What is the main constituent of blood plasma, interstitial fluid, and intracellular fluid?
- A. potassium
- B. sodium
- C. water
- D. calcium
Correct Answer: C
Rationale: The correct answer is C: water. Water is the main component of blood plasma, interstitial fluid, and intracellular fluid. It plays a crucial role in various bodily functions, including transporting nutrients, regulating body temperature, and maintaining cell structure. Choices A, B, and D are incorrect because while potassium, sodium, and calcium are essential electrolytes found in the body, they are not the main constituents of these fluids as water is.
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What are the small, fingerlike projections into the intestinal lumen called?
- A. Villi
- B. Goblets
- C. Lacteals
- D. Polyps
Correct Answer: A
Rationale: The correct answer is A: Villi. Villi are small fingerlike projections in the intestine that increase the surface area for nutrient absorption. Goblets (choice B) are mucus-secreting cells in the intestines. Lacteals (choice C) are lymphatic vessels in the small intestine that absorb dietary fats. Polyps (choice D) are abnormal tissue growths.
The lining of the stomach and intestine is protected from self-digestion by:
- A. pepsinogen.
- B. bile.
- C. mucus.
- D. fat.
Correct Answer: C
Rationale: The correct answer is C: mucus. Mucus forms a protective barrier that prevents the stomach and intestine from digesting themselves. Pepsinogen (choice A) is an inactive form of pepsin, a digestive enzyme, and does not protect the stomach lining. Bile (choice B) aids in the digestion and absorption of fats but does not protect the stomach lining. Fat (choice D) is a nutrient and energy source; it does not play a role in protecting the stomach and intestine from self-digestion.
After absorption, the end products of carbohydrate and protein digestion enter the:
- A. enterohepatic circulation.
- B. gastrointestinal circulation.
- C. common bile duct.
- D. portal blood system.
Correct Answer: D
Rationale: The correct answer is D: portal blood system. After absorption, carbohydrates and proteins are transported via the portal blood system to the liver for further processing and distribution to the rest of the body. Choices A, B, and C are incorrect. Enterohepatic circulation refers to the recycling of compounds between the liver and the intestines, not the direct route for absorbed nutrients. Gastrointestinal circulation is a vague and non-specific term, not specifically related to the transport of absorbed nutrients. The common bile duct is involved in transporting bile from the liver and gallbladder to the small intestine, not the end products of carbohydrate and protein digestion.
Where does gluconeogenesis occur?
- A. Muscles.
- B. Pancreas.
- C. Liver.
- D. Spleen.
Correct Answer: C
Rationale: Gluconeogenesis mainly occurs in the liver. It is a process where glucose is synthesized from non-carbohydrate sources such as amino acids and glycerol. The liver is the primary site for gluconeogenesis due to the presence of key enzymes and substrates required for this process. Muscles do not play a significant role in gluconeogenesis, making choice A incorrect. The pancreas is involved in the regulation of blood sugar levels through insulin and glucagon but is not the primary site for gluconeogenesis, so choice B is incorrect. The spleen is not a major organ involved in glucose metabolism, making choice D incorrect.
What is the primary nutritional function of the large intestine?
- A. Absorption of fats.
- B. Excretion of waste products.
- C. Excretion of bacteria.
- D. Absorption of water.
Correct Answer: D
Rationale: The correct answer is D: Absorption of water. The primary nutritional function of the large intestine is to absorb water from the indigestible food residue that enters it from the small intestine. This absorption of water helps to form solid waste, which is then eliminated from the body. Choices A, B, and C are incorrect because the large intestine is not primarily responsible for the absorption of fats, excretion of waste products, or excretion of bacteria. While the large intestine does play a role in waste elimination and contains bacteria beneficial for digestion, its main function in terms of nutrition is the absorption of water.