hemodynamics Flashcards
Which vessel in the body serves as the pressure resorvoir
arteries
what vessels are the primary resistance vessels
arterioles
Which vessels serve as the blood reservoir?
systemic vein
what is the secondary blood reserve in the body
the pulmonary circulation
which vessels undersee the biggest pressure drop in blood flow
arterioles
Which vessels are responsible for maintaining MAP
arteries
what is the driving force for blood flow
the MAP
What blood pressure do you obtain auscultating
systolic and diastolic
What blood pressure do you obtain by palpating
just systolic
How do you calculate MAP at rest
diastolic BP + 1/3(SBP-DBP)
What is the pulse pressure
difference between diastolic and systolic
Where is the greatest pressure of arteries when laying supine
at the aorta
where is the greatest pressure of arteries when standing
dorsalis pedis
What vessels have the greatest cross sectional area
the capillaries
What is Fick’s principle
CO= oxygen consumption
_______________________
A- V O2 difference
Is blood flow velocity directly or indirectly related to the cross sectional area of a vessel
indirect
what is a noninvasive measure of blood flow velocity
doppler ultrasound
easy calculation for flow velocity
Flowvelocity= CO/Cross sectional area
What concept explains how the same volume passes through each segment of vasculature per minute
the blood flow velocity. allows rapid delivery and exchange
how does laminar flow sound compared to turbulent
laminar is silent
turbulent sounds like murmurs
Increased Reynolds number suggests what
increased turbulence
What can cause an abnormal increase in velocity of a vessel
sudden decrease in diameter like atherosclerosis or cardiac valve lesions
what causes increased turbulence
increased velocity
increased diameter
decreased viscosity (anemia)
If you decrease a vessles radius by half how does that affect velocity
increases 4 fold
what is the formula for vessel compliance
C= change volume over change of pressure
What will have the greater pulse pressure, a compliant arteryr or a stiff artery
stiff artery
Why does pulse pressure increase with age
lose compliance of vessels
What is the concept behind LaPlace’s law
explains how tiny walled capillaries can withstand pressure because of tiny radius
Which vessel in the body has the greatest wall tension
the aorta because greatest pressure and radius
damage to elastic fibers in a vessel can lead to what clinically
aneurysm
if the radius of a vessel surpasses the LaPlace equilibrium what could happen
increase wall tension to burst
How do we calculate CO
MAP/TPR
TPR is the resistance where
sytemic
What law is CO formula based on
ohms law I=V/R
if pressure at one end is 90mmHg and at the other 10mmHg what is the flow
80mmHg because it is the change in pressure
Does the body supply all vessels at once
no because it depends on local metabolic demands in organs
how is flow distribution regulated
resistance
Adding resistance in a series affects overall resistance how
increases it
adding resistance in parallel affects overall resistance how
decreases it
How does obesity arrange the vessels and what are its affects on TPR?
parallel. So decreases TPR which causes CO to increase to keep MAP constant
How does changin radius affect resistance and flow
increase radius decrease resistance increas flow
Blood flow is directly proportional to what
pressure gradient and the vessel radius to the 4th power
blood flow is inversely proportional to what
vessel length and blood viscosity
What are anemia and polycythemia’s affects on flow, and how?
anemia decreases viscosity so increase flow
polycythemia increases viscosity so decrease flow
If you increase radius by 2X its normal how does resistnace change? flow?
resistance is decreased 1/16 and flow increased 16 times
What are the intrinsic controls of arteriolar radius
local metabolic changes in O2 and CO2
what are the extrinsic controls of arteriolar radius
sympathetic activity(vasoconstriction)
What are the 2 major extrinsic controler types for blood pressure regulation
neural and endocrine
Describe the neural control/regulation of blood pressure
sympathetic influence on smooth m.
vasoconstriction- alpha 1 R and norepi
vasodilation- beta2 R and epi
What tissues are mainly regulated by extrinsic factors
cutaneous circulation and skel m at rest
How does endocrine have affect on vessel pressure
vasoactive endocrine and paracrine compunds are released into blood near vascular smooth m and change the radius
What are the 5 main endocrine componds that change MAP
Epi histamine Angiotensin II antidiuretic hormone (vasopressin) atrial natriuretic peptide
what is the effect of epinephrine on sm mm in vessels
vasoconstriction via alpha 1 R and vasodilation via Beta2
what is the effect of histamine on sm mm in vessels
arteriolar vasodilation, venoconstriction
What is the effect of angiontensin II on sm mm in vessels
vasoconstiction, blood loss and reduction or renal BP via renin
What is the effect of antidiuretic hormone/vasopressin on sm mm in vessels
vasoconstriction
in what clinical scenario is vasopressin released alot in body
hemorrhagic shock
what is the effect of atrial natriuretic peptide on arterial sm mm
vasodilation in myocytes
what is the most powerful natural diuretic
atrial natriuretic peptide because it dec BP
What two ligands cause sympathteic vasoconstriction via alpha 1 R
norepi and epi
Describe orthostatic hypotension
mechanism of extrinsic control to TPR is impaired
Intrinsic control: Is flow dependent or independent of blood pressure
independent
Intrinsic control: is flow dependent or indeendent of nervous reflexes
independent
What tissues are mainly regulated by intrinsic controls
cerebral, coronary, skel m in exercise and renal circulation
What is active hyperemia vs reactive
active is like when exersiing, the blood flow to tissue is proportional to metabolism
reactive is if there is an occlusion, flow following inclusion will be greater if time occluded increases
decreased pO2 and increasedpCO2 will cause what in sm arterial m
vasodilation
