mass transport in animals Flashcards
what is haemoglobin
a globular protein
what’s haemoglobin’s structure
curled up so hydrophilic side chains face outwards and the hydrophobic side chains face inwards
how does it’s structure make it effective
(side chains) makes haemoglobin soluble and good for transport in the blood
3 functions of HG
- associates w oxygen in the lungs
- transporting oxygen to the tissue
- dissociating w oxygen in the tissues
what is association
process in which HG binds to oxygen
what is dissociation
the process in which HG releases its oxygen
what is partial pressure
concentration of oxygen (kPa)
what is affinity
how easily the oxygen binds to the HG
how many molecules of oxygen can bind to one molecule of HG
4
Hb + 4O2 —> HbO8
haemoglobin + oxygen = ?
oxyhaemoglobin
what do HG and oxygen do in the lungs and why
associate - in lungs, partial pressure of oxygen is high so haemoglobin has high affinity for oxygen so oxygen associates
what is the partial pressure like in the lungs
high
what do HG and oxygen do in the respiring tissues
dissociate - partial pressure in tissues is low so HG has a low affinity for oxygen, the high concentration of CO2 causes the HG to change shape and dissociate
describe a dissociation curve and how the 4 oxygens associate with the HG
1 O2 - IN RESPIRING TISSUES, hard for the first O2 to associate with the iron ion (in haemoglobin) in the blood bc not quite the right shape
2+3 O2 - the association of 1st O2 causes a positive allosteric effect (change in shape) to allow 2+3 to associate easily
4 O2 - IN LUNGS, hard for 4th O2 to associate, this is bc there’s a low probability that the single O2 molecule will find an empty binding site to bind to (as 3/4 binding sites are occupied)
how does CO2 effect how HG functions
HG gives up its oxygen more readily at high partial pressure of CO2, this enables more oxygen to get to cells that are respiring at a high rate
when cells respire they produce CO2
why does HG have a high affinity for oxygen in the lungs?
at the gas exchange surface CO2 is constantly being removed. the pH is slightly raised due to the low conc of CO2, the higher pH changes the shape of the HG into one that enables it to load oxygen readily
how does decreased CO2 effect the dissociation curve
shifts it to the RIGHT - bohr effect
why does HG have a low affinity for oxygen in respiring tissues?
in tissues, CO2 is produced by respiring cells, CO2 is acidic so pH of blood is lowered. the lower pH changes the shape of HG to one with a lower affinity for oxygen. HG releases its oxygen into the respiring tissues
how does blood temperature affect dissociation?
increased blood temp reduces HG affinity for oxygen so more oxygen is delivered to the warmed up tissue
how does CO2 conc affect dissociation
the higher O2 conc in tissues, the less affinity HG has for oxygen, so the harder the tissue is working the more oxygen is released
what is the double circulatory system
two circuits to the circulatory system - pulmonary (lungs) and systemic (rest of the body)
when blood goes round the body it passes the heart twice
advantages of the double circulatory system
- blood pressure can be maintained at a high level
- oxygenated and deoxygenated blood doesn’t mix
what’s the closed circulatory system
blood stays in the blood vessels all of the time
advantages of the closed circulatory system
- high pressure can be maintained
- less transport fluid is needed
- complete separation of function between organs
what are coronary arteries
the heart’s own blood supply, they branch in order to supply all cardiac cells with glucose and oxygen required for respiration
how does the blood get from the heart and back via blood vessels
heart —> artery —> arteriole —> capillary —> venule —> vein —> heart
what are the different layers of a blood vessel
OUTWARDS
lumen (just the hole) —> endothelium layer —> elastic layer —> muscle layer —> tough outer layer
function of the arteries
carry blood away from the heart and to the arterioles
structure of arteries
- thick muscle layer
- thick elastic layer
- great overall thickness
- no valves
why do arteries have thick muscle layers?
so they can be constructed and dilated in order to control the volume of blood passing through them
why do arteries have thick elastic layers?
to keep blood pressure in the arteries high so that the blood can get to all around the body
why are arteries overall very thick?
stops the artery bursting under pressure
why don’t arteries have valves
blood pressure is high so blood tends not to flow backwards
function of aterioles
smaller arteries that control blood flow from the arteries to capillaries
structure of arterioles
- muscle layer thicker than arteries
- elastic layer thinner than arteries
why do arterioles have thicker muscle layers
the contraction of the muscle layer allows the lumen to construct, thus restricts the blood flow and controls its movement into the capillaries
why do arterioles have thin elastic layers
because blood pressure is lower and doesn’t need to be kept high
function of veins
transport blood slowly under low pressure from the capillaries to the heart
structure of veins
- thin muscle layer
- thin elastic layer
- small overall thickness
- valves at intervals throughout
why do veins have thin muscle layers
carry blood away from tissues so their constriction and dilation cant control the flow of blood to the tissues
why do veins have a thin elastic layer
the low pressure of blood won’t cause it to burst and pressure is to low to create a recoil action
why are veins overall quite thin
no need for a thick wall bc the pressure within the veins is too low to create any risk of bursting, also allows them to be flattened easily aiding the blood flow within them
why do veins have valves at intervals throughout?
to ensure blood doesn’t flow backwards because blood pressure is low
function of capillaries
exchange metabolic materials such as oxygen and CO2 between the blood and the body cells, the blood flow is much slower and allows time for the exchange of materials
structure of capillaries
- walls consist mostly of lining layer
- numerous and highly branched
- v narrow lumen
- spaces between the endothelium lining cells
why are capillaries numerous and highly branched
to provide a larger surface area for exchange
in capillaries why are there spaces between the lining cells
allow white blood cells to escape in order to deal with infections within tissues
why do capillary walls consist of mainly the lining layer
makes them extremely thin so the distance over which diffusion takes place is short - allows for rapid diffusion between blood and cells
why do capillaries have a narrow lumen
so their red blood cells are squeezed flat against a side of the capillary, brings them even closer to the cells they supply oxygen to - decreased diffusion pathway
