Gas Exchange Flashcards
what do single celled organisms do?
- absorb and release gases by diffusion through their cell-surface membrane
what adaptations do single-celled organisms have?
- relatively large surface area
- thin surface
- short diffusion pathway
why do fish need to have a specialised gas exchange surface?
- lower concentration of oxygen in water than in air
what is the function of the gills?
water containing oxygen enters the fish through its mouth and passes out the mouth through the gills
what is each gill made of?
- lots of thin plates called gill filaments
why is it a good thing to have gill filaments?
- there are many of them which gives a large surface area for exchange of gases = increases the rate of diffusion
what are the gill filaments covered in?
- tiny structures called lamellae
why is it good to have lamellae?
increases the surface area
how are lamellae adapted for diffusion?
- lots of blood capillaries = ventilation
- thin surface layer of cells = thin diffusion pathway
what is the counter-current system?
- in the gills of fish water and blood flow in opposite directions through the lamellae
what does the counter-current system enable?
- a concentration gradient of oxygen to be maintained across the whole length of the lamella
why is it good to have a counter current system?
- ensures that as much oxygen can diffuse from the water into the blood
- oxygen can diffuse across the whole length of the lamellae
what concentration does blood enter the lamella in?
low concentration of oxygen
what are the adaptations of fish in gas exchange?
- gills
- gill lamellae
- gill filaments
- counter current principle
what is the main gas exchange surface in the leaf?
mesophyll cells