Download presentation
Presentation is loading. Please wait.
1
Glenlola Collegiate School
excellence through commitment, contribution and caring DIGESTION
2
LEARNING OUTCOMES ALL MUST…
Know that enzymes are used in the digestion of food in the body, which can then be absorbed into the bloodstream
3
LEARNING OUTCOMES ALL MUST…
Know that enzymes are needed to break down (digest) large, insoluble molecules into small, soluble ones:
4
starter activity View the photograph on the next slide and jot down
Where you would find it What produced it What it is Possible use of venn diagram to show comparison.
5
Discuss the idea of digestion being vital for all living organisms
6
The Human Digestive System
The process of digestion has 5 functions: Ingestion: taking food into the body Digestion: breakdown of insoluble substances into soluble ones Absorption: uptake of soluble substances into cells Assimilation: how cells use food Egestion: removal of undigested waste
7
Digestion Egestion faeces Ingestion Absorption
8
Food is broken down into smaller pieces by biting, chewing,
churning, bile action. These pieces are not soluble but have a large surface area for enzymes to work on.
9
Surface area = 24 cm2 Volume = 8 cm3 SA : V ratio = 24:8 = 3:1
10
Carbohydrases break down carbohydrates into sugars
Digestive enzymes break chemical bonds to make insoluble food particles soluble. Carbohydrases break down carbohydrates into sugars Proteases break down proteins into amino acids Lipases break down fats (lipids) into fatty acids and glycerol
11
model gut experiment boiling tube
12
LEARNING OUTCOMES ALL MUST…
Label a diagram of the component parts of the digestive system and identify their function.
13
LEARNING OUTCOMES to include:
buccal cavity - the mechanical digestion by teeth and the chemical digestion of starch by amylase;
14
LEARNING OUTCOMES to include:
stomach - the production of gastric juice containing protease enzyme and acid, and the digestion of proteins;
15
starter activity Pin the pancreas on the body
Possible use of venn diagram to show comparison.
16
What do you remember
17
Add gall bladder, bile duct, sphincter Buccal cavity Salivary gland
Oesophagus Liver Stomach Duodenum Pancreas Worksheet to go with this Ileum Colon Appendix Rectum Anus
18
The ball of food is called a bolus
The Buccal cavity (mouth) Mechanical: chewing, biting Chemical: Saliva from the salivary glands contains the enzyme CARBOHYDRASE. Starch + carbohydrase sugar (maltose) The ball of food is called a bolus
19
NO FOOD IS BROKEN DOWN HERE
The oesophagus NO FOOD IS BROKEN DOWN HERE Muscles in the wall of the oesophagus contract, pushing food down to the stomach. This is called PERISTALSIS
20
peristalsis
22
Muscles in wall contract
Oesophagus wall FOOD Food moves forwards PERISTALSIS
23
The stomach The strong muscle walls contract to churn and mix food with stomach juices called GASTRIC JUICES. Cells in the stomach wall produce a protease enzyme that digests proteins, breaking them down into amino acids.
24
The stomach cells also produce hydrochloric acid HCl, which
Lowers the pH for the protease enzyme to work Kills bacteria Stops salivary amylase from working A circular, sphincter muscle at the exit of the stomach opens to allow food into the small intestine. It controls release of food from the stomach.
25
LEARNING OUTCOMES to include:
liver - the production of bile, its storage in the gall bladder and its actions in the duodenum in neutralisation of acids and emulsification of fats
26
LEARNING OUTCOMES to include:
duodenum - enzyme production by the pancreas and the duodenal wall to include carbohydrases, lipases and proteases
27
LEARNING OUTCOMES to include:
ileum - relate its structure to its function of absorption of digested food molecules and the ways it is adapted: large surface area (length, folds and villi), good blood supply, and thin and permeable membranes;
28
LEARNING OUTCOMES HIGHER TIER SOME MAY…
explain how the structure of a villus (finger-like shape, single layer of surface cells, capillary network and lacteal) is adapted for the efficient absorption of digested food molecules.
29
This is called emulsification.
The liver Bile, made in the liver and stored in the gall bladder passes along the bile duct into the duodenum. Bile breaks fats into very small droplets, increasing the surface area for enzymes to work on. This is called emulsification. Bile is alkaline and therefore also neutralises acid from the stomach.
30
passes into the gall bladder
bile made in the liver passes into the gall bladder gall bladder digestive enzymes produced in pancreas pancreatic duct bile duct duodenum
31
The duodenum ENZYMES are added to the duodenum from: The pancreas
The wall of the duodenum Carbohydrases break down starch to sugars Proteases break down protein to amino acids Lipase breaks down fat to fatty acids and glycerol
32
Main function is absorption.
The ileum Main function is absorption. The walls are adapted for efficient diffusion of the soluble products of digestion.
33
villus muscle layer ridge covered with villi network of blood
capillaries lacteal absorbs fatty acids single layer of epithelial cells villus muscle layer arteriole venuole
34
A villus ileum wall blood capillaries lacteal sugar amino acids
Made of epithelial cells amino acids blood capillaries fatty acids lacteal to liver
35
how the ileum is adapted for absorption
Long length (5m), folds and villi increase the surface area for absorption Villi contain blood vessels to carry away absorbed nutrients Villi contain lacteals to carry away absorbed fats The walls are thin, one cell thick, and permeable to form a short diffusion distance
36
The absorbed nutrients, amino acids and sugars are carried in the blood to the liver in the
HEPATIC PORTAL VEIN.
37
LEARNING OUTCOMES to include:
colon - large surface area for water absorption; rectum & anus - storage and removal of faeces.
38
NO DIGESTION OCCURS HERE
the colon NO DIGESTION OCCURS HERE The colon has a large surface area for the absorption of water from the fluid we drink, food we eat, mucus and digestive juices. It also absorbs mineral salts.
39
the rectum & anus Solid waste made up of undigested food, bacteria and cells from the gut forms faeces, which is stored in the rectum before passing out of the body through the anus.
40
transverse colon descending colon ascending colon rectum appendix anus
41
Summary bbc learning zone clip 4180
42
dvd
43
Cut & stick activity
Similar presentations
© 2025 SlidePlayer.com Inc.
All rights reserved.