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)
What does plasma do
Carries dissolved substances such as glucose, carbon dioxide and urea
Why are red blood cells and packed with haemoglobin
This substance binds with oxygen in the lungs and releases it again in tissues
Btw when a lot of oxygen is bound to haemoglobin molecules, cells bright red but dark red when less oxygen attached
How are erythrocytes adapted (red blood cells)
They have no nucleus so there’s more space for haemoglobin- cells are shaped like discs with a dimple on each side
BICONCAVE shape - large surface area to volume ratio for oxygen to diffuse in and out
What are the 2 types of white blood cell
Phagocytes and lymphocytes
Both remove foreign cells that get inside you
What do lymphocytes do
Produce proteins called antibodies that stick to foreign cells and help to destroy them
What do phagocytes
Surround forieign cells and digest them
What do platelets do
They are tiny fragments of cells that have no nuclei, they produce substances needed to clot the blood at the site of an injury - eg a cut on the skin
When does a heart attack occur
When blood stops flowing to muscles in part of the heart - damaging them and stopping the heart pump properly - if it stops completely it can often be started again by using electric shocks in a defibrillator
How many chambers does the heat have
Four
4
Tell me how the heart works
Blood from most of the body enters through the right atrium through the vena cava
At the same time blood from the lungs enters through the pulmonary vein into the left atrium , when theses top chambers are full, muscles around them contract to push blood into ventricles - walls in ventricles contract forcing blood out of the heart - as this happens muscles in the atria walls relax and these chambers re fill with blood
Tell me about atria
In the heart, there are 2 atria which contract and push blood into ventricles
What’s the aorta
Carries blood to rest of body
What’s the superior vena cava
BRings blood from the upper body
Where does the pulmonary artery go
To the lungs
Where does the pulmonary vein go
From the lungs
What’s the inferior vena cava
Brings blood from the lower body
What are tendons in the heart
Stop valves turning inside out
What is the septum in the heart
Comepeltly separates the two sides of the heart
What colour are parts of the heart with deoxygenated blood
Dark red
What colour are parts of the heart that pump oxygenated blood
Bright red
What is the contraction and relaxation of muscles during each heart beat caused by
They are controlled by impulses from the nervous system
What is heart rate
The number of times the heart beats in a minute
What’s the stroke volume
The volume of blood pushed around into the aorta in each beat
Measured in litres
What is cardiac output
The volume of blood pushed into the aorta each minute calculated using equation=
Cardiac output(litres/min) = stroke volume (litres/beat) x heart rate (beat/min)
Why do fitter people often have bigger stroke volumes and hearts can beat more slowly to achieve same cardiac output
Regular expertise increases the strength of heart muscle and ventricle size
What’s cellular respiration
A series of chemical reactions that release energy from glucose - some energy transferred out of cells by heating
What type of reaction is respiration
Exothermic
Where do most of the reactions in aerobic respiration happen
It needs oxygen, most processes occur in mitochondria of the cell
Tell me the word equation of aerobic respiration
Glucose + oxygen —> carbon dioxide + water
What does the circulatory system ensure for aerobic respiration
Cells have a good supply of oxygen and glucose and waste is carried away from cells
Why does rate of Aerobic respiration increase during exercise
Muscles neee more energy, cells take more oxygen and glucose from the blood - hear beats faster, breath faster and deeper and increase amount of oxygen diffusing into the blood in your lungs - faster breathing allows your lungs to excrete more carbon dioxide
When is anaerobic respiration used
During very strenuous exercise, oxygen is used up faster than it’s replaced
What happens in anaerobic respiration
Occurs in the cytoplasm of cells, it does not require oxygen but produces lactic acid
Glucose —-> lactic acid
Which respiration releases more energy from glucose
Anaerobic respiration release less energy from glucose, anaerobic causes muscle to tire quickly but can have bursts of energy without needing an increase in oxygen supply
When is anaerobic respiration useful
When animals need to move fast and suddenly - such as moving away from a predator
Why can heart and breathing rates remain high after exercise
Because extra oxygen is needed to replace the oxygen lost from blood and muscles
Extra oxygen is also needed to release the extra energy required to get rid of lactic acid
