Vascular Physiology Flashcards
Elderly patients typically have____ arterial wall compliance resulting in____.
Decreased, increased systolic pressure
The elastic arteries filter and smooth out the pulsatilla pressure within the aorta. This effect is termed
Windkessel effect
The definition of vascular compliance is
D = change in
D volume/ D pressure
The aorta stores blood during systole and releases it during diastole. This physical compliance is analogous to electrical
Capacitance
Systolic arterial blood pressure is inversely proportional to
Arterial compliance
Venous capacitance (compliance) is normally ____ times greater than arterial capacitance.
20
The normal static circulatory pressure at zero cardiac output is approximately
7 to 13mmHg
In a large vessel with fully developed laminar flow the velocity of the central stream is
Twice the mean velocity
The velocity of blood touching any arterial wall always equals
Zero
Blood flow will change from laminar to turbulent at a Reynolds number
Over 2000-3000
The cerebral circulation is a
High-flow, low resistance system
How is cerebral blood flow effected by changes in blood pressure?
Cerebral perfusion decreases in hypotension. (Mean BP less 75)
What happens to the metabolic rate of the brain with sleep?
Brain metabolic rate is unchanged, compared to waking
What mechanism is primarily responsible for returning venous blood to the heart while walking?
Skeletal muscle
When a Doppler probe is directed at an arterial stenosis the operator hears a high pitched rushing sound because of
Increase of velocity of blood flow at the lesion.
What is the peripheral or systemic vascular resistance formula?
SVR = (mean AO-mean RA)/ CO
Blood behaves as a ____ fluid in very small vessels.
Non-Newtonian
Poiseuille’s law is not applicable in capillaries because the apparent viscosity of blood decreases as blood flow rate and vessel diameter decrease. This is termed
Shear thinning
Which fluid has the highest viscosity?
Polycythemic blood
In the Bernoulli equation, what is the relationship between the kinetic and potential energy?
Their sum is constant.
1/2mv squared + mgh
Bernoulli law law explains why in aortic stenosis the aortic blood flow velocity is ____ and the aortic pressure is _____.
Increased, decreased
Normally the pulmonary and systemic blood flow circuits are arranged _____ to/with each other. (Unless there is a shunt)
In series
Two arteries in the kidneys in series are the peritubular and glomerular arteries. They have resistance of 80 units each. If the mean arterial BP is 100 and CVP=0, calculate flow through the kidney.
625 cc/min
Calculate the equivalent resistance of 2 blood vessels in parallel. Each is 50 resistance units(Ohms) as shown.
25 units
Calculate the equivalent total resistance of the arteries shown if the combined flow = 3L/min and the pressure drop = 80 mmHg.
26.6 Wood or HRU units
The hemodynamic effect of increasing a patient’s peripheral vascular resistance is to: (assume constant CO)
Increased BP
At peak exercise a normal individual’s mean blood pressure may not significantly elevate, even though CO may increase up to 7 times. This regulation of BP on exercise is due to _____ vascular resistance.
Decreased systemic
Who developed the law:
T=PxR/(2x wall thickness)?
T= wall tension P=pressure R=radius
La Place
Thin-walled capillaries can withstand high internal pressure without bursting because of their narrow lumen. Who’s law?
La Place’s
The law of La Place explains why small blood vessels may collapse during circulatory shock. This is because tension within the small vessel wall
Increases above what the reduced BP can overcome
Leg stockings will increase which variable of the starling fluid movement hypothesis?
Pi interstitial fluid hydrostatic pressure
What pathologic condition is likely to occur when the pulmonary capillary pressure is greater than plasma oncotic pressure?
Pulmonary edema
The key factor restraining fluid loss from a systemic capillary is
Osmotic pressure due to plasma proteins
If arterial blood flow is stopped for several minutes by pumping up a BP cuff around a limb and then releasing it, the resulting flow exceeds basil flow. This is termed
Reactive hyperemia
Dilation of arteries may occur due to increased flow through to them. This occurs after liberation of “endothelial derived relaxation factor” that is composed of
Nitric oxide
Brief exposure of an extremity to extreme cold temperatures results in _____ the vessels in that extremity.
Neural mediated vasoconstriction
Soldiers standing at attention for long periods often faint because
Venous pooling reduces preload and cardiac output
An embolus can be best described as any: (remember even air can embolize)
Foreign material that travels downstream and plugs up a vessel
Elevated blood Angiotensin II and aldosterone levels cause
Arteriolar vasoconstriction
Angiotensin II liberates aldosterone, which is a ____ causing the kidneys to____ Na.
Corticosteroid, retain
The chief regulation of blood flow within the lung away from atelectatic areas is local vasoconstriction due to ______ in that atelectatic area.
Decreased PO2 tension
Active transport of substances across endothelial walls, especially large lipoproteins, is termed
Pinocytosis
