Gastrointestinal

Question 1

what are the three main components of food

Answer 1

carbohydrates, proteins, fats

Question 2

what are carbohydrates used for

Answer 2

ATP

Question 3

what are proteins used for

Answer 3

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

Question 4

what are lipids used for

Answer 4

ATP and building blocks of a cell

Question 5

can we absorb both large and small molecules

Answer 5

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

Question 6

what parts of the body are involved in mechanical digestion

Answer 6

mouth (chewing) and stomach (propulsion and retropulsion)

Question 7

what does mechanical digestion do

Answer 7

breaks the food into smaller pieces

Question 8

what does chemical digestion do

Answer 8

breaks the particles into smaller pieces

Question 9

what does chemical/enzymatic digestion do to carbohydrates

Answer 9

turns them from polysaccarides or disaccharides into monosaccarides

Question 10

what does chemical/enzymatic digestion do to proteins

Answer 10

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

Question 11

what does chemical/enzymatic digestion do to lipids

Answer 11

turns them from triglycerides to 2 fatty acids and one monoglyceride

Question 12

what are the accessory organs of the GI system

Answer 12

salivary glands, liver, gall bladder, pancreas

Question 13

what keeps food moving through the GI tract

Answer 13

peristalsis

Question 14

what stops food from going the wrong way

Answer 14

sphincters

Question 15

how many sphincters in the GI tract

Answer 15

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

Question 16

what controls the GI tract

Answer 16

enteric nervous system

Question 17

what roles do the enteric nervous system have

Answer 17

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

Question 18

what roles do mouth and salivation have

Answer 18

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

Question 19

what is the role of oesophagus

Answer 19

transport

Question 20

how big is your stomach at empty

Answer 20

1 cup

Question 21

how big is your stomach after a large meal

Answer 21

4-6 times bigger, 1.5 litres

Question 22

is food mechanically or chemically digested in the stomach

Answer 22

both

Question 23

what are the peristaltic contractions in the stomach called

Answer 23

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

Question 24

what is propulsion in the stomach

Answer 24

movement of food forward

Question 25

what is retropulsion in the stomach

Answer 25

movement of the food backwards

Question 26

what enzyme breaks down protein in the stomach

Answer 26

pepsin

Question 27

what does acid do to proteins in the stomach

Answer 27

unfolds them

Question 28

what does pepsin do to proteins in the stomach

Answer 28

chops them up

Question 29

what food component does the stomach contribute chemical digestion for

Answer 29

only proteins

Question 30

why is protein chemically digested in the stomach

Answer 30

it is the most complex food component so starts earlier

Question 31

chemical digestion uses ______ to break nutrients into smaller pieces

Answer 31

enzymes

Question 32

what is the brain (cephalic) phase

Answer 32

preparing the stomach for food

Question 33

what does the brain (cephalic) phase respond to

Answer 33

seeing, smelling, tasting, thinking about food

Question 34

what does the cephalic phase trigger

Answer 34

activation of the central nervous system

Question 35

what does triggering of the CNS in the cephalic phase release

Answer 35

gastrin from cells in the stomach

Question 36

what does gastrin cause in the stomach

Answer 36

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

Question 37

what is the function of the gastric phase

Answer 37

maximise mechanical digestion and begin protein chemical digestion

Question 38

what does the gastric phase respond to

Answer 38

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

Question 39

what does the gastric phase trigger

Answer 39

activation of the enteric nervous system

Question 40

what does activation of the enteric nervous system cause

Answer 40

release of gastrin

Question 41

does the gastric phase include the brain

Answer 41

no

Question 42

what is the intestinal phase

Answer 42

slow controlled release of food into the small intestine

Question 43

what does the intestinal phase respond to

Answer 43

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

Question 44

what does the intestinal phase trigger

Answer 44

release of SI hormones

Question 45

what is the outcome of the intestinal phase

Answer 45

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

Question 46

carbohydrates ____ rate of stomach emptying

Answer 46

increase

Question 47

proteins ______ rate of stomach emptying

Answer 47

decrease

Question 48

fats _____ rate of stomach emptying

Answer 48

decrease

Question 49

what is the role of the small intestine

Answer 49

completion of chemical digestion and absorption of 90% of nutrients

Question 50

what does the duodenum secrete

Answer 50

HCO3- and mucus

Question 51

why does the duodenum secrete bicarbonate and mucus

Answer 51

to protect itself from stomach acid

Question 52

what do the digestive enzymes secreted by the pancreas do

Answer 52

chemical digestion of protein, fat and carbohydrate

Question 53

what is the role of the liver

Answer 53

makes bile salts

Question 54

what is the role of the gall bladder

Answer 54

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

Question 55

what are the enzymes released by the pancreas into the duodenum

Answer 55

amylase, protease and lipase

Question 56

what does amylase do

Answer 56

digests carbohydrates from starches into disaccharides

Question 57

what does protease do

Answer 57

digests proteins from polypeptides to amino acids and short peptides

Question 58

what does lipase do

Answer 58

digests fats from triglycerides to 2 fatty acids and one monoglyceride

Question 59

what is chemical digestion finished by

Answer 59

brush border enzymes

Question 60

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

Answer 60

break them down from disaccharides to monosaccharides

Question 61

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

Answer 61

break them down from peptides to amino acids

Question 62

what is segmentation

Answer 62

rhythmic contraction and relaxation with no set pattern

Question 63

what is segmentation important for

Answer 63

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

Question 64

what is segmentation controlled by

Answer 64

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

Question 65

is segmentation the movement of chyme through intestine

Answer 65

no, only mixes food with secretions

Question 66

is segmentation mechanical or chemical digestion

Answer 66

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

Question 67

what is peristalsis

Answer 67

wavelike contractions that propel chyme through the SI towards the LI

Question 68

what stimulates the change from segmentation to peristalsis

Answer 68

less stretch of the SI walls as nutrients are absorbed

Question 69

what is the role of the LI

Answer 69

absorption of some nutrients and mostly water

Question 70

what creates microbial fermentation/flatus (farts)

Answer 70

Large intestine

Question 71

what is faeces made of

Answer 71

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

Question 72

how long does food stay in the stomach

Answer 72

2-4 hours

Question 73

how long does chyme stay in the small intestine

Answer 73

3-5 hours

Question 74

how long does chyme stay in the large intestine

Answer 74

10 hours to several days

Question 75

why do we need the GI tract

Answer 75

to absorb nutrients into the bloodstream from our food

Question 76

what is absorbed in the small intestine

Answer 76

carbohydrates, fats, proteins, most ions, most water

Question 77

what is absorbed in the large intestine

Answer 77

some water and some ions (fine tuning)

Question 78

the three types of dietary carbohydrates are

Answer 78

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

Question 79

only what type of carbohydrate can be absorbed

Answer 79

monosaccharides

Question 80

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

Answer 80

lower

Question 81

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

Answer 81

sodium electrochemical

Question 82

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

Answer 82

driving force, glucose

Question 83

how is glucose absorbed into the small intestine

Answer 83

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

Question 84

what follows glucose and sodium absorption

Answer 84

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

Question 85

how to maximise isosmotic fluid intake

Answer 85

sodium and glucose in drinks

Question 86

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

Answer 86

about 2 times too much

Question 87

how many lives have rehydration after diarrhoea saved

Answer 87

more than 50 million

Question 88

only what type of proteins can be absorbed

Answer 88

single amino acids and peptides

Question 89

what are sources of protein

Answer 89

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

Question 90

source of amino acids

Answer 90

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

Question 91

lifecycle of proteins in the body

Answer 91

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

Question 92

how are proteins absorbed into the small intestine

Answer 92

the same way as carbohydrates

Question 93

why are lipids essential

Answer 93

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

Question 94

only what form of lipids can be absorbed

Answer 94

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

Question 95

what breaks lipids down into smaller pieces

Answer 95

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

Question 96

what is emulsification

Answer 96

breaking down fats into smaller droplets called micelles

Question 97

micelles enter the small intestine cells and then are

Answer 97

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

Question 98

how much blood flow to GI tract at rest

Answer 98

25%

Question 99

how much blood flow to GI tract during light exercise

Answer 99

12%

Question 100

how much blood flow to GI tract during heavy exercise

Answer 100

3%

Question 101

what happens to colon transit during heavy exercise

Answer 101

increases due to reduced blood flow

Question 102

what happens to small intestine transit and absorption during heavy exercise

Answer 102

decreases due to reduced blood flow

Question 103

what happens to heat loss demand during heavy exercise

Answer 103

increases due to increased blood flow

Question 104

where is the brush border located

Answer 104

the small intestine