Digestion Flashcards
Name the three enzymes and what they digest
Carbohydrases - hydrolyse carbohydrates to monosaccharides
Lipases - hydrolyse lipids (fats and oils) into glycerol and fatty acids
Proteases - hydrolyse proteins to amino acids
Define Digestion
Digestion is the process in which large (insoluble) molecules are hydrolysed by enzymes into small, soluble molecules, which can be absorbed and assimilated.
Absorption
Soluble molecules are taken into the blood stream through the intestinal lining
Explain what role the mouth has in the digestive system
The mouth contains teeth which break down food into smaller pieces and increases the surface area to volume ratio. Carbohydrates digestion begins here
Explain the role of the structure Oesophagus
A hallow tube with muscular walls through which food passes from the mouth to the stomach.
Contractions of the smooth muscles in the wall of the oesophagus help move food down towards the stomach
Explain the role the stomach has in the digestive system
Protein digestion begins here
Glandular tissue produces enzymes and stomach acid
Muscular tissue churns food miking it with enzymes and acid
the acids help to unravel the proteins to enable enzymes activity, as well as lowering ph which is optimal for stomach enzymes to work
Explain the role of the llumen in digestion (end of small intestine)
Long and lined with microvilli to increase the surface area over which asportion can take place
Explain the role of the large intestine in digestion
any water remaining that was not able to be digested such as cellulose found in plant fiber, is absorbed here
Explain the role of the rectum in the digestive system
Undigested food materials in the rectulm and removed through the anus
Explain the role of the salivary glands in the digestive system
produces digestive juices- anyalse
Explain the roles of the pancreas in the digestive system
Produces digestive juices
Digestion of starch
Starch (long and branched) -analyse a digestive enzyme breaks down starch to maltose (prdouced in the salivary glands and dudenium)- disaccharide- maltase (dudodium and illumen-inside of the cell of gut muscua) in the small intestine breaks down maltose to glucose - monosaccride (glucose)
describe digestion of carbohydrates by amylases and membrane-bound disaccharidases in mammals?
Mouth
Mastication
Salivary amylase
Starch hydrolysed to maltose
Stomach
Acidic pH denatures amylase
Small intestine (duodenum - ileum)
Pancreatic amylase continues starch hydrolysis / neutral pH
Peristalsis
Maltase hydrolyses maltose to glucose
Maltase is a membrane-bound disaccharidase
PLUS
Sucrase
Lactase
Structural features of ilumen
Cell surface membrane is heavily folded with microvilli to greatly increase the surface area for transport.
Many protein transport channels / carrier proteins to increase the rate of absorption.
Large numbers of mitochondria to produce ATP via aerobic respiration for active transport / cotransport.
Explain the co transport of glucose
Sodium ions are being actively pumped out of the cuboidal cells by active, ATP driven Na / K exchange pumps.
This sets up a sodium ion concentration gradient., with a higher concentration of sodium ions on the outside.
The co-transporter then facilitates the sodium ions diffusing in down their gradient to “pull in” glucose molecules into the cytoplasm against its gradient (maximum absorption).
The glucose can then passively diffuse out through other carrier proteins onto the other side / passing into the blood capillaries.
