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Biology > the digestive system > Flashcards

the digestive system Flashcards

1
Q

name components of digestive system

A

salivary glands
tongue
epiglottis
oesophagus
liver
stomach
gall bladder
pancreas
duodenum
ileum
colon
rectum
anus

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2
Q

what does saliva consist of

A

mucin
amylase
mineral salts

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3
Q

peristalsis definition

A

involuntary construction or relaxation of muscles

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4
Q

what happens in the oesophagus

A

peristalsis of the circular muscle contracts and relaxes to push food down

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5
Q

what does the liver do

A

produces bile

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6
Q

what does bile contain (and function of components)

A

bile salts - aids digestion of fats
mineral salts - neutralise stomach acid

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7
Q

function of gall bladder

A

stores bile

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8
Q

function of stomach

A

produces enzymes
stores and digests food

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9
Q

pancreas function

A

produces pancreatic juices

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10
Q

ileum structure and function

A

longest part of small intestine
enzymes produced in wall
inner walls have villi

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11
Q

colon (large intestine) function

A

absorbs water (via osmosis)
absorbs mineral and vitamins

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12
Q

function of duodenum (first section of small intestine)

A

receives secretions from the liver and pancreas
further digestion occurs

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13
Q

physical breakdown of food

A

slicing and chewing action of the teeth
increases surface area for enzyme action
continues with churning action caused by contraction of muscles in the stomach wall

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14
Q

chemical digestion of food

A

enzyme hydrolyse molecules into smaller soluble molecules

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15
Q

why are multiple enzymes needed for molecules to be chemically digested

A

enzymes are specific so more than one is needed to hydrolyse a large molecule

one enzyme will hydrolyse a large molecule into sections and then the other will hydrolyse these sections into their monomers

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16
Q

carbohydrases function

A

hydrolyse carbohydrates ultimately to monosaccharides

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17
Q

lipases function

A

hydrolyse lipids into glycerol and fatty acids

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18
Q

proteases function

A

hydrolyse proteins ultimately to amino acids

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19
Q

starch digestion

A

salivary glands secrete salivary amylase
amylase hydrolyses starch into maltose
duodenum has pancreatic juices which contains pancreatic amylase which hydrolyses starch
peristalsis moves food along the intestine membrane bound maltase
hydrolyses maltose into alpha glucose

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20
Q

what do the mineral salts in salvia do

A

maintain a pH 7

21
Q

what do disaccharidase enzymes do

A

hydrolyses disaccharides into monosaccharides

22
Q

3 disaccharidase enzymes

A

sucrase
lactase
maltase

23
Q

what does sucrase breakdown

A

sucrose to glucose and fructose

24
Q

what does lactase breakdown

A

lactose to glucose and galactose

25
Q

what does maltase breakdown

A

maltose to alpha glucose

26
Q

which enzymes break down proteins

A

peptidases (proteases)

27
Q

what do endopeptases do

A

hydrolyse peptide bonds between amino acids in the central region of the molecule

28
Q

where are endopeptidases found

A

in the stomach

29
Q

what do exopeptidases do

A

hydrolyse the peptide bonds on the terminal amino acids of the peptide molecule to release dipeptidases and single amino acids

30
Q

where are exopeptidases found

A

the duodenum

31
Q

what do dipeptidases do

A

hydrolyse the bond between the dipeptide to release amino acids

32
Q

where are dopeptidases found

A

they are membrane bound
found on epithelial cells lining the ileum

33
Q

what do lipases do

A

hydrolyse lipids

34
Q

where are lipases produced

A

the pancreas

35
Q

what do lipases do

A

hydrolyse the ester bond to form fatty acids and monoglycerides

36
Q

what is the structure of a monoglyceride

A

a glycerol with one fatty acid attached

37
Q

what does bile do

A

emulsifies large fat droplets to small droplets called micelles
this increases the surface area of the lipids

38
Q

where are bile salts made

A

liver

39
Q

where are bile salts stored

A

gall bladder

40
Q

order of lipid digestion

A

bile emulsifies large lipid globules to small lipid globules
lipase hydrolyses ester bond
forms fatty acids and glycerol

41
Q

where are sucrase lactase and maltase made

A

ileum epithelial cells

42
Q

where does the absorption of hydrolysed products of digestion occur

A

in the ileum

43
Q

structure of ileum wall (4)

A

folded
villi
thin walls
lined with epithelial cells

44
Q

adaptations of the ileum

A

villi increase surface area for diffusion
thin wall reduces diffusion pathway
blood vessels carry away absorbed material maintaining the gradient
microvilli increase surface area for absorption

45
Q

where are microvilli

A

on the epithelial cells lining the villi on the ileum wall

46
Q

how are glucose and amino acids absorbed into the epithelial cell

A

co transport

47
Q

how are glucose and amino acids moved from the ileum epithelium cell to the blood

A

facilitated diffusion

48
Q

explain the transport of amino acids/glucose from the lumen of the ileum into the bloodstream (sodium potassium pump)

A

1 sodium ions transported out of epithelial cell membrane into the blood via the sodium potassium pump (ATP)
2 this maintains a low concentration of sodium ions inside the epithelial cell compared to the gut lumen
3 sodium ions diffuse down a concentration gradient from the lumen into the epithelial cell by facilitated diffusion
4 brings a glucose/amino acid molecule with it by co transport via carrier protein against concentration gradient
5 glucose/amino acids pass into the blood via facilitated diffusion

49
Q

how are lipids absorbed

A
  • micelles contain bile salts and fatty acids
  • maintains a higher concentration of fatty acids to lining of the ileum
  • fatty acids absorbed by diffusion
  • triglycerides formed in cells
  • vesicles move to cell membrane

Biology (20 decks)

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