movement of blood and fluid Flashcards
explain the difference in pressure in the systemic circulation compared to the pulmonary circulation
systemic (left) is a high pressure system due to the pump being much stronger to overcome the pressure and push blood to the extremities and pulmonary circulation is low pressure due to a much weaker pump.
define bulk flow
the movement of fluid (blood) by means of pressure difference
define diffusion
tendency for solutes to move along a concentration gradient from an area of high concentration of the solute to an area of low concentration of the solutes until the concentrations are equalised.
explain how perfusion pressure can be generated and how it can be affected
generated by the pumping actions of the ventricles
the difference between 2 points in a blood vessel
describe how variation of transmural hydrostatic and oncotic pressures affect the movement of fluid across the capillary wall
osmotic pressure = high oncotic pressure inside vessel draws water in, fluid moves from an area of low osmotic pressure to an area of high oncotic pressure.
transmural hydrostatic pressure = expels fluid if perforated - pressure exerted by fluid inside of vessel - outside of vessel
source of energy for bulk flow
derived from hydrostatic pressure difference
what is hydrostatic pressure
the pressure that fluid exerts on its container
what is perfusion pressure
the pressure needed for blood to move through blood vessels
what is osmotic pressure
the drive for water to move into a solution by osmosis
explain how cardiac output is generated and varied in the normal animal
stroke volume x heart rate
only altered by these 2 variables
what is preload
the filling pressure of the ventricle
what is afterload
resistance overcome to let the blood out
what is oedema
leaking fluids
how to increase preload
increase in pressure in the atria and veins
what does increasing preload also increase
end diastolic ventricular volume
why does exercise increase preload
increased action of the respiratory and skeletal muscle pumps compresses veins thereby increases venous return to the heart.
what is heterometric autoregulation
increase in stroke volume on one side of the heart leads to increase blood flow through the tissues, an increase venous return and hence preload to the other side of the heart and therefore an increased stroke volume on that side too.
what are the phases of the cardiac cycle
isovolumetric contraction
rapid ejection
reduced ejection
isovolumetric relaxation
rapid filling
reduced filling
how is arterial pressure generated
pressure of blood within a vessel
what is compliance
measure of how readily the ventricular walls stretch during diastolic filling
how does diastolic filling time impact EDVV
if too little time, it will prevent the ventricle from filling optimally and hence reduce stroke volume
what does the heart rate govern
length of systole and diastole
what is atrial systole responsible for
higher percentage of ventricular filling at higher heart rates.
what is atrial fibrillation
disease where the atria doesn’t contract properly
clinical presentation of atrial fibrillation
exercise intolerance
what will a higher afterload increase
end systolic ventricular volume
why does a higher afterload increase ESVV
heart has to work harder to maintain the same CO when afterload increases - more pressure must be generated during isovolumetric contraction to overcome arterial pressure, open the semilunar valves and allow blood to exit.
what can an increase in end systolic wall stress lead to
myocardial hypertrophy (thickening of the heart muscle)
what control vasoconstriction and vasodilation
autonomic nervous system
what is the total peripheral resistance
net resistance of the whole circulation
what is systolic pressure
during systole, ventricles eject blood into the aorta and pulmonary artery under high pressure, pressure rises to systolic pressure
what is diastolic pressure
pressure in the aorta drops as blood flows out into the circulation when entering diastole - this is the lowest point.
