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What is nutrition
Nutrition is the way and organism obtains and uses its food
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What is autotrophic
A type of nutrition where an organism makes its own food
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What is heterotrophic
A type of nutrition where an organism cannot make its own food
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What is a parasite
An organism that lives on a living organism ex. Flea
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What is a saprophyte
An organism that lives on a non living organism ex. Fungi
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What is digestion
The physical and chemical breakdown of good into soluble particles small enough to pass into body cells
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Need for a digestive system
Food can be digested in a single location and individual cells to not have to contain a full range of digestive enzymes
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Stages of human nutrition
1. Indigestion, food taken into alimentary canal
2. Digestion, food broken down into smaller pieces
3. Absorption, the movement of digested good from the alimentary canal into the blood stream
4. Egestion, removal of unabsorbed material as farces
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What is peristalsis
Peristalsis is the rhythmic contraction and relaxation in the walls of the alimentary canal causing the food to move along the canal
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Human teeth and functions
Incisors - cutting
Canines - tearing
Premolars + molars - cutting grinding
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What is saliva made of
- Water
- Salts
- Amylase
- Lysozyme
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What is chyme
Food and gastric juice, made in stomach
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What does gastric juice contain
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Functions of gastric juice
Pepsinogen: Converts to pepsin by HCl. Digests protein to peptides
HCl: kills bacteria, activates pepsinogen
Mucus: lines and protects stomach wall
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Protection from self digestion
Mucus lines stomach, is alkaline and reduced acidity near stomach wall
Pepsin is released in inactive form. Does not come into contact with stomach rolls.
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Sphincter muscles, and importance
Cardiac sphincter muscle: closes entry from oesophagus to stomach
Pyloric sphincter muscle: contracts to close entry to duodenum from stomach
Importance: to prevent self digestion from stomach acids
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Function of small intestine
Digestion and absorption
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3 parts of small intestine
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Function of duodenum
Most digestion
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Functions of jejunum and ileum
Absorb nutrients
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Adaptions for absorption
1. Long tube, gives time for absorption
2. Villi, infoldings increase surface area for absorption of food
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Parts of villus
Lacteal and blood vessel
Lacteal: absorbs fatty acids and glycerol
Blood vessels: all other digested food glucose, amino acids, vitamins and minerals
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Parts of large intestine
- Colon
- Caecum
- Appendix
- Rectum
- Anus
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Functions of colon
- 1. Reabsorb water
- 2. Produce B group vitamins*
- 3. Digest cellulose*
- *Symbiotic bacteria
- Human benefit: B
- Bacteria benefit: nutrition
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What are symbiotic bacteria
Bacteria that lies in close contact with another organism where at least one organism benefits
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Function of caecum and appendix
Function unknown
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Function of rectum
Stores faeces
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Role of liver
Produces bile
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Where is bile stored
Gall bladder
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Bile consists of
- Water
- Bile salts
- Bile pigments
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Functions of bile
Emulsifies fat: increases surface area of fat droplets
Neutralises: acidic chyme from stomach
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What does fibre so
Fibre stimulates peristalsis in the colon
- Prevents constipation
- Occurs when material passes through colon too slow, leads to too much water reabsorbed
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Three enzymes in digestion a
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Salivary amylase
Role, production site, where acts, pH, product
- R: digest starch
- P: salivary glands
- W: mouth
- pH: 8
- P: maltose
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Pepsin
Role, production site, where acts, pH, product
- R: digest protein
- P: gastric glands
- W: stomach
- pH: 2
- P: peptides
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Lipase
Role, production site, where acts, pH, product
- R: digest fat
- P: pancreas
- W: duodenum
- pH: 8
- P: fatty acids+glucerol
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Absorption of nutrients
Fatty acids and glycerol are absorbed from lacteal (small intestine) into the lymphatic system for transport to liver
Glucose, amino acids, vitamins and minerals pass into the blood capillaries
Hepatic portal vein brings these nutrients directly to liver
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What is a portal vein
A vein that starts with a capillary becomes a vein and ends in a capillary
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Blood transport from intestine to liver
1. Hepatic portal vein connects the small intestine to the liver, transporting glucose, amino acids, minerals and vitamins
2. The hepatic vein transports nutrients and waste urea from liver to heart
3. From the heart nutrients are transported away through aorta to body cells dissolved in plasma
4. From the heart waste is transported away from the heart to the kidney through the aorta
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Functions of liver
- 1. Makes bile
- 2. Stores glycogen
- 3. Breaks down vitamins
- 4. Stores vitamins A, D, K (fat soluble)
- 5. Make plasma proteins
- 6. Makes urea from excess protein
- 7. Produces heat
- BGTVPUH
- Bile gets too violent please use heat
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What is a balanced diet
Taking in the correct amounts of all the essential nutrients in the diet
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How to get a balanced diet
- Eat a variety of foods
- Eat each food type in moderatoon
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Amount of food required depends in
AGE (young more than old)
GENDER (males more than females)
ACTIVITY (active more than inactive)
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What is the food pyramid
The daily food portion types an a average adult should eat
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Importance of water
- Provides a medium for transport
- Provides a medium for reactions to occur
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