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Biology - Exchange And Transport > Digestion > Flashcards

Digestion Flashcards

1
Q

digestion

A

the mechanical and chemical break down of food so it can be absorbed into the blood

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2
Q

mechanical digestion

A

breaking down large food by grinding and churning to increase SA available for chemical digestion

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3
Q

chemical digestion

A

enzymes hydrolyse covalent bonds to break down large molecules into smaller soluble molecules that can be absorbed into te blood

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4
Q

two types of chemical digestion

A

intracellular and extracellular

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5
Q

intracellular digestion

A

occurs in epithelial cells of ileum

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6
Q

extracellular digestion

A

enzymes are secreted out of cells ito the gut lumen

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7
Q

4 examples of extracellular digestion organs and glands

A
  • salivary glands –> mouth
  • gastric glands –> stomach
  • pancreas –> duodenum
  • liver –> duodenum (bile)
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8
Q

2 enzymes involved in intracellular digestion

A

disaccharidases and dipeptidases

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9
Q

what is the benefit of requiring multiple enzymes to fully digest a food type

A

the action of the fist enzyme icreases the SA available for the second enzyme so increases rate of digestions

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10
Q

why do different regions ofthe gut have different pHs?

A

enzymes have different optimum pHs

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11
Q

3 roles of mucus

A
  • important in maintaining correct pH of particular regions of the gut –> neutralise stomach acid in duodenum
  • provides lubrication for food to move along gut
  • protects gut lining from erosion (acid atack)
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12
Q

what, how, where

2 steps of carbohydrate digestion

A
  1. starch is broken down into maltose by salivary and pancreatic amylase in the stomach and duodenum
  2. maltose is broken down into glucose by maltase in the epithelial cells of the ileum
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13
Q

2 disaccharidases

A

sucrase and lactase

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14
Q

what, how, where

3 steps of protein digestion

A
  1. proteins are broken down into polypeptide chains by endopeptidases (pepsin) in the stomach
  2. polypeptide chains broken down into shorter polypeptide chains by endopeptidases (trypsin) in the duodenum
  3. shorter polypeptide chains are proken down into dipeptides and amino acids by exopeptidases in the duodenum
  4. dipeptides are broken down into amino acids by dipeptidases (exopeptidases) inthe epithelial cells lineing the ileum
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15
Q

peptidases

A

hydrolyse peptide bonds in a polypeptide chain

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16
Q

endopeptidases

A

hydrolyse inner peptide bonds in a polypeptide chain

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17
Q

exopeptidases

A

hydrolyse end (terminal) peptide bonds in a polypeptide

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18
Q

3 types of exopeptidases

A
  1. aminopeptidases = N-terminal (left end)
  2. carboxypeptidases = C-terminal (right end)
  3. dipeptidases = dipeptides
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19
Q

2 steps of lipid digestion

A
  1. mechanical brekadown of lipid droplets into micelles by bile salts in the duodenum
  2. chemical digestion of micelles into monoglycerides and fatty acids by lipase in the duodenum
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20
Q

what is the role of bile salts in digestion of lipids?

A

emulsify lipid droplets to increase SA available for action of lipase

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21
Q

function of sodium hydrogencarbonate in lipid digestion

A

neutralise stomach acid in duodenum

22
Q

contents of bile

A

bile salts and sodium hydrogencarbonate

23
Q

where is bile produced, stored and released?

A

produced in liver
stored in gall bladder
released via bile duct into the duodenum

24
Q

advantage of micelles forming

A

micelles are water soluble so are more easily transported to the epithelial cells in the ileum

25
Q

pH of mouth

A

pH 6.5-7.5

26
Q

mechanical digestion in the mouth

A

teeth break up food to increase SA for chemical digestion

27
Q

chemical digestion in mouth

A
  • salivary glands secrete saliva containing amylase, mucus and mineral ions
  • starch digested
28
Q

function of mucus and mineral ions in mouth

A

mucus = lubrication
mineral ions = maintain neutral pH

29
Q

oesophagus in digestion

A

lined by epthelial tissue, containing goblet cells which secrete mucus for lubrication

peristalsis occurs = coordinated contraction of circular and longitudinal muscle

30
Q

mechanical digestion in stomach

A

churn contents to form acidic chyme (has extra layer of muscle - oblique - to aid churning

31
Q

chemical digestion in stomach

A

gastric gland secrete gastric juice containing hydrochloric acid, endopeptidases (pepsin) and mucus
digest proteins

32
Q

pH of stomach

A

2

33
Q

function of hydrochloric acid in stomach

A

decrease pH to activate enzyes and kill bacteria by denaturing their enzymes

34
Q

function of mucus in stomach

A

lubrication and protection from erosion

35
Q

two sphincters of the stomach

A

cardiac sphincter and pyloric sphincter

36
Q

pH of the duodenum

A

7-8

37
Q

where is the main sitee of chemical digestion?

A

duodenum

38
Q

what 3 glands secrete juices into the duodenum and what do they secrete??

A
  • pancreas - pancreatic juice
  • liver - bile
  • Broner’s gland - mucus
39
Q

what does pancreatic juice contain?

A
  • endopeptidase and exopeptidases
  • lipase
  • amylase
  • hydrogen carbonate ions
40
Q

function of mucus in duodenum

A

neutralise stomach acid and protect wall from acid erosion

41
Q

2 steps of digestion in ileum

A
  1. as molecules move across epithelial cell membrane, theyre hydrolysed by proteins in the cell into their monomers
  2. taken away in blood so maintains concentration gradient from ileum lumen to epithelial cell
42
Q

what two molecules are digested in the ileum?

A

disaccharides and dipeptides?

43
Q

function of the colon

A

absorbs remaining waater and vitamins from bacteria
absorbs water so we can produce solid faeces as this stimulates peristalsis

44
Q

contents of faeces

A

undigested material (cellulose) - fibre
souughed cells
bacteria

45
Q

function of the rectum

A

temporary store of faeces before egestion

46
Q

egestion

A

removal of undigested and waste material from the body

47
Q

what are sloughed cells

A

cells scraped off the gut wall

48
Q

site of action of amylase

A

mouth and duodenum

49
Q

site of action of endopeptidases

A

stomach and duodenum

50
Q

site of action of exopeptidases

A

duodenum and ileum

51
Q

site of action of lipase

A

duodenum

52
Q

site of action of disaccharidases

A

ileum

Biology - Exchange And Transport (7 decks)

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