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Biology 3 - Organisms Exchange Substances With Their Environment > 3.3.3 Digestion + Absorption > Flashcards

3.3.3 Digestion + Absorption Flashcards

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1
Q

What are the 2 types of digestion

A

Physical digestion

Chemical digestion

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2
Q

2 examples of physical digestion

A

Teeth chew food to mechanically break down food into smaller pieces
Walls of stomach contain muscle tissue that contracts to churn food

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3
Q

What do enzymes do in chemical digestion

A

Hydrolyse food into smaller molecules

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4
Q

What are the 3 main enzymes in chemical digestion

A

Carbohydrases
Lipases
Proteases

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5
Q

What does carbohydrase do

A

Digests carbohydrates into monosaccharides

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6
Q

What do lipases do

A

Hydrolysed fats into glycerol and fatty acids

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7
Q

What do proteases do

A

Hydrolyse proteins into amino acids

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8
Q

What are the 2 main carbohydrate digestion enzymes

A

Amylase

Maltase

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9
Q

Where is amylase enzyme made (2)

A

Salivary gland - saliva

Pancreas

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10
Q

What does amylase enzyme do and produce

A

Hydrolyses alternate glycosidic bonds in starch to produce maltose (disaccharide)

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11
Q

Where is maltase enzyme made

What does it do

A

In the ileum

Hydrolyses maltose to produce alpha glucose

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12
Q

What is maltase known as as it isn’t secreted but is bound to the lining of the ileum

A

Known as a membrane-bound disaccharide

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13
Q

3 places where carbohydrate digestion occurs

A

Mouth
Stomach
Small intestine

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14
Q

What happens to the amylase enzyme from the salivary gland (mouth) in the stomach

A

Stomach acid dentures the amylase

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15
Q

What in the liver neutralises stomach acid

A

Bile

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16
Q

What enzymes does the small intestine receive/have (2)

A

Pancreatic amylase

Maltase

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17
Q

2 other carbohydrates (disaccharides)

A

Sucrose

Lactose

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18
Q

What’s sucrose found in

A

Fruits

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19
Q

What happens to sucrose

A

It’s hydrolysed by sucrase (produce by ileum)

Produces glucose + fructose (2x monosaccharides)

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20
Q

What’s lactose found in

A

Milk (yoghurt, cheese)

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21
Q

What happens to lactose

A

Hydrolysed by lactase (produced by ileum)

Produces glucose + galactose (2x monosaccharides)

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22
Q

What’s the lack of lactose production also known as

A

Lactose intolerance

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23
Q

When do babies produce large amounts of lactose

A

When they feed on milk

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24
Q

Where is lactose hydrolysed

What does this produce

A

Not on the small intestine but in the colon

Produces small,soluble molecules(sugars) + gas - diarrhoea

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25
Q

What’s the role of the colon

A

To absorb water into the bloodstream to produce solid faeces

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26
Q

How can the colons Job be disrupted

How is faeces produced

A

If water potentials are changed

Water potential in the colon’s lumen is lowered
So water is drawn into the lumen from the epithelial cells by osmosis
This causes faeces

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27
Q

What enzymes digest lipids + how

What forms

A

Pancreatic lipase enzymes hydrolyse Ester bonds

Fatty acids + monoglycerides are formed

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28
Q

What process assists lipid digestion

What does it involve

A

Emulsification

Bile salts made by the liver split the lipids into micelles (fat droplets)

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29
Q

What does emulsification into micelles do to help lipase work

A

It increases the surface area of the lipid to speed up lipase action

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30
Q

What’s the bile salt like in lipid digestion

So how are they arranged

A

1 end of bile salt is soluble in water (hydrophobic) but not lipid soluble (lipophobic)
The other end is lipophilic but hydrophobic

The salts are arranged so the lipophilic/hydrophobic end is attached to the lipid

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31
Q

What does the lipophobic end of bile salt do

A

Sticks out repelling other lipids

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32
Q

What do micelles transport and where to

A

Digested lipids + vitamins to the epithelial cells of the small intestine

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33
Q

What do micelles do at epithelial cells

A

Micelles fuse with epithelial cells

They then release the lipids/vitamins into epithelial cells allowing it to be absorbed

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34
Q

What are proteins hydrolysed by

A

Peptidase enzymes (proteases)

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35
Q

3 different types of peptidase enzymes in the digestive system

A

Endopeptidases
Exopeptidases
Dipeptidases

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36
Q

What do endopeptidases do and form

A

Hydrolyse the peptide bonds between amino acids in the central region of the protein -> forming peptide molecules

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37
Q

Who do exopeptidases do and form

A

Hydrolyse peptide bonds at terminal amino acids on peptide chains formed by endopeptidase -> forming dipeptides + amino acids

38
Q

What do dipeptidases do and form

A

Hydrolyse bonds between the 2 amino acids of a dipeptide -> producing single amino acids

39
Q

What are dipeptidases like in the small intestine

A

Membrane bound

40
Q

How do things get absorbed in the small intestine

A

Through villi + microvilli

41
Q

What’s villi

A

Finger-like projections 1mm long that increase SA for absorption

42
Q

What is each villus separated by

How does this speed up nutrient absorption

A

Each villus separated by a capillary

Reduces diffusion distance speeding up absorption

43
Q

What gives villi a larger surface area

A

They’re folded and have microvilli on the epithelial cells there

44
Q

What do villi have to reduce diffusion distance

A

Thin membrane

45
Q

What do villi contain that allows them to move to maintain diffusion gradients

A

Muscle tissue that contracts

46
Q

What does villi moving do (2)

A

Mixes the food in the ileum

Maintains concentration gradient to maximise food absorption

47
Q

How’s the small intestine adapted to maximise nutrient absorption (4)

A

Long organ
Large SA - folded villi + microvilli
Mitochondria - active transport
Carrier proteins - active transport/facilitated diffusion
Blood supply close by
Enzymes to digest carbohydrates,fats + proteins
Cotransport (sodium + glucose)

48
Q

What’s celiac disease

A

Intolerance to gluten

49
Q

What’s gluten

A

A protein in wheat,rye + barley

50
Q

What can eating gluten if you have celiac disease do to you

A

Stimulate the immune system to damage the small intestine, causing malnourishment

51
Q

What does gluten attack in celiac disease

So what do this make difficult for this body

A

Gluten attacks the villi that lines the small intestine

so your body can’t take in nutrients from food in the bloodstream

52
Q

How do most nutrients get into epithelial cells (sodium)

A

By moving passively from the lumen of the small intestine into the epithelial cell

53
Q

E.g of a nutrient that can’t move passively into epithelial cells

A

Glucose

54
Q

What’s the co-transport pump in the small intestine

A

Sodium-glucose symporter

55
Q

In the sodium-glucose symporter what must happen before the molecules can be moved by the protein

A

Both sodium + glucose must bind

56
Q

What makes it easier for the other molecule to bind in the sodium-glucose symporter

A

The binding of 1 molecule

57
Q

What keeps the sodium-glucose symporter pump moving in the right direction

A

The concentration gradient of sodium

58
Q

If sodium levels in the epithelial cells were allowed to accumulate what would happen

A

Sodium actively pumped out of epithelial cells and into body by Na/K+ pump
Maintains concentration gradient to allow glucose co-transport
Glucose passes into blood via facilitated diffusion (uniporter)

59
Q

How are triglycerides absorbed (7)

A
  1. Micelles break down when come into contact with epithelium of ileum
  2. Monoglycerides + fatty acids (non-polar) diffuse across membrane into epithelial cells
  3. They’re transported to ER in epithelial cells to reform triglycerides
  4. Bind to cholesterol and lipoproteins in ER and Golgi to form chylomicrons
  5. Chylomicrons enter lacteals
  6. They travel through lymphatic system + pass into blood stream
  7. Triglycerides are then hydrolysed by lipase enzymes + enter cells that need them
60
Q

What 3 things are involved in absorbing triglycerides

A

Micelles (bile salts), monoglycerides + fatty acids

61
Q

What are monoglycerides and fatty acids formed from

A

Lipase enzyme

62
Q

What do monoglycerides and fatty acids reform at the ER in epithelial cells

A

Triglycerides

63
Q

What do triglycerides bind to in ER + Golgi

What does this form

A

Bind to cholesterol and lipoproteins

Forms Chylomicrons

64
Q

What are lacteals

A

Lymphatic capillaries

65
Q

What’s the lymphatic system

A

A series of thin tubes filled with lymph

Contains large number of white blood cells (lymphocytes)

66
Q

What produces the enzymes that hydrolyse molecules for absorption

A

Glands

67
Q

What does the oesophagus do

A

Carries food from mouth to stomach

68
Q

What’s the ileum

A

Long muscular tube

69
Q

What does the large intestine do

A

Absorbs water

70
Q

What’s the process called when faeces are removed by the anus

A

Egestion

71
Q

What’s the pancreas

A

Large gland below the stomach

72
Q

What is the solution called that pancreas secretes containing enzymes

A

Pancreatic juice

73
Q

What does the saliva contain to help maintain the pH for enzymes around neutral

A

Mineral salts

74
Q

What are micelles

A

Tiny fat droplets

75
Q

What are villi well supplied with to maintain diffusion gradient

A

Blood vessels

76
Q

What do micelles do when they come into contact with the epithelial cells lining the villi of the ileum

A

Break down, releasing the monoglycerides and fatty acids

77
Q

Why do monoglycerides and fatty acids easily diffuse into epithelial cells

A

As they’re non-polar

78
Q

Where are monoglycerides and fatty transported to once they’re in the epithelial cells
What happens

A

The endoplasmic reticulum

Recombined to form triglycerides

79
Q

What do the triglycerides form in the endoplasmic reticulum and Golgi apparatus

A

Form chylomicrons

80
Q

What 2 things do triglycerides associate with to form chylomicrons

A

Cholesterol

Lipoproteins

81
Q

What are chylomicrons adapted for

A

Transport of lipids

82
Q

What do chylomicrons enter after they’ve exited the epithelial cells (exocytosis) to enter the bloodstream

A

Lymphatic capillaries (lacteals)

83
Q

How are glucose and amino acids absorbed from small intestine

A

Co-transport

84
Q

Why is it co-transport

A

As either glucose/amino acids are drawn into cells with sodium ions that have been actively transported out by the sodium-potassium pump

85
Q

Where is the higher concentration of sodium ions when they’re transported out of epithelial cells by the pump

A

In the lumen of the intestine rather than epithelial cells

86
Q

What do sodium ions diffuse into the epithelial cells through
What are they now carrying

A

Through a co-transport protein

Either amino acids molecules/glucose molecules

87
Q

How do the glucose/amino acids pass into the blood plasma after this, by using a different carrier

A

Facilitated diffusion

88
Q

What molecules move against their concentration gradient in do-transport

A

The glucose

89
Q

Where is bile made and stored

A

Made - liver

Stored - gall bladder

90
Q

What type of digestion is bile

A

Physical and it has no enzymes

Biology 3 - Organisms Exchange Substances With Their Environment (6 decks)

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