THE DIGESTIVE

SYSTEM

Learning Objectives

To state the function of the digestive system.

To describe the structure and workings of the digestive system.

To describe the effects of physical activity on the digestive system.

What makes up the digestive system.

The digestive system or alimentary canal

starts at the mouth and ends at the anus

and includes the pharynx, esophagus,

stomach, small intestine and large

intestine.

The functions of the Digestive System

Take food into the body through the mouth.(Ingestion)

Break food down into smaller particles to be used by the body. (Digestion)

Pass the digested food to the bloodstream.(Absorption)

Eliminate the undigested waste from the body.(Excretion).

Digestion

Digestion is the breakdown of complex food

particles into smaller units so that they can

be used by the body.

How does Digestion Occur?

*THE MOUTH

The digestive process begins in

the mouth. The food is chewed by the

teeth and mixes with saliva. The enzyme,

amylase starts to break down the starch.

The food is swallowed and enters the

stomach via the esophagus.

*THE STOMACH In the stomach the food is churned by

that organ’s strong muscular wall and mixes with other enzymes and is further broken down. The food is now in a liquid form called chyme.

* THE SMALL INTESTINE The liquid food enters the small

intestine and mixes with more enzymes to complete the digestive process. The nutrients are small enough to pass through the walls of the small intestines, into the blood. They are carried away to the liver and other body parts to be processed, stored and distributed as they are needed in the body.The small intestine is divided into three parts. The duodenum, jejunum and the lleum.

*THE LARGE INTESTINES

The remaining undigested waste enters the large intestine where any useful substances such as water and minerals are absorbed through its walls and into the blood. The only thing left is faeces.

*THE RECTUM AND ANUS

The faeces move to the rectum which is at the end of the large intestine where it passes through the anus, and out of the body.

Organs that aid in Digestion

*THE LIVER

This is a large internal organ in that

weighs between 1.4 –1.6 kg and is responsible

for

• The production of bile to aid digestion

• Storage of digested food which can be used to

provide energy

• Stores vitamins

• Removes waste products

Organs that aid in Digestion

*THE PANCREAS

It is a long gland about 15cm long

which produces digestive juices.

*THE GALLBLADDER

This stores bile fluid which passes

to the duodenum to break down fats

What are the nutrients absorbed during digestion?

Food provides us with energy which we need to work and play, as well as the raw materials to build new cells. During the digestive process our bodies absorb:

• Carbohydrates

• Protein

• Fats

• Vitamins

• Water and Mineral salts

Nutrients Uses Foods

Carbohydrates Provides us with

energy.

Bread, potatoes,

rice, sugar, fruits

and vegetables

Proteins Building and

repairing our

bodies

Meat, eggs,

beans.

Fats A rich source of

energy

Butter and oil

Vitamins Keeping our body

healthy

Fruits and fish

Water and Mineral

Salts

These are vital to

proper functioning

of our bodies,

They are found in

most of the foods

we eat.