Digestion Flashcards
What is heterotrophic nutrition
Organisms that must ingest complex organic molecules and break them down into simple ones to absorb
What is autotrophic nutrition
Organisms that synthesise their own food from simple organic molecules to make complex ones
What is a holozoic feeder
Organisms that break food down in digestion
What is a saprophyte
Feed on dead and decaying matter using secreted enzymes and absorbing through skin. Do not have a specialised digestive system
What is a parasite
An organism that lives in or on a host, for their nutritional benefit and to the host’s disadvantage
What is symbiosis
When organisms live on or in a host to the host and the organisms benefit
Describe unicellular digestion
Food is ingested by engulfing in phagocytosis, and is digested intracellularly by lysosomes.
Describe hydra digestion
The mouth (in the middle of the tentacles) is the only opening. The inner layer of cells is called the gastrodermis; the gastrodermis secretes digestive enzymes into the lumen of the gut. Digested food is absorbed by the gut wall. Undigested food is egested via the mouth.
Describe earthworm digestion
A tube-like gut with an opening at both ends; a mouth for ingestion and an anus for egestion. The gut has different regions
Through which organs does food pass in humans for digestion
Oesophagus
Stomach
Small intestines
Large Intestines
Which organs create secretions for digestions
Liver
Pancreas
Stored in gall bladder
How is food moved through the gut
Peristalsis
What is mechanical digestion
Cutting or crushing of large pieces of food into smaller pieces to increase surface area
What is chemical digestion
Break down of large insoluble molecules into smaller soluble molecules
What are the layers of the gut
Serosa Longitudinal muscle Circular muscle Sub-mucosa Mucosa Epithelium
How are polysaccharides digested
Salivary amylase secreted begins breakdown. Amylase denatured in the stomach in the acid. Pancreatic amylase secreted in the duodenum breaks polysaccharides into disaccharides. Maltase in the cell wall of epithelium cells breaks down maltose into glucose which is then absorbed into the bloodstream.
How are polypeptides digested
Pepsinogen secreted in gastric juice. Endopeptidases turn proteins into smaller polypeptides. Exopeptidases break down polypeptides in the duodenum into amino acids and absorbed in the ileum.
How are fats digested
Bile emulsifies fats. increasing their surface area. Pancreatic lipase is secreted to break them down into fatty acids and glycerol to be absorbed.
How are the small intestines adapted to absorption
They contain villi to increase surface area, and the epithelial cells have microvilli. They also have large numbers of mitochondria for active transport.
How are the following absorbed into the gastric cells
Fatty acids Glycerol Vitamins Amino acids Monosaccharides
Diffusion Diffusion Diffusion Active transport Active transport
How are the following absorbed into the blood capillaries
Fatty acids Glycerol Vitamins Amino acids Monosaccharides
Diffusion Diffusion Diffusion Diffusion Diffusion
How do herbivore and carnivore guts differ
Herbivore guts are much longer
How do herbivore and carnivore teeth differ
Herbivore jaws move laterally and carnivore jaws move vertically
Herbivore teeth are flat for grounding, and carnivore teeth are sharp for ripping
Herbivores have a diastema and carnivores have carnassials
Describe ruminant digestion
Grass is eaten and swallowed, and digested by bacteria. Then its regurgitated and rechewed, then passed back to the rumen, reticulum, omasum and abomasum before continuing to be digested in the intestines.
