Digestion - Chpt 15

Physical Digestion

Movement in the body digests foods

Examples of physical digestion

• chewed in the mouth

• mixed with saliva

• churned in stomach

• melts in stomach at 37 degrees

Chemical Digestion

Enzymes and water break down nutrients

Enzymes break down…

• Protein into amino acid

• Carbohydrates into simple sugars e.g. glucose

• Fats into fatty acids and glycerol

Amylase

Breaks down starch into maltose in the mouth with saliva

Pepsin

Breaks down protein into amino acids in stomach

How to have a healthy digestive system & expand

• Drink 2 litres of water daily

• Eat probiotic yoghurts

• Eat a high fibre diet

• Avoid too much caffeine, spicy food and alcohol

Mouth

• Food chewed with teeth

• Food mixed with saliva

• Saliva contains amylase which changes starch into maltose e.g. bread

Epiglottis

A flap in the throat that covers the trachea when eating to prevent choking

Oesophagus

Peristalsis moves food down it to the stomach

Stomach

• Food is churned into chyme (liquid)

• Fat melts (37 degrees)

• Gastric juice contains pepsins which breaks down protein into amino acids

• Hydrochloric acid kills bacteria preventing food poisoning

Small Intestine

• Intestinal juice completes the digestion of carbs. protein and fat

• Digested nutrients pass through the villi in the wall of the small intestine into the blood stream and are absorbed

Duodenum

• Liver and pancreas

• Produces pancreatic juice which has enzymes that break

  • protein into amino acids

  • starch into simple sugars

  • fat into fatty acids and glycerol  

• Produces bile which helps break down fats

Large Intestine

Waste becomes solid as it moves through the bowel by peristalsis and more to the rectum and out the anus

Water is absorbed into the blood stream

Vitamin B and K are made