Digestion of Human 11.

How do human processing food

1. Ingestion: Mastication (food in the mouth, chewed, swallowed.)

2. Digestion: Break down of large, insoluble molecules into small molecules. It includes two types of digestion, mechanical digestion: chewing; chemical digestion: enzymes involved.

3. Absorption: Small molecules moving into the blood stream.

4. Assimilation: Making new molecules (e.g. muscles).

5. Egestion: Removal of waste (faeces).

1. Mouth

Food is ingested, and with help of the teeth and tongue, it is rolled into a bolus. Salivary glands add salivary amylase.

2. Epiglottis

Flap of skin that closes the trachea when we swallow, it prevents food going down the wrong way.

3. Oesophagus

Tube allowing food to travel from mouth to stomach by peristalsis.

4. Stomach

A muscular bag where food is churned and mixed with:

1. protease enzyme - pepsin

2. HCl to make acid PH to kill bacteria

5. Duodenum

The first part of the small intestine. Bile, NaHCO3, protease-trypsin and pancreatic enzymes are added here.

Small Intestine

Food reaching the small intestine is called chyme, digestion finishes here and the useful nutrients are absorbed into the blood stream.

Large Intestine / Colon

Water is absorbed into blood stream, waste products will be egested.

Rectum

Final part of the large intestine, stores faeces.

Anus

An opening (sphincter) allowing egestion to happen here. Bile is produced.

Liver

Many metabolic reactions happened here and bile is produced.

Gall Bladder

Bile is stored here.

Pancreas

It secretes several enzymes including:

1. Pancreatic amylase

2. Lipase

Peristalsis

Peristalsis is the unvoluntary, wave-like contraction of muscles in tubular organs, primarily to move food through the digestive tract. It works by contracting behind a bolus to push it forward while relaxing ahead of it.

What is Bile

A secretion with bile pigments and bile salts. 

Produced in the liver and stored in the gall bladder. It is secreted through the bile duct into the small intestine. 

The role of bile

1. To neutralise the food making it more alkaline. 

2. To emulsify fat