Where are most fat-digesting enzymes produced?

Answer Explanation

d) all of the above

- Correct: All of the listed stimuli activate sensors in the walls of digestive organs:

a) Breakdown products of digestion: The presence of breakdown products, such as nutrients and smaller molecules resulting from digestion, can activate sensors in the walls of digestive organs. These sensors help regulate various digestive processes and signal the release of digestive enzymes and hormones.

b) Distension: Distension, or stretching of the walls of the digestive organs, is a stimulus that activates sensors. It occurs as the volume of the digestive tract increases due to the presence of ingested food, and it triggers reflexes that coordinate muscular contractions for propulsion and mixing.

c) pH of chyme: The pH of the chyme (the semi-liquid mixture of food and digestive juices in the stomach and small intestine) is another stimulus that activates sensors. Changes in pH can signal the need for adjustments in the secretion of digestive enzymes and the regulation of gastric and intestinal functions.

Therefore, all of the mentioned stimuli play a role in activating sensors and regulating digestive processes in response to the specific conditions within the digestive organs.

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.

Answer Explanation

c) pyloric sphincter

- Correct: During gastric emptying, chyme (partially digested food) is released from the stomach into the duodenum through the pyloric sphincter. The pyloric sphincter is a muscular valve located at the junction between the stomach and the duodenum. It regulates the passage of chyme from the stomach into the small intestine, allowing for controlled release and preventing backflow of intestinal contents into the stomach.

a) pyloric antrum

- Incorrect: The pyloric antrum is the lower portion of the stomach that leads into the pyloric canal. It is involved in mixing and churning food, but it does not regulate the release of chyme into the duodenum.

b) pyloric canal

- Incorrect: The pyloric canal is the narrow portion of the stomach that connects the pyloric antrum to the pyloric sphincter. It is involved in directing chyme toward the pyloric sphincter for release into the duodenum, but it is not the site of chyme release itself.

The esophageal hiatus is an opening in the diaphragm through which the esophagus passes as it descends from the thoracic cavity into the abdominal cavity. It is not directly involved in gastric emptying.