home ec- chp 15: digestion

digestion

the breakdown of nutrients so that they can be absorbed into the bloodstream

enzymes

chemicals that help the breakdown of food

physical changes

food broken down by mechanical action

chemical changes

chemical changes brought about by enzymes

proteins are broken down to…

amino acids

carbohydrates are broken down to…

simple sugars such as glucose

fats are broken down to…

fatty acids and glycerol

why don’t vitamins, minerals and water need to be broken down

as they are simple substances that can be absorbed as they are

what type of digestion occurs in the mouth

physical and chemical

peristalsis

muscular contractions that push food through the digestive system

aborption

the passing of digested food into the bloodstream

how food is digested in the mouth

1- broken down by teeth

2- mixed with saliva which contains the enzyme amylase, which begins the breakdown of starch

digestion in the oesophagus

no digestion, food is moved to the stomach by peristalsis

digestion in the stomach

1- food is churned in the stomach where it mixes with gastric juices

2- the enzyme pepsin in the gastric juices begins the breakdown of proteins

3-fat melts in the heat of the stomach

4- hydrochloric acid kills any bacteria in food

5- food remains in the stomach for4-6 hours until it is passed to the small intestine

small intestine

there are 2 digestive juices in the small intestine: 1- bile 2- pancreatic juice

1- bile emulsifies fat

2- pancreatic juice contains enzymes which break down fats, proteins and carbohydrates

3- other enzymes complete the break down of nutrients

4- digested nutrients are absorbed into the blood through the villi.

large intestine

1- water is absorbed into the bloodstream

2- vitamin b and k are manufactured

3- waste is expelled.