Digestive System

Question 1

What is the role of the digestive system?

Answer 1

It’s responsible for chemically and physically digesting large insoluble molecules into smaller soluble molecules, which can be absorbed into the blood stream,

And used for bodily processes (e.g. respiration, protein synthesis).

Question 2

Buccal Cavity-
Chemical Digestion

Answer 2

Amylase breaks down starch and glycogen into maltose

Question 3

Buccal Cavity-
Saliva

Answer 3

Moistens food and maintains pH (for enzyme activity)

Question 4

Buccal Cavity-
Mechanical Digestion

Answer 4

The tongue moves food to the cutting and grinding surfaces of the teeth

Tongue rolls food into a bolus which is swallowed

Question 5

Bolus

Answer 5

a ball like mixture of food and saliva that forms during chewing (mechanical digestion) which is swallowed into the stomach
It’s the same colour as the food eaten, and saliva gives it an alkaline pH

Question 6

Oesophagus

Answer 6

A long tube which extends from the buccal cavity to the stomach.
It’s responsible for pushing the bolus into the stomach using peristaltic waves of muscle contraction. It’s also lubricated with mucus.

Question 7

Layers of the gut

Answer 7

Serosa (outermost)
Muscle Layers
Sub-mucosa
Mucosa
Lumen

Question 8

Serosa

Answer 8

The outer most layer of the gut made of a thick tough connective tissue to provide protection.

Question 9

Muscle Layers

Answer 9

The second outer most layer of the gut. Used to contract in waves and squeeze food down (peristalsis)

Question 10

Sub mucosa

Answer 10

The second inner most layer of the gut. Contains connective tissue, nerves, blood & lymph capillaries

Question 11

Mucosa

Answer 11

Inner most layer of the gut. This area secretes mucus and can secrete digestive juices.

In the ileum it’s covered with microvilli to increase SA

Question 12

Stomach

Answer 12

A J shaped organ found at the end of the oesophagus which physically churns up food using muscles from the stomach wall
It also chemically breaks down food by releasing gastric juices

Question 13

Mucus

Answer 13

Produced by goblet cells throughout the digestive system (e.g. stomach) to lubricate food and protect organ walls from self digestion via enzymes

Question 14

Gastric Juice

Answer 14

A digestive fluid produced within the stomach lining with an acidic pH made up of mainly HCl, mucus, endopeptidase (pepsin), lipase

Question 15

What produces gastric juice?

Answer 15

Gastric glands in the mucosa

Question 16

Oxyntic Cells

Answer 16

Produce hydrochloric acid (HCl) in the stomach which kills bacteria and lowers pH down to 2 (for optimum pepsin enzyme activity)

Question 17

Pepsinogen

Answer 17

The inactive form of endopeptidase (pepsin) which is activated by HCl to break down polypeptides into peptides

Question 18

Liver

Answer 18

Produces Bile

Question 19

Gall Bladder

Answer 19

Stores Bile and releases it to the duodenum from the bile duct

Question 20

Bile

Answer 20

Emulsifies lipids to maximise the SA for lipase enzyme action & digestion/absorption

Alkaline in pH to neutralise stomach acid and form slightly alkaline (food)

Question 21

Pancreas

Answer 21

Produces enzymes that are released into the duodenum via the pancreatic duct

Question 22

Pancreatic Juice

Answer 22

The pancreatic enzymes produced by the pancreas and released into the duodenum by the pancreatic duct (slightly alkaline in pH)

Question 23

What (pancreatic) enzymes does the pancreas produce?

Answer 23

Carbohydrase (pancreatic amylase)
Lipase
endo & exopeptidase

Question 24

Duodenum

Answer 24

The start of the small intestine (connected to the stomach) where food is further digested on the epithelial cells of the villi

Question 25

What enzymes are in the duodenum?

Answer 25

amylase maltase lactase sucrase endopeptidase exopeptidase dipeptidase

Question 26

Amylase

Answer 26

A type of carbohydrase which hydrolyses starch into maltose It is found in the mouth (from salivary glands) and duodenum (from pancreas)

Question 27

Maltase

Answer 27

A type of disaccharidase which hydrolyses maltose into alpha glucose Found membrane bound in the duodenum

Question 28

Sucrase

Answer 28

A type of disaccharidase which hydrolyses sucrose into glucose and fructose Found membrane bound in the duodenum

Question 29

Lactase

Answer 29

A type of disaccharidase which hydrolyses lactose into glucose and galactose Found membrane bound in the duodenum

Question 30

(pancreatic) Lipase

Answer 30

Hydrolyses triglycerides into monoglycerides (and then eventually into fatty acid and glycerol)

Question 31

Endopeptidase

Answer 31

A type of protease which hydrolyses non-terminal (central) peptide bonds to form smaller poly peptides Found in the stomach and duodenum

Question 32

Trypsinogen

Answer 32

The inactive form of Trypsin (a type of endopeptidase) which becomes activated by enterokinase

Question 33

Exopeptidase

Answer 33

Type of protease which hydrolysis terminal (end) Peptide bonds to form dipeptides and amino acids Found in the stomach and ileum

Question 34

Dipeptidases

Answer 34

Type of protease which hydrolyses specifically peptide bonds on dipeptides to form amino acids Found membrane bound in the duodenum

Question 35

Absorbing Glucose

Answer 35

Na+ actively transported out of the ileum into the blood using sodium potassium pump. (Low concentration in ileum cells). Na+ diffuses from lumen to epithelium by sodium glucose co transporter. Glucose then diffuses out of the cell into the bloodstream through facilitated diffusion

Question 36

Absorbing Amino Acids

Answer 36

Active transport using carrier proteins into villi cells and then facilitated diffusion into capillaries

Question 37

Absorbing minerals

Answer 37

facilitated diffusion and active transport

Question 38

Absorbing fats

Answer 38

Lipase breaks down lipids into monoglycerides & fatty acids Bile & lipase act on the triglycerides to form a micelle made up of monoglycerides, fatty acids and bile salts Break and move into the cell membrane, reform before moving to the ER or Golgi Modified into chylomicrons, which allow them to move into the lacteal by exocytosis and then be drained into the blood

Question 39

Ileum

Answer 39

The final part of the small intestine (connected to the duodenum) which mainly absorbs any left over nutrients/substances

Question 40

Colon

Answer 40

The longest section of the large intestine, which is responsible for absorbing any excess water and some nutrients

Question 41

Rectum and Anus

Answer 41

Rectum- lower part of the large intestine where faeces (waste products of digestion) are stored Anus- the opening at the end of the rectum where faeces are released from

Question 42

Tapeworm

Answer 42

A (parasite) disease caused by eating uncooked/ raw meat or by not washing hands The heads attach to the inner walls of the small intestine and feed off food being digested

Question 43

Identifying Tapeworms

Answer 43

Pieces of white, flat, rectangular worms in the faeces about the size of a grain of rice

Question 44

Symptoms of Tapeworm

Answer 44

tummy pain diarrhoea nausea vomiting weight loss change in appetite

Question 45

Transmission of Tapeworm

Answer 45

raw/undercooked meat faecel contaminated water very close contact to those infected

Question 46

Treating Tapeworm

Answer 46

Anti Worm medication

Question 47

Reducing spread of Tapeworm

Answer 47

food well cooked fruit & veg throughly washed only drink clean water Hands thoroughly washed before food, after toilet or after touching animals