SB8- Exchange And Transport In Animals Flashcards
Tell me ways to speed up diffusion
Surfaces are thin - distance the particles travel is not far
Have large surface area - more room for particles to diffuse
Capillaries are just one cell thick, continual blood flow maintains concentration gradient
Tell me about the surface area to volume ratio
The larger a cells surface area - the more of a substance can diffuse in and out at a time - if volume too big, it can’t fill up quickly enough
Surface area divided by volume - bigger the ratio, more diffusion
If ratio too small, cells can’t get materials fast enough so there is a limit to the size of cells
How do the lungs have a large surface area to volume ratio
Lungs are packed with alveoli - which increase surface area and increase the amount of gas exchange
How are alveolus adapted
Alveoli (plural)
Has a one cell thick wall to decrease diffusion distance, round shape gives larger surface area
Carbon dioxide moves in to alveoli and oxygen out to blood cells
What’s the concentration
The amount of a substance in a certain volume
Common unit is g/cm^3 or g cm^-3
What is 1 dm equal to?
1 litre
What’s 1 litre equal to
1000cm^3
How do you calculate concentration
Concentration = mass of solute in g / volume of solution in dm^3
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Why is a movement in diffusion a “net” movement of solute particles
Particles in a solution move randomly in all directions - so the overall movement is a net movement
What happens when there’s no concentration gradient and concentrations are the same
Ther is no net movement but individual particles are still moving
What’s a concentration gradient
The difference between 2 concentrations form a gradient - bigger difference makes steeper gradient and faster rate of diffusion
What is the relationship between rate of diffusion and difference between 2 concentrations
There’s a linear relationship, on a graph the line goes through the origin
It’s a directly proportional relationship ship ship
Rate of diffusion (weird is proportion sign) concentration difference
What maintains a concentration gradient in the lungs
A good blood supply moves oxygen quickly out of the lungs
How does surface area increase rate of diffusion
When surface area is increased - there’s a bigger space on the membrane for particles to cross through in a certain time so overall rate of diffusion increases
But rate at which particles pass through each unit area of the surface membrane is unchanged
Rate of diffusion is proportional to surface area
How does distance change the rate of diffusion
The farther particles have to diffuse. The slower the rate of diffusion- so increasing the thickness of a memebrane decreases the rate of diffusion
This is an inversely proportional relationship- when distance doubles, the other halves
Rate of diffusion is proportional to 1 divided by thickness of membrane
What is Ficks law
Shows the relationship between variables that affect diffusion
Rate of diffusion is proportional to= surface area x concentration difference / thickness of membrane
Simplify the circulatory system
Blood flows away from the heart into the arteries and divide into narrow capillaries which form networks running through tissues, blood returns to the heart in veins
How and why is a pulse formed
With each beat, the heart squirts blood into arteries under high pressure
Artery walls are thick to withstand the sudden increase in pressure - but this makes them stretch, a wave of stretching then passes all by the artery walls which is felt as a pulse
A pulse is not your blood moving
What do elastic fibres in the artery walls cause and why is this useful
Muscle and elastic fibres in the artery walls cause the arteries to contract again, the stretching and contracting of arteries makes the blood flow more smoothly
Why do veins have thin walls
They carry blood under low pressure
What do valves do in the veins
Prevent blood flowing the wrong way
How does blood move along veins
As You move, muscles in your skeleton help to push blood along the veins
What does an arteries thick wall consist of
Thick layer of elastic and muscle fibres
What does consist of
Plasma
White blood cells
Platelets
Erythrocytes (red blood cells)