes, while the large intestine absorbs water and salts, not nutrients. The esophagus is a muscular tube that connects the mouth to the stomach and does not participate in nutrient absorption.

Correct Answer: B

Rationale: The primary role of the stomach in the digestive system is to break down food. It accomplishes this through the action of gastric acid and digestive enzymes, which work together to break down food into a semi-liquid mixture known as chyme. Option B, 'To break down food,' is the correct answer. Option A, 'To absorb nutrients,' is incorrect because absorption mainly occurs in the small intestine. Option C, 'To secrete digestive enzymes,' is partially correct as the stomach does secrete digestive enzymes, but its primary function is to break down food. Option D, 'To store glucose,' is incorrect as glucose storage primarily occurs in the liver and muscles, not the stomach.

Correct Answer: B

Rationale: The primary function of the respiratory system is to facilitate the exchange of gases. It transports oxygen from the air into the bloodstream, which is crucial for cellular respiration and providing energy to the cells. Additionally, it removes carbon dioxide, which is a waste product that needs to be eliminated. Choices A, C, and D are incorrect because while the respiratory system does remove carbon dioxide, its primary role is oxygen transport, not nutrient delivery, sound, or speech production.

Correct Answer: B

Rationale: The pharynx is indeed a structure located in the upper respiratory tract. It acts as a common passageway for both air heading to the lungs and food traveling to the esophagus, making it a vital structure for breathing and swallowing functions. The larynx, trachea, and esophagus are also part of the respiratory and digestive systems but are not specifically located in the upper respiratory tract. The larynx is situated below the pharynx, while the trachea is found below the larynx, and the esophagus is part of the digestive system, not the respiratory tract.

Correct Answer: B

Rationale: Vitamin D is the correct answer. It is essential for the absorption of calcium in the intestines, facilitating the maintenance of strong bones and teeth. Vitamin D helps regulate calcium levels in the blood and promotes bone mineralization, making it crucial for overall bone health. Choices A, C, and D are incorrect because Vitamin C is not directly involved in calcium absorption, Vitamin A is more related to vision and immune function, and Vitamin K plays a role in blood clotting and bone mineralization but is not primarily responsible for calcium absorption.

Correct Answer: B

Rationale: The circulatory system's primary function is to transport oxygen, nutrients, and hormones to cells and remove waste products. Choice A is incorrect because hormone production is primarily carried out by endocrine glands. Choice C is incorrect as fighting infections is a role of the immune system. Choice D is incorrect as regulating body temperature is mainly controlled by the integumentary and nervous systems.

Correct Answer: A

Rationale: The correct answer is A: To secrete digestive enzymes. The pancreas is responsible for secreting digestive enzymes that aid in breaking down carbohydrates, fats, and proteins in the small intestine, facilitating the process of digestion. Choice B is incorrect because the pancreas does not store bile; that is primarily the function of the gallbladder. Choice C is incorrect as the absorption of nutrients mainly occurs in the small intestine, not the pancreas. Choice D is incorrect as the transport of glucose is primarily regulated by insulin produced in the pancreas, but this is not the main role of the pancreas in digestion.

Correct Answer: A

Rationale: The correct answer is A: 'To filter waste from the blood.' The primary function of the kidneys in the urinary system is to filter waste products and excess substances from the blood, forming urine, which is then excreted from the body. This process helps maintain the body's internal environment by regulating the balance of electrolytes, fluid levels, and eliminating metabolic waste products. Choices B, C, and D are incorrect because while the kidneys do produce urine, regulate blood pressure, and maintain fluid balance, their primary function within the urinary system is the filtration of waste from the blood.