2.1 The Digestive System Flashcards
Glands produce:
Enzymes, that break down large insoluble molecules into small soluble ones ready for absorption.
The human digestive system is made up of:
A long muscular tube and it’s associated glands.
Parts of the digestive system:
Lostsparls
Tongue Salivary glands Oesophagus Liver Stomach Pancreas Large intestine Small intestine Rectum Anus
Role of the Oesophagus in digestion:
Carries food from the mouth to the stomach, made up of thick muscular walls.
What part does the stomach play in digestion.
It is a muscular sac with an inner layer which produces enzymes. It stores and digests food, particularly proteins. It has glands which produce enzymes which digest protein and also glands producing mucus (so the stomach is not digested by its own enzymes).
What does the small intestine do in digestion?
It is a long muscular tube, food is further digested by enzymes produced in the wall glands. The inner walls are folded into villi and then there are microvilli on the epithelial cells of each villus (more surface area for absorption).
What does the large intestine do in digestion?
Absorbs water
(Most of which comes from secretions of the many digestive glands).
Becomes dry and thick = faeces
What role does the rectum play in digestion?
The faeces are stored here before being removed via the anus by egestion.
What is the role of the salivary glands in digestion?
The salivary glands pass their secretions via a duct into the mouth, they contain amylase which breaks down starch into maltose.
What is the role of the pancreas in digestion?
It produces pancreatic juice which contains proteases, carbohydrases (amylase) and lipases.
Digestion takes place in two stages…
- Physical breakdown
2. Chemical digestion
What happens in physical digestion?
Broken down by teeth - provides large surface area for chemical digestion. Food is churned by the muscles in the stomach wall which also breaks it up.
What is absorption?
Taking in soluble molecules into the body.
What is assimilation?
Incorporating absorbed molecules into the body tissues.
What happens in chemical digestion?
Breaks down large insoluble molecules into smaller soluble ones.
Hydrolysis - splitting up molecules by adding water to the chemical bonds which hold them together. (These enzymes are hydrolases).
Name the three most important types of digestive enzymes.
Carbohydrases - break down carbohydrates to monosaccharides.
Lipases - break down lipids into fatty acids and glycerol.
Proteases - break down protein to amino acids.
What happens after large food molecules have been hydrolysed?
They are absorbed by various means from the small intestine into the blood. They are carried to different parts of the body and often built up again into large molecules ( which are not necessarily the same type the molecules from which they were derived.) They are assimilated.
Polysaccharides are…
Polymers (made up of monomers) (so are polypeptides) (not lipids)
Carbohydrates contain the elements…
Carbon, hydrogen and oxygen
Proteins contain the elements…
Carbon, hydrogen, oxygen and nitrogen
A single carbohydrate monomer is known as…
A monosaccharide
A pair of monosaccharides is…
A disaccharide
Many monosaccharides is…
A polysaccharide
Monosaccharides are sweet-tasting…
Soluble substances which have the general formula (CH2O)n where n is any number from 3 to 7
Examples of some monosaccharides are:
Glucose
Fructose
Galactose