Topic 8 - Exchange and Transport in animals Flashcards
Describe the need for oxygen to be transported around the body.
Oxygen is needed to burn the sugars and fatty acids in our cells to produce energy.
Describe the need for Carbon Dioxide to be transported around the body.
Carbon dioxide must be transported out of the body because it is a waste product of respiration so they need to be transported to the lungs so that they can be exhaled.
Describe the need for water to be transported around the body.
If the amount of water is wrong, cells can be damaged because too muh water enters or leaves them. Therefore it needs to be transported out of the body at a controlled rate.
Describe the need for Urea to be transported around the body.
Urea must be removed from the body. If they aren’t, they will increase in concentration and may interfere with chemical reactions or damage cells.
Describe the need for mineral ions to be transported around the body.
Maintaining the correct balance of mineral ions is essential for cells to function efficiently and effectively. If the water and ion content of the body changes, it can cause too much water to move into or out of its cells - possibly leading to them becoming damaged.
Why do we need exchange surfaces and transport systems?
The surface area of a multicellular organism, such as a plant or animal, is small compared to its volume. As a result, multicellular organisms need specialised exchange surfaces (such as lungs or gills) and transport systems.
How is alveoli adapted for its uses?
- They are folded, providing a much greater surface area for gas exchange to occur.
- The walls of the alveoli are only one cell thick. This makes the exchange surface very thin - shortening the diffusion distance across which gases have to move.
- Each alveolus is surrounded by blood capillaries which ensure a good blood supply. This is important as the blood is constantly taking oxygen away and bringing in more carbon dioxide - which helps to maintain the maximum concentration gradient between the blood and the air in the alveoli.
- Each alveolus is ventilated, removing waste carbon dioxide and replenishing oxygen levels in the alveolar air. This also helps to maintain the maximum concentration gradient between the blood and the air in the alveoli.
Describe factors affecting rate of diffusion. (3)
- Diffusion distance as substances diffuse more quickly when they haven’t got far to move.
- Surface area as the more surface area there is available for molecules to move across, the faster they can get from one side to the other.
- Concentration gradient as substances diffuse faster if there’s a big difference in concentration between the area they are diffusing from and the area that they are diffusing to. If there are lots more particles on one side, there are more there to move across.
Describe what Fick’s law tells us about rate of diffusion
It states that the rate of diffusion will double when the surface area or the difference in concentration double or when the thickness halves.
Rate of diffusion = (surface area x concentration difference) ÷ thickness of membrane
How does the structure of red blood cells relate to its function?
The job of a red blood cell(erythrocytes) is to carry oxygen from the lungs to all its cells in the body. They have a biconcave disc shape to give a large surface area for absorbing oxygen. They don’t have a nucleus which allows more room to carry oxygen. A red pigment called Haemoglobin (containing iron) binds with oxygen in the lungs to create oxyhaemoglobin. In body tissues the oxyhaemoglobin splits up into oxygen and haemoglobin to release oxygen to cells.
How does the structure of white blood cells relate to its function?
White blood cells can defend against infections. Phagocytes are white blood cells that engulfs unwelcome microorganisms - called Phagocytosis. Lymphocytes are white blood cells that produce antitoxins against microorganisms. Some produce antitoxins to neutralise any toxins produced by the microorganisms. When you have infections white blood cells multiply to fight it off so a blood test will show a high white blood cells count. These cells have a nucleus.
How does the structure of platelets relate to its function?
These are small fragments of cells. They have no nucleus. They help the blood clot at the wound - to stop all your blood pour out and to stop microorganism from getting in. Lack of platelets lead to excessive bleeding and bruising.
How does the structure of plasma relate to its function?
This a pale coloured liquid which carries most things in the blood. Such as:
- Red blood cells, white blood cells and platelets
- Nutrients lie glucose and amino acids
- Carbon dioxide from the organs to the lungs
- Urea from the liver to the kidney
- Hormones
- Proteins
- Antibodies and antitoxins
How does the structure of arteries relate to its function?
Arteries carry blood away from the heart at high pressure so the artery walls are strong and elastic. the walls are thick compared to the size of the hole down the middle (the lumen). The walls contain thick layers of muscle to make them strong and elastic fibres to allow them to stretch and spring back.
How does the structure of capillaries relate to its function?
Capillaries exchange materials at the tissues. They branch from arteries. They are very narrow so they can carry blood close to every cell in the body to exchange substances with them. They have permeable walls, so substances can diffuse in and out. One cell thick walls to allow a quicker rate of diffusion. They supply oxygen and food and take away waste like carbon dioxide.
