exchange and transport in animals Flashcards
why do multicellular organisms need exchange surfaces
multicellular organisms have a smaller surface area to volume ratio - this makes it harder to the exchange enough substances to supply their entire volume using their outside surface area
they need an exchange surface therefore for efficient diffusion as well as a mass transport system
surface area (formula)
2((l x w) + (w x h) + (h x l))
volume (formula)
l x w x h
surface area : volume ratio
divide both sides of the ratio by the volume to simplify
what happens in the alveoli
gas exchange in mammals
blood arrives at the alveoli from the rest of the body with a high concentration of CO2 and a low concentration of O2
this maximises the concentration gradient for the diffusion of both gases
O2 diffuses out of the air and into the blood
CO2 diffuses out of the blood and into the air to be breathed out
what are 3 adaptations of the alveoli
good blood supply to maintain concentration gradient
one cell thick walls minimises diffusion distance
large surface area
diffusion
the net movement of particles from an area of high concentration to an area of low concentration
what 3 factors affect rate of diffusion
diffusion distance
concentration gradient
surface area
how does diffusion distance affect rate of diffusion
the shorter the distance that substances have to travel, the greater the rate of diffusion
how does concentration gradient affect rate of diffusion
the greater the concentration gradient, the higher the rate of diffusion
how does surface area affect the rate of diffusion
the larger the surface area for particles to move across, the greater the rate of diffusion
Fick’s law
describes the relationship between the rate of diffusion and the factors affecting it
Fick’s law formula
rate ‘∝’ surface area x concentration gradient / diffusion distance
respiration
the process of transferring/releasing energy from the breakdown of organic compounds, generally glucose
what kind of reaction is respiration
exothermic , transferring energy to the environment
what is energy from respiration used for
metabolic processes such as protein synthesis
contracting muscles
maintaining body temperature (thermoregulation)
aerobic respiration
respiration using oxygen
symbol equation aerobic respiration
C6H12O6 + 6O2 —> 6CO2 + 6H2O
anaerobic respiration
respiration without oxygen
word equation anaerobic respiration animals
glucose -> lactic acid
word equation anaerobic respiration (plants/yeast)
glucose -> ethanol + carbon dioxide
respirometer
a piece of equipment that allows you to measure the effect of temperature on the rate of respiration
method to investigate the uptake of oxygen in a given time to work out the rate of respiration
1) add soda lime granules to both test tubes to absorb CO2 produced by the respiring insects (or cotton wool soaked in potassium hydroxide solution)
2) insects are placed on the cotton wool in one tube and the same mass of glass beads on cotton wool on cotton wool in the other tube
3) set up respirometer
4) syringe is used to set the fluid in the MANOMETER to a known level
5) leave apparatus for a set amount of time with the water bath at 15°C
6) the distance moved by the liquid in the given time is measured and can be used to calculate the volume of oxygen taken in by the insects per minute
7) repeat at different temperatures
why does the manometer move
in the time that the apparatus is left, there will be a decrease in the volume of air in the test tube containing the eggs as they will have used up oxygen as they respire
this decreases the pressure in the tube, causing the manometer fluid to move towards the insect test tube
what are the 4 parts of the blood
erythrocytes
white blood cells - phagocytes and lymphocytes
platelets
plasma
erythrocytes
red blood cells carry oxygen from the lungs to all other cells in the body
adaptations of erythrocytes
biconcave disc shape - increases surface area for absorbing oxygen
no nucleus - increases room for carrying more oxygen
contain haemoglobin - binds to oxygen to form oxyhaemoglobin which then splits up at the cells
phagocytes
white blood cells that change shape to engulf unwanted microorganisms - PHAGOCYTOSIS
lymphocytes
white blood cells that produce antibodies against microorganisms
some produce antitoxins to neutralise toxins made my microorganisms
platelets
small fragments of cell
help the blood to clot at a wound, preventing all the blood from pouring out and microorganisms from entering
what happens if you have a shortage of platelets
can lead to excessive bleeding and bruising
plasma
a pale straw-coloured liquid that carries everything in the blood
what are 9 things carried by the plasma
erythrocytes white blood cells platelets nutrients (soluble products of digestion such as glucose and amino acids) CO2 urea hormones proteins antibodies/antitoxins
3 types of blood vessel
arteries
veins
capillaries
arteries
carry blood away from the heart
arteries branch into capillaries
capillaries (role)
involved in the exchange of materials at the tissues
supply food and oxygen and transport waste products away
veins
carry blood back to the heart
capillaries join back up to form veins
structure of an artery (4 points)
- strong, elastic artery walls to cope with blood being pumped out of the heart at a high pressure
- thick walls compared to the lumen (small lumen)
- thick layers of muscle make them strong
- elastic fibres allow the artery walls to stretch and spring back
structure of capillaries (3 points)
- very narrow so can squeeze in gaps between cells allowing them to carry blood close to every cell in the body
- permeable walls for diffusion that are one cell thick
- very small lumen
structure of veins (4 points)
- less thick walls as blood is travelling at a lower pressure
- larger lumen than arteries to help blood flow despite lower blood pressure
- thin layer of elastic fibres and smooth muscles
- valves to prevent backflow
how does blood flow through the heart (blood vessels and chambers)
vena cava -> right atrium -> right ventricle -> pulmonary artery -> TO THE LUNGS -> pulmonary vein -> left atrium -> left ventricle -> aorta -> TO THE BODY
how does the wall of the left and right ventricle differ and why
the left ventricle has a much ticker wall than the right ventricle as it has to pump blood around the body at a much higher pressure so needs more muscle
cardiac output formula
cardiac output (cm^3min^-1) = heart rate x stroke volume (cm^3)
