Exchange and transport in animals Flashcards
(43 cards)
How do you work out surface area: volume ratios?
Calculate surface area, then the volume of object. To get ratio in the form n:1, divide both sides by the volume.
Multicellular organisms require what?
Exchange surfaces.
Why are exchange surfaces needed?
Multicellular organisms have a smaller surface area compared to there volume. This makes it difficult to exchange enough substances to supply there entire volume across there outside surface alone.
The rate of diffusion is affected by what factors?
- Surface area
- Concentration difference
- Distance
Gas exchange in mammals happens in the what?
Alveoli.
Explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries.
- Blood arriving at alveoli has just returned to the lungs from the rest of body
- So it contains a lot of carbon dioxide and less oxygen
- This maximises the concentration gradient for diffusion
- O₂ diffuses out of air and into the alveoli (where O₂ conc. is high) and into the blood (where conc. of O₂ is lower). CO₂ diffuses in the opposite direction.
How are alveoli specialised to maximise the diffusion of O₂ and CO₂?
- A moist lining for dissolved gases
- A good blood supply to maintain conc. gradients of O₂ and CO₂
- Thin walls - minimise distance
- A large surface area
What is Fick’s Law?
rate of diffusion ∝ surface area x conc. difference
—————————————————
thickness of membrane
What is the job of red blood cells?
To carry oxygen from the lungs to all cells in the body.
What is the shape of red blood cells and why is it like this?
Biconcave disc shape - Large surface for absorbing oxygen.
Red blood cells contain a pigment called what?
Haemoglobin, which contains iron.
What does haemoglobin do in the lungs?
It binds to the oxygen to become oxyhaemoglobin.
What does haemoglobin do in body tissue?
Oxyhaemoglobin splits into haemoglobin and oxygen, to release oxygen to the cell.
What are phagocytes?
They are white blood cells that can change shape to engulf unwelcome microorganisms.
What are Lymphocytes?
They are white blood cells that produce antibodies against microorganisms. Some produce antitoxins to neutralise ant toxins produced by microorganisms.
What do platelets do?
Help blood clot.
What is plasma and what does it do?
It is a straw-coloured liquid which carries just about everything in blood.
There are 3 different types of blood vessel, what are they?
- Veins
- Capillaries
- Arteries
What do arteries do?
These carry the blood away from the heart.
What is the structure of an artery?
-The walls are thick and the elastic fibres allow them to stretch as the blood the heart pumps is at a high pressure.
What do veins do?
These carry the blood to the heart.
What is the structure of a vein?
- The veins don’t need to be thick as the blood is at a low pressure
- They have valves to keep the blood flowing in the right direction
What do capillaries do?
These are involved in the exchange of materials at the tissues.
What is the structure of a capillary?
- They have permeable walls, so substances can diffuse in and out
- One cell thick walls
- They are narrow so they can squeeze into the gaps between cells, this means they can carry blood to every cell for the exchange of substances
