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AQA A Level Biology > Digestion > Flashcards

Digestion Flashcards

1
Q

what do the salivary glands produce?

A

salivary amylase and saliva

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2
Q

what do the salivary glands do?

A

lubricate food to make it easier to swallow

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3
Q

what does the liver produce?

A

bile and urea

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4
Q

what does the liver store?

A

glycogen, iron, vitamins, ADEK

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5
Q

what does the liver remove?

A

toxins

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6
Q

what does the gall bladder store?

A

bile

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7
Q

what is the ileum?

A

a long, muscular tube

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8
Q

what does the ileum absorb?

A

soluble food into the bloodstream

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9
Q

how does the oesophagus move?

A

peristalsis

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10
Q

what does the oesophagus carry?

A

food from the mouth to the stomach

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11
Q

what is the stomach?

A

a muscular sac with an inner layer that produces enzymes

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12
Q

what does the stomach do?

A

stores and digests food

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13
Q

what does the HCL acid in the stomach do?

A

neutralises bacteria

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14
Q

what does the pancreas secrete?

A

digestive enzymes and neutraliser (sodium hydrogen carbonate)

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15
Q

what does the large intestines store?

A

faeces in the rectum

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16
Q

what do the villi of the iluem do?

A

increase SA for faster absorption of soluble food

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17
Q

where are microvilli found?

A

on the epithelial cells of the lining of the ileum

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18
Q

how is the lining of the ileum adapted for quick absorption?

A

one cell thick and rich blood supply

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19
Q

where is bile produced?

A

liver

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20
Q

where is bile stored?

A

gall bladder

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21
Q

where is bile released into?

A

small intestine

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22
Q

what does bile do?

A

emulsifies fats and neutralises stomach acid

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23
Q

what is the purpose of digestion?

A

hydrolyse large, insoluble molecules into small soluble molecules so they can be absorbed and assimilated

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24
Q

what is physical digestion?

A

structures like teeth break down large food into smaller pieces to increase SA

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25
what is chemical digestion?
enzymes hydrolyse large, insoluble molecules into small, soluble molecules
26
what enzyme hydrolyses starch?
salivary and pancreatic amylase
27
what enzyme hydrolyses maltose?
maltase
28
what enzyme hydrolyses sucrose?
sucrase
29
what enzyme hydrolyses lactose?
lactase
30
what enzyme hydrolyses lipids?
lipase
31
what enzyme hydrolyses proteins?
endo-peptidase, exo-peptidase, and dipeptidases
32
what is the product of the hydrolysis of starch?
maltose
33
what is the product of the hydrolysis of maltose?
2x alpha glucose
34
what is the product of the hydrolysis of sucrose?
alpha glucose and fructose
35
what is the product of the hydrolysis of lactose?
alpha glucose and galactose
36
what is the product of the hydrolysis of lipids?
3 fatty acids and 1 glycerol
37
what is the product of the hydrolysis of protein?
``` endo-peptidase = peptides exo-peptidase = peptides dipeptidases = amino acids ```
38
How many enzymes does it take to completely hydrolyse a starch molecule?
more than one
39
How must enzymes be added when hydrolysing starch?
in the right order
40
Hydrolysis of starch step 1
saliva enters the mouth from the salivary glands and mixes with food
41
Hydrolysis of starch step 2
salivary amylase hydrolyses starch to maltose
42
what does saliva also contain?
mineral salts to maintain pH at neutral (optimum for salivary amylase)
43
Hydrolysis of starch step 3
food enters stomach. Acidic conditions denature the amylase, preventing further hydrolysis of starch
44
Hydrolysis of starch step 4
food in small intestine mixes with pancreatic juice which contains pancreatic amylase. This hydrolyses the remaining starch to maltose.
45
What do alkaline salts do?
keep pH neutral so the amylase can function
46
where are alkaline salts produced?
pancreas and intestinal wall
47
Hydrolysis of starch step 5
the epithelial lining of the ileum produces maltase which hydrolyses the maltose into alpha glucose
48
what is maltase?
a membrane-bound disaccharide
49
what is maltase a part of?
the cell surface membrane of the epithelial cells lining the ileum
50
what bond do lipases hydrolyse?
the ester bond in triglycerides
51
what is formed when lipase hydrolyses a triglyceride?
fatty acids and monoglycerides
52
what is a monoglyceride?
a glycerol molecule with a single fatty acid molecule attached
53
what do bile salts produced in the liver do?
emulsify lipids into tiny droplets called micelles
54
what do endo-peptidases hydrolyse?
the peptide bonds between amino acids in the central region of a protein. This forms peptides.
55
what do exo-peptidases hydrolyse?
the peptide bonds on the terminal amino acids of the peptides formed from endo-peptidase hydrolysis.
56
what do dipeptidases hydrolyse?
the bond between the 2 amino acids of a dipeptide.
57
are dipeptidases membrane-bound?
yes - they are part of the cell surface membrane of the epithelial cells lining the ileum
58
ingestion
putting food into the alimentary canal/digestive system
59
digestion
breakdown of large insoluble molecules into small soluble ones
60
absorption
the uptake of soluble food molecules into body cells
61
assimilation
incorporation and use of soluble food molecules into body cells
62
egestion
removal of undigested food from the body
63
what is the ileum adapted for?
absorbing the products of digestion
64
how long are villi?
1mm
65
where do villi sit?
the interface between the lumen (cavity) of the intestines, and the blood and tissues inside the body
66
what do the villi do?
increase SA for diffusion
67
what do the thin walls of the villi do?
reduce the distance diffusion takes place over
68
what do the muscles of the villi do?
allow them to move. This helps maintain a diffusion gradient as the movement mixes the content of the ileum, so new material rich in digestion products is readily available
69
what does a good blood vessel supply to the villi do?
maintain a diffusion gradient
70
what do microvilli do?
increase SA for absorption
71
absorption of triglycerides step 1
fatty acids and monoglycerides emulsified by bile then hydrolysed by lipase bile salts surround the digestion products to form micelles
72
absorption of triglycerides step 2
micelles come into contact with the epithelial cells lining the villi of the ileum and breakdown this releases the monoglycerides and fatty acids. these are non-polar so diffuse easily into the epithelial cells across the CSM
73
absorption of triglycerides step 3
inside the epithelial cells monoglycerides and fatty acids are transported to the SER where they recombine to form trigylcerides
74
absorption of triglycerides step 4
in the golgi apparatus triglycerides associate with cholesterol and lipoproteins to form chylomicrons (special particles adapted for the transport of lipids)
75
absorption of triglycerides step 5
chylomicrons move out the epithelial cells by exocytosis. They enter lymphatic capillaries celled lacteals in the centre of each villus
76
absorption of triglycerides step 6
chylomicrons pass via lymphatic vessels into the blood system. The triglycerides inside are hydrolysed by an enzyme in the endothelial cells of blood capillaries where they diffuse into cells.

AQA A Level Biology (5 decks)

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