Digestive system

Question 1

Definition of mechanical digestion

Answer 1

The physical breakdown of food into smaller pieces.

Question 2

Function of mechanical digestion

Answer 2

Increase surface area for chemical digestion and speed up digestion

Question 3

Where does mechanical digestion occur

Answer 3

Mouth- teeth chew, tear, grind food. Stomach- churning/peristalsis of food. Small intestine- gall bladder releases bile to small intestine and bile emulsifies fats breaking large globules into smaller droplets.

Question 4

Definition of chemical digestion

Answer 4

Uses enzymes to break large, complex molecules into small, simpler molecules.

Question 5

Function of chemical digestion

Answer 5

Break down large molecules so they are small enough to enter the bloodstream

Question 6

Where does chemical digestion occur

Answer 6

Mouth-Salivary glands/saliva
Stomach-enzymes
Small intestine-enzymes

Question 7

What is the alimentary canal

Answer 7

The continuous tube that food passes through and undergoes active digestion and nutrient absorption.

Question 8

What makes up the alimentary canal

Answer 8

Mouth cavity, Esophagus, Stomach, Small and large intestine, Rectum, Anus

Question 9

What are the accessory organs

Answer 9

Organs that secrete or store substances (enzymes) that pass through ducts and are needed for digestion.

Question 10

What makes up accessory organs

Answer 10

Salivary glands, liver, gall bladder, pancreas

Question 11

Mouth cavity structure to function

Answer 11

Structure- Contains teeth, the tongue and salivary glands
Function- Cut, grind and tear food through mastication and Secrete salivary amylase which breaks starch down into simple sugars

Question 12

Esophagus structure to function

Answer 12

Structure- Connect pharynx to stomach
Contains layers of circular and longitudinal muscle
Function- Tube for bolus to pass through from the mouth to the stomach through peristalsis

Question 13

What is bolus

Answer 13

Solid ‘ball’ of food created in mouth that travels down esophagus into stomach

Question 14

What is chyme

Answer 14

Liquid food created/formed in stomach

Question 15

Stomach structure to function

Answer 15

Structure-J shaped bag with circular, longitudinal and oblique layers of muscles. Contains mucosa that secretes gastric juice
Function-Waves of muscular contractions churn the food into chyme and Pepsinogen in the gastric juices break proteins down into polypeptides

Question 16

Small intestine structure to function

Answer 16

Structure-6m long divided into 3 sections: duodenum, jejunum and ileum
Contains villi
Function-Segmentation breaks the bolus down and mixes it with the juices and bile salts which breaks down fats + Secretes intestinal juice
Nutrient absorption

Question 17

Large intestine structure to function

Answer 17

Structure-1.5m long divided into 4 sections: caecum, colon (ascending, transverse and descending) rectum and anus
No villi or digestive juices
Function-Absorb water and vitamins
Formation of faeces from undigested food, water, bile and bacteria
Store faeces and begin defecation

Question 18

Liver function and substance/secretion

Answer 18

Function-Produces bile
Substance/secretion-Bile emulsifies fats breaking it into tiny droplets to increase surface area (mechanical digestion) for enzymes to act.

Question 19

Gall bladder function and substance/secretion

Answer 19

Function-Stores bile
Substance/secretion-Bile emulsifies fats breaking it into tiny droplets to increase surface area (mechanical digestion) for enzymes to act.

Question 20

Pancreas function and substance/secretion

Answer 20

Function-Secretes pancreatic juice through the pancreatic duct
Substance/secretion-Pancreatic juice neutralizes the gastric juices and contains:
Pancreatic amylase =Starch → disaccharides
Pancreatic protease=Proteins → peptides
Pancreatic lipase=Fats → fatty acids & glycerol
Deoxyribonuclease and ribonuclease=Digest DNA & RNA

Question 21

What does intestinal juice contain

Answer 21

peptidase, lipase, sucrase, maltase, lactase

Question 22

intestinal juice-peptidase-target nutrient, purpose and product

Answer 22

Target nutrient-proteins
Purpose-Breaks down peptides
Product-amino acids

Question 23

intestinal juice-lipase-target nutrient, purpose and product

Answer 23

Target nutrient-fats/lipids
Purpose-Breaks down lipids
Product-fatty acids and glycerol

Question 24

intestinal juice-sucrase-target nutrient, purpose and product

Answer 24

Target nutrient-carbs(starch)
Purpose-Breaks down sucrose
Product-glucose

Question 25

intestinal juice-maltase-target nutrient, purpose and product

Answer 25

Target nutrient-carbs(starch)
Purpose-Breaks down maltose
Product-galactose

Question 26

intestinal juice-lactase-target nutrient, purpose and product

Answer 26

Target nutrient-carbs(starch)
Purpose-Breakdown lactose
Product-fructose

Question 27

Regions that make up small intestine

Answer 27

Duodenum, jejunum, ileum

Question 28

Duodenum

Answer 28

First part of small intestine, connects stomach to small intestine, (25 cm) Most chemical digestion occurs here

Question 29

Jejunum

Answer 29

second part of small intestine, Absorbs most carbohydrates and proteins

Question 30

Ileum

Answer 30

Last/third part of small intestine, Absorbs vitamin B12, bile salts and last parts of digestion

Question 31

How does structure and characteristics of small intestine relate to nutrient absorptions

Answer 31

High surface area which is achieved by- Length: It is 6-7m long, Folds: The inner lining (mucosa), Villi: Finger like projections on the mucosa and Microvilli: Microscopic projections on the surface of cells

Question 32

Villi structure of function

Answer 32

Structure-1mm long, Thin walls - 1 cell thick, Lymph capillary in the centre, Network of capillaries around lymph capillary, Covered by a single layer of cells which have microvilli

Function-Nutrient absorption
Simple diffusion of-Fatty acids and glycerol, Water and vitamins, Active transport-Amino acids, Glucose

Question 33

What happens to substances after absorbed by villi

Answer 33

Enter bloodstream or lymph: Substances that are absorbed into the blood by the capillaries and are taken to the liver by the hepatic portal vein. Here they may be removed or stay in the blood to be carried to other parts of the body.
Substances that enter the lymph capillary go into the lymph system which empties into the veins in the chest.

Question 34

What is speed that materials move through alimentary canal dependent on

Answer 34

Size and contents of meal. Large meals cause the stomach to stretch and move though the small intestine quicker. High protein and fat diets slow movement in the stomach and small intestine. Alcohol and caffeine stimulate stomach movements.

Question 35

What is result of dysfunctional digestive system

Answer 35

Issues such as; constipation, diarrhoea, coeliac disease, bowel cancer

Question 36

Large intestine structure and function

Answer 36

Structure- 1.5m long, larger diameter, no villi or digestive juices, lining does secrete mucus.
Made up of- caecum, colon, rectum, anus. Appendix attachés to caecum.
Function- absorb water (and some mineral nutrients) so contents again become more solid. Form/store faeces. Faeces pass through the rectum and anus to exterior (defacation).

Question 37

What is faeces composed of

Answer 37

Water, undigested food material, bacteria, bile pigments, remains of cells.