Regulation of Blood Pressure Flashcards
Define Preload
End diastolic volume
Increased preload, increases contractility
Decreased preload, decreases contractility
Describe relationship between preload and contractility
Increased preload, increased contractility
Decreased preload, decreased contractility
What drugs/drug classes decrease preload? (4)
ACE
ARB
CCB
Nitro
What drugs/drug classes decrease preload? (4)
Fluids
Define Afterload
Pressure that must be overcome by the left ventricle or pulmonary artery pressures that must be overcome by the right ventricle
What ‘symptoms’ can develop with a decrease in perload? (2)
Reflex Tachycardia
Angina
What drugs/drug classes decrease afterload? (4)
ACE
ARB
CCB
Nitro
What drugs/drug classes increase afterload? (9)
Dobutamine Dopamine Epi Ketamine Norepi ADHD eds TCAs Vasopressin Effexor (venlafaxine
Define baroreceptor reflex.
How does it work?
Homeostatic mechanism that helps to maintain nearly constant levels.
Baroreceptors stretch and respond to pressure changes in the arterial wall in vessel they are found in
Where are baroreceptors located? (2)
Carotid sinus
Aortic Arch
What condition can impairment of the baroreceptor reflex cause? (2)
Hypertension
Heart Failure
Baroreceptors in which location respond to INCREASE in arterial pressures?
Aortic arch
Baroreceptors in which location respond a DECREASE in arterial pressures?
Carotid Sinus
Which part of the baroreceptor reflex (carotid sinus or aortic arch) do most anti-hpertensives affect?
Carotid Sinus
What is the body’s response to activation of the baroreceptor reflex in carotid sinus?
Increased HR
Increased Contractility
Vasoconstriction of arterioles and veins (activation of sympathetic NS)
Name all 4 Nodal Cells
SA
AV
Purkingi Fibers
Bundle of His
Define Chronotrophy
Changes in heart rate via an increase or decrease in firing of the SA node
Define Dromotrophy
Speed of Contraction
The speed of movement from the atrium through the AV node (CCB effect) SLOWS pulse and prolongs the PR interval
Define Inotrophy
Force of Contraction
Lusitrophy
Relaxation of hearth (diastole)
How fast Ca++ is removed from the cell (no heart contraction)
What Drugs/drug classes decrease chronotrophy? (4)
BB
Verapamil
Diltiazem
Methyldopa
What drugs/drug classes increase chronotrophy? (4)
Epi
Nor-epi
CCB
A1 Blockers (doxaxosin, Prazosin, Terazosin
What phase of the action potential represents dromotrophy?
Phase 0
What drugs/class of drugs affect dromotrophy?
Antiarrthymics (amioderone, sotalol), phase 4 CCB Class (IV (Diltiazem, verapamil), phase 0
The influx of what ion into the cell strengthens inotrophy?
Ca++
Explain what happens in an Action Potential
Phase 0, SA/AV Node
Phase 0, Ventricular Myocyte
Phase 3 of Both
Phase 0 in SA/AV node: influx of ca causing the inside of the cell to become and more (+)
Phase 0 in ventricular myocyte: influx of Na making cell less more (+)
Phase 3 of both: K+ out of the cell making the inside of the cell more (-)
Explain what happens in an Action Potential in SA/AV Node
Phase 4
Phase 0
Phase 3
Phase 4: NA+ moves inside of the cell causing it to be more (+) (THRESHOLD) THEN FIRES resulting in
Phase 0: influx of Ca++ causing the inside of the cell to be rapidly (+) then has to restart by becoming more (-)
Phase 3: K+ moves outside of the cell causing the inside of the cell to become more (-)
Explain what happens in an Action Potential in the Ventricular Myocyte
Phase 0
Phase 1
Phase 2
Phase 0: rapid influx of Na+ into cell causing it to be more (+)
Phase 1: initial repolarization; K+ moves out of the cell (via Na/K pump) causing inside of cell more (-)
Phase 2: Ca++ is moving in to cause contraction (systole) QT interval
Phase 3: repolarization; K+ moves out (diastole)
Phase 4: Inward/outward K+
Absolute Refractory Period
Period where ventricular myocyte cannot receive another action potential
Explain the role of Angiotensin II on Blood Pressure
Increases Altosterone release (increases Na+/H20 reabsorption and K+ excretion DRT
This increases thirst and H20 consumption
Angiotnesin II is a strong vasoconstrictor, participates in vascular remodeling
What phases of the ventricular myocyte action potential represent systole?
0
1
2
What phases of the ventricular myocyte action potential represent diastole?
3
4
If age 40-70 years with baseline BP of 75/115-115/185 and SBP raises 20mmHG and/or DBP increases by 10mmHG, what happens to the risk of CVD?
It doubles with each increase of 20 or 10, respectively.
What are the hemodynamic and pathophysiologic factors that contribute to blood pressure? (5)
Autonomic NS Heart Blood Vessel Anatomy Distribution and Movement of Blood Hormonal Influences and Plasma Volume
Define systolic Blood Pressure
HIGHEST arterial pressure during the cardiac cycle
Pressure generated during systole/ventricular contraction where blood being ejected out of arterial system
Define Diastolic Blood Pressure
LOWEST arterial pressure during the cardiac cycle.
Pressure generated during diastole/relaxation phase
‘Resting Pressure”
Define Mean Arterial Pressure (MAP)
‘Average Pressure’ in vascular system with respect to time
What is the clinical application of understanding MAP?
Vasomotor center in brain usually maintains a MAP of 100mmHG
Goal in sepsis, spinal cord injury less
Define Pulse Pressure
Difference between SBP & DBP
Formula for Cardiac Output?
SVxHR
Define Stroke Volume
Volume of blood ejected with each ventricular beat
Influences pulse pressure
Influenced by: preload, afterload & inotrophy
Define Ejection Fraction
Fraction of end diastolic volume (EDV) ejected out of heart with a ventricular bat and related to contractility
Formula for ejection fraction?
EF=SV/EDV
Normal percentage for Ejection Fraction?
60%
Formula for MAP?
CO x SVR
What happens to the aorta during systole and diastole?
expands during systole, recoils in diastole
What part of the Nodal Action Potential is a primary influence on chronotrophy?
Primarily influenced by rate of rice in Phase 4 (pacemaker cells & inward Ca++ current
What drug classes decrease chronotropy? (4)
a2 agonists
Beta Blockers
Digoxin
Non-DHP CCB
What a2 Agonists decrease chronotrophy? (3)
Clonidine
Guanfacine
Methyldopa
What Beta Blockers decrease chronotrophy (3)
atenolol
esmolol
metoprolol
What non-DHP CCBs decrease chronotropy? @)
Diltiazem
Verapamil
Activation of what receptor increases Chronotropy?
Beta 2
What specific drugs increase chronotropy directly? (4)
Dobutamine
Dopamine (high dose)
Epi
NorEpi
What classes of drugs increase chronotroy by affecting baroreceptor reflex? (7)
(decrease TPR/preload)
a1 Blockers DHP CCB Diuretics Fenoldopam Hydralazine Nitroprusside Phentolamine
What classes of drugs decrease dromotropy? (3)
Beta Blockers
Class 1 Antiarrthymics
Non-DHP CCB
What Beta Blockers decrease dromotropy? (3)
Atenolol
Esmolol
Metoprolol
What Class I Antiarrthymics decrease dromotropy? (4)
Procanamide
Lidocaine
Flecainide
Propafenone
What non-DHP CCB decrease dromotropy?(1)
Diltiazem
What drugs increase dromotropy?
NONE
What drug lasses decrease inotropy?(4)
a2 Agonists
beta blockers
Non-DHP ccB
Class III Anti-arrhythmics
What a2 agonists are used to decrease inotropy? (3)
Clonidine
Guanfacine
Methyldopa
What Beta Blockers are used to decrease inotrophy? (3)
Atenolol
Esmolol
Metoprolol
What Non-DHP CCB are used to decrease inotropy? (2)
Diltiazem
Verapamil
What Class III Antiarrhymics are used to decrease inotropy? (2)
Amiodarone
Sotolol
What classes of drugs increase Lusitropy? (3)
Beta agonists
Catecholamines
Dobutamine
What classes of drugs decrease lusitropy? (4)
beta blockers
Non-DHP CCB
+/- Digoxin
What factors influence increase of MAP? (4)
Increase heart rate
Increase contractility and SV
Increase vasoconstriction of arterioles (Increases TPR)
Increase Vasoconstriction of veins
