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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 these statements about bile is true?

    A. About 500 mL is secreted daily.

    B. Its main function is the denaturation of proteins.

    C. It is synthesized in the gallbladder.

    D. Bile salts are recycled.

    Answer Explanation

    d) Bile salts are recycled.

    - Correct: Bile salts are recycled in the enterohepatic circulation. After aiding in the digestion and absorption of fats in the small intestine, bile salts are reabsorbed in the terminal ileum and transported back to the liver via the portal vein. Once in the liver, they are re-secreted into bile, allowing for their reuse in subsequent digestive processes. This recycling of bile salts is an important mechanism for conserving these critical components of bile.

    a) About 500 mL is secreted daily.

    - Incorrect: The daily secretion of bile by the liver is approximately 600-1000 mL, not 500 mL. Bile is continuously produced by hepatocytes (liver cells) and stored and concentrated in the gallbladder until it is released into the small intestine to aid in fat digestion.

    b) Its main function is the denaturation of proteins.

    - Incorrect: The main function of bile is not the denaturation of proteins. Bile aids in the emulsification and digestion of fats by breaking them down into smaller droplets, increasing the surface area for the action of pancreatic lipase and facilitating the absorption of lipids and fat-soluble vitamins.

    c) It is synthesized in the gallbladder.

    - Incorrect: Bile is not synthesized in the gallbladder. It is produced by hepatocytes (liver cells) in the liver and then stored and concentrated in the gallbladder until needed for digestion.

  • Q #2: Which of the following membranes covers the stomach?

    A. falciform ligament

    B. mesocolon

    C. parietal peritoneum

    D. visceral peritoneum

    Answer Explanation

    d) visceral peritoneum

    - Correct: The visceral peritoneum covers the stomach. The peritoneum is a serous membrane that lines the abdominal cavity and covers most of the abdominal organs. The portion of the peritoneum that directly covers the surface of an organ is called the visceral peritoneum. In the case of the stomach, the visceral peritoneum covers its outer surface, providing a protective and lubricating layer.

    a) falciform ligament

    - Incorrect: The falciform ligament is a fold of peritoneum that attaches the liver to the anterior abdominal wall and diaphragm. It does not cover the stomach.

    b) mesocolon

    - Incorrect: The mesocolon is a fold of peritoneum that attaches the colon to the posterior abdominal wall. It does not cover the stomach.

    c) parietal peritoneum

    - Incorrect: The parietal peritoneum lines the abdominal cavity but does not cover individual organs. It forms the outer layer of the peritoneum and is not directly associated with covering the stomach.

  • Q #3: Which of these ingredients in saliva is responsible for activating salivary amylase?

    A. mucus

    B. phosphate ions

    C. chloride ions

    D. urea

    Answer Explanation

    b) phosphate ions

    - Correct: Phosphate ions are responsible for activating salivary amylase. Saliva contains salivary amylase (also known as alpha-amylase or ptyalin), which is an enzyme that catalyzes the hydrolysis of starch into maltose and other smaller carbohydrates. However, salivary amylase is only activated in the presence of certain ions, particularly phosphate ions. These ions help to stabilize the enzyme's structure and facilitate its enzymatic activity. Therefore, phosphate ions play a crucial role in the function of salivary amylase.

    a) Mucus

    - Incorrect: Mucus in saliva serves primarily as a lubricant and protective barrier for the oral mucosa and facilitates swallowing. It does not directly activate salivary amylase

    c) Chloride ions

    - Incorrect: Chloride ions are electrolytes present in saliva, but they do not directly activate salivary amylase. Instead, they help maintain the osmotic balance and pH of saliva.

    d) Urea

    - Incorrect: Urea is a waste product found in urine and is not directly involved in the activation of salivary amylase.