Question

What is a digestive reflex? Why are they important for efficient digestion of nutrients? Examples of how the digestive system responds to stimuli to get ready to break down the food that we eat into digestible molecules?

Answer 1

Digestive Reflex: The digestive system of the body helps to breakdown of food that we eat and to form digestable molecules. During this procedure body gets nutrition, electrolytes as the source of energy. There are some reflexes are presents in the body which helps in the digestion of the food materials. i) Chewing reflex ii)parasympathetic reflex of salivation iii) swallowing reflex, these three reflexes are important for the digestion of nutrients. These reflexes are called digestion reflex.

i) Chewing reflex: When the food is place inside the mouth it initiates the stretchning of the jaw muscle which lead to contraction and results in closure of mouth. Then after the closure of mouth, food presents on the buccal cavity and in the contact of buccal receptor which causes the reflex inhibition of muscle of chewing and contraction of pterygoid muscle and results in opening of mouth. This way the closure and opening of mouth is happened cyclically and leads to proper chewing of food materials, so that it can be properly digested.

ii) parasympathetic reflex of salivation: This reflex is initiates in the buccal cavity when the tactile stimulation from the mouth, tongue, pharynx stimulates the receptor in buccal cavity, The salivary center in the superior and inferior salivary nuclei is stimulated by the afferent pathway from the mechanoreceptor of the buccal cavity and chemoreceptor in the taste buds of the tongue. The efferent pathway from the salivary nucleus stimulates the submandibular, sublingual and parotid gland to initiates the salivation process. The saliva then mix with the chewed food materials to transform it into a easily palatable materials.

iii) swallowing reflex : In this phase the bolus of food from the mouth, enters into pharyngeal phase and in the oeasophagus. When food enters into the oesophagus from the pharynx upper oesphageal sphingter contract to prevent the reverse movement of food. The perstaltic movements of the oesophagus lead the food to enter in the stomach through contenious contraction and relaxation of the smooth muscle of oesophagus. The lower oesphageal sphingter relaxes when peristaltic movement arrives, it causes the bolus of food to enters in stomach. This peristaltic movement of oesophagus is co-ordinated by the vagus nerve from the swallowing center.

These reflexes are important for the proper digestion of food into digestable molecules by chewing, salivation and peristaltic movement. Through this reflexes the digestable molecules can easily be palatable by the stomach and absorbed in the intestine.

For example when we eat chicken as food materials, at first the food is chewed by the teeth by chewing reflex of the mouth. The chewed food then mixed with the salivary juices from thr salivary gland to for bolus through the salivary reflex from the mechanoreceptor in buccal cavity and chemoreceptor in the taste buds. These reflexes is important to transform the whole flesh into small particles to form bolus. This bolus then enters in to oesophagus through pharynx. The oesopgeal smooth muscle initiates peristalsis by vagus nerve to start swallowing reflex and ultimately send the digestable food bolus into stomach. SO, this way digestive system responds to the stimuli from the food materials when it places in the mouth and break it down into small palatable molecules by these reflexes.