A organism that makes its own food through photosynthesis
An organism that cannot make its own food

Heterotrophic
(Take in food)
Saprophytic
Live off dead food source
Parasitic
Live off live source (host)

Animals that feed only on plants eg.. rabbit
Animals that feed on other animals eg..fox

Animals that feed on plants and animals
Badger

The physical and chemical breakdown of food
To breakdown large food particles until they are small enough to pass into body cells
Some animals (tapeworm) do not require digestive systems as they have all digestive enzymes in their cells

Ingestion
Food
Digestion
Simple substances
Absorption
Circulatory system
Assimiliation
Complex substances
Egestion

• Hollow muscular tube
• Runs from mouth to anus
• Food is moved through canal by peristalsis which is the relaxation and contraction of muscles

Ingestion Food is taken into the alimentary canal
Digestion
Absorption
Food is broken down into smaller soluble pieces physically and chemically
The movement of digested from the alimentary canal into the blood system
Assimilation Building up of the simple food product molecules into the cells of animals
Egestion Removal of unabsorbed material as faeces

Answer the following on the video
1. Food is broken down in 2 ways. Name them
2. Name an enzyme secreted in the mouth.
3. How is food moved through the oesophagus?
4. Food enters the stomach through the
_____________ region.
5. What does gastric juice contain
6. Name 2 ducts that empty their secretions into the small intestine
7. What is the function of the folds in the small intestine
8. What is the name of these folds?
9. Where are nutrients transported to when they enter the capillaries? Name 2 ways these nutrients are used

3.3.4 Digestion.ram

Answer the following on the video
1. Food is broken down in 2 ways. Name them
2. Name an enzyme secreted in the mouth.
3. How is food moved through the oesophagus?
4. Food enters the stomach through the
_____________ region.
5. What does gastric juice contain
6. Name 2 ducts that empty their secretions into the small intestine
7. What is the function of the folds in the small intestine
8. What is the name of these folds?
9. Where are nutrients transported to when they enter the capillaries? Name 2 ways these nutrients are used

• Mechanical/Physical
• Chemical

1. Teeth
2.
Contractions in stomach wall
3. Peristalsis
Muscular contractions in the walls of the alimentary canal to move food

Incisors Cutting
Canines Tearing
Pre molars
Crushing and grinding
Molars

Incisors
The number of each type of tooth in the upper jaw one side of the mouth
Canines
Pre molars
Molars

• 32 teeth in a full set of human permanent teeth
• Dental formula for an adult is
2(I 2/2 C1/1 PM 2/2 M3/3)

•
Mouth
• 3 pairs of salivary glands secrete saliva
• Saliva = water + salts+ salivary amylase
• Water lubricates food
• Salt provides alkaline medium (pH 7-9) which is optimum pH for amylase

• Bolus: small ball of food.
• Moved by peristalsis.
• Epiglottis closes over entrance to windpipe when swallowing.
Prevents food entering windpipe

Stomach
Food enters through a ring of muscle called the cardiac sphincter
Stores food for about 4 hours
Churns and mixes food with gastric juice forming Chyme
Digest food

Digestion in the Stomach
Food enters stomach through a ring of muscle called the cardiac sphincter
1. Mechanical Digestion
Peristalsis physically breaks up food particles
2. Chemical Digestion using Gastric Juice containing a. Mucus b. HCl c. Pepsinogen
Food is churned and mixed with gastric juices is to form chyme – a semi solid acidic liquid

Functions of gastric juice
1. Mucus
Lines and protects the stomach wall from HCl
2. HCl and pepsin a. Kills bacteria b. Activates pepsinogen
3. Pepsinogen
Converted to the active enzyme Pepsin by HCl.
Pepsin has an optimum pH of 2 .
Pepsin is a protease that digests protein to peptides

Gastric juices

Small Intestine
Muscular tube 5-6m long
Functions
Digestion
Absorption
Has three parts
1. duodenum
2. jejunum
3. ileum

Duodenum
1 foot long muscular tube
Function: Digestion
• Where most digestion takes place
• Arrival of chyme causes the release of
• pancreatic juices (from pancreas)
• bile (from the gall bladder in the liver)
• These mix with the digestive juices from the wall of the duodenum

Role of the Liver in digestion
The liver produces bile
Bile is a yellow-green liquid which contains sodium hydrogen carbonate .
It neutralises the acid chyme .
Bile is stored in the gall bladder
Bile enters the duodenum through the bile duct

Bile consists of
1.
Water 2.
Bile salts 3.
Bile pigments
Function of bile
1.
Emulsifies fats
Breaks fats - increases the surface area of the fat droplets and allows lipase to work on it
2. Neutralises the acidic chyme from stomach
(sodium hydrogen carbonate)

Fat Digestion

1. Regulates use of fats, carbohydrates and proteins
• Stores excess glucose as glycogen
• If glucose is needed, fats are broken down
• Urea is made from unwanted amino acids ( deamination)
• Produces bile
2. Breaks down poisonous substances
3. Stores vitamins and minerals
4. Maintains constant body temperature

• Lies under the stomach
• Makes hormone insulin
• Secretes pancreatic juice into duodenum
• Pancreatic juice
– water
– Sodium hydrogen carbonate(neutralises chyme)
– lipase (works best at pH 7-9)
– amylase

Ileum
Function
Food is absorbed

Infolding in the lining of the small intestine

• Fatty acids and Glycerol are absorbed into the
Lacteal (part of lymphatic system
• All other digested food are absorbed into the blood vessels and taken to the liver by the hepatic portal vein.
• The liver acts as a warehouse for nutrients

Large Intestine
Caecum
Appendix
Rectum
Colon
Anus

• Caecum is the junction between the large and small intestine
• The appendix is at the end of the caecum
• Function = unknown
(vestigial organs)

Colon
Reabsorbs water
Faeces moves to rectum where it is stored
Egested through the anus

• Video

• Fibre stimulates peristalsis
• It absorbs and stores water, wastes expand, stimulates intestinal wall to work

Symbiotic bacteria
Bacteria
• feed on waste in colon. They produce vitamins B & K which are absorbed back into the blood stream
• Breakdown cellulose
• Prevent growth of pathogenic microorganisms

Benefits of a Balanced Diet
Consists of the right amounts of each type of food
Amount of energy required depends on sex, age and activity levels
A food pyramid shows the right amount of each food type

Summary of amylase, protease and lipase
Protease

2010 Question 15

15. (b
)
(i) Diagram (liver, connection, gut)
Labels (liver, intestine and portal vein)
3, 0
3(2)
(ii) Named food or CO
2
(iii) *Hepatic artery
3
3
3 (iv) Above or to the right or behind
(v) *Gall bladder 3
(vi)
Emulsify fats (or explained) or neutralise (or comment on pH)
(vii) Storage of (fat-soluble) vitamins (or glycogen or named mineral) / deamination / heat generation / detoxification / plasma protein production / cholesterol production
Any two
3
2(3)

•
•
•
•
Amylase, protease and lipase and give their function under the following
(1) Role in chemical digestion
(2) Production Site
(3) pH at the site of action
(4) Products