CV A&P Flashcards
cardiac output
amt of blood the heart pumps out of the L ventricle each minute
CO = stroke volume x heart rate
cardiac output in HF
diminished because the L ventricle is weakened and cannot adequately pump blood out of the chamber
stroke volume
difference between end-diastolic volume (volume of blood at end of relaxation) and end-systolic volume (volume of blood remaining in ventricle after each ejection)
3 major factors that influence stroke volume
- preload (volume of blood in heart)
- afterload (force opposing ejection of blood from ventricle)
- contractility
preload
chamber volume right before contraction
*lower preload leads to lower SV and vice versa
pt with hypovolemia will have…
___ ventricular filling
___ preload
___ stroke volume
less
reduced
lower
frank-starling law
states that an increase in resting muscle fiber length results in greater muscle tension
the heart has the ability to change its force of contraction (and SV) in response to change in venous return
starling’s capillary forces
3 fluid compartments:
intracellular: fluid inside cells
interstitial: fluid surrounding cells
extracellular: fluid inside capillaries
hydrostatic pressure
fluid within the blood exerts hydrostatic pressure
a force that attempts to PUSH fluid out of capillaries and INTO interstitial and intracellular space
oncotic (osmotic) pressure
particles within the blood (album, sodium, glucose) exert oncotic pressure
a force that attempts to PULL fluid from interstitial and intracellular space INTO capillaries
starlings law of capillary forces
oncotic pressure forces and hydrostatic pressure forces OPPOSE each other at every capillary membrane in attempt to balance each other out
(increase in hydrostatic = decrease in oncotic)
afterload
resistance that must be overcome in order to eject blood from chamber
increase in after load –> decrease in SV
what determines L ventricular after load?
aortic BP
a person with high BP will have…
___ afterload
___ stroke volume
high
be at risk for lower SV
contractility is primarily determined by
amount of free calcium within myocardial (heart) cell
increased contractility –> increased SV by causing a greater % of volume to be ejected
blood flow
- superior vena cava and coronary sinus
- R atrium
- R ventricle
- pulmonary artery
- pulmonary vein
- L atrium
- L ventricle
- aorta
*know the valves
L ventricular failure: backward effects
creates a buildup of hydrostatic pressure in the L atrium, pulmonary veins, and pulmonary capillaries
causes pulmonary edema
L ventricular failure: forward effects
cause decreased perfusion to brain, kidneys and other organs
activates stimulation of RAAS, ADH, SNS
posterior pituitary release ADH — increases water and increases blood volume
pulmonary edema
crackles - opening/closing of alveoli through fluid
*fine = mild
*coarse, bubbly = severe
*cough, dyspnea, orthopnea, paroxysmal nocturnal dyspnea
*pink frothy sputum (severe)
BACKWARD EFFECT OF LVF
when the kidneys sense decreased perfusion, what happens?
releases renin from the nephron juxtaglomerular apparatus and initiates cycling of RAAS
RAAS: renin –> angiotensinogen –> angiotensin I –> angiotensin II –> peripheral vasoconstriction and stimulation of adrenal gland –> aldosterone –> Na + H2O reabsorption –> increase blood volume and BP
