Human Body: Digestive System

The human body’s digestive system is an essential organ system that oversees the breakdown of food into nutrients and waste for eventual disposal.
Its components are the salivary glands, oesophagus, stomach, liver, gallbladder, pancreas, small intestine, large intestine, and the rectum.
The process begins when food enters the mouth, where salivary glands produce saliva which contains enzymes to initiate the breakdown of starch into glucose.
The masticated food then travels down the oesophagus via peristalsis - a wave-like muscle contraction - into the stomach.
In the stomach, gastric juice (containing hydrochloric acid and pepsinogen enzyme) acts on the food bolus, further breaking down proteins into amino acids. This results in a semi-fluid mass called chyme.
The chyme then moves into the small intestine, where most of the nutrient absorption happens. The liver produces bile that aids fat digestion, and the pancreas produces enzymes that further digest the fats, proteins, and carbohydrates in the food.
Absorption of nutrients happens through the villi and microvilli found in the small intestine, which provide a large surface area for efficient absorption.
The remaining undigested food is then transported to the large intestine, where water is reabsorbed, and the rest is compacted into faeces.
Ultimately, the faeces leave the body through the rectum and anus - thus completing the process of digestion.
Disorders related to the digestive system may involve the improper functioning of one or more components and can range from common problems like indigestion to chronic diseases such as Crohn’s disease or cancer.
Understanding the structure and the functions of each part of the digestive system is fundamental to understanding the larger system of transportation and transformation of nutrients in the body.