The Dance of Digestion Trivia Quiz

There are three major pairs of salivary glands that are present in the oral cavity (buccal cavity) - parotid glands, submandibular glands and sublingual glands. They produce most of the saliva that is involved in the digestion of food. Saliva contains specific enzymes, such as amylase, which help in breaking down starch. Saliva also acts as a lubricant which helps in the movement of food.

After the oral cavity, food moves to the pharynx and then the esophagus. The esophagus is commonly referred to as the 'food pipe'. It is a tube which is made of muscles and food passes through this pipe through an action called peristalsis.

The esophagus passes behind the trachea and the heart and pierces the diaphragm before emptying into the stomach. The esophagus has two muscular rings called esophageal sphincters - one is present near the start of the esophagus and another is present near the end of the esophagus.

The greater and lesser curvatures are parts of the bag-like organ called the stomach. Food passes from the esophagus and is emptied into the stomach. Other parts of the stomach include the fundus and the pylorus.

Digestion in the stomach occurs due to hydrochloric acid and pepsin which form a part of the gastric juices. A large proportion of proteins are digested in the stomach.

The duodenum is the first part of the small intestine. The stomach allows partially digested food to pass into the duodenum through the pyloric valve. The small intestine is a tubular structure made of smooth muscle fibres.

In the duodenum, food comes in contact with pancreatic and bile juices which further the process of digestion. Most nutrients required for the body are absorbed in the small intestine.

The second part of the small intestine is called the jejunum. Nutrients which are not absorbed in the duodenum are absorbed in the jejunum. These nutrients are then transported to the liver via the circulation, mainly the portal vein.

The jejunum has a large number of circular folds called plicae circulares which increase the surface area of absorption.

The third and final region of the small intestine is called the ileum, which has the very specific function of absorbing vitamin B12 & bile salts. Other nutrients which were not absorbed in the duodenum and the jejunum are absorbed here.

The anatomical differences between the jejunum and the ileum are very minor and there is no specific demarcation of where the jejunum ends and the ileum begins. The ileum opens into the caecum of the large intestine.

The large intestine begins with the cecum which leads into the ascending colon. As given in the name, the ascending colon travels upwards towards the liver.

It leaves an impression called the colic impression under the surface of the right lobe of the liver. From here the ascending colon turns left and becomes the transverse colon. Water is mainly absorbed from the digested food in the large intestine.

The transverse colon is the longest part of the large intestine. The transverse colon becomes the descending colon near the spleen as it moves downwards.

The descending colon continues as the sigmoid colon which is an S-shaped tube. It is sometimes referred to as the pelvic colon. The sigmoid colon has a higher number of muscle fibres to increase pressure inside the large intestine.

The sigmoid colon ends at the rectum, which is the last part of the large intestine. It is a straight tube which functions as a storage space for faeces. The walls of the rectum have many nervous receptors which instigate the process of defecation when the rectum is full.

Doctors may do a rectal exam in order to test for many diseases such as prostate cancer and internal haemorrhoids. Rectal temperature can also be taken by inserting a thermometer into the rectum. Some medications can also be given through the rectum, like suppositories. This route is sometimes preferred for children or terminally ill patients.

The anus is the final part of the human digestive system that continues from the rectum. It contains two muscular rings called the internal anal sphincter and the external anal sphincter. They control the exit of faeces from the human body.

Tears that occur in the anus are called anal fissures. The anus can also be the site of haemorrhoids which sometimes need surgery to be cured. The anus and anal canal can also be affected by anal cancer.