Digestive System - Chapter 6 - Science

Digestion

The breakdown of food in our body so it can be absorbed into the blood and used by cells for growth, energy and repair

Stages of Digestion

1. Ingestion

2. Digestion

3. Absorption

4. Assimilation

5. Egestion

Ingestion

Taking food into the body through the mouth

Absorption

Digested food is taken into the bloodstream and cells for energy and nutrients.

Assimilation

Digested molecules are used by the cells for energy, growth and repair

Egestion

When undigested food is passed out of the bodgy

Physical Digestion

Mechanical process of the breaking down of large pieces of food into smaller pieces, making it easier to swallow

Where does Physical Digestion Occur?

• Mouth - teeth

• Stomach, where food is churned

Incisors

Narrow and sharp - biting, cutting and slicing food - front of mouth

Canines

Long and pointy - gripping and tearing food

Premolars

Large with flat surface - crushing and grinding foodMol

Molars

Larger than premolars - crushing and grinding food

Chemical Digestion

The process of breaking down complex food molecules into simpler food molecules by enzymes

Substrate

A substance acted on by an enzyme

Product

The result of an enzyme acting on a substrate

Amylase

Substrate: starch

Product: maltose

Location: mouth

Pepsin

Substrate: protein

Product: peptide

Location: stomach

Mouth

Physically breaks down food with teeth

Chemically breaks down food with amylase

Oesophagus

Transports food from the mouth to the stomach with peristalsis (muscular contractions)

Stomach

Physically breaks down food by churning

Chemically breaks down protein with pepsin

Liver

Produces bile

Bile

Helps digest fats

Pancreas

Produces enzymes that are used to break down food in the small intestine

Small Intestine

Absorbs nutrients and minerals form food into the bloodstream

Large Intestine

Absorbs water from food into bloodstream

Rectum

Stores waste (faeces) until it’s ready to leave the body through the anus

Villi

Small, finger-like projections in the small intestine

Increases surface area for absorption, helping nutrients absorb effectively