Which of these is most associated with villi?

Answer Explanation

d) The laryngopharynx is composed partially of cartilage.

- True: The statement that the laryngopharynx is composed partially of cartilage is true. The pharynx, commonly known as the throat, is a muscular tube that extends from the base of the skull to the level of the sixth cervical vertebra. It serves as a passageway for both air and food. The pharynx is divided into three regions: the nasopharynx, oropharynx, and laryngopharynx.

a) It extends from the nasal and oral cavities superiorly to the esophagus anteriorly.

- False: The pharynx extends from the nasal and oral cavities superiorly to the esophagus and larynx inferiorly, not anteriorly.

b) The oropharynx is continuous superiorly with the nasopharynx.

- False: The oropharynx is continuous inferiorly with the oral cavity, not superiorly with the nasopharynx. The nasopharynx is continuous superiorly with the nasal cavity.

c) The nasopharynx is involved in digestion.

- False: The nasopharynx is primarily involved in respiration and the passage of air. It contains the openings of the auditory tubes and tonsils but is not directly involved in digestion.

Answer Explanation

A) liver

- Correct: Urea is produced in the liver as a result of the breakdown of amino acids. Amino acids are the building blocks of proteins, and when proteins are metabolized for energy or other purposes, their constituent amino acids are broken down in a process called deamination. During deamination, the amino groups (-NH2) are removed from the amino acids, forming ammonia (NH3). The liver converts ammonia into urea through a series of biochemical reactions known as the urea cycle. Urea is then excreted by the kidneys in the urine, helping to remove nitrogenous waste from the body.

B) pancreas

- Incorrect: The pancreas is an organ involved in the production of digestive enzymes and hormones such as insulin and glucagon. It is not primarily responsible for the production of urea from the breakdown of amino acids.

C) stomach

- Incorrect: The stomach is primarily involved in the mechanical and chemical digestion of food, particularly proteins. While protein digestion begins in the stomach with the action of gastric juices containing enzymes such as pepsin, urea production from the breakdown of amino acids occurs mainly in the liver.

D) small intestine

- Incorrect: The small intestine is primarily involved in the absorption of nutrients from digested food, rather than the production of urea from the breakdown of amino acids. While some amino acids may be absorbed in the small intestine, urea production primarily occurs in the liver.

Answer Explanation

The digestive system typically works on the foods you eat for about 10 hours. The entire process of digestion, from the moment food enters the mouth until waste is eliminated from the body, generally takes around 24 to 72 hours. However, the actual time it takes for food to move through the digestive tract and be fully digested varies depending on factors such as the type of food consumed, individual metabolism, and overall gastrointestinal health. On average, food spends approximately 4 to 6 hours in the stomach and small intestine, and another 12 to 36 hours in the large intestine before being eliminated as waste. Therefore, the total time for digestion and elimination is typically around 24 to 72 hours.