Which part of the large intestine attaches to the appendix?

Answer Explanation

A. plicae circulares

- Correct: The small intestine possesses permanent folds along its length known as plicae circulares, also called circular folds or valvulae conniventes. These folds are permanent transverse ridges of the mucosa and submucosa that project into the lumen of the small intestine. They increase the surface area for absorption and digestion by slowing the passage of chyme and increasing contact between chyme and the intestinal lining, facilitating nutrient absorption.

B. haustra

- Incorrect: Haustra are pouches or sacculations formed by the muscularis externa of the colon (large intestine), not the folds of the small intestine.

C. villi

- Incorrect: Villi are finger-like projections of the mucosa of the small intestine that extend into the lumen. While villi increase the surface area for absorption, they are not permanent folds along the length of the small intestine.

D. intestinal crypts

- Incorrect: Intestinal crypts, also known as crypts of Lieberkühn, are invaginations of the epithelium located between villi in the mucosa of the small intestine. They contain stem cells that continuously divide and give rise to new epithelial cells, helping to replenish the epithelial lining of the intestine. Crypts are not permanent folds along the length of the small intestine.

Answer Explanation

c) Food that distends the stomach initiates long reflexes.

- False: This statement is false. Food that distends the stomach initiates short reflexes, not long reflexes. Short reflexes are local reflexes that are mediated by the enteric nervous system, which consists of a network of neurons within the walls of the digestive tract. When food stretches or distends the stomach, sensory neurons in the stomach wall detect this mechanical stimulus and initiate short reflexes that regulate local gastrointestinal functions, such as gastric motility and secretion.

Answer Explanation

D) The internal temperature increases by about 1ºC.

- Correct: As environmental temperature increases from 20ºC to 30ºC, the body's internal temperature tends to increase slightly. This is due to the body's thermoregulatory mechanisms, which work to maintain a relatively constant internal temperature (around 37ºC or 98.6ºF) despite fluctuations in environmental temperature. When the environmental temperature rises, the body responds by increasing blood flow to the skin and by initiating mechanisms such as sweating to dissipate heat and maintain thermal equilibrium. However, the increase in environmental temperature may result in a slight increase in internal temperature, typically by about 1ºC, as the body works to dissipate excess heat.

A) Both the internal and the skin temperatures reach 40ºC.

- Incorrect: A 10ºC increase in environmental temperature from 20ºC to 30ºC is not likely to cause both internal and skin temperatures to reach 40ºC. Such a significant increase would likely lead to heatstroke or hyperthermia, which can be life-threatening.

B) Both the internal and the skin temperatures increase by about 7ºC.

- Incorrect: A 10ºC increase in environmental temperature is not likely to cause both internal and skin temperatures to increase by about 7ºC. Such a large increase in temperature would be excessive and would likely lead to severe heat-related illnesses.

C) The skin temperature decreases to about 30ºC.

- Incorrect: In response to an increase in environmental temperature, the body typically increases blood flow to the skin and initiates mechanisms such as sweating to dissipate heat. This would not result in a decrease in skin temperature to match the environmental temperature of 30ºC.