Human Digestive System

Introduction

• The Human digestive system is a complex process that consist of breaking down large organic masses into smaller particles that the body can use as a fuel.

Types of Digestion

• Mechanical digestion:• The physical

breakdown of food through mastication (chewing), mixing with saliva by tongue action, churning in stomach.

• Chemical digestion: The chemical

breakdown of food because of substances secreted by accessory organs.It is accomplished by enzymes in digestive juices.

Parts of Digestive System

Main Parts

• Mouth• Esophagus• Stomach• Small Intestine• Large Intestine

Accessory Parts

• Liver • Pancreas• Gall bladder• Salivary glands

Mouth: The mouth is

the beginning of the digestive system, and, in fact, digestion starts here before you even take the first bite of a meal.

There are two major processes which take place

Mastication: - Breaks down large food molecules - Increases surface area of food particles

Secretion of Saliva: - Contains salivary amyles (ptylain) that digest starts to

maltose

- It lubricants and moistens food

- Provides alkaline medium

Esophagus: - It is a mucus muscular

membrane lined tube - Muscles move the food to

the stomach through a wave-like motion refferred to as“ Peristalsis”

Peristalsis: It is an involuntary

process of muscular contraction forcing the food (bolus) down to the stomach

Stomach: The stomach is hollow,

muscular holding pouch for food. The stomach has 3 regions:

• The fundus• The body• The pylorus

The food enters this part of stomach from the esophagus. The esophageal (cardiac) sphincter, a circle of muscular tissue, surrounds the place where the esophagus enters the stomach and keeps food from going back up the esophagus after it has entered the stomach.

Functions of Stomach:

churns, mixes and stores food site of food breakdown using HCL and Pepsin chemical breakdown of protein begins

• Small Intestine:

The small intestine is the body’s

major digestive organ. It is a muscular tube extends approximately 20 feet.

Nutrients are absorbed in small intestine through villi (which increases surface area) into the blood stream.

Parts of Small Intestine:

Duodenum

Jejunum

Ileum

• Large Intestine:

The distal portion of the intestine, about 5 feet long, extending from its junction with the small intestine to the anus and comprising the cecum, colon, rectum, and anal canal.

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