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IGCSE BIOLOGY > digestive system > Flashcards

digestive system Flashcards

1
Q

balanced diet

A

consists of all food groups in correct porportions

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2
Q

food groups

A

carbohydrates
proteins
lipids
dietary fibre
vitamins
minerals
water

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3
Q

what can having an unbalanced diet lead to

A

malnutritions

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4
Q

causes of starvation

A

taking in less energy than is used over a long period

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5
Q

effect of starvation

A

the body breaks down energy stores
- first fat, then muscle tissue
- severe weight lose and damage to heart and immune system

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6
Q

coronary heart diseases cause

A

diet too high in saturated fat and cholesterol

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7
Q

constipation cause

A

lack of fibre in diet

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8
Q

effect of constipation

A
  • food lacks bulk for muscles to push through the alimentary canal
  • risk of bowel cancer increases
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9
Q

obesity cause

A

taking in more energy than used

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10
Q

obesity effect

A
  • extra energy stored as fat
  • mass increases and contributes to heart diseases and type 2 diabetes.
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11
Q

carbohydrate function

A

source of energy

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12
Q

protein function

A

growth and repair

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13
Q

lipid function

A

insulation and energy storage

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14
Q

dietary fibre

A

provides bulk for the intestine to push food through it

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15
Q

vitamins

A

needed in small quantities to maintain health

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16
Q

minerals

A

needed in small quantities to maintian health

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17
Q

water funcation

A

needed for chemical reactions to take place in the cell

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18
Q

calcium function

A

needed for strong teeth and bones and involved in the clotting of blood.

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19
Q

calcium deficiency

A

osteoporosis

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20
Q

vitamin D function

A

helps absorb calcium and is required for strong bones and teeth

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21
Q

vitamin D source

A

oily fish, dairy, made naturally by sunlight

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22
Q

vitamin C function

A

collagen, protein, gums and bones

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23
Q

vitamin C deficiency

A

scurvy

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24
Q

vitamin A function

A

needed to make pigment in retina for vision

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25
Q

vitamin A sources

A

meat, liver, dairy, leafy greens

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26
Q

iron function

A

needed to make haemoglobin, which transports oxygen

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27
Q

iron sources

A

red meat, liver, leafy greens

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28
Q

age dietary needs

A

amount of energy that young people need increases towards adulthood for growth.
- energy needs of adults decreases as they age

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29
Q

activity dietary needed

A

more active, more energy as muscles are contracting more and respiring faster

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30
Q

pregnancy dietary needs

A
  • more energy required to support the growth of the foetus and the larger mass the woman carries around
  • extra calcium and iron needed to help build bones, teeth and blood
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31
Q

breastfeeding dietary requirements

A

energy increases and extra calcium is needed to make high quality breast milk

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32
Q

sex dietary needes

A

male need more energy as they tend to exceed that of females due to larger proportion of muscles

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33
Q

digestion

A

large, insoluble molecules in food are broken down into smaller, soluble molecules which can be absorbed into the blood stream.

34
Q

what are small, soluble molecules used

A

provide energy via respiration or to build other molecules to grow, repair and function

35
Q

alimentary canal

A

channel through which food flows through the body starting with the mouth and ending at anus

36
Q

mouth/salivary gland

A
  • teeth chew food to break into smaller pieces
  • increases SA:V
  • amylase enzyme digests starch into maltose
  • food shaped into a bolus by the tongue and lubricated by saliva so it can be swallowed easily.
37
Q

oesophagus

A
  • the tube which connects mouth to stomach
  • food bolus swallowed with wave like contractions to push to food bolus down
38
Q

stomach

A
  • food digested by churning actions
  • protease starts to chemically digest proteins
  • HCL acid present to kill bacteria in food and provide optimum pH for protease enzyme to work.
39
Q

duodenum

A
  • food finishes being digested by enzymes produced and secreted from the pancreas
  • pH is alkaline (9)
40
Q

ileum

A
  • absorption of digested food molecules takes place
  • long and lined with villi to increase SA over which absorption can take place.
41
Q

large intestine

A

water is absorbed from the remaining material in the colon to produce faeces
- faeces stored in rectum and removed through anus

42
Q

pancreas

A
  • produced all 3 types of digestive enzymes
  • secretes enzyme in an alkaline fluid into duodenum for digestion to raise the pH
43
Q

liver

A
  • produces bile
  • amino acids not used to make proteins breakdown here to produce urea
44
Q

bile function

A

emulsify fats
breakdown of large droplets into small droplets

45
Q

gall bladder

A

stores the bile to release into duodenum

46
Q

stages of food breakdown

A

1) ingestion
2) mechanical digestion
3) chemical digestion
4) absorption
5) assimilation
6) egestion

47
Q

ingestion

A

the taking in of substances

48
Q

mechanical digestion

A

the breakdown of food into smaller pieces without chemical change to the molecules

49
Q

chemical digestion

A

breakdown of large insoluble molecules, into small soluble molecules

50
Q

absorption

A

movement of small food molecules and ions through the walls of the intestine into blood

51
Q

assmilation

A

movement of digested food molecules into the cells of the body where they are used to becoming part of the cells

52
Q

egestion

A

passing out of food that has not been digested or absorbed through anus

53
Q

peristalsis

A

mechanism which helps food move along the alimentary canal

54
Q

what is peristalsis controlled by

A

circular and longitudinal muscles

55
Q

circular muscles

A

reduced the diameter of the lumen of the oesophagus

56
Q

longtitudinal muslces

A

reduced length of that section the oesophagus or the small intestine

57
Q

mucus in oesophagus

A

produced to lubricate food mass and reduce friction

58
Q

dietary fibre in oesophagus

A

provides roughage required for the muscles to push against

59
Q

why is mechanical digesition useful

A

increases surface area for enzymes to work on

60
Q

what is chemical digestion controlled by

61
Q

what are enzymes

A

biological catalysts which speeds up chemical reactions without themselves being used in the reaction

62
Q

3 main types of digestive enzymes

A

carbohydrases
proteases
lipases

63
Q

amylase

A

breaking down of starch into maltose

64
Q

maltase

A

breaking down of maltose into glucose

65
Q

where is amylase produced

A

salivary glands
pancrease
small intestine

66
Q

where is pepsin made

67
Q

pepsin

A

breaks down proteins into smaller polypeptide chains

68
Q

where is protease made

A

pancrease and small intestine

69
Q

proteases

A

breaks down peptide into amino acids

70
Q

where is lipase produced

A

pancrease and secreted into small intestine

71
Q

lipase

A

breaks down lipids into glycerol and fatty acids

72
Q

role of bile

A
  • neutralizes HCL acid
  • breaks apart large drops of fat into smaller ones.
73
Q

what allows lipase to chemically break down the fats molecules into glycerol and fatty acids

A
  • alkaline conditions
  • larger SA:v ratio
74
Q

where is small digested food molecules absorbed to

A

blood (glucose and amino acids)
lymph (fatty acids and glycerol

75
Q

through which process are small molecules absorbed into the blood by

A

diffusion and active transport

75
Q

by which process is water absorbed and to where

A

osmosis in the small intestine and colon

76
Q

adaptations of small intestine

A
  • very long
  • highly folded surfaces with millions of villi to increase the SA
77
Q

adaptations of villi

A
  • large SA
  • short diffusion distance (one cell thick)
  • steep concentration gradient
78
Q

what are villi supplied with

A

network of blood capillaries that transport glucose and amino acids away from the small intestine

79
Q

what runs through the centre of thr villus and why

A

lacteal
transpot fatty acids and glycerol away from the small intestine in the lymph

IGCSE BIOLOGY (22 decks)

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