4.7 Evolution of the Digestive System Flashcards
different digestive systems in animals
Main purpose of the digestive
- obtain and convert nutrients into usable energy (ATP)
- to perform all necessary cellular functions.
Two main mechanisms of getting nutrients
AUTOTROPHS
&
HETEROTROPHS
What is Autotrophs
- use energy to build organic molecules by photosynthesis;
- cellular respiration to release that energy as ATP
2 types of Autotrophs
- > Photoautotrophs: use solar energy
- > Chemoautotrophs: use chemical energy
What is Heterotrops
- variety of feeding devices and behaviours to obtain nutrients
Mechanisms of feeding (3)
- Filter/Suspension Feeding
- Fluid feeders
- Bulk feeding
What is Filter/Suspension Feeding?
- Non-specific ingestion
- filter out what they don’t want or need.
Filter/Suspension Feeding
of Baleen Whales
- use baleen plates [bristles made of keratin]
- filter, sift, sieve and trap plankton and small fish.
Filter/Suspension Feeding of Shellfish
- filter microscopic organisms through gill plates
What is fluid feeding?
examples?
Animals pierce and suck the fluid from animals / plants.
eg. Mosquitoes and leeches use anticoagulants– keep blood from clotting while they eat
eg. Tapeworms attach to intestinal lining to absorb nutrient-rich fluids from hosts digestive tract
Bulk Feeding [Most animals, including humans
]
- Large chunks of food at a time,
- require specialized structures to assist in capturing and digesting food
Evolution of digestion (2)
- Closed tube (ex: Hydra): one opening for food nad wastes. Waste through various points along the length of the organisms body.
- Open tube (ex: Humans): an opening for obtaining food and a second opening for eliminating waste.
Types of digestion (2)
- Intrcellular (ex: paramecium)- Inside cell
- Extracellular (ex: Mammals, fungi)- Outside cell
Overview of Digestion (6)
- Ingestion 2. Digestion
- Absorption 4. Transport
- Metabolism 6. Excretion
What is Ingestion
bring food and drink into the body
What is digestion? Egestion/elimination?
- Physical and chemical breakdown of food and drink into small molecules
→ Expelling unusable parts of food ex. feces
What is Absorption?
Nutrients from internal cavities into the bloodstream
What is Transport?
Getting nutrients to the cells, where needed
What is Metabolism?
Chemical processes of using nutrients and oxygen
What is Excretion?
Expelling waste products of metabolism
