Adaptations For Nutrition Flashcards
How do unicellular organisms absorb nutrients - use amoeba as example
- Amoeba pseudopodia move around prey and enclosed it in a food vacuole
- Enzymes are released from lysozymes that fuse with the food vacuole and the prey is digested
- Products of digestion are absorbed into the cytoplasm sand the undissolved waste is egested by exocytosis
What type do guts do the following multicellular organisms have
Hydra, earthworm and human
Hydra - single food source - undifferentiated, sac like gut with single opening
Earthworm - varied foods - a tube gut with different openings for ingestion and digestion and specialised regions for the digestion of different food.
Human - omnivorous diet - specialised regions of gut. The wall of the gut contains the following layers ( muscle layers, serosa, longitudinal muscles, circular muscle, sub-mucosa, mucosa, epithelium)
Features of the serosa (human gut)
Tough outer coat of connective tissue
Features of muscle in human gut
Longitudinal muscle contracts to shorten the gut and circular muscle contracts to reduce the diameter (peristalsis)
What is the feature of the sub-mucosa
Contains blood and lymph vessels to remove digested food products
What is the feature of the mucosa
Inner layer that secreted mucus for lubrication. In some areas it secretes digestives juices; in others it absorbs products
What are features for the epithelium in the human gut
Layer of cells in contact with food
Define what autotrophic
Makes complex organic molecules from simple inorganic ones
Define heterotrophic
Consume complex organic food molecules
Describe two most common types autotrophism
Photoautotrophic- use light as a source of energy for synthesis of food
Chemoautotrophic - oxidise inorganic molecules to provide energy for the synthesis of food
Describe two types of heterotrophic
Saprophytic - external digestion of food using secretion of enzymes followed by absorption of the products of digestion into the organism e.g fungi
Holozoic - internal digestion of food. Involved ingestion, absorption, assimilation and egestion.
Name two types of protease
Endopeptidase and exopeptidases
What does endopeptidase do
Hydrolyse peptide bonds between specific amino acids in the middle of the peptide chain to form shorter polypeptide chains
What does exopeptidases do
Hydrolyse peptide bonds on the end of peptides, from the free amino acids or free carboxylic end
What’s the function and structure of the buccal cavity in the digestive system
Mechanical, digestion of food occurs here. The tongue moves the food to the cutting and grinding surfaces of the teeth. Chemical digestion of starch and glycogen into maltose by amylase. Saliva moistens the food and maintains the pH for the enzyme. The tongue then rolls the food into a bolus which is swallowed
What’s the function and structure of the oesophagus in the digestive system
Peristaltic waves of muscle contractions push the bolus of food down to the stomach, mucus lubricates the way
What is the structure and function of the liver in the digestive system
Produced bile. Bile emulsifies lipids to increase the surface area available for lipase enzymes to digest them. It also neutralised the stomach acid to create a slightly alkaline pH in the duodenum for the pancreatic enzymes
What’s the structure and function of the stomach in the digestive system
Gastric glands in the mucosa produce gastric juice. The oxyntic cells produce HCl that kills bacteria and lowers pH to 2. the chief cells produce pepsinogen, the active precursor of the endopeptidase enzyme, pepsin.nthisnjs activated by HCl. Finally the goblet cells produce mucus to protect the stomach lining
What’s the structure and function of the gall bladder in the digestive system
Stores the bile before delivering it to the duodenum via the bile duct
What’s the structure and function of the pancreas in the digestive system
Produces enzymes that are transported to the duodenum via the pancreatic duct. Carbohydrase - pancreatic amylase
What is protease in the pancreas and how does pancreatic lipase work
Trypsinogen that is activated into the endopeptidase trypsin by enterokinase in the duodenum. Pancreatic lipase enzymes digest triglycerides into mono glycerides and eventually glycerol and fatty acids
What’s the function of the duodenum
Further digestion occurs on the epithelial cells of the villi
-sucrose digested by sucrase into glucose and fructose
-lactose digested by lactase into glucose and galactose
- further digestion of polypeptides by endopeptidases and exopeptidases
Describe absorption In the ileum by the villi
-amino acids are actively transported into the epithelial cells of the villi; facilitated diffusion then occurs in the capillaries in the villi
-glucose and other monosaccharides move into the epithelial cells by co-transport with sodium ions; facilitated diffusion that occurs in the capillaries in the villi
-fatty acids and glycerol diffuse into the epithelial cells and then reassembled into triglycerides and carried by the lacteal into this lymphatic system
What is the structure of a villus and it’s purpose
-the villi increases the surface area in the small intestine for absorption of digested food into the blood
Contains capillary, lacteal and columnar epithelium
