Exchange Flashcards
Where is oxygen exchanged?
The alveoli in lungs, oxygen needs to be exchanged because it is needed for respiration
Where is carbon dioxide exchanged?
The alveoli in lungs, it needs to be exchanged because it is a waste product of metabolism
Where is water exchanged?
The nephrons in the kidneys, it needs to be exchanged so cells can function properly
Where are dissolved food molecules exchanged?
In the small intestine, they’re exchanged as they’re needed for respiration
Where are mineral ions exchanged?
In the small intestine, they’re exchanged as cells need them to function properly
Where is urea exchanged?
The nephrons in kidneys, it’s exchanged because it’s a waste product of metabolism
What are the lungs adapted to exchange?
Gases
What is the small intestine adapted to exchange?
Solutes
What happens to an organism’s surface area to volume ratio as it gets bigger?
It gets smaller meaning they can’t rely on diffusion, they need to have specialist exchange surfaces and transport systems
What happens in the lungs?
Oxygen diffuses into the blood from the air taken in by the lungs, carbon dioxide diffuses out of the blood and into the air that has been taken in by the lungs
How are the lungs adapted for gas exchange?
- They have millions of tiny alveoli which create a large surface area
- Each alveolus is closely associated with a capillary, the alveoli have walls that are only one cell thick to minimise the diffusion distance
- Continual blood flow through capillaries and ventilation of alveolus maintains high concentration gradients to maximise the rate of diffusion
What is Fick’s law?
Rate of diffusion ∝ (surface area x concentration difference) / thickness of membrane
How can rate of diffusion be maximised using the principles of Fick’s law?
The surface area and concentration difference need to be as large as possible, the thickness of the membrane needs to be as small as possible
What factors affect diffusion?
- Surface area
- Distance for diffusion /thickness of membrane
- Concentration gradient
What are the four main things that make up blood?
- Plasma
- WBCs
- RBCs
- Platelets