Haemodynamics Flashcards
What is serum?
Plasma without the clotting factors
How common are blood viscosity changes? Example?
Uncommon. Occurs in Leukemia
Why would you measure CRP?
C reactive protein is used to measure plasma viscosity as a marker of inflammation.
What is haemodynamics?
Factors that govern the movement of blood from one area of the CVS to to another.
Blood moves along?
A pressure gradient (high—>low)
Explain the features of laminar and turbulent flow
Laminar - smooth, maintains energy (Vmax - maximum velocity in the middle of the lumen as less resistance to the blood vessel walls)
Turbulent- multi-directional, loss of energy (found stenosed arteries/ areas of branching)
What is flow measured in?
Volume per unit time (e.g. ml/ min or l/hour)
What is pressure measured in?
Force per unit area (mmHG used when measuring BP)
Why is resistance in the aorta low?
Large diameter, relatively short
What vessels contribute the greatest component of total peripheral resistance?
Smallest arteries/ arterioles- as biggest jump in pressure across vessel class.
Arterioles are the seat of total peripheral resistance!
Why is the left ventricle thicker and more muscular than the right ventricle?
The right ventricle pumps deoxygenated blood to the lungs and the left ventricle pumps blood to the rest of the body - needs higher pressure to do so - therefore it is thicker etc.
Difference between flow and velocity?
Flow -volumes per unit time
Velocity - speed at which fluid travels. Distance per unit time.
They are related - if want to increase flow can increase velocity (if the vessel remains the same diameter).
Why is lower velocity useful in capillaries?
Capillaries have the greatest cross sectional area and so the lowest velocity -useful for the diffusion of substances into/out of the blood.
How do you calculate Pulse pressure?
Peak systolic pressure - end diastolic pressure (SBP-DBP)
How do you calculate MAP (mean arterial pressure?)
MAP= DBP + (SBP - DBP)/3) or DBP + (PP/3)
Below what mean arterial pressure does organ perfusion become impaired?
70mmHG
Define pulse pressure
The volume of blood ejected and the compliance of the the arterial system to govern pulse pressure.
What is the feeling that we call a pulse?
Shock wave appearing just before the blood itself
What impact will exercise have on pulse?
Increased stroke volume, with relative compliance of vessels= increase PP
Name two environmental factors that decrease peripheral resistance
A hot bath and pregnancy
In fit athletes what would systole/ diastole look like?
Diastolic decreases, systolic increases
what is mean arterial pressure?
The average arterial pressure in the systemic system at any one time. MA= CO (cardiac output) x TPR (total peripheral resistance)
What vessel factors determine resistance?
Only true one is diameter as blood vessel length and viscosity are pretty standard.
Give one example of what pathological turbulence caused by and how we can detect it?
Caused by atheroma (degeneration of walls of arteries, build up of fat and scar tissue - leads to restriction of circulation. Detect: thrill is felt, bruit is heard.
