digestion and absorbtion Flashcards
how molecules broken down ?
hydrolysis
what two enzymes are involved in carbohydrate digestion ?
Amylases
membrane bound diassaccarides
where is amylase produce ?
pancreas
salivary gland
what does amylase do ?
hydrolyse polysaccarides into diassaccarides maltose by hydrolysing glysocidic bonds
what does amylase do ?
sucrase and lactase are membrane bound organnelles that hydrolyse sucrose and lactose into monosaccharides
where does digestion of carboydrates occur?
mouth -> duodenum ->ileum
what are three enzymes in protein digestiion ?
endopeptidase
exopeptidase
membrane bound dipeptidase
what does endopeptidase do?
hydrolyse peptide bond between amino acid in middle of polymer chain
what do exopeptidases do ?
hydrolyse peptide bond between amino acid on ends of a polymer chain
what membrane bound dipeptiidases do ?
hydrolyse peptide bonds between two amino acids
where does protein digestion occur ?
stomach ->duodenum -> fully digested in ileum
what enzymes are involved in lipids ?
lipase and bile salts
where is lipase produces ?
pancrease
what can lipase do ?
hydrolyse ester bonds in triglycerides to form monoglycerides and fatty acids
where do lipase secrete its enzymes
duodenum and ileum
where are bile salts produce?
liver
what can bile salts do ?
emulsify lipids and form tiny droplets called micelles
what is the purpose of bile salts producing micelles ?
increases surface area for lipase to act on
what are the two stages of lipid digestion ?
physical and chemical
what is physical digestion of lipids?
emulsification and micelle formation
what is chemical digestion of lipids ?
lipase
what happens in physical digestion of lipids ?
lipids get coated in bile salts to create an emulsion .many small droplets of lipids provides a larger surface area to provide faster hydrolysis by lipase
what happens in chemical digestion if lipids?
lipase hydrolyses triglycerides into triglycerides , glycerol and fatty acids
what is a micelle ?
water solouble vesicles formed of fatty acids , monoglycerides , glycerol and bile salts
what do micelles do ?
deliver the fatty acids , glycerol and monoglcerides to the epithelial cells of ileum for absorbtion
where are the products of digestion absorbed ?
across cells lining the ileum
what is the ileum cell wall covered in ?
villi
how are villi adapted for absorbtion ?
thin walls
surronded by capillary network
epithelial cells have microvilli
increases surface area,decreases diffusion distance and maintains a concentration gradient
what method are monosaccarrides and amino acids absorbed in ?
co transport
what does there need to be in order for glucose and amino acids to be be absorbed from the lumen to the gut facillitated diffusion ?
a higher concertration in the lumen compared to the epithelial cells
why can’t glucose and amino acids be absorbed from the lumen to the gut through facillitated diffusion ?
their is usually a higher concetration of them in the epithelial cells compared to the lumen .
how do sodium ions move from epithelial cells to blood ?
active transport
why do sodium ions move from epithelial cells to blood ?
lower concentration in epithelial cells compared to lining of ileum .So sodium ions can diffuse from the ileum down the concentration gradient into the epithelial cells
what type of protein do sodium ions diffuse through?
co transport protein
what does the sodium ion co transport protein allow?
either glucose or amino acid can attach and are transported into the epithelial cell against their concentration gradient.so glucose has a high concentration in epithelial cell and moves by facillitated diffusion into the blood
how are lipids absorbed
encouters ileum epithelial cells fatty acids and monoglycerides can simply diffuse across the cell membrane to enter the epithelial cells
what happen to monoglycerides ,fatty acids and glycerol once inside the epithelial cell ?
modified back into triglycerides by endoplasmic recticulum and golgi body
what is it called when the products of lipids are being processed by the golgi body and bind to a protein ?
chylomicrons
where a chylomicrons released
golgi vesicles
what do golgi vesicles containing chylomicrons do ?
move to other end of epithelial cells and releases by exocytosis
how are what gets released from a golgi vesicle in lipid absorbtion absorbed into rest of body ?
absorb into lacteal and get transported round in lymph vessel which eventually gets drained into cappillary system
