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PHSL101 > Gastrointestinal > Flashcards

Gastrointestinal Flashcards

1
Q

what are the three main components of food

A

carbohydrates, proteins, fats

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2
Q

what are carbohydrates used for

A

ATP

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3
Q

what are proteins used for

A

building blocks of cells (e.g. organelles, membranes etc)

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4
Q

what are lipids used for

A

ATP and building blocks of a cell

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5
Q

can we absorb both large and small molecules

A

no, only small ones. this is why digestion is needed

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6
Q

what parts of the body are involved in mechanical digestion

A

mouth (chewing) and stomach (propulsion and retropulsion)

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7
Q

what does mechanical digestion do

A

breaks the food into smaller pieces

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8
Q

what does chemical digestion do

A

breaks the particles into smaller pieces

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9
Q

what does chemical/enzymatic digestion do to carbohydrates

A

turns them from polysaccarides or disaccharides into monosaccarides

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10
Q

what does chemical/enzymatic digestion do to proteins

A

turns them from proteins to amino acids or short peptides (2-3 amino acids joined)

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11
Q

what does chemical/enzymatic digestion do to lipids

A

turns them from triglycerides to 2 fatty acids and one monoglyceride

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12
Q

what are the accessory organs of the GI system

A

salivary glands, liver, gall bladder, pancreas

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13
Q

what keeps food moving through the GI tract

A

peristalsis

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14
Q

what stops food from going the wrong way

A

sphincters

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15
Q

how many sphincters in the GI tract

A

5, mouth-oesophagus, oesophagus-stomach, stomach-small intestine, small intestine-large intestine, large intestine-anus

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16
Q

what controls the GI tract

A

enteric nervous system

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17
Q

what roles do the enteric nervous system have

A

control movement of food (mixing waves, peristalsis, segmentation) opening and closing of sphincters, secretion of mucus and enzymes, communication between different organs, absorption of water, ions and nutrients

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18
Q

what roles do mouth and salivation have

A

chewing (mechanical digestion), lubrication and protection, dissolves food so you can taste it

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19
Q

what is the role of oesophagus

A

transport

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20
Q

how big is your stomach at empty

A

1 cup

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21
Q

how big is your stomach after a large meal

A

4-6 times bigger, 1.5 litres

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22
Q

is food mechanically or chemically digested in the stomach

A

both

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23
Q

what are the peristaltic contractions in the stomach called

A

mixing waves, peristalsis here is not movement of the food, for mixing

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24
Q

what is propulsion in the stomach

A

movement of food forward

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25
Q

what is retropulsion in the stomach

A

movement of the food backwards

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26
Q

what enzyme breaks down protein in the stomach

A

pepsin

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27
Q

what does acid do to proteins in the stomach

A

unfolds them

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28
Q

what does pepsin do to proteins in the stomach

A

chops them up

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29
Q

what food component does the stomach contribute chemical digestion for

A

only proteins

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30
Q

why is protein chemically digested in the stomach

A

it is the most complex food component so starts earlier

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31
Q

chemical digestion uses ______ to break nutrients into smaller pieces

A

enzymes

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32
Q

what is the brain (cephalic) phase

A

preparing the stomach for food

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33
Q

what does the brain (cephalic) phase respond to

A

seeing, smelling, tasting, thinking about food

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34
Q

what does the cephalic phase trigger

A

activation of the central nervous system

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35
Q

what does triggering of the CNS in the cephalic phase release

A

gastrin from cells in the stomach

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36
Q

what does gastrin cause in the stomach

A

increased secretion of mucus, acid and pepsin from cells in the stomach and increased mixing waves

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37
Q

what is the function of the gastric phase

A

maximise mechanical digestion and begin protein chemical digestion

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38
Q

what does the gastric phase respond to

A

stretch in the stomach, increased pH (due to food being less acidic than stomach), undigested food (especially protein)

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39
Q

what does the gastric phase trigger

A

activation of the enteric nervous system

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40
Q

what does activation of the enteric nervous system cause

A

release of gastrin

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41
Q

does the gastric phase include the brain

A

no

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42
Q

what is the intestinal phase

A

slow controlled release of food into the small intestine

43
Q

what does the intestinal phase respond to

A

stretch of the SI wall, decreased pH (due to the food being mixed with the acid), fats and carbohydrates in the intestine

44
Q

what does the intestinal phase trigger

A

release of SI hormones

45
Q

what is the outcome of the intestinal phase

A

inhibition of the enteric nervous system, decreased secretion of acid and pepsin, decreased mixing waves

46
Q

carbohydrates ____ rate of stomach emptying

A

increase

47
Q

proteins ______ rate of stomach emptying

A

decrease

48
Q

fats _____ rate of stomach emptying

A

decrease

49
Q

what is the role of the small intestine

A

completion of chemical digestion and absorption of 90% of nutrients

50
Q

what does the duodenum secrete

A

HCO3- and mucus

51
Q

why does the duodenum secrete bicarbonate and mucus

A

to protect itself from stomach acid

52
Q

what do the digestive enzymes secreted by the pancreas do

A

chemical digestion of protein, fat and carbohydrate

53
Q

what is the role of the liver

A

makes bile salts

54
Q

what is the role of the gall bladder

A

storage and release of bile salts needed for the absorption of fat

55
Q

what are the enzymes released by the pancreas into the duodenum

A

amylase, protease and lipase

56
Q

what does amylase do

A

digests carbohydrates from starches into disaccharides

57
Q

what does protease do

A

digests proteins from polypeptides to amino acids and short peptides

58
Q

what does lipase do

A

digests fats from triglycerides to 2 fatty acids and one monoglyceride

59
Q

what is chemical digestion finished by

A

brush border enzymes

60
Q

what do enzymes on the brush border do to finish chemical digestion of carbohydrates

A

break them down from disaccharides to monosaccharides

61
Q

what do enzymes on the brush border do to finish chemical digestion of proteins

A

break them down from peptides to amino acids

62
Q

what is segmentation

A

rhythmic contraction and relaxation with no set pattern

63
Q

what is segmentation important for

A

chemical/enzymatic digestion, mixes digested food with pancreatic enzymes and increases contact with brush border on intestinal wall

64
Q

what is segmentation controlled by

A

the stretch of the SI wall, pacemaker cells of the enteric nervous system

65
Q

is segmentation the movement of chyme through intestine

A

no, only mixes food with secretions

66
Q

is segmentation mechanical or chemical digestion

A

chemical digestion, mechanical has already been finished by the mouth and stomach

67
Q

what is peristalsis

A

wavelike contractions that propel chyme through the SI towards the LI

68
Q

what stimulates the change from segmentation to peristalsis

A

less stretch of the SI walls as nutrients are absorbed

69
Q

what is the role of the LI

A

absorption of some nutrients and mostly water

70
Q

what creates microbial fermentation/flatus (farts)

A

Large intestine

71
Q

what is faeces made of

A

bacteria, old epithelial cells, undigested food matter (corn), fibre, some water

72
Q

how long does food stay in the stomach

A

2-4 hours

73
Q

how long does chyme stay in the small intestine

A

3-5 hours

74
Q

how long does chyme stay in the large intestine

A

10 hours to several days

75
Q

why do we need the GI tract

A

to absorb nutrients into the bloodstream from our food

76
Q

what is absorbed in the small intestine

A

carbohydrates, fats, proteins, most ions, most water

77
Q

what is absorbed in the large intestine

A

some water and some ions (fine tuning)

78
Q

the three types of dietary carbohydrates are

A

polysaccharides (most) e.g. glycogen (meat) and starch (plants), disaccharides (some) e.g. sucrose and monosaccharides (a little) e.g. glucose

79
Q

only what type of carbohydrate can be absorbed

A

monosaccharides

80
Q

sodium in the small intestine has a __ concentration inside cells that outside cells

A

lower

81
Q

what gradient do molecules use to travel into the small intestine cells

A

sodium electrochemical

82
Q

the sodium electrochemical gradient is used as a __ __ to pull __ up its concentration gradient

A

driving force, glucose

83
Q

how is glucose absorbed into the small intestine

A

apical way (into the cell) with sodium-coupled secondary active transport, baso-lateral way (travelling out of the cell) with facilitated diffusion all driven using the sodium electrochemical gradient

84
Q

what follows glucose and sodium absorption

A

water absorption by osmosis, the more glucose and sodium absorbed, the more water absorbed

85
Q

how to maximise isosmotic fluid intake

A

sodium and glucose in drinks

86
Q

sports drinks have about how much over what is needed for sodium and glucose in drinks for optimal rehydration

A

about 2 times too much

87
Q

how many lives have rehydration after diarrhoea saved

A

more than 50 million

88
Q

only what type of proteins can be absorbed

A

single amino acids and peptides

89
Q

what are sources of protein

A

diet, old GIT cells (recycled), digestive enzymes (enzymes are proteins)

90
Q

source of amino acids

A

some can be made by body, some need to be consumed in food (essential, our body can’t make these)

91
Q

lifecycle of proteins in the body

A

dietary proteins, enzymatic digestion, amino acids, absorption, body proteins

92
Q

how are proteins absorbed into the small intestine

A

the same way as carbohydrates

93
Q

why are lipids essential

A

for the phospholipid bilayer, essential for cell growth, division and making steroid hormones

94
Q

only what form of lipids can be absorbed

A

single fatty acids and monoglycerides, these must be broken into small droplets and emulsified

95
Q

what breaks lipids down into smaller pieces

A

bile salts, have hydrophobic tale that is lipid loving and hydrophilic head that loves water

96
Q

what is emulsification

A

breaking down fats into smaller droplets called micelles

97
Q

micelles enter the small intestine cells and then are

A

reassembled into triglycerides and other lipids and repackaged into chylomicrons absorbed into the blood

98
Q

how much blood flow to GI tract at rest

A

25%

99
Q

how much blood flow to GI tract during light exercise

A

12%

100
Q

how much blood flow to GI tract during heavy exercise

A

3%

101
Q

what happens to colon transit during heavy exercise

A

increases due to reduced blood flow

102
Q

what happens to small intestine transit and absorption during heavy exercise

A

decreases due to reduced blood flow

103
Q

what happens to heat loss demand during heavy exercise

A

increases due to increased blood flow

104
Q

where is the brush border located

A

the small intestine

PHSL101 (10 decks)

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