digestive system Flashcards

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1
Q

what does the alimentary canal do?

A

forms a tube through the centre of the body

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2
Q

food is… from this canal for the purpose that the food can be…

A

ingested, digested, absorbed, egested
assimilated

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3
Q

what makes up the small intestine?

A

duodenum and ileum

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4
Q

what makes up the large intestine?

A

the colon and the anus

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5
Q

what is ingestion?

A

taking food in through the mouth and swallowing

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6
Q

what is digestion?

A

breaking down large insoluble molecules in food into smaller pieces and smaller soluble molecules

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7
Q

what is absorption?

A

the movement of small soluble molecules out of the gut and into the blood by diffusion and active transport

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8
Q

what is egestion?

A

passing out undigested food through the anus

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9
Q

what is assimilation?

A

building larger biological molecules from the small soluble molecules, in all cells

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10
Q

what is the first structure in the alimentary canal?

A

the mouth

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11
Q

where does ingestion take place?

A

the mouth

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12
Q

what also happens in the mouth?

A

digestion

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13
Q

what is an example of mechanical digestion in the mouth?

A
  • food is broken up into smaller pieces in the mouth by chewing
  • this increases the surface area for enzymes and also prevents discomfort when swallowing
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14
Q

what is an example of chemical digestion in the mouth?

A
  • saliva is released into the mouth by the salivary glands
  • makes the food easier to swallow
  • contains amylase
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15
Q

what does amylase break down starch to?

A

starch-> maltose

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16
Q

what happens when amylase reaches the stomach?

A

amylase works best at a neutral pH so it is denatured when it reaches the stomach and stops working

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17
Q

what happens before swallowing?

A

the food is shaped into a ball by the tongue and moved towards the back of the mouth

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18
Q

what is the ball of food called?

A

a bolus

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19
Q

what is the epiglottis and what does it do?

A

a flap which blocks the food from entering the trachea

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20
Q

what is the oesophagus?

A

a long tube that connects the mouth to the stomach

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21
Q

what process occurs in the oesophagus?

A

peristalsis

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22
Q

what is peristalsis?

A
  • two sets of muscles push the food down the oesophagus
  • the circular muscles contract behind the bolus pushing it along
  • when the longitudinal muscles contract, they make the oesophagus wider and the circular muscles relax
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23
Q

what do the gastric glands in the stomach wall secrete?

A

the enzyme pepsin

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24
Q

what does pepsin do?

A

begins the process of digesting proteins into peptides

25
Q

what are peptides?

A

shorter chains of amino acids

26
Q

what does the contraction of the stomach wall cause?

A

mixing of the contents of the stomach- maximising contact between enzymes and food

27
Q

what are pepsin’s optimum conditions?

A

an acidic pH

28
Q

why are the conditions in the stomach acidic?

A

the release of hydrochloric acid by the gastric glands

29
Q

pepsin has a high or low pH?

A

very low

30
Q

pepsin is covered in what?

A

a mucus lining

31
Q

what does the hydrochloric acid in our stomach do?

A

kills many bacteria and fungi which may be present in the food we eat

32
Q

what 2 processes occur in the small intestine?

A

digestion and absorption

33
Q

what process happens in the duodenum?

A

digestion

34
Q

the duodenum is the final site of what?

A

chemical digestion

35
Q

what enzymes does the pancreas make?

A

trypsin, amylase and lipase

36
Q

where does the pancreas secrete the enzymes into?

A

the duodenum

37
Q

what does trypsin do?

A

breaks down protein into peptides

38
Q

what does lipase do?

A

breaks down lipids into glycerol and 3 fatty acids

39
Q

what does the duodenum wall also contain?

A

glands which make enzymes and secretes them into the duodenum

40
Q

the glands in the duodenum wall make what enzymes?

A

maltase and peptidase

41
Q

what does maltase do?

A

breaks down maltose into glucose

42
Q

what does peptidase do?

A

breaks down peptide into amino acids

43
Q

bile is found where?

A

in the duodenum

44
Q

where is bile produced?

A

in the liver

45
Q

where is bile stored?

A

in the gall bladder

46
Q

where is bile released into and through where?

A

released into the duodenum through the bile duct

47
Q

what are the two functions of bile?

A

1) neutralises the stomach acid- enzymes in the duodenum work best at pH 7-8
2) emulsifies lipids- breaks large droplets into smaller droplets- increasing SA for lipase to digest the fats

48
Q

what happens once the food has entered the ileum?

A

digestion is over and absorption begins

49
Q

what are the finger like projections found in the ileum called?

A

villi

50
Q

what does the villi do?

A

absorb small soluble molecules

51
Q

how are the small soluble molecules absorbed?

A
  • some by diffusion
  • however, some such as glucose are also absorbed by active transport
52
Q

how is the rate of diffusion in the ileum increased?

A
  • large SA- folding of ileum, villi and microvilli
  • short diffusion distance- villi walls are one cell thick
  • high concentration gradient- provided by capillary network and lacteals removing absorbed molecules
53
Q

what is the colon the site for?

A

all reabsorption of water

54
Q

where is faeces stored?

A

in the rectum

55
Q

where are faeces egested from?

A

the anus

56
Q

what is excretion?

A

the expulsion of faeces from the anus- the removal of undigested food from the body

57
Q

what is excretion?

A

the removal of waste substances produced by chemical reactions in the body

58
Q

what are some examples of excretion?

A
  • carbon dioxide- removed by the lungs
  • urea- removed by the kidneys and sweat
59
Q

where does assimilation occur?

A

takes place in all cells using the food molecules absorbed to build more complex molecules such as proteins