Which of these statements about bile is true?

Answer Explanation

C. stomach

- Correct: The stomach has three layers of smooth muscle in its muscularis externa, which is the muscular layer of the gastrointestinal tract responsible for peristalsis and mixing of food. These muscle layers are arranged in longitudinal, circular, and oblique orientations, allowing for the mechanical processing of ingested food and the propulsion of food through the digestive tract. This muscular arrangement contributes to the stomach's ability to churn and mix food with gastric juices during digestion.

A. small intestine

- Incorrect: While the small intestine does have smooth muscle in its muscularis externa, it typically has two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.

B. esophagus

- Incorrect: The esophagus also has smooth muscle in its muscularis externa, but it typically has two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.

D. large intestine

- Incorrect: The large intestine, like the small intestine, typically has two layers of smooth muscle in its muscularis externa: an inner circular layer and an outer longitudinal layer.

Answer Explanation

b) lacteals

- Correct: Villi are small, finger-like projections that extend into the lumen of the small intestine, increasing its surface area for absorption. Lacteals are specialized lymphatic vessels located within the villi. They play a crucial role in the absorption of dietary fats and fat-soluble vitamins. Lacteals absorb digested fats and fat-soluble nutrients and transport them through the lymphatic system to the bloodstream.

a) haustra

- Incorrect: Haustra are pouches or sacculations formed by the longitudinal muscle of the colon. They are characteristic features of the large intestine, particularly the colon, and are not directly associated with villi.

c) bacterial flora

- Incorrect: Bacterial flora (microbiota) refers to the diverse population of microorganisms inhabiting the gastrointestinal tract. While they play important roles in digestion, nutrient absorption, and immune function, they are not specifically associated with villi. They primarily inhabit the large intestine, where they aid in the fermentation of undigested carbohydrates and the production of certain vitamins.

d) intestinal glands

- Incorrect: Intestinal glands, also known as crypts of Lieberkühn or intestinal crypts, are invaginations of the epithelium located between the villi in the mucosa of the small intestine. They contain stem cells that continuously divide to replace the epithelial cells lining the intestine. While they are anatomically close to villi, they are distinct structures responsible for epithelial cell renewal and secretion of intestinal juices, but they are not directly associated with villi.

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.