Nutrition Flashcards
How do Unicellular organisms absorb nutrition?
Amoeba pseudopodia move around prey and enclose it in a food vacuole, enzymes are released and prey is digested. Products of digestion are absorbed into cytoplasm and undissolved waste is left behind.
Name examples of multicellular organisms
- Hydra
- Earthworm
- Human
Describe the Hydra’s gut
Undifferentiated sac-like gut with a single opening
Describe the digestion of an Earthworm
Tube gut, has different openingsfor ingestion and egestion. it has specified regions for the digestion of different foods
Describe the digestion of a human
Specialised regions of gut, the wall contains: muscle layers, sub-mucosa, mucosa and epithelium
Define autrophic nutrition
Makes complex organic molecules from simple inorganic ones
Define Heterotrophic nutrition
Consume complex organic food molecules
Define Photoautotrophic nutrition
Uses light as a source of energy for synthesis of food
Define Chemoautotrophic nutrition
Oxidise inorganic molecules to provide energy for the synthesis of food
Define Saprophytic nutrition
External digestion of food using secretion of enzymes followed by absorption of the products of the products of digestion into the organism (eg. fungi)
Define Holozoic nutrition
Internal disgestion of food, involves ingestion, absorption, assimilation and egestion
What is the type of protease hydrolises peptide bonds?
Endopeptidases- hydrolise bonds between specific amino acids in the middle of polypeptide chains to form peptides
What type of protease hydrolises peptide bonds at the end of peptides?
Exopeptideases
Describe the Human digestive system, giving details of each part.
Buccal Cavity- mechanical digestion (teeth + tongue), tongue moves food to teeth to cut and grind, amylase is produced from salivary glands which breakes down starch and glucose into maltose.
Oesophagus- peristalic waves of muscle contraction push the bolus of food down to the stomach, mucus lubricates the way.
Stomach- gastric glands in mucosa produce gastric juice. Oxyntic produces HCl that kills bacteria and lowers pH to 2, the cheif cells produce pepsinogen the inactive precursor of the endopeptidase enzyme, peptin.
Liver- produces bile that emulsifies lipids to increase the surface area available for lipase enzymes to digest them. Neutrilises the stomach acid.
Gall bladder- stores bile before delivering to duodenum via bile duct.
Pancreas- produces enzymes that are transported to the duodenum via pancreatic duct.
Duodenum- further digestion occurs on the epithelial cells of the villi, sucrose digested into glucose and fructose by sucrase, maltose digested into alpha glucose by maltase, lactose digested into glucose and galactose.
Ileum- Amino acids are actively transported into the epithelial cells of the villi (facilitated diffusion to capillaries), glucose and other monosaccharudes move into epithelial cells, fatty acids and glycerol diffuse into epithelial cells and are reassembled into triglycerides and carried to the lymphathic system.
Rectum and Anus- waste products
What’s the features of the serosa layer?
Tough outer coat of connective tissue
What are the features of the muscle layers?
Longitudinal muscle contracts to shorten the gut and circular muscle contracts to reduce diameter. these waves of contraction called peristalsis force food along the gut.
What are the feautures of the submucosa layer?
Contains blood and lymph vessels to remove digested food products
What are the features of the mucosa layer?
Inner layer, secretes mucus for lubrication.
What are the features of the epithelium layer?
Layers of cells in contact with food
Describe the dentition of a Carniover
Canines- long and pointed to pierce flesh and kill prey
Incisors- upper and lower jaw to grip and tear flesh
Carnassial- act like shears, sliding to rip muscle from bone
Premolars and molars- have sharp cusps that cut and crush, the jaw muscles are strong and moves in a vertical plane to strongly clamp down to hold prey.
Describe the Canrivore gut
- relatively short
- usually a large stomach for digestion of mostly protein diet
- small, useless caecum
Describe the dentition of a Herbivore
Diastema- space where tongue can push food to the grinding cheek teeth
incisors- lower jaw and cut vegetation against the horny pad.
Canines- absent
Premolars and molars- fit together in an MW shape and jaw moves horizontal so the interlocking teeth can grind food. These teeth regrow throughout life as they are quickly warn down.
Describe the NON-RUMINANTS Herbivore gut
- Very long gut for difficult process of cellulose digestion
- large caecum containing bacteria that produces cellulase for cellulose digestion.
Describe the RUMINANTS herbivore gut
- grass is chewed and swallowed as cud
- cud enters the rumen, cellulose digesting bacteria produce cellulase to break it down into glucose and is absorbed into bloodstream
- cud enters the second chamber, the reticulum, the cud is regurgitated to be rechewed in mouth
- rechewed cud is swallowed and enters third chamber, the omasum, water is absorbed
- food enters the abomasum and protein is digested
- products of digestion are absorbed into blood stream in small intestine
