3.3.3 digestion and absorption Flashcards
what is the process of carbohydrate digestion
starch is hydrolysed by salivary amylase
starch is hydrolysed into maltose by amylase
any undigested starch is hydrolysed to maltose by pancreatic amylase
maltose is hydrolysed by membrane bound maltase in ileum
maltose is hydrolysed into 2 glucose molecules
where is amylase produced
salivary gland
small intestines
pancreas
where does amylase act
mouth
small intestine
what substrates are hydrolised by amylase
amylose/ starch
what are the products produced by amylase
sugars
what are the products produced by amylase used for
energy release by respiration
where is protease produced
stomach
pancreas
small intestine
where does protease act
stomach
small intestine
what substrates are hydrolised by protease
proteins
what are the products produced by protease
amino acids
what is chemical digestion
chemicals / enzymes produced by organs used to digest food
what is mechanical digestion
use of physical structures to break down food
what is the function of the mouth
tongue and teeth used to chew food
what is the function of the salivary glands
produces the salivary amylase enzyme
what is the function of the oesophagus
pushes food down to the stomach using muscles which contract
what is the function of the stomach
produces protease and HCl destroys pathogens
what is the function of the large intestines
absorbs water from food
what is the function of the small intestines
produce amylase, lipase and protease
co transport of molecules
absorbs food molecules
what is the function of the rectum
stores faeces
what is the function of the anus
egestion, waste is removed
what is the function of the liver
makes bile to neutralise acid before reaching the small intestines
(bile- emulsifies fats)
what is the function of the pancreas
makes lots of chemicals
what is the function of the gall bladder
stores bile produced in stomach
examples of chemical digestive organs
salivary glands
stomach
small intestine
pancreas
liver
examples of mechanical digestive organs
mouth
oesophagus
stomach
large intestine
small intestine
rectum
anus
where is lipase produced
small intestines
pancreas
where does lipase act
small intestine
what are the substrates that get hydrolised by lipase
lipids
what are the products produced by lipase
fatty acids
gluderol
what are the products of lipase used for
making call membranes
what is the process of digestion
digestion is the process of breaking large molecules of food into smaller molecules to be absorbed into cells for chemical reactions
after starch (carbohydrate) is digested into glucose, what happens to the glucose?
glucose is absorbed from the ileum into bloodstream via co transport
1. sodium leaves the cell via active transport using atp, through sodium potassium pump which creates a concentration gradient
2. glucose binds to sodium ions and goes through a channel protein
3. glucose exits cell via facilitated diffusion through glut2 channel into bloodstream
how is protease able to work in the stomach
it’s optimum ph is 2 so it does not get denatured by HCl
what is the process of protein digestion in the stomach
- exopeptidase- hydrolised terminal peptide bonds in a polypeptide
- endopeptidase- hydrolises internal bonds and produce smaller polypeptides with more ends for faster hydrolysis
- exopetidase + endopeptidase can’t hydrolyse dipeptides as they aren’t complimentary
- membrane bound dipeptidase hydrolised peptide bonds in dipeptides into 2 amino acids
what si the function of exopeptidase
hydrolised the terminal bonds on the outside of polypeptides
what is the function of endopeptidase
hydrolised internal bonds on the inside of a polypeptide
what is the function of membrane bound dipeptidase
hydrolyse peptide bonds in dipeptides into 2 amino acids
why does exopeptidases alone digest polypeptides slowly
there are less ends which leads to slower rate of hydrolysis
how does salivary amylase digest starch
hydrolised it using water to break glycosidic bonds and for maltose
what is maltose hydrolised into
2 glucose molecules
what is the process of protein absorption
1.sodium ions exit ileum via active transport using ATP through sodium potassium pump which creates a concentration gradient in bloodstream
2. amino acid bind to sodium and enter ileum cell via facilitated diffusion through a channel protein
3. amino acids exit ilium cell via facilitated diffusion by carrier proteins back into the bloodstream
what are the adaptations of the ileum epithelial cells
wall of the ileum cell is folded into many microvili supplied with capillaries= large SA, thin diffusion distance, maintains blood concentration of glucose
what types of lipids does lipase break down
triglycerides
what does lipase hydrolise a triglyceride into
triglyceride> diglyceride> monoglyceride + 2 FA
why does lipase struggle to digest lipids
lipase is an enzyme/ protein which is soluble in water, lipids are insoluble
why is the reaction of lipase slow
triglycerides are hydrophobic and it’s difficult for dissolved lipase to approach them
what is the function of bile
emulsify fats to help lipase digest them
what is the function of bile salts
emulsify fats to make lipids water soluble
causes lipids to form small droplets
what is the process of lipid digestion
the hydrophobic part of the bile salt binds to the fat globule
hydrophilic part of the bile salt attracts water which the lipase is dissolved in
lipase is then able to bind to the triglyceride to digest and produce 1 monoglyceride and 2 fatty acids
what is the process of lipid absorption
monoglyceride and 2 fatty acids combine with bile salts and form micelles
micelles carry contents to epithelial cells membrane in small intestines
monoglycerides and fatty acids can simply diffuse into cell and reform a truglyceride using lipase
triglycerides combine with lipoproteins and cholesterol to form chylomicrons
chylomicrons are packages into vescicles which move to cell membrane and are released into the lymph
why does ph of solution decrease during lipid digestion
more fatty acids are released from triglycerides which decrease ph
how do bile salts increase rate of digestion
emulsify lipids and make them smaller to make them soluble in water so lipase is able to hydrolyse it
