BP regulation Flashcards
What is the equation for the mean arterial pressure?
CO x TPR
What is the definition of BP?
Force exerted by the blood against any unit area of the vessel wall
Pressure is directly related to the product of what two variables?
Flow and resistance
True or false: CO is usually kept constant
True
What is the variable that is usually regulated to control BP?
Resistance
What is the cause of the dicrotic notch (incisura) in the arterial pressure waveform?
Due to closure of the aortic valve
“separation of the heart from the peripheral circulation”
What is the diastolic run off?
The drop in BP d/t blood flowing downstream after the aortic valve has closed
Increasing peripheral resistance (vasoconstriction), will change the slope of the diastolic run off curve how?
Decrease the slope d/t lowered flow
Decreasing peripheral resistance (vasodilation), what will happen to the slope of the diastolic run off curve?
Increases the slope (increases flow)
What is the equation for the estimated MAP?
1/3(SBP-DBP) + DBP
Why is the DBP weighted more in the equation for the estimated?
Stays longer in diastole
What is the equation for the pulse pressure?
SBP - DBP
How do you measure BP?
Cuff, listening for Korotkoff sounds
What are the limitations of measuring BP with a cuff?
Less accurate
Appropriate cuff size
The pulse pressure generates what? (What enables feeling the pulse in the radial artery prior to blood actually arriving)
A wave that travels faster than the blood
What are the two conditions that can lower the stroke volume output?
Persistent Ductus Arteriosus
Aortic regurg
What are the two factors that can change the compliance of vessels?
Arteriosclerosis
Aortic stenosis
The pressure wave is faster or slower with aortic distensibility?
Slower speed the more distensible
What are the four factors that affect the wave propagation of the pressure pulse wave?
Velocity
Stroke volume
Aortic compliance
Distance to reflection pts
What happens to the amplitude of the pressure pulse wave as you move downstream from the heart?
Increases since it is close to the point of reflection
What happens to the reflected pressure pulse wave if the aortic compliance is reduced?
Increases speed, and thus a higher reflected wave
What happens to the pressure pulse wave as we age?
Amplification d/t increased summation of the forward and reflected waves
Why does the amplitude of the pressure pulse wave increase in decreased aortic compliance?
increased summation of the forward and reflected waves
What happens to the incisura as you go distally?
Moves farther down the curve (felt later)
What happens to the wave oscillations as the pressure pulse wave hits the arterioles? What is the consequence of this on the capillaries?
Decreases to protect the delicate capillaries
Where is the resistance change the greatest in the blood circulation?
Arterioles
What happens to capillary pressure if the arteriole is constricted (increased resistance)? Why do you want to do this in skeletal muscle?
Decreases, to allow more time for the tissues to extract oxygen and nutrients
What happens to capillary pressure if the arteriole is dilated (lowered resistance)?
Increases
What are the acute changes in tone that can control blood flow control in tissues?
Vasoconstriction/dilation
What are the long term changes that can control the blood flow?
Change in size/number of capillaries in a tissue
Increasing metabolism in tissue (blanks) blood flow to those tissues
Increases
Decreasing oxygen saturation changes blood flow how?
Increases it
What is the myogenic theory of autoregulation of blood flow?
Stretching vessels will elicit contraction
What is the chemical that dilates arterioles, and is released from the endothelial cells of vessels?
NO (=EDRF)
What is the MOA of NTG?
“Donates” NO
What is the MOA of NO, bradykinin, and histamine?
Inhibit MLCK (myosin long chain kinase) and activates MLCP myosin long chain phosphatase)
What is the MOA of Endothelin, Norepi, angiotensin II, and vasopressin?
Inhibits MLCP (myosin long chain phosphatase)
Acute regulation of BP is mediated through change in what variable? Why part of the nervous system is responsible for this effect?
Resistance (acting on actin and myosin)
ANS
Long term changes in BP is mediated through what? What is the organ responsible for this?
Changes in salt and water reabsorption (changes volume)
Kidney effects this change
What is the SNS receptors on blood vessels? What is the effect they produce when stimulated?
Alpha 1
Vasoconstriction (thus increase in resistance)
What is the SNS receptors on the heart? What is the effect that these produce?
Beta 1
Increase in contractility, HR
What are the SNS receptors on the kidney? Effects (2)?
Beta 2
Decreased GFR
Releases renin
What is the effect of angiotensin II, that is produced from Renin release by activation of the SNS?
Vasoconstriction
What is the effect of SNS stimulation of the adrenal glands?
(Nor)epi release
What is the effect of the PNS on the heat?
Decreased HR
M2 receptors!!
How do you pharmacologically decrease BP?
Decrease SNS (alpha 1) of the vessels