The Digestive System Flashcards
What is chemical digestion?
The breakdown of large molecules into smaller molecules, it uses water and digestive enzymes which causes hydrolysis reactions.
What is mechanical digestion?
The physical breakdown of food, it’s cut and crushed into smaller manageable pieces by the teeth and is churned by muscular contractions of the stomach. It increases the SA for chemical digestion.
What’s the digestive system made up of?
Oesophagus Stomach Ileum Large intestine Rectum Salivary glands Pancreas
What does the Oesophagus do?
Carries food from the mouth to the stomach, it is made up of a thick muscular wall.
What does the stomach do?
Muscular sacs with an inner layer the produces enzymes. It’s role is to store and digest food. It produces mucus.
What does the ileum do?
A long muscular tube in which food is further digested by enzymes that are produced by its walls and glands that pour their secretion into it. It has villi and micro villi.
What does the large intestine do?
Absorbs water that comes from secretions of many digestive glands. The food within it becomes drier and forms faeces.
What does the rectum do?
It the final section of the intestines, the faeces are stored her before egestion.
What do the salivary glands do?
They pass their secretions via a duct in the mouth. They contain amylase which hydrolyses starch to maltose.
What does the pancreas do?
A large gland situated below the stomach. It produces pancreatic juice, the contains protease to digest proteins, lipase and amylase.
Carbohydrate digestion?
Starch is first digested in the mouth. Amylase hydrolyses starch to maltose. It is denatured in the stomach so there is no further breakdown of starch. Then in the small intestine as pancreatic juices are released containing pancreatic amylase, this also hydrolyses starch to maltose. Maltose is then hydrolysed to its monosaccharide in the ileum producing two alpha glucose molecules. This disaccharide maltose is embedded in the cell membrane of cell lining the ileum, it is known as a membrane bound disaccharide. Bothe sucrose and lactose are hydrolysed by the membrane bound disaccharide.
How is sucrose broken down?
Sucrase hydrolyses the single glycosidic bond which produces 2 monosaccharides, glucose and fructose.
How is lactose broken down?
Lactase hydrolyses the single glycosidic bond which produces 2 monosaccharides, glucose and galactose.
The digestion of lipids?
Lipids are emulsified by bile salts, produces by the liver, then hydrolysed by lipase. This splits the lipids into micelles which increases SA speeding up the action of the lipase, which are produced in the pancreas. This hydrolyses the ester bond in triglycerides and diglycerides to monoglycerides. This happens in the small intestine.
Digestion of proteins?
Hydrolysed by enzymes called peptidases. Endopeptidase hydrolysed the peptide bond between amino acids in the central region of the protein this forms a series of smaller peptide molecules. Exopeptidase hydrolyses the peptide molecules produced form action of endopeptidase. This hydrolyses the peptide bond on the terminal amino acid, it removes the terminal amino acids. Dipeptidase is found in the cell surface membrane of the cells lining the ileum, it is membrane bound and hydrolyses the peptide bond between 2 amino acids producing amino acids.
