7.2/7.3 Digestive system

Question 1

Main organs of digestive system

Answer 1

Alimentary canal: mouth, oesophagus, stomach, small intestine (duodenum + ileum) + large intestine (colon + rectum + anus)
Assotiated organs: salivary glands +pancreas + liver + gall bladder

Question 2

Ingestion

Answer 2

taking of substances (mouth)

Question 3

Digestion

Answer 3

breakdown of food
Chemical: breakdown of large insoluble molecules into small soluble ones (enzymes)

Physical/mechanical: breakdown of food into smaller pieces without chemical change to the food molecules
(increase the surface area of the food so that enzymes can more effectively break it down (chewing/churning)

Question 4

Absorption

Answer 4

movement of nutrients from intestine into the blood (SI)
nutrients/digested molecules cross the wall of intestine to bloodstream

Question 5

Assimilation

Answer 5

uptake and use of nutrients by the cell used for energy growth and repair

Question 6

Egestion

Answer 6

removal of undigested food from body as feces (anus) - defecation (fiber, feces, etc.)

Question 7

Mouth

Answer 7

ingestion (start of alimentary canal)
Food –> bolus of food (teeth + saliva)
has salivary glands

(Ingestion ,chem+phy digestion)

Question 8

salivary glands

Answer 8

3 pairs; produce saliva through the salivary duct
- produces salivary amylase to break down starch

Secrete - make and release

Question 9

Oesophagus

Answer 9

muscular tube helping food move down by peristalsis
(Chemical digestion)

Question 10

Liver

Answer 10

Produce bile which help neutralize acidic chyme + emulsifies fats (Assimilation)

Question 11

Stomach

Answer 11

muscular bag that stores food + mixes food with acidic digestive juice to make chyme

Churns food up with muscular wall
produces pepsin + gastric juice(with HCl) to:
kill bacteria in food and provide optimum pH for pepsin

(Chemical/physical digestion)

Question 12

Gall bladder

Answer 12

stores bile before poured into duodenum (bile duct)

Question 13

Small intestine

Answer 13

2 parts, where most absorption happens
1. Duodenum
2. Ileum

Question 14

Pancreas

Answer 14

produses pancreatic juice (with enzyme + mucus + hydrogencarbonate - neutralises chyme)

It produces - protease(Trypsin), amalase and lipase –> small intestine (pancreatic duct)

Question 15

Large intestine

Answer 15

3 parts - reabsorb excess water + vitamin/minerals
1. colon (absorption)
2. Rectum
3. Anus (egestion)

Question 16

Rectum

Answer 16

last fart of LI, stores feces before egested

Question 17

Anus

Answer 17

feces is egested (controlled by 2 anal sphincters)

Question 18

Amalase

Answer 18

Breaks down starch –> maltose
Optimum = 7ph
salivary amylase
pancreatic amylase

Question 19

Protease

Answer 19

Breaks down protein –> peptides + amino acids
Pepsin - Optimum(2pH) in stomach
Trypsin - Optimum(8pH) in pancreas

Question 20

Lipase

Answer 20

Breaks down lipids (neutral pH) –> fatty acids and glycerol (acidic pH)
Optimum = 8pH
In pancreas, secreted to duodenum

Question 21

Bile, what does it do

Answer 21

Slightly alkaline, released from gal bladder
1. Neutralizes the chyme
- alkaline environment for enzymes
2. Bile salts, emulsify fat and break it down
- lipid molecules attract each other and stick making it slow for enzymes to digest them
- bile salt causes emulsification
-globules –> smaller droplets
- increases SA of oil = rate of lipase activity increase

Question 22

Hydrolysis

Answer 22

Breaking down large molecules into smaller ones by adding water.
Large insoluble molecule —enzyme+water–> small, soluble molecules

Chemical reaction where food molecules are broken down with water and catalyzed by enzymes

Question 23

Benefits of chewing food

Answer 23

-food has a larger SA
- this increases rate of digestion
- as the enzymes can go from different angles

Question 24

What is the process of muscle contraction that pushes food down

Answer 24

Peristalsis

Question 25

Fats break down to

Answer 25

glycerol + fatty acids

Question 26

Carbohydrates break down to

Answer 26

Starch –> maltose —-maltase—> glucose

Question 27

Proteins break down to

Answer 27

Polypeptides —-peptidases—> peptide/amino acids

Question 28

Hydrogen carbonate +HCl

Answer 28

Hydrogen carbonate - alkaline (environment for enzymes)
HCl - acidic environment for pepsin + kill bacteria

Question 29

Duodenum

Answer 29

1st part of small intestine where food is mixed with pancreatic juice and bile
(Chem/Phys digestion)
breaks starch, protein and fats

Question 30

Ileum

Answer 30

the longest part of SI where food is absorbed to blood (absorption) - intestinal juice from villi (maltase)
breaks maltose that wasn’t fully broken up

Question 31

Villi

Answer 31

Finger-like projections that line the inner surface of the small intestine. (with epithelial cells)
This increases SA for absorption

Question 32

Phenophthalein

Answer 32

Pink above 8.2 pH
colorless at lower pH

Question 33

Risk assessment for
buffers, chemicals in eyes, broken glass ware, and hydrogen peroxide

Answer 33

1. buffers - wash off with water if spilt on skin
2. chemicals in eyes - wear safety goggles
3. broken glass ware - ask teacher to clean up and seek medical attention
   4.hydrogen peroxide - if it is on skin, wash it up