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Which of these statements about reflexes in the GI tract is false?

A. Short reflexes are provoked by nerves near the GI tract.

B. Short reflexes are mediated by the enteric nervous system.

C. Food that distends the stomach initiates long reflexes.

D. Long reflexes can be provoked by stimuli originating outside the GI tract.

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.

Therefore, the Correct Answer is C.

More Questions on TEAS 7 Science

  • Q #1: Which of the following stimuli activates sensors in the walls of digestive organs?

    A. breakdown products of digestion

    B. distension

    C. pH of chyme

    D. all of the above

    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.

  • Q #2: Which of the following organs is supported by a layer of adventitia rather than serosa?

    A. esophagus

    B. stomach

    C. small intestine

    D. large intestine

    Answer Explanation

    a) esophagus

    - Correct: The esophagus is supported by a layer of adventitia rather than serosa. The adventitia is a connective tissue layer that covers organs and structures that are not located within the peritoneal cavity. In the case of the esophagus, it lies behind the trachea and heart and passes through the diaphragm before connecting to the stomach. Since it is located outside the peritoneal cavity, it is covered by adventitia instead of serosa, which is the visceral peritoneum that covers organs within the abdominal cavity.

    b) stomach

    - Incorrect: The stomach is supported by a layer of serosa, which is the visceral peritoneum covering organs within the abdominal cavity.

    c) small intestine

    - Incorrect: The small intestine is supported by a layer of serosa, which is the visceral peritoneum covering organs within the abdominal cavity.

    d) large intestine

    - Incorrect: The large intestine is supported by a layer of serosa, which is the visceral peritoneum covering organs within the abdominal cavity.

  • Q #3: During gastric emptying, chyme is released into the duodenum through the ________.

    A. esophageal hiatus

    B. pyloric antrum

    C. pyloric canal

    D. pyloric sphincter

    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.