Chapter 8 The Heart Flashcards
Look at graphs of ventricular pressure
Look at a labelled diagram of the heart
What causes the sounds of the heart?
Lub- closing of atrioventricular valves when ventricles contract
Dub- closing of semilunar valves as ventricles relax
What molecule transports oxygen in the body?
Oxygen binds loosely to haemoglobin in RBCs, loaded
Each haemoglobin molecule can bind 4 oxygen molecules, forming oxyhaemoglobin
Hb+4O2 –> Hb(O2)4
How does the ease of loading and unloading oxygen upon haemoglobin change with saturation?
When one oxygen binds to haemoglobin, it causes a change in the tertiary structure of haemoglobin which makes it easier to load more oxygen
= Positive cooperativity
When 3 oxygen molecules loaded, tertiary structure changes to make it harder to load the fourth molecule
Opposite when unloading easier to unload each time
What does an oxygen dissociation curve look like and represent?
X axis= Partial pressure of oxygen
Y Axis= Percentage saturation of haemoglobin with oxygen (how much o2 bound)
S shaped, positive cooperativity
Shows oxygen affinity
What is the bohr effect and why does it occur? What happens to the oxygen disassociation curve?
Increasing concentration of carbon dioxide will reduce the oxygen affinity of haemoglobin
Shifts right, lower affinity
H+ ions produced bind to haemoglobin, alters tertiary structure to make it harder to load oxygen
Why is the Bohr effect useful?
Active tissues produce lots of CO2, and require lots of O2 for respiration, easier to unload
At lung, low CO2 so easier to loads/binds
Hb more easily binds to CO2 than oxygen, carbaminohaemoglobin
Compare the oxygen affinity of haemoglobin of a foetus and mother. Why does this occur?
Fetal haemoglobin has a higher affinity, to the left, than the mother, to enable oxygen transfer, as the foetus is completely dependent on the mothers circulatory system for oxygen
Low partial pressures of oxygen at the placenta
Oxygen disassociates from the maternal haemoglobin, diffuses from maternal to foetal blood, and then uploaded to foetal haemoglobin
Why would the haemoglobin of a high altitude organism not be helpful at normal height?
High altitude- low p(O2). Haemoglobin adapted to maximise uptake from environment, so at low p(O2) saturated, so graph shifts to the left.
Very high oxygen affinity, unable to unload so cannot be delivered to cells
Even when needed by cells, still too saturated as partial pressure still too high
Why would a very active organism have a different version of haemoglobin?
Haemoglobin which has a lower oxygen affinity allows an increased amount to be unloaded, for the high demands for respiration
It is still suffiently high enough to bind to enough oxygen from the environment
How is carbon dioxide transported generally?
5% dissolved in blood plasma
10-20% binds with amino groups in Hb to form carbaminohaemoglobin
The remained is transported in the cytoplasm of RBCs as HCO3- ions
What is the mechanism of CO2 transport in cytoplasm?
CO2 + H20 <—> H2CO3 <—-> HC03- + H+
Catalysed by carbonic anhydrase (first part), in RBC cytoplasm
HCO3- ions diffuse in the blood plasma, Cl- ions diffuse in to balance charge= chloride shift
At lungs, enzyme catalyses breakdown of carbonic acid, also HCO3- diffuses back in, then reforms and breaks down in CO2
Cl- diffuses out
CO2 diffuses out as a gas
Hb as a buffer, accepting H+, forming haemoglobinic acid
Why is the method for transporting CO2 efficient?
As HCO3- ions, allows CO2 to keep diffusing in as concentration gradient maintained
What is diastole? What is systole?
Diastole= Relaxation
Systole= Contraction
