2.4 Nutrition in multicellular organisms Flashcards
name 3 examples of holozoic multicellular organisms
- hydra
- earthworms
- human
how does a hydra digest things
(undifferentiated gut - sac like body)
- single opening for ingestion + egestion
- central cavity = digestive cavity
->Tentacles capture prey and pass into mouth
->Enzymes secreted into cavity (extra cellular digestion)
->Partially digested food is engulfed by cells.
->Digestion is completed intracellularly
how do earthworms digest things
(tube gut)
- 2 openings: mouth(ingest) + anus(egestion)
- specialised to cope with a varied diet
->Pharynx sucks up food.
->Oesophagus connects to crop(crop stores food)
->gizzard mechanically digests food with aid of grit(soil)
->food chemically digested(extracellular) and absorbed in intestine
->indigestible food egested through anus
what are the main 8 parts of digestion in the human body
- mouth(buccal cavity)
- oesophagus
- stomach
- liver
- pancreas
- small intestine
- large intestine
- anus
what occurs in the human mouth
(ingestion)
- food is mechanically broken down(increasing surface area)
- starch digestion chemically breaks down glucose(by amylase)
what occurs in the human stomach
food is churned up by peristalsis
protein digestion begins, protease enzymes are secreted
what occurs in the human liver
bile is secreted which emulsified fats.
what occurs in the human pancreas
proteases, lipase and carbohydrase are made here before being secreted into small intestine.
what occurs in the human small intestine
- start of fat digestion by bile and lipase
- continued digestion of starch and proteins
- absorption of small soluble molecules into bloodstream
- walls covered with villi to increase surface area for absorption
what is the function of bile
emulsifies fats, turns them into droplets
