Movement of blood and fluid Flashcards
Which side of the heart is pulmonary and which is systemic?
Right = pulmonary Left = systemic
What is meant by bulk flow?
Movement of fluid by means of pressure difference - in this case hydrostatic pressure
What is hydrostatic pressure?
The pressure a fluid exerts on its container e.g. blood within a vessel
What is perfusion pressure?
The pressure difference between two points in a blood vessel - pressure needed for blood to flow
What is transmural hydrostatic pressure?
Pressure across the vessel wall
- calculated as the difference between the pressure exerted by the fluid inside the vessel and outside the vessel
How is bulk flow referred in a capillary?
Into a capillary = absorption
Out of a capillary = filtration
What does Fick’s law of diffusion state?
The rate of diffusion is equal to the conc gradient
What is osmosis dependent on?
The presence of a semipermeable membrane for the water to diffuse across, and on the osmotic pressure difference between the inside of the capillary and the ISF
The net movement of water between the capillaries and the ISF is decided by the balance between … ?
Osmotic and hydrostatic pressures across the capillary wall
A positive answer to the Starling equation means?
Water will be filtered out of the capillary
What effect would dilation of arterioles have on hydrostatic pressure in the capillaries?
Increase, leading to filtration along the whole length of the capillary
What is the effect of constricted arterioles?
- greater resistance to flow and result in less blood entering the capillary bed
- drop in hydrostatic pressure
- more absorption of fluid from the ISF
Where are some portal systems found?
- the kidney
- between the hypothalamus and pituitary
- splanchnic circulation
Define cardiac output
The volume of blood pumped by one ventricle in a minute
What is the end systolic ventricular volume?
Residue volume in the ventricles as they do not completely empty with each systolic contraction
What is the end diastolic ventricular volume?
The volume in the ventricles after diastolic filling
What is the stroke volume?
The difference between the ESVV and EDVV = the volume of blood pumped out of the ventricle each cardiac cycle
Which 3 factors influence the EDVV?
- diastolic filling time
- preload
- compliance
Which two factors influence ESVV?
- afterload
- contractility
The cardiac output is = ….. x …..
Stroke volume x heart rate
How can stroke volume be increased?
Either increase the EDVV or decrease the ESVV
What is preload?
The filling pressure of the ventricles during distole
How is preload increased?
Pressure in atria and veins must increase
- increase overall blood volume
- reducing the space the blood needs to occupy
How does increasing preload affect the stroke volume?
increased preload = increased EDVV = increased SV
What is heterometric autoregulation?
How the sides of the heart exist in series e.g. increased SV on one side causes an increased SV on the other side
What is compliance?
A measure of how readily the ventricular walls stretch during diastolic filling
The ability of the ventricle to relax adequately called?
Lusitrophy
How does the sympathetic NS act on the heart?
- increases contractility
- decreased ESVV
- shortens systole
- increases HR
What is afterload?
Resistance that needs to be overcome to force blood out - vascular resistance
How does afterload affect ESVV?
Increase in afterload, increases ESVV
What is hypertrophy?
Thickening of heart muscle
Aortic pressure (Pa) = ….. x …. ?
CO x TPR
Why does TPR reduce during exercise?
Dilation of arterioles in skeletal muscle
pulse pressure = … - … ?
systolic pressure - diastolic pressure
