HDS Flashcards
What are biological molecules and what do they contain?
Critically important molecules needed for organisms to survive; carbon
What are the 3 main nutrients in food
Carbohydrates
Lipids
Proteins
Molecule size of proteins
Very large
Function of carbohydrates
Immediate source of energy
Some make up fibre that the body cannot digest. Passes out undigested and forms the bulk of our faeces
Functions of lipids
Energy reserve and acts as insulation against heat loss from body
Size of carbohydrate molecules
Big/small
Function of proteins
Make new cells for body growth and repair worn out tissues
Size of lipid molecules
Often small
Definition of enzymes
Biological catalysts. Speed up the rate of chemical reactions without themselves being chemically changed at the end of reactions
What are the associated organs and glands in the digestive system
Liver, gall bladder, pancreas
What is the tube in the mammalian digestive system called
Alimentary canal
Definition of digestion
Process that breaks down large, insoluble, complex food substances into small, soluble, simple molecules
Why is digestion necessary
Turn complex food substances into smaller, soluble molecules that are small enough to be easily absorbed into the cells of the small intestine and rest of the body
What are the two types of digestion
Physical & chemical
What is physical digestion
Breaking up food into smaller pieces
List the physical digestion processes and what they are done by
Chewing (teeth), churning (stomach), bile emulsification
Why is physical digestion needed
Increase surface area to volume ratio of the ingested food so that enzymes can digest it more efficiently
What does chemical digestion involve
Breaking down large molecules into small soluble molecules by digestive enzymes
Why is chemical digestion needed
So small soluble molecules can be easily absorbed by cells in small intestine
What do the salivary glands produce
Saliva
Function of salivary amylase
Digest starch into maltose
What is the optimum pH of salivary amylase
pH 7
The tongue rolls up the chewed food into a ______
Bolus
What moves the bolus along the oesophagus
Peristalsis (rhythmic wave-like contractions of the muscles)
What is found in the gastric juice
Hydrochloric acid and pepsin
Function of pepsin
Digests proteins into polypeptides
Optimum pH of pepsin
pH 1
What does the liver produce
Bile
Where is bile stored and released
Gall bladder
Released into the small intestine via the bile duct
Functions of bile
Emulsifies lipids by breaking up large fat droplets into tiny fat droplets -> increases surface area to volume ratio to increase rate of lipid digestion by lipases
Neutralise the acidic chyme from the stomach
What does the pancreas produce
Pancreatic juice
What digestive enzymes do the walls of the small intestine secrete
Carbohydrases
Peptidase
Intestinal Lipase
What does the pancreatic juice contain
Pancreatic Amylase
Trypsin
Pancreatic Lipase
Function of carbohydrases
Digest disaccharides into monosaccharides
Function of pancreatic amylase
Digest starch to maltose molecules
Function of peptidase
Digest polypeptides to individual units of amino acids
What is one example of a carbohydrase and say its function
Maltase- Digest maltose to glucose molecules
Function of trypsin
Digest proteins to polypeptides
Function of intestinal lipase
Digest lipids to fatty acids and glycerol
Function of pancreatic lipase
Digest lipids to fatty acids
Where are faeces temporarily stored
Rectum
What is the process of expelling the faeces via the anus called
Egestion
