Health and Social Care Unit 4 LO3

Structure of the digestive system and functions of the component parts

The digestive system processes the breakdown and absorption of food and the removal of waste food products from the body.

• Buccal cavity is where food is chewed to break it down.

• Salivary glands produce saliva, which helps moisten food and make it easy to swallow.

• Epiglottis is a flap of cartilage behind the root of the tongue, which covers the opening of the windpipe when swallowing food.

• Oesophagus is a muscular tube that connects the throat with the stomach. Food moves down through the oesophagus to the stomach.

• Peristalsis, a squeezing action by the muscles, helps the food move downwards to the stomach.

• Stomach is a sac with muscular walls that churn the food to break it up. It produces hydrochloric acid and enzymes to digest the food.

• Small intestine is the duodenum. Here the food, partially digested by the stomach, now called chyme, is chemically altered by fluids from the liver and by bile from the pancreas. The duodenum is lined with villi, whch increases the surface area and help the absorption of nutrients into the bloodstream.

• Large intestine reabsorbs fluids and processes waste products in preparation for elimination from the body.

• Rectum is the last part of the colon and links it to the anus. It stores faeces until they can be expelled from the body.

• Anus is the opening in the body through which the faeces are expelled by the process of defecation. The anal sphincter muscle controls the opening and closing of the anus.

Mechanical and chemical digestion

Mechanical digestion

Mechanical digestion is when food is physically broken down to make it smaller:

• Chewing action - the teeth break down large pieces of food into smaller ones that can be swallowed.

• The stomach churns food to break it down.

• In the small intestine the bile emulsifies lipids which helps with the mechanical digestion of fats.

Chemical digestion

Chemical digestion is where nutrients are broken down by enzymes to smaller molecules that can be absorbed into the blood and used by cells:

• In the buccal cavity, food is dissolved with saliva, which contains an enzyme called amylase.
• The stomach mixes food with enzymes and hydrochloric acid while churning it.
• Chemical digestion of proteins - broken down by pepsin in the stomach and small intestine.

Ingestion: Food is taken into the body through the mouth

--> Digestion: Physical and chemical breakdown of the food

--> Absorption: Food passes through the intestine walls into the bloodstream

--> Elimination: The undigested waste…