digestive system

Question 1

what does the alimentary canal do?

Answer 1

forms a tube through the centre of the body

Question 2

food is… from this canal for the purpose that the food can be…

Answer 2

ingested, digested, absorbed, egested
assimilated

Question 3

what makes up the small intestine?

Answer 3

duodenum and ileum

Question 4

what makes up the large intestine?

Answer 4

the colon and the anus

Question 5

what is ingestion?

Answer 5

taking food in through the mouth and swallowing

Question 6

what is digestion?

Answer 6

breaking down large insoluble molecules in food into smaller pieces and smaller soluble molecules

Question 7

what is absorption?

Answer 7

the movement of small soluble molecules out of the gut and into the blood by diffusion and active transport

Question 8

what is egestion?

Answer 8

passing out undigested food through the anus

Question 9

what is assimilation?

Answer 9

building larger biological molecules from the small soluble molecules, in all cells

Question 10

what is the first structure in the alimentary canal?

Answer 10

the mouth

Question 11

where does ingestion take place?

Answer 11

the mouth

Question 12

what also happens in the mouth?

Answer 12

digestion

Question 13

what is an example of mechanical digestion in the mouth?

Answer 13

• food is broken up into smaller pieces in the mouth by chewing
• this increases the surface area for enzymes and also prevents discomfort when swallowing

Question 14

what is an example of chemical digestion in the mouth?

Answer 14

• saliva is released into the mouth by the salivary glands
• makes the food easier to swallow
• contains amylase

Question 15

what does amylase break down starch to?

Answer 15

starch-> maltose

Question 16

what happens when amylase reaches the stomach?

Answer 16

amylase works best at a neutral pH so it is denatured when it reaches the stomach and stops working

Question 17

what happens before swallowing?

Answer 17

the food is shaped into a ball by the tongue and moved towards the back of the mouth

Question 18

what is the ball of food called?

Answer 18

a bolus

Question 19

what is the epiglottis and what does it do?

Answer 19

a flap which blocks the food from entering the trachea

Question 20

what is the oesophagus?

Answer 20

a long tube that connects the mouth to the stomach

Question 21

what process occurs in the oesophagus?

Answer 21

peristalsis

Question 22

what is peristalsis?

Answer 22

• two sets of muscles push the food down the oesophagus
• the circular muscles contract behind the bolus pushing it along
• when the longitudinal muscles contract, they make the oesophagus wider and the circular muscles relax

Question 23

what do the gastric glands in the stomach wall secrete?

Answer 23

the enzyme pepsin

Question 24

what does pepsin do?

Answer 24

begins the process of digesting proteins into peptides

Question 25

what are peptides?

Answer 25

shorter chains of amino acids

Question 26

what does the contraction of the stomach wall cause?

Answer 26

mixing of the contents of the stomach- maximising contact between enzymes and food

Question 27

what are pepsin's optimum conditions?

Answer 27

an acidic pH

Question 28

why are the conditions in the stomach acidic?

Answer 28

the release of hydrochloric acid by the gastric glands

Question 29

pepsin has a high or low pH?

Answer 29

very low

Question 30

pepsin is covered in what?

Answer 30

a mucus lining

Question 31

what does the hydrochloric acid in our stomach do?

Answer 31

kills many bacteria and fungi which may be present in the food we eat

Question 32

what 2 processes occur in the small intestine?

Answer 32

digestion and absorption

Question 33

what process happens in the duodenum?

Answer 33

digestion

Question 34

the duodenum is the final site of what?

Answer 34

chemical digestion

Question 35

what enzymes does the pancreas make?

Answer 35

trypsin, amylase and lipase

Question 36

where does the pancreas secrete the enzymes into?

Answer 36

the duodenum

Question 37

what does trypsin do?

Answer 37

breaks down protein into peptides

Question 38

what does lipase do?

Answer 38

breaks down lipids into glycerol and 3 fatty acids

Question 39

what does the duodenum wall also contain?

Answer 39

glands which make enzymes and secretes them into the duodenum

Question 40

the glands in the duodenum wall make what enzymes?

Answer 40

maltase and peptidase

Question 41

what does maltase do?

Answer 41

breaks down maltose into glucose

Question 42

what does peptidase do?

Answer 42

breaks down peptide into amino acids

Question 43

bile is found where?

Answer 43

in the duodenum

Question 44

where is bile produced?

Answer 44

in the liver

Question 45

where is bile stored?

Answer 45

in the gall bladder

Question 46

where is bile released into and through where?

Answer 46

released into the duodenum through the bile duct

Question 47

what are the two functions of bile?

Answer 47

1) neutralises the stomach acid- enzymes in the duodenum work best at pH 7-8 2) emulsifies lipids- breaks large droplets into smaller droplets- increasing SA for lipase to digest the fats

Question 48

what happens once the food has entered the ileum?

Answer 48

digestion is over and absorption begins

Question 49

what are the finger like projections found in the ileum called?

Answer 49

villi

Question 50

what does the villi do?

Answer 50

absorb small soluble molecules

Question 51

how are the small soluble molecules absorbed?

Answer 51

- some by diffusion - however, some such as glucose are also absorbed by active transport

Question 52

how is the rate of diffusion in the ileum increased?

Answer 52

- large SA- folding of ileum, villi and microvilli - short diffusion distance- villi walls are one cell thick - high concentration gradient- provided by capillary network and lacteals removing absorbed molecules

Question 53

what is the colon the site for?

Answer 53

all reabsorption of water

Question 54

where is faeces stored?

Answer 54

in the rectum

Question 55

where are faeces egested from?

Answer 55

the anus

Question 56

what is excretion?

Answer 56

the expulsion of faeces from the anus- the removal of undigested food from the body

Question 57

what is excretion?

Answer 57

the removal of waste substances produced by chemical reactions in the body

Question 58

what are some examples of excretion?

Answer 58

- carbon dioxide- removed by the lungs - urea- removed by the kidneys and sweat

Question 59

where does assimilation occur?

Answer 59

takes place in all cells using the food molecules absorbed to build more complex molecules such as proteins