Enzyme present in saliva?

Appeared in: VSSC Nursing Officer - 2021

Explanation

Ptyalin, also known as salivary amylase, is the primary digestive enzyme found in saliva.
It is secreted by the salivary glands, mainly the parotid glands.
Its function is to initiate the digestion of carbohydrates (starches) in the mouth by breaking them down into smaller sugar molecules like maltose.

Option A: Trypsin is a proteolytic enzyme, meaning it digests proteins, not carbohydrates. It is not found in saliva.
Option B: While a small amount of lingual lipase is secreted in the mouth, the primary site of lipase action is the small intestine. Ptyalin is the major digestive enzyme in saliva.
Option D: Pepsin is a protein-digesting enzyme and is not present in saliva. It requires a highly acidic environment to function.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Digestive Enzymes and their Secretion Sites as background academic context rather than a clinical decision trigger.
Understanding the function of ptyalin is crucial for patient education on nutrition and digestion, emphasizing the importance of thorough chewing to allow the enzyme to work effectively.
In conditions like xerostomia (dry mouth), reduced saliva production impairs ptyalin secretion, leading to difficulty in swallowing and the initial phase of carbohydrate digestion.
What if? If a patient has their parotid glands removed (parotidectomy), they will have significantly reduced ptyalin levels. A nurse would advise them to chew food longer and expect that carbohydrate digestion will rely more heavily on pancreatic amylase in the small intestine.

How to Approach the Question

First, identify the key term in the question: 'saliva'.
The question asks for the enzyme present in saliva. This is a direct recall question from physiology.
Mentally review the main digestive enzymes and their locations.
Evaluate the options: Trypsin (pancreas/small intestine), Lipase (pancreas/small intestine), Ptyalin (saliva), Pepsin (stomach).
Select the option that correctly matches the enzyme with its location in saliva.

Concept Tested & Keywords

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

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