Blood Pressure Regulation Flashcards
Cardiac Output Formula
CO=HRxSV
Regular Cardiac Output
5000mL
72bpmx70mL
Stroke Volume Formula
SV=EDV-ESV
70mL=120mL-50mL
Frank Sterling Law
heart has intrinsic ability to change SV in response to input (venous return)
the heart pumps what it recieves
Preload
filling of the ventricle
increases SV
direct result of venous return
Contractility
heart contracts more or less forcefully
increases SV
Afterload
pressure the heart must overcome to eject blood
decreases SV
blood pressure
Ejection Fraction
SV/EDV
normally 60%-70%
Positive Inotropes
increase contractility, increase Ca++ flow, increases cAMP
examples are Epinephrine, Caffiene, and digitalis
Chronotropes
increase cardiac rate
Sympathetic Chronotropes
positive inotropes, increases cardiac rate,
Epinephrine, Norepinephrine
Parasympathetic Chromotropes
negative inotropes, decreases cardiac rate
Vagus Nerve via ACh
Atropine blocks ACh, stimulating cardiac rate
Max Heart Rate Formula
- Old Formula: 220-age in years
- New Formula: 208-(0.7xage in years)
CO in Tachycardia
in a heart rate over 170bpm CO is decreased die to insufficient filling time
Digitalis
enhances Ca++ entry, increases contractility
antidepressant
Nitroglycerin
cardiac vasodilator, increases preload
Ca++ channel blockers
smooth muscle antagonist, dilates smooth muscle, lower BP
decreases afterload, negative inotrope
Fick Principle
used to estimate Cardiac Output in living subjects, application of law of conservation of mass
can be estimated knowing O2 consumption, with arterial pulmonary and venous valves for O2
Fick Principle
C.O. (Q) formula
(O2 consumption(mL/min))/(O2 arterial - O2 venous)
Fick Principle Thermodilution
cold saline is used instead of dye and thermal identification is used
Fick Principle Thermodilution
C.O. formula
(mg of dye injectedx60 sec)/(avg dye conc.(mg/L)xduration of curve in seconds)
atherosclerosis
hardening of arteies due to gradual plaque buildup
treated by beta blockers, calcium channel blockers, and anti-clotting medications
Angina Pectoris
squeezing, heaviness, tightness, or pain in the chest
caused by reduced blood flow to the heart muscle (ischemia)
Coronary Bypass
surgical procedure to treat coronary artery disease
reroutes blood flow from clogged coronary arteries to arteries and veins harvested from elsewhere, utilizes a bypass machine
Angioplasty
minimally invasive procedure meant to widen narrowed or obstructed arteries and veins
uses guide wire, catheter, and a balloon
The Sounds of Korotkoff
the sounds heard during the measurement of blood pressure
Pulse Pressure Formula
Systolic-Diastolic=Pulse Pressure
120mmHg-80mmHg=40mmHg
Mean Arterial Pressure
Effectivness of the heart as a pump, resistance to blood flow, distribution of blood between arterial and venous blood vessels
Mean Arterial Pressure Formulas
MAP=(1/3)Pulse Pressure + Diastolic Pressure
MAP=(1/3)(2Diastolic Pressure + Systolic Pressure)
MAP=COxTPR(total peripheral resistance)
Formulas for Flow
DeltaP/R
MAP/Resistance
Resistance to flow = 1/(radius)^4 or MAPx(radius^4)
Arterioles
Resistance vessels in system
pressure flow regulators
small in diameter
Venuoles and Veins
capacitance vessels
volume storage
54% of blood volume is in venous system
Capillaries
exchange vessels (O2, CO2, hormones)
largest area
5 liters or blood but 8-10 liters of capillary space
shunting example
increased blood flow to the digestive system after eating, reducing blood to other systems
Which organ requires the most blood?
the kidney requires the most blood per gram
Continuous Capillary
body capillaries with confluent lining
Fenestrated Capillaries
capillary endothelium has windows or pores called fenestra
in kidneys and intestines
Sinusoidal Capillaries
wide clefts between endothellial cells
in liver, bone marrow, and lymphatic system
Law of Laplace Formula
Pressure = Wall Tension / radius
T/r
Batista Procedure (Brazil)
removes part of the ventricular wall of an enlarged heart, reducing the radius, then less tension is required to mantain blood pressure