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. Parietal cells secrete ________.

A. gastrin

B. hydrochloric acid

C. pepsin

D. pepsinogen

Answer Explanation:

b) hydrochloric acid

- Correct: Parietal cells, also known as oxyntic cells, secrete hydrochloric acid (HCl) into the stomach lumen. HCl plays a critical role in the digestive process by creating an acidic environment necessary for the activation of pepsinogen to pepsin and for the breakdown of food proteins. Parietal cells also secrete intrinsic factor, which is essential for the absorption of vitamin B12 in the small intestine.

a) gastrin

- Incorrect: Gastrin is a hormone secreted by G cells in the gastric glands of the stomach. It stimulates the secretion of gastric acid (HCl) by parietal cells and promotes gastric motility and emptying.

c) pepsin

- Incorrect: Pepsin is an enzyme that digests proteins by breaking them down into smaller peptides. Pepsin is formed from the precursor molecule pepsinogen, which is secreted by chief cells in the gastric glands. Parietal cells do not directly secrete pepsin.

d) pepsinogen

- Incorrect: Pepsinogen is the inactive precursor of pepsin. It is secreted by chief cells in the gastric glands of the stomach. Pepsinogen is activated to pepsin by the acidic environment created by hydrochloric acid secreted by parietal cells.

Therefore, the Correct Answer is B.

More Questions on TEAS 7 Science

  • Q #1: 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 #2: Which is a function of the liver in human adults?

    A. manufacturing red blood cells

    B. producing chemical compounds known as auxins

    C. storing the carbohydrate reserve glycogen

    D. synthesizing the hormone insulin

    Answer Explanation

    C) storing the carbohydrate reserve glycogen

    - Correct: One of the functions of the liver in human adults is storing the carbohydrate reserve glycogen. Glycogen is a polysaccharide that serves as a storage form of glucose in the body. When blood glucose levels are high, such as after a meal, the liver takes up excess glucose and converts it into glycogen for storage. When blood glucose levels drop, such as between meals or during fasting, the liver breaks down glycogen and releases glucose into the bloodstream to maintain blood sugar levels within a normal range.

    A) manufacturing red blood cells

    - Incorrect: The primary site of red blood cell production (erythropoiesis) in adults is the bone marrow, not the liver. While the liver is involved in the production of blood proteins and components, such as albumin, clotting factors, and plasma proteins, it is not responsible for manufacturing red blood cells.

    B) producing chemical compounds known as auxins

    - Incorrect: Auxins are a class of plant hormones involved in various physiological processes, such as cell elongation, apical dominance, and root development. They are not produced by the liver in human adults.

    D) synthesizing the hormone insulin

    - Incorrect: Insulin is a hormone produced by the pancreas, not the liver. Insulin plays a crucial role in regulating blood sugar levels by facilitating the uptake of glucose into cells for energy production or storage. While the liver responds to insulin by regulating glucose metabolism and storage, it does not synthesize insulin itself.

  • Q #3: The digestive system breaks down food into:

    A. nutrients

    B. amylase

    C. saliva

    D. sphincters

    Answer Explanation

    a. nutrients

    - Correct: The digestive system breaks down food into nutrients. These nutrients include carbohydrates, proteins, fats, vitamins, minerals, and water, which are essential for various physiological functions in the body. Once broken down into nutrients through mechanical and chemical digestion, these substances are absorbed by the intestines and transported via the bloodstream to cells throughout the body for energy production, growth, repair, and other metabolic processes.

    b. amylase

    - Incorrect: Amylase is an enzyme involved in the digestion of carbohydrates. It is produced by salivary glands in the mouth and by the pancreas and helps break down complex carbohydrates into simpler sugars. While amylase is an important component of the digestive process, it is not the end product of digestion.

    c. saliva

    - Incorrect: Saliva is a fluid secreted by salivary glands in the mouth. It contains water, electrolytes, mucus, and enzymes such as amylase. Saliva helps moisten food, initiate the digestion of carbohydrates, and facilitate swallowing, but it is not the end product of digestion.

    d. sphincters

    - Incorrect: Sphincters are ring-like muscles that control the movement of materials through various parts of the digestive tract by opening and closing. While sphincters play a crucial role in regulating the flow of food and waste through the digestive system, they are not the end products of digestion.