Exchange and Transport in Animals T8 Flashcards
(38 cards)
What do cells need for aerobic respiration?
Cells need oxygen for aerobic respiration, which produces carbon dioxide as a waste product. These 2 gases move between cells and the environment by diffusion.
How is water taken in by cells in the body?
Water is taken up by cells by osmosis. In animals, dissolved food molecules and mineral ion diffuse with it.
How is urea removed from the body?
Urea is removed from the body by diffusing from cells to the blood plasma for removal from the body by the kidneys.
Surface area to volume ratio shows what?
How easy it is for an organism to exchange substances with its environment depends on the organism’s surface are to volume ratio
How do single celled organisms exchange substances?
In single celled organisms, gases and dissolved substances can diffuse directly into or out of the cell across the cell membrane - it’s because they have a large surface area compared to their volume.
How do Multicellular organisms exchange substances?
How do Multicellular organisms (such as animals) have a smaller surface area compared to their volume. This makes it difficult to exchange enough substances to supply their entire volume.
What 3 things does the rate of diffusion depend on?
Distance, concentration difference and surface area
What is alveoli and what does it do?
Alveoli are tiny air sacs in the lungs which is where gas exchange takes place.
What does blood arriving to the lungs contain?
Lots of CO2 and not much O2. This maximises the concentration gradient for the diffusion of both gases.
How does diffusion work in alveoli?
O2 diffuses out of the air in the alveoli (where the concentration of O2 is high) and into the blood (where the concentration of O2 is low) CO2 diffuses in the opposite direction to be breathed out.
How is the alveoli specialised for maximum diffusion?
- a moist lining for dissolving gases
- a good blood supply to maintain the concentration gradients of O2 and CO2
- very thin walls - minimising the distance that gases have to move
- an enormous surface area (about 75m in humans)
How do you calculate the rate of diffusion
Rate of diffusion = (surface area x concentration difference) / thickness of membrane
What is another name of red blood cells?
Erythocytes
Describe the shape of the red blood cell?
They have a biconcave disc shape to give a large surface area to absorb oxygen.
What are the 2 main types of white blood cells?
Phagocytes and lympocytes
What do phagocytes remove foreign cells?
They surround foreign cells and digest them.
How do lymphocytes remove foreign cells?
Lymphocytes produce proteins called antibodies which stick to the foreign cells and help destroy them.
What are platelets?
These are small fragments of cells, the have no nucleus and they help the blood to clot at the wound.
What 7 things does plasma carry around the body?
1) red and white blood cells and platelets 2) nutrients like glucose and amino acids 3) carbon dioxide 4) urea 5) hormones 6) proteins 7) antibodies and antitoxins
What are arteries?
Blood vessels that carry blood away from the heart
What are capillaries?
Blood vessels that are involved in the exchange of materials at the tissues
What are veins?
Blood vessels that carry the blood to the heart
What are features of the artery?
The heart pumps blood at high pressure so the artery walls are strong and elastic. The walls are thick compared to the size of lumen. They also contain thick layers of muscle to make them strong, and elastic fibres to allow them to stretch and spring back
What are features of the capillary?
Arteries branch into capillaries. Capillaries are really tiny - too small to see. They are very narrow, so they can squeeze into the gaps between cells. This means they can carry blood really close to every cell in the body.
