Arterial and Venous systems and Lymphatics Flashcards
Which of the following factors affects pulse pressure?
- Vascular elastance
- arterial compliance
- stroke volume
- all of the above
- the first and third only
vascular elastance AND stroke volume
Which of the following is the most important means for the exchange of substances between the blood and the interstitial fluid?
- blood hydrostatic pressure
- osmosis
- capillary oncotic pressure
- diffusion
- interstitial fluid hydrostatic pressure
diffusion
Vascular distensibility equation
Vascular distensibility = increase in volume/ (increase in pressure * original volume)
What happens when the distensibility is decreased in veins when it comes to blood storage?
the amount of blood stored there decreases
Vascular compliance (capacitance) equation:
Vascular compliance (capacitance) = (increase in volume)/(increase in pressure)
What characteristic of blood vessels does capacitance describe?
distensibility
What is capacitance inversely proportional to?
elastance
How does a greater amount of elastic tissue in blood vessels affect compliance? why?
the blood vessels have a lower compliance because due to the higher amount of elastic tissue the blood vessels have a higher elastance
Pulse pressure equation
Pulse pressure = stroke volume/arterial compliance
What occurs at the sharp incisura?
the closing of the aortic valve
What is the progressive reduction of the pulsations in the periphery known as?
damping of the pressure pulses
Why does the mean arterial pressure lie closer to diastolic than to systolic?
because about 60% of the cardiac cycle is spent in diastole and 40% in systole
Mean arterial pressure equation
Mean arterial pressure = diastolic pressure + 1/3 pulse pressure
What is central venous pressure?
pressure in the right atrium
What is the most important factor regulating vasomotion?
concentration of oxygen in the tissues
Net filtration Pressure equation
Net filtration pressure (NFP) = Capillary pressure (outward)(Pc) - interstitial fluid pressure (inward) (Pif) - plasma colloid osmotic (oncotic) pressure (inward) ( np) + interstitial colloid osmotic (oncotic) pressure (outward)(nif)
NFP = Pc - Pif - np + nif
The least amount of damping of the pressure pulses would occur in which of the following components of the circulatory system?
- arterioles
- venules
- femoral artery
- capillaries
femoral artery
What are the comparison of distensibility between arteries and veins?
- veins are about 8 times more distensible than arteries
- Pulmonary vein distensibilities are about the same as for systemic veins
- pulmonary artery distensibilities are about 6 times that of systemic arteries
What is capacitance directly proportional to and inversely proportional to?
it is directly proportional to volume and inversely proportional to pressure
Where is capacitance higher? veins or arteries
veins
How does age affect capacitance and what does this cause?
it decrease with age and can be a cause of hypertension
What are the factors that increase venous return and increase right atrial pressure?
- increased blood volume
- increased peripheral venous pressures due to increased large vessel tone
- dilation of arterioles
What is the precapillary sphincter’s function?
it is smooth muscle fiber that encircles capillary at point where it orginates from a metarteriole and controls how much blood will enter the system
What are starling forces and what do they determine?
they are the forces inside and outside the capillary that determine direction of diffusion into or out of a capillary
