What structure rises reflexively during swallowing to prevent food from entering the nasopharynx?
Epiglottis
Tongue
Soft palate and uvula
Larynx
The Correct Answer is C
A. Epiglottis: This cartilaginous structure folds downward to cover the glottis during deglutition. Its primary function is to prevent bolus entry into the laryngeal inlet. It protects the lower respiratory tract, not the nasopharynx.
B. Tongue: The tongue moves upward and backward against the hard palate to push the bolus into the oropharynx. While it initiates the voluntary phase of swallowing, it does not seal the nasopharynx. It acts as a mechanical plunger.
C. Soft palate and uvula: During the pharyngeal phase of swallowing, these structures move superiorly to seal off the opening to the nasal cavity. This prevents the retrograde movement of food or liquids into the nose. It ensures one-way bolus transit.
D. Larynx: The larynx is pulled superiorly and anteriorly under the tongue during swallowing. This movement helps open the upper esophageal sphincter and allows the epiglottis to cover the airway. It does not interact with the nasopharyngeal opening.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A. Help buffer chyme:Buffering is primarily performed by bicarbonate ions secreted by the ductal cells, not the digestive enzymes. These enzymes focus on the hydrolysis of macromolecules. They do not have the chemical properties to neutralize acid.
B. Are absorbed in the stomach:These enzymes are secreted into the duodenum for intestinal digestion. They are proteins themselves and would be denatured by the low pH of the stomach. Their site of action is distal to the pylorus.
C. Are already denatured:If these enzymes were denatured, they would lose their tertiary structure and catalytic functionality. The pancreas secretes them in a functional state to ensure nutrient breakdown. Denaturation would render them useless for digestion.
D. Don't harm pancreatic tissue:Unlike proteases, which are secreted as inactive zymogens to prevent autodigestion, these enzymes do not digest the structural lipids or proteins of the pancreas. They only target specific dietary substrates. This prevents acute pancreatitis.
Correct Answer is D
Explanation
A. Oblique:An inner oblique layer of smooth muscle is unique to the stomach, where it facilitates complex churning. It is not found in the small intestine. The intestinal muscularis is limited to two standard layers for peristalsis.
B. Transverse:There is no "transverse" muscle layer in the standard histological description of the alimentary canal. Muscles are oriented either parallel or perpendicular to the long axis of the organ. This term is not used in this anatomical context.
C. Skeletal:The muscularis externa of the small intestine is composed entirely of visceral smooth muscle under autonomic control. Skeletal muscle is only found in the upper esophagus and the external anal sphincter. It does not exist in the mid-gut.
D. Longitudinal:The outer layer of the muscularis externa consists of longitudinal smooth muscle fibers. Contraction of these fibers shortens the intestinal segment, working with the circular layer to propel chyme. This dual-layer arrangement enables effective peristaltic movements.
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