L16 Cariac structure: Function and assessment Flashcards
what is the relationship between maximal cardiac output and VO2 max
For each L of O2 consumed you need about 6L of cardiac output
What are the 6 functions of the cardiac system?
Delivery - of O2 and nutrients Removal - of CO2 and metabolic wastes Transports - hormones Maintenance - of temp and pH Prevention - of infection
Describe the flow pathway of oxygenated blood and deoxygenated blood
Deoxygenated blood –> through the vena cava into the right atrium, and through the tricuspid valve into the right ventricle. then through the pulmonary semi lunar valve, out through the right pulmonary artery
Oxygenated blood –> for the lungs back into the heart via the pulmonary veins into the left atrium. Through the left bicuspid AV vale into the left atrium. Pushed through aortic semi lunar vale through aorta
What is the role of the sino-atrial node
it is as pace maker that generates is own action potential. A wave of depolarization travels tough the AVN, bundle of his, through the purkinje fibres so the heart repolarizes and contracts form the bottom up.
This is known as the intrinsic innervation of the heart
Describe each section of an ECG
P wave = atria begins depolarizing
Q –> R = ventrical depolarisation and moving up towards atrium
R –> S = ventrical depolarisation done
T-wave = ventrical repolarising
What is the extrinsic innervation of the heart?
Parasympathetic nervous system used acetylcholine as a neurotransmitter
Sympathetic nervous system used nor-adrenaline as a neurotransmitter
What does your cardiac cycle consist of and what do these two mean?
systole - contraction of heart
diastole - relaxation of heart
What is the end systolic volume?
Amount of blood in the ventricle after contraction
What is end diastolic volume?
Amount of blood collected in a ventricle during diastole
How do you calculate stroke volume?
end diastolic volume - end systolic volume
what are the 3 methods in which you can measure cardiac output?
Direct fick method
Indicator Dilution
Thermodilution
What is the principle of the direct Fick method
VO2 = CO x arterio-venous O2 difference
- GOld standard method
Very invasive and requires medical people
What is the principle of indicator dilution
Add know volume of dye into an unknown volume and measure it concentration
V = mass of known / conc of unknown after dilution
What is the principle of thermodilution
same process as indicator dye but you inject an ice cold solution into the blood and then measure the temperature as the indicator
Describe what happens to cardiac output during exercise
Increases rapidly during transition from rest to exercise
At maximum exercise CO increases by 4 times in untrained people and 8 times in elite endurance athletes - due to a larger SV
