Topic 8 - Exchange And Transport In Animals Flashcards
How are gases exchanged into the lungs?
Diffusion.
What and how is the rate of diffusion affected by?
DISTANCE - substances diffuse more quickly when they haven’t got as far to move.
CONCENTRATION GRADIENT - Substances diffuse faster if there’s a big difference in concentration between the area they are diffusing from and the area they are diffusing to. If there are lots more particles on one side, there are more there to move across.
SURFACE AREA - The more surface are there is available for molecules t move across, the faster they can get from one side to the other.
What is the job of the lungs?
To transfer oxygen to the blood and to remove waste carbon dioxide from it.
What are alveoli?
Little air sacs where gas exchange takes place.
When blood arrives at the alveoli, why is concentration gradient maximised for both gases?
It’s just returned from the rest of the body so it contains lots of C02 and not much oxygen. This maximises concentration gradient for diffusion for both gases.
How is gas exchange taken place in the alveoli?
Oxygen diffuses out of the air in the alveoli (where oxygen concentration is high) and into the blood (where oxygen concentration is low). CO2 diffuses in opposite direction to be breathed out.
How are alveoli specialised to maximise the diffusion rate?
- They have a moist lining for dissolving gases
- They have a good blood supply to maintain the concentration gradients of O2 and CO2.
- They have very thin walls to minimise the distance the gases have to move
- They have a huge surface area (about 75m² in humans).
What is the rate of diffusion proportional to?
Thickness of membrane
What is the job of red blood cells?
To carry oxygen from the lungs to all cells in the body.
How are blood cells specialised for carrying oxygen?
- They have a biconcave disc shape to give a large surface area for absorbing oxygen.
- They don’t have a nucleus - this allows more room to carry oxygen
- They contain a red pigment called haemoglobin which contains iron.
What does haemoglobin do?
In the lungs, haemoglobin binds to oxygen to become oxyhemoglobin. In body tissues, the reverse happens - oxyhemoglobin splits up into haemoglobin and oxygen to release oxygen to the cells.
What are phagocytes and lymphocytes examples of?
White blood cells.
What do phagocytes do?
They are white blood cells that can change shape to engulf unwelcome microorganisms - this is called phagocytosis.
What do lymphocytes do?
They’re white blood cells that produce antibodies again microorganisms. Some also reduce antitoxins which neutralise any toxins produced by the microorganisms.
How can a blood test show if you have an infection?
When you have an infection, your white blood cells multiply to fight it off - therefore a blood test will show a high white blood cell count.
What are platelets and what do they do?
These are small fragments of cells that help the blood to clot at a wound - stop blood pouring out and microorganisms getting in.
What does plasma carry?
Red and white blood cells and platelets Nutrients like glucose and amino acids Carbon dioxide Urea Hormones Proteins Antibodies and Antitoxins
What are the three type of blood vessel and their functions?
ARTERIES - these carry blood away from the heart.
CAPILLARIES - these are involved in the exchange of materials at the tissues
VEINS - these carry blood to the heart.
How are arteries adapted to carrying blood out at high pressures?
- Artery walls are strong and elastic
- The walls are thick compared to the size of the lumen (hole down middle of artery)
- They contain thick layers of muscle to make them strong and elastic fibres to allow them to spring back.