Question

You just ate a piece of corn on the cob, which is basically carbohydrates and undigestible material. Now you are going to describe what happens to that food until it exits the body by indicating digestive processes and the structures that make it happen.

List the physical pathway from the mouth to the the point it leaves the body, that form the GI tract, include valves.

What are the accessory structures located along the pathway?

What are the digestive processes that occur at each point along the pathway?

Answer 1

1)Digestive system is responsible for processing of food particles, it's digestion and absorption of nutrients.

Piece of the corn will first enter oral cavity, where is it masticated with the help of teeth, tongue and hard palate in presence of saliva which contains salivary amylase responsible for 30% of digestion in mouth.

As the food is masticated it is put backwards on the posterior part of tongue and is converted into the bolus which is then passed along oropharynx, and esophagus.

Epiglottis covers the glottis and prevents antry of food into airway and allows it to pass along esophagus.

At lower esophagus, lower esophageal sphincter relaxes and allows food to pass into stomach.

In the stomach mechanical and chemical digestion takes place with the help of enzymes such as amylase, proteinases and lipase secreted by stomach in presence of hydrochoric acid.The food is mechanically mixed with the help of churning movements and help in mechanical digestion of food.

This processed food then enters small intestine which has three parts- duodenum, jejunum and ileum, when pyloric

spectrum relaxes. Duodenum is the site where more digestion of food takes place into simplest form with the help of pancreas which secretes pancreatic enzymes such as carboxypeptidase, lipases , amylase etc.

This food is then absorbed via microvilli present in the small intestine and sent into the circulation.

The left out protion is further processed into large intestine where certain drugs and water is reabsorbed.

The remaining protion of the digested food is called feces which passes along rectum and finally leaves anal canal.

2)Accessory digestive organs are -

Pancreas

Salivary glands

Gallbladder

Liver

3) Digestive processes occuring are -

a)Ingestion - occurs at the level of mouth and oral cavity.

Swallowing occuring at the level of oropharync and peristalsis at the level of esophagus and stomach.

2) Digestion - chemical and physical digestion occurs in stomach and small intestion.

3) Absorption - it occurs in small intestine and large intestine.

4) assimilation - it is the process in which absorbed nutrients are utilized in the body.

5) Excretion - it occurs at the level of rectum and Ana l canal.