Topic 8 - Exchange and Transport in Animals Flashcards
What must organisms exchange substances with?
Their environment
What affects the ability to exchange substances with the environment?
An organisms SA:V ratio
Finish the sentence: The larger the organism, the _______ its SA:V ratio.
Smaller
What do multi-cellular organisms need that single-celled organisms do not?
Exchange surfaces
What 3 factors affect the rate of diffusion of any substance?
- Distance: Substances diffuse more quickly when they travel a smaller distance
- Concentration difference: A higher difference causes a quicker rate of diffusion
- Surface Area: More surface for molecules to move across means a quicker rate of diffusion
Where in animals does gas exchange take place?
Alveoli
What is the job of the lungs?
To transfer oxygen to the blood and remove waste carbon dioxide from it
What is an alveolus?
An air sac where gas exchange takes place
Describe what the alveolus does:
- Arriving blood has lots of carbon dioxide and little oxygen, increasing the concentration gradient
- Oxygen diffuses out of the alveolus and into the blood
- Carbon dioxide diffuses out of the blood and into the alveolus
- Blood is now oxygenated and flows to the rest of the body
How are alveoli specialised to their function?
- Moist lining for dissolving gases
- Good blood supply
- Very thin walls
- Enormous surface area
What does Fick’s Law state?
Rate of diffusion ∝ (Surface area x Concentration difference) / Thickness of membrane
What do red blood cells carry?
Oxygen
How are red blood cells specialised to their function?
- No nucleus, so more oxygen can be carried
- Biconcave disc shape, increasing surface area
- Contain haemoglobin, which contains iron
What do white blood cells defend against?
Infection
What are the two types of white blood cell, and what are their functions?
- Phagocyte: Change shape to engulf microorganisms
- Lymphocytes: Production of antibodies
