BY2 Nutrition (2)
- Created by: beth-marie2511
- Created on: 22-03-16 08:17
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- BY2 - Nutrition (2)
- Mammalian Gut; Digestive System & Alimentary Canal
- Mouth
- Mechanical digestion by the teeth.
- Increases surface area for enzyme action.
- Alkaline
- Mechanical digestion by the teeth.
- Stomach
- Acidic
- Optimum pH for enzymes and kills bacteria.
- Mechanical digestion
- Chemical digestion
- Glands release gastric juice
- Mucus is released
- Lubrication and prevents auto digestion (enzymes digest stomach walls
- Acidic
- Small Intestine - Duodenum
- Secretes an alkaline liquid.
- From the Brunner's gland.
- Pancreas releases pancreatic juice.
- Enters duodenum via pancreatic duct.
- Contains amylase, endopeptidase and lipase.
- Exopeptidases hydrolise peptide bonds on terminal amino acids.
- Polypeptides ---> Peptides
- Bile enters via the bile ducts.
- Contains bile salts.
- Neutralise stomach acids.
- Emulsify lipids
- Contains bile salts.
- Goblet cells release mucus.
- Secretes an alkaline liquid.
- Small Intestine - Ilium
- Methods of Transport
- Glucose and amino acids are absorbed across the epithelium of the villi via diffusion and active transport (if the diffusion rate is too slow).
- They pass into the capillary of the villus and are then transported to the hepatic portal vein to the liver.
- Fatty acids and glycerol are absorbed into the lacteal via diffusion.
- They are transported to the lymphatic system which opens up into the blood stream at the thoracic duct.
- Glucose and amino acids are absorbed across the epithelium of the villi via diffusion and active transport (if the diffusion rate is too slow).
- Absorption Features
- Large Capillary Network
- Absorbs glucose and amino acids
- Maintains concentration gradient.
- Lacteal or Lymph Vessel
- Absorbs fatty acids and glycerol.
- Thin Epithelium
- Short diffusion pathway.
- Ilium is long.
- Increases surface area to increase rate of diffusion.
- Villi
- Increases surface area to increase rate of diffusion.
- Villi
- Lots of Mitachondria.
- Provides ATP for active transport.
- Large Capillary Network
- Methods of Transport
- Large Intestine
- Colon, appendix and rectum.
- Function is to reabsorb water and minerals back into the blood stream.
- Vitamins are secreted by bacteria (E-coli) e.g. vitamin K.
- When the food reaches the rectum it is in a semi solid condition.
- e.g Faeces
- Consist of undigested food (cellulose, bacteria and dead cells).
- e.g Faeces
- When the food reaches the rectum it is in a semi solid condition.
- Fate of Digested Products
- Glucose releases energy into respiration.
- Amino acids are used in protein synthesis.
- Or they are deaminated (amine group is removed) and converted into urea.
- Lipids used for membranes and hormones.
- Or stored as fat under the skin.
- Mouth
- Dentition
- Types of Teeth
- Molars
- For chewing and grinding.
- Incisors
- For slicing and cutting.
- Canines
- For ripping and tearing.
- Molars
- Herbivores
- Jaw moves in horizontal plane (side-to-side).
- No canines.
- No carnassial teeth.
- Open roots for continuous growth.
- Cheek teeth are flattened with enamel ridges.
- Molars/Pre-Molars are in a ridged W-M arrangement.
- Diastema - separates front teeth from the pre-molars and helps to chew food.
- Cellulose is part of diet.
- Carnivores
- Canines present.
- Jaw movement is vertical (mouth opens wider to grip onto prey).
- Well developed jaw muscles powerful enough to crush bones.
- Carnassial teeth.
- Pointed cheek teeth.
- No W-M arrangement.
- Incisors in upper and lower jaw.
- No horny pad.
- No diastema.
- Teeth do not grow continuously.
- No cellulose in diet.
- Types of Teeth
- Herbivore Gut
- Long
- More difficult to digest plant material.
- Larger caecum.
- Contains bacteriato help digest plant material.
- Carnivore Blood
- Short
- Shows how easily protein is digested.
- Shorter caecum.
- Don't need to digest plant material.
- Caecum contains bacteria to digest cellulose.
- Short
- Rabbits eat their droppings in a process called refection for more time to absorb nutrients.
- Long
- Ruminants
- Specialised stomachs have mutualistic bacteria - both organisms benefit from the relationship.
- e.g. Cow
- 1. Grass enters rumen which contains cellulose digesting bacteria - celluloses moves into the second chamber.
- 2. Cud is regurgitated for further chewing and then swallowed to move into the next chamber, where water is reabsorbed.
- 3. Cud enters the final chamber - the 'true stomach' where protein is digested.
- Fermentation takes place which produces CO2 and methane gases (CH4).
- When the bacteria die they provide a source of protein for the cow.
- 3. Cud enters the final chamber - the 'true stomach' where protein is digested.
- 2. Cud is regurgitated for further chewing and then swallowed to move into the next chamber, where water is reabsorbed.
- 1. Grass enters rumen which contains cellulose digesting bacteria - celluloses moves into the second chamber.
- Cellulose is digested into glucose in the rumen.
- Mammalian Gut; Digestive System & Alimentary Canal
- Salivary glands produce saliva
- Lubricates food.
- Mouth
- Mechanical digestion by the teeth.
- Increases surface area for enzyme action.
- Alkaline
- Mechanical digestion by the teeth.
- Microvilli
- Increases surface area to increase the rate of diffusion.
- Absorption Features
- Large Capillary Network
- Absorbs glucose and amino acids
- Maintains concentration gradient.
- Lacteal or Lymph Vessel
- Absorbs fatty acids and glycerol.
- Thin Epithelium
- Short diffusion pathway.
- Ilium is long.
- Increases surface area to increase rate of diffusion.
- Increases surface area to increase rate of diffusion.
- Lots of Mitachondria.
- Provides ATP for active transport.
- Large Capillary Network
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