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- Nutrients required by an animal
- Include minerals and organic molecules that can't be produced by raw materials
- 4 classes
- Amino acids, fatty acids, vitamins, minerals
Essential amino acids
- Must be obtained from food
Essential fatty acids
- Must be ingested
- Ex, linoleic acid makes phospholipids in cell membrane
Organic molecules required in the diet in small amounts
Simple inorganic nutrients that are required in the diet in small amounts
4 main stages in food processing
The act of taking in food
- Breakdown of food into small molecules capable of being absorbed by the cells of the body.
- Enzymatic hydrolysis, breaking of bonds with the addition of a water molecule, is reaction type by which macromolecules are digested
Stage in food preceding when body's cells take up small molecules such as amino acids and simple sugars from the digestive tract
Passing of undigested material from the digestive tract
- Within a cell enclosed by a protective membrane
- Most animals
- Food is broken down outside cells. Allows the animal to devour much larger sources of food
- Single opening through which food enters and waste exits.
- Cnidarians, flatworms
Complete digestive tract (alimentary canals)
One way digestive tubes that begin at the mouth and terminate at the anus
- Rhythmic waves of contraction by smooth muscle in the walls of the alimentary canal
- Controls movement of food throughout digestive system
Muscular, ring like valves that regulate the passage of material between digestive compartments
- Nervous reflex occurs that causes saliva, which lubricates the food to allow swallowing
- Starts chemical digestion
Enzyme in saliva which hydroxides starch and glycogen into smaller polysaccharides and maltose
Ball food is shaped into during chewing
- Where bolus enters during chewing.
- Junction that opens to the esophagus and trachea
- Flap made of cartilage that covers the trachea during swallowing.
- Diverts food down esophagus, out of airway
Moves food from the pharynx down to the stomach through peristalsis
- Digestive fluid
- Hydrochloric acid- pH 2, breaks down ECM of meat and plant materials, kills most bacteria ingested
- Pepsin- enzyme that begins to hydro lie proteins into smaller polypeptides.
- Secreted in inactive form pepsinogen, activated by Hydrochloric acid. Inactive form protects cells that produce digestion enzyme from self digestion.
- Thick mucus produced by lining of stomach
- Results from digestion in stomach.
- Shunted from stomach via pyloric sphincter
- First section of small intestine.
- Major site of chemical digestion
- Acid chyme mixes with secretions from pancreas and liver. Pancreas releases bicarbonate fluid
- Produced by pancrease
- Acts as buffer against acidic contended from stomach
- Meade in liver, stored in gall bladder
- Coats fat droplets turning large fat droplets into small fat droplets, which are easier to diget
- Breakdown of starch and glycogen began with amylase.
- Small intestine, pancreatic amylases break down starch, glycogen, etc into monomers at wall of duodenal epithelium
- Pepsin begins breakdown
- Trypsin and chymotrypson brk polypeptides into smaller chains
- Dipeptodases break polypeptides into amino acids
- Starts with hydrolysis of DNA and RNA into nucleotides.
- Nucleotides broken down into nitrogenous bases, sugars, and phosphate groups.
- Digests starts in small intestine
- Bile coats fats, keeps them from clumping.
- Lipase, produced in pacrease, hydrolyzes small fat droplets
Folds on epithelial lining of small intestine
- Projections of villi
- Increase surface area available for absorption
Capillaries on villi for absorption. Absorb small fatty acids
Hepatic portal vessel
- Blood vessel that goes to liver, formed by capillaries and veins that drain nutrients away from villi.
- Liver then regulates distribution of nutrients
- Produced by stomach
- Increases production of gastric juices
- Produced by duodenum in presence of fats, slows peristalsis
- Allows more time for fat digestion
Secretin and CCK
- Secreted by walls of duodenum
- Increase flow of digestive juices from pancreas and gall bladder
Large intestine (colon)
- Connected to small intestine by a sphincter
- Cecum- point of connection site. Small pouch with extension called appendix
Large intestine functions
- Compact waste
- recover water
- At end of colon
- Where feces is stored until it is eliminated
- Correlated with diet.
- Mammals have specialized that best enables them to ingest food