Microvilli form the on the apical surface of epithelial cells, which aids in digestion and absorption.
Brush border
Lymphatic plexus
Submucosal layer
Gastric pit
The Correct Answer is A
A. Brush border: This ultra-structural feature consists of thousands of microscopic, finger-like projections called microvilli. It vastly increases the surface area for membrane-bound enzymes and nutrient transporters. It is the primary site for terminal carbohydrate and protein hydrolysis.
B. Lymphatic plexus: This network of vessels is located within the deeper layers of the mucosa and submucosa. It is responsible for the drainage of lymph and the transport of absorbed dietary fats. It is an internal vascular structure.
C. Submucosal layer: This is a distinct histological layer composed of dense irregular connective tissue containing blood vessels and nerves. It supports the overlying mucosa but does not form the apical surface. It provides structural integrity to the gut.
D. Gastric pit: These are deep pores in the stomach lining that lead to the gastric glands. They are macroscopic or microscopic depressions rather than apical cellular modifications. They serve as conduits for exocrine secretions like hydrochloric acid.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. HCI is only formed in the bloodstream before entering the stomach:Gastric acid is never found in the systemic circulation. Blood pH is strictly maintained at 7.35 to 7.45. Acid production is localized exclusively to the secretory canaliculi of the gastric mucosa.
B. HCI is too acidic and would damage the parietal cells:The intracellular pH of 7.2 would be instantly neutralized by the high acidity of hydrochloric acid. To prevent cytoplasmic denaturation, hydrogen and chloride ions are secreted separately. They only combine within the lumen.
C. The cytoplasm lacks the necessary enzymes for HCI production:Parietal cells contain high concentrations of carbonic anhydrase and H+/K+ ATPase pumps. The machinery for acid production is present within the cell. The restriction is a matter of safety, not enzymology.
D. It requires oxygen, which is absent in the cytoplasm:Parietal cells are densely packed with mitochondria and require significant aerobic metabolism to power their proton pumps. Oxygen is abundant in the cytoplasm to support this high energy demand. Acid production is ATP-dependent.
Correct Answer is B
Explanation
A. A person drinks a lot of water quickly:Rapid water ingestion does not typically stimulate excessive salivation beyond what is needed for swallowing. The salivary glands respond more to gustatory and olfactory stimuli than to volume. Hydration status remains the primary regulator here.
B. A person sees delicious food but cannot eat it:Visual and olfactory stimuli activate the parasympathetic nervous system via the salivary nuclei in the medulla. This causes a significant increase in watery, enzyme-rich saliva in anticipation of mastication. This is the classic cephalic response.
C. A person is experiencing dehydration:Dehydration triggers the sympathetic nervous system to reduce salivary secretion to conserve body water. This results in xerostomia, or a dry mouth, rather than overproduction. It is a protective mechanism against fluid loss.
D. A person is giving a public speech:Stress and anxiety associated with public speaking activate the sympathetic "fight or flight" response. This leads to the production of thick, mucus-rich saliva and a dry sensation. It does not cause excessive watery drooling.
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