Transport in animals Flashcards
Why do animals need specialised transport systems?
Smaller SA:V ratio
High metabolic demands
Transportation of hormones/enzymes
Waste products of metabolism needs to be transported to excretory organs.
Digested food need to be transported to every cell for respiration.
Key features of circulatory systems?
Liquid transport medium = circulates around system (blood)
Vessels carry transport medium.
Pumping mechanism moves fluid around system.
Example of open circulatory system?
Mainly invertebrate animals.
Haemolymph transports food/nitrogenous waste.
Hameolymph circulates but steep diffusion gradients cannot me maintained for efficient diffusion.
Amount of haemolymph cannot be varied to meet changing demand.
What is an open circulatory system?
Few vessels to contain transport medium.
From heart to body cavity of animal (haemocoel)
Low pressure.
Direct contact with tissues + cells.
What is a closed circulatory system?
Blood enclosed in blood vessels.
Substances leave/enter blood by diffusion of walls of blood vessels.
Blood pigment = respiratory gases.
What are single closed circulatory systems?
Blood flows through heart -> pumped out to whole body b4 returning to heart.
Travels only once through heart for each complete circulation.
Limits efficiency
Why do fish only need a single closed circulatory system?
Counter current system = lots of O2 from water.
Do not maintain own body temperature
Body weight supported by water.
Reduces metabolic demands.
What is a double closed circulatory system?
🩸 pumped from 🫀 to 🫁 = pick up O2/unload CO2 —> returns back to 🫀
🩸 flows through 🫀 and pumped around whole body b4 returning back to 🫀
Blood travels twice through heart for each circuit of body.
