34b Respiration system Flashcards
how does gas exchange occur between the alveolie and blood and between blood and tissues?
though diffusion!
gas diffuses from high areas of concentration (ie the external enviornment) to low areas of concetnation (ie inside the lungs)
this is due to the partial pressure of oxygen and carbon dioxide!!
how does partial pressure of O2 and CO2 affect respriation?
gases moving from high presure to low pressure.
partial pressure of O2 faciliate movmenet of O2 along concetnration gradeients from air –> alveoli –> blood –> tissues
CO2 moves along contration gradeints in the opposite direction
tissues –> blood –> alveoli –> air
what are the two ways oxygen is transported?
its dissolved in the plasma (2% of it)
combined with haemoglobin molecules
whats the molar ratio for haemoglobin to O2
1 haemoglobin can carry 4 molecules of O2
what is a full saturate, partially saturated and desaturated haemoglobin?
fully saturated: carries all 4 O2 molecules
partially saturtated: carries 1-3
desaturated: carries no O2
what does the amount of oxygen that binds with haemoglobin dependant on?
the partial pressure of oxygen in the body
when the partial pressure (PO2) is high: Hb and O2 bind easy (lungs)
PO2 low: dont bind easily (tissues)
what are three ways CO2 transported in the body?
7% dissolved in plasma
23% carried on haemoglobin
70% hydrogen in the CO2 combine with H2O
how does the CO2 end up back in the alveoli to be expired (hint - bonding and dissociation)
CO2 + H2O = H2CO3 (carbonic acid)
H2CO3 disociates –> HCO3- and H+ (bicarbonate and hydrogen)
H+ is carried by haemoglobin to the lungs
process reverses and the CO2 diffuses into alveolie to be expired
how is ventialtion controlled in mammals?
chemoreceptors in vessels and brain are sensitive to changes in concentration of CO2, O2 and H
what is the respiratory control centre? what does it control?
the medulla oblongata which controls the rhythm, depth of breathing and rate of breathing.
what is the strongest stimulator of respriation and why?
CO2, its picked up by chemoreceptrs because its poisonous in small amounts, therefore must be removed
what two things does the the hb oxygen dissociation curve show and what is it determined by?
its shows the oxygen saturation and partial pressure of oxygen in the blood
is determined by the haemoglobin affinity to oxygen which is how readily hemoglobin acquires and releases oxygen molecules into the fluid that surrounds it.
what is significant about the hb-oxygen dissociaition curves shape?
a shift to the right (less curve) shows haemoglobin having less affinity for the oxygen.
This makes it more difficult for hemoglobin to bind to oxygen (requiring a higher partial pressure of oxygen to achieve the same oxygen saturation)
but it makes it easier for the hemoglobin to release oxygen bound to it.
what four things determine the shape of the curve and if it move to the right?
temperature
acidity
pH
CO
