Chapter 34, Problem 1.1BGL

Summary Introduction

To label: The digestive structures in the given figure.

Introduction: The process of digestion involves the breakdown of complex substances into simpler ones so that they can be easily absorbed and assimilated by all cells of the body. For this purpose, the digestive system involves the gastrointestinal tract or alimentary canal and accessory digestive organs.

Answer to Problem 1.1BGL

Pictorial representation: Fig.1 represents the digestive system of humans.

Fig.1: Human digestive system.

Explanation of Solution

The alimentary canal starts from the mouth or buccal cavity where mastication takes place. This process is accompanied by three pairs of salivary glands, namely, the parotid gland, submandibular gland, and sublingual gland. They are exocrine in nature and produce saliva that is rich in a digestive enzyme called ptyalin. The masticated food called bolus passes to the pharynx through a short tube called the oesophagus and reaches the bag-like structure called the stomach. Gastric digestion of the bolus takes place in the stomach after which it is propelled down to the small intestine. The gall bladder and pancreas are accessory digestive glands that pour their secretions in the small intestine. The gall bladder secretes bile that is stored in the liver and later reaches the stomach through the bile duct. The digested food from the small intestine is pushed into the large intestine where the absorption process takes place. After absorption, the undigested food and other waste are excreted through the anus.