Topic 8 - Exchange and Transport in animals Flashcards
What does the ease of ability to exchange substances with its environment depend on?
epends on the organisms surface area to volume
SA:V
e.g Something with 6;1 fins it easier than 2:1
Why do multi-cellular animals need exchange surfaces?
They have a smaller surface area (than unicellular) compared to their volume. This makes it difficult to exchange enough substances to supply their entire volumr across thei outer surface alone. So they need some sort of echange surface across their mass transport system
the surfaces are adapted to maximise effectiveness
What are the 3 things rate of diffusion depends on?
Distance - less=Quicker
Concentration distance (Gradient)
Surface area
Why does concentration difference (Gradient) affect rate of diffusion?
Substances diffuse fatser if theres a big difference in concentration between the area they are diffusing from and the area they are diffusing to. If there are lots more particles on one side, there are more there to move across
How
How does surface area affect rate of diffusion?
the more surface there is avaliable for molecules to move across, the faster they can get from one side to the other
Where does gas exchange in mammals happen?
the alveoli
What is the job of the lungs, how are they adapted to this function?
to transfer oxygen to the blood and to remove waste carbon dioxide from it.
The lungs contain millions of air sacs callled aveoli where gas exchange takes place
how does the alveoli work with blood ariving?
Blood ariving has just returned to the lungs after ciruclating aorund the body, so had low oxygen and lots of carbon dioxide. This maximises the conc radient for diffusion of both gases
how does the alveoli work with blood leaving?
Oxygen diffuses out of the air in the alveoli ( 02 conc os high) and into the returning blood ( Low 02 conc). Co2 diffuses in the opposite direction to be breathed out
How is the alveoli specialised to maximise the diffusion of O2 and CO2
- Moist lining for dissolving gases
- Good blood supply to maintain conc gradients
- Very thin walls - minimising distance gases have to move
- Enormous surface area
What is ficks law?
Rate of diffusion ∝ (surface area × concentration) / difference thickness of membrane.
What is the job of red blood cells ( Erythrocytes) ?
To carry oxygen from the lungs to all the cells in the body
How are red blood cells specialised ?
- Biconcave Disc shape - Max surface area
- No Nucleus - more room to carry O2
- Contain Haemoglobin
How does haemoglobin work?
in the lungs it binds to oxygen to become oxyhaemoglobin. In body tissues, the reverse happens and it split up to release oxygen to cells
What is the purpose of white blood cells?
To defend against infection - when you have an infection, your white blood cells multiply to fight it off
what are the 2 types of white blood cells?
Phagocytes
Lymphocytes
