Transport In Cells, Blood & Blood Vessels Flashcards
What is gas exchange?
The physical process of gas moving by diffusion ( going from an area of high concentration, to an area of low concentration) across a surface.
What is an example of where gas exchange occurs?
Oxygen moves from the lungs to the bloodstream. At the same time carbon dioxide passes from the blood to the lungs. This happens in the alveoli and capillaries.
What are some adaptions made to maximise effectiveness of gas exchange?
- Thin membrane; substances have a short diffusion pathway.
- Large surface area; lots of substances can diffuse at once.
What are adaptions of the alveoli for gas exchange?
- Large surface area.
- Moist lining.
- Very thin walls.
- Good blood supply.
What is the definition and function of blood?
A tissue which transports substances around the body, e.g. oxygen.
What are the functions and adaptations of red blood cells?
Transport oxygen around body:
- Biconcave shape to give large surface area.
- Has haemoglobin which carries oxygen.
- Has no nucleus to carry more oxygen.
What are the functions and adaptations of white blood cells?
Defend against microorganisms that cause disease:
- Engulf unwelcome microorganisms.
- Produce antibodies.
- Produce antitoxins to neutralise toxins.
What are the functions and adaptations of platelets?
Help blood to clot:
- No nucleus.
- Stops microorganisms from getting in.
What are the functions and adaptations of plasma?
Carries all the other components of blood including:
- Red & White blood cells & platelets.
- Nutrients (glucose & amino acids).
- CO2.
- Hormones.
- Antibodies.
What are the three main blood vessels?
Arteries, Veins & Capillaries.
What are arteries?
Carry blood away from the heart:
- Artery walls are thick/ elastic as blood comes at high pressure.
- Contain thick layers of muscle to make them strong.
What are capillaries?
Branch off from arteries; help with exchange of gases & supply food/oxygen to cells and remove waste products like CO2:
- Have permeable walls so substances can diffuse.
- Very narrow & large surface area; increases rate of diffusion.
What are veins?
Formed from joined capillaries; carry blood to the heart:
- Walls not as thick as artery walls as blood comes in lower pressure.
- Have a bigger lumen (central hole) than arteries to help blood flow.
- Have valves to help keep blood flowing in one direction.
