The chemical action of saliva is due to?

Appeared in: MNS 2015

Explanation

Ptyalin, which is the primary enzyme responsible for the chemical action of saliva.
Ptyalin, also known as salivary amylase, is secreted by the salivary glands (parotid, submaxillary, and sublingual).
Its main function is to initiate the digestion of carbohydrates (starches) by breaking them down into simpler sugars like maltose.
This chemical process begins as soon as food enters the mouth and is mixed with saliva.

Option A: Prolactin is a hormone, not a digestive enzyme. It is secreted by the anterior pituitary gland.
Option B: Pepsin is a digestive enzyme, but it is found in the stomach, not in saliva. It requires a highly acidic environment (low pH) to function, which is characteristic of the stomach, not the mouth.
Option C: Renin is an enzyme secreted by the kidneys. It plays a crucial role in the renin-angiotensin-aldosterone system to regulate blood pressure.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Enzymatic digestion by saliva as background academic context rather than a clinical decision trigger.
Understanding the function of saliva is crucial for nurses when assessing a patient's nutritional status and oral health. Conditions that reduce saliva production (xerostomia) can impair initial digestion, increase the risk of dental caries, and cause difficulty swallowing (dysphagia).
Nurses often provide oral care to patients, especially those who are NPO (nothing by mouth) or have a nasogastric tube. This helps stimulate saliva production and maintain oral hygiene, preventing infections.
What if? If a patient is taking medications that cause dry mouth (an anticholinergic effect), the nurse should anticipate a decreased chemical digestion of carbohydrates in the mouth, potential for oral discomfort, and an increased risk for cavities. Interventions would include encouraging sips of water, providing sugar-free lozenges, and ensuring meticulous oral hygiene.

How to Approach the Question

First, identify the key terms in the question: "chemical action" and "saliva". This directs you to the function of enzymes in the mouth.
Recall the basic physiology of digestion. Digestion begins in the mouth, and saliva contains enzymes.
Evaluate each option based on its known physiological role.
Eliminate Prolactin, as it is a hormone related to milk production.
Eliminate Pepsin, as it is a stomach enzyme for protein digestion.
Eliminate Renin, as it is a kidney enzyme for blood pressure control.

Concept Tested & Keywords

QL6X4VlGJKmZqh23uZ3YRh

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 2 p. 72-74

E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 181-183

Practise the full MNS 2015

Attempt every question from this paper in a timed mock, then review the full solution for each one.