Question

If we take food rich in lime juice, then
(a)Action of ptyalin on starch is enhanced
(b)Action of ptyalin on starch is reduced
(c)Action of ptyalin on starch is unaffected
(d)Action of ptyalin on starch stops

Answer 1

Hint: Ptyalin also known as salivary amylase is a digestive enzyme released along with saliva by the salivary glands present in the mouth. It is a type of amylase and thus it acts upon saccharides to break them down.

Complete Answer:
The saliva that is secreted into the oral cavity contains electrolytes, salivary amylase, and antibacterial lysozyme. The carbohydrate splitting enzyme salivary amylase is responsible for initiating the process of digestion by hydrolyzing starch present in the food. Up to 30% of starch is hydrolyzed to maltose in the mouth itself because of this enzyme. Like all enzymes, salivary amylase also works at an optimum pH of 6.8 When food rich in lime juice is taken, the citric acid present in that juice results in the lowering of pH inside the mouth. Thus, the action of ptyalin on starch gets reduced as optimum pH conditions are no longer provided to it.

Additional information:
There are three salivary glands in our body responsible for releasing saliva into the mouth.
Parotid Glands (cheek): They are the largest salivary glands and are situated in front of the ears. Each parotid gland consists of two lobes known as the superficial lobe and deep lobe. The saliva produced by these glands is released into the mouth by a duct that is present near the upper second molar.
Submandibular/Submandibular Glands (lower jaw): The submandibular glands are about the size of a walnut and are present below the jaw. The saliva is released from a duct that is under the tongue.
Sublingual Glands (below the tongue): They are the smallest salivary glands and are almond-shaped structures. These glands are present on either side of the tongue.

So, the correct option is ‘Action of ptyalin on starch is reduced’.

Note:
-The saliva is released into the oral cavity through the ducts of the salivary glands. The Stenson duct is the major duct of the parotid gland, Wharton duct for the submandibular duct, and Bartholin duct for the sublingual gland.
-The sublingual gland has many multiple ducts that drain the saliva into the mouth known as the ducts of Rivinus.
-Mumps is a viral disease that affects the parotid glands by causing painful inflammation. It can be prevented by the MMR vaccine.