⭐️SB8 - Exchange And Transport In Animals Flashcards
What waste product is removed by the kidneys and what is it?
Urea - a poison produced by breaking down amino acids
What substances are needed to produce new substances in the body
Dissolved food molecules and mineral ions
What properties must surfaces have to maximise rate of diffusion in an organism?
- must be thin so particles do not need to move very far
- must have a large surface area so there is more rook for particles to diffuse
Why do multicellular organisms have transport systems?
As it would take too long for materials to diffuse through cells on the outside of a tissue to reach cells on the inside
What is the transport system in humans?
A fine network of capillaries in the circulatory system which uses blood to transport substances to and from the cell
Describe the diffusion happening in the capillaries
What goes out?
What goes in?
- oxygen molecules diffuse out
- glucose molecules diffuse out
- carbon dioxide molecules overall move into the capillary down the concentration gradient
How are capillaries efficient at diffusing particles?
They are only one cell thick
What maintains the concentration gradient in a capillary?
The continual flow of blood
What is the surface area to volume ration and what does it mean?
The surface area / volume and so the bigger it is the more surface area something has
how does size of cells depend on SA:V ratio?
The larger the ratio the smaller the cells and so the smaller the ratio the larger the cells
What does it mean if an organ has a large SA:V ratio?
Then that organ moves substances into and out of the body
How does blood move through and alveolus?
- It enters from the rest of the body with a higher concentration of carbon dioxide and a lower concentration of oxygen
- There is a net movement of CO2 into the alveolus and out of the blood
- There is a net movement of oxygen out of the alveolus and into the blood
- Blood goes to the rest of the body with a lower concentration of carbon dioxide and a higher concentration of oxygen
How is an alveolus adapted to its function
- It has a one cell thick wall of alveolus
- it has a one cell thick wall of capillary
- it has a higher concentration of oxygen and lower concentration of carbon dioxide than blood to have more oxygen in the blood and less carbon dioxide
- its shaped a certain way so it has a larger surface area
What is concentration?
The amount of substance in a certain volume
How do you calculate concentration in g dm cubed?
Concentration = mass of solute (g) / volume of solution ( dm cubed)
What does it mean that particles in a solution move randomly in all directions?
It causes an overall net movement of the solute particles from higher concentration to lower concentration
What forms a concentration gradient? What is the link between greater difference in concentration and rate of diffusion?
The difference between two concentrations and the greater the difference between them, the steeper their concentration gradient and the faster the rate of diffusion
What is the relationship between rate of diffusion and difference In concentrations and how do you know this?
They are directly proportional to each other because on a graph the line goes through the origin so:
Rate of diffusion ∝ concentration difference
How is concentration gradient maintained in the lungs?
A good blood supply moves oxygen quickly out of the lungs so this keeps rate of diffusion high
How does surface area affect the rate of diffusion? Explain it
The rate of diffusion ∝ the surface area
As if surface area of a membrane is increased, there is more space through which particles can pass so rate of diffusion increases
How does distance effect the rate of diffusion and explain
Rate of diffusion ∝ 1 / thickness of membrane. This makes it inversely proportional because the slower particles have to diffuse the slower the rate of diffusion
What does fick’s law show?
The relashionship between the variables that affect diffusion:
Rate of diffusion ∝ surface area x concentration difference / thickness of membrane
Describe the flow of blood in the circulatory system
It flows away from the heart, into the arteries which divide into capillaries and form fine networks running through tissues. Blood then returns to the heart in veins
What are valves for?
To prevent blood flowing the wrong way
Explain the pulse you feel in the arteries
Its when the artery wall stretches due to sudden increase in blood pressure (not movement of blood)
What happens to artery walls after a sudden increase in pressure
They stretch and then muscle and elastic fibres cause them to contract again
Why does the artery stretch and contract?
So the blood flows more smoothly
What helps push blood along veins?
Muscles in the skeleton
For an artery,
Describe the Lumen, thickness of muscular wall, pressure and wether valves are present
- lumen is narrow
- has a thick layer of elastic and muscle fibres
- pressure is high
- has no valves
For a vein,
Describe the Lumen, thickness of muscular wall, pressure and wether valves are present
- lumen is wide due to a thin muscular wall which is flexible
- low pressure hence why the wall is thin
- contains valves
For capillaries
What process mainly happens in them and describe the Lumen, thickness of muscular wall, pressure and wether valves are present
Mainly diffusion occurs here,
- very narrow lumen
- thickness is only one cell thick to allow faster diffusion of substances in and out
- low pressure
- no valves
What is blood made up of
- Erythrocytes (red blood cells)
- platelets
- white blood cells
- plasma