Digestion Flashcards
Define digestion
Enzymes break down large complex insoluble molecules into small simple molecules so they can be digested easier
Define ingestion
Food taken in by the mouth
Define absorption
Products of digestion are absorbed through the lining of the intestine
Define assimilation
Uptake of nutrients by cells and their use in the cells
Define Egestion
Removal of faeces containing undigested food, bacteria, enzymes and cells from the intestine lining
What order does food go through the human body
Mouth
salivary gland
oesophagus
Stomach
liver
gall bladder
pancreas
duodenum
ileum
large intestine
appendix
rectum
Define mechanical digestion
Large pieces of food can be broken down into smaller pieces using body structures such as teeth, stomach and muscles to increases SA
Describe the breakdown of starch
Starch is hydrolysed into maltose by salivary gland amylase in the mouth and prancreatic amylase in the small intestine
Describe the breakdown of maltose
Maltose is hydrolysed into glucose by maltase enzymes embedded in microvilli of intestinal epithelial cells
Describe the breakdown of protein
Protein is hydrolysed by protease into polypeptides
Polypeptides are hydrolysed by protease to dipeptides
Dipeptides are hydrolysed by dipeptidases into AAs
3 types of protease enzymes
Endopeptidases, exopeptidases and dipeptides
Describe what endopeptidases do
Break bonds in the middle of the polypeptide to produce shorter polypeptides
Describe what exopeptidases do
Break bonds at the end of the polypeptides
Describe what dipeptides do
Break dipeptides down into AAs
Where are amino acids absorbed
Cells lining the ileum of the Small intestine
What do bile salts do
Emulsifies lipids to increase SA for pancreatic lipids
associate with monoglycerides and cholesterol to form micelles
What enzyme acts on lipids
Lipase
What are lipids hydrolysed to
Fatty acids by lipase
Describe lipid digestion
Lipids are emulsified by bile salts in order to increase surface area
They are then hydrolysed into fatty acids and glycerol
fatty acids and monoglycerides are not very soluble in water so its hard to carry them to the villi
Describe the absorption of lipids
micelles breakdown into fatty acids and monoglycerides which diffuse through the cell mebrane
in the endoplasmic reticulum monoglycerides and fatty acids are used to reform triglycerides
Next they go to the golgi body where triglycerides are packaged with protein and cholesterol into chylomicrons
chylomicrons move to and fuse with the cell membrane to release triglycerides into the lacteals by exocytosis
chylomicrons pass via lymphatic vessels into the blood stream
Explain how cells lining the ileum of the mammals absorb glucose by co transport with sodium
Sodium ions actively transported from ileum cell to blood
This maintains the concentration gradient for sodium to enter the cells from gut.
Glucose enters by facilitated diffusion with sodium ions
Describe how proteins are digested in the human gut
Hydrolysis of peptide bonds.
Endopeptidases break polypeptides into smaller pieces
Exopeptidases remove terminal amino acids
Dipeptidases hydrolyse dipeptides to amino acids
What two enzymes are required for the complete breakdown of starch
amylase and maltase
Describe how digestion of starch in the human gut would lead to an increase in glucose in the blood
Starch hydrolysed by maltase and amylase
Producing glucose
Glucose molecules small enough to cross the gut wall into the bloodq
Suggest a method in order to estimate the concentration of glucose in a solution to turn brick red
Time how long it takes to go brick red
weigh the precipitate
Why would pH increase when lipase is added to milk
As fatty acids are produced
Why are the combined use of endopeptidase and exopeptidase more efficient than just one
endopeptidase hydrolyses internal peptide bonds
exopeptidase hydrolyse external peptide bonds
more ends increase surface area
What would the addition of a respiratory inhibitor prevent the absorption of Amino Acids
Less ATP produced so no active transport
Sodium not moved out of the cell
No diffusion gradient for sodium to move into the cell with amino acids1
Explain how epithelial cells that line the small intestine are adapted for the absorption of glucose
Microvilli provide a large SA
Have large amounts of mitochondria to produce ATP for active transport
Contains Carrier proteins for active transport and facilitate diffusion
