16: Cardiovascular Physiology Flashcards
EDV: where is equilibrium around?
125-150mL
Why does the plateau occur in the venous return curve?
Plateau occurs due to collapse of veins entering chest
CO equilibrium
Volume of blood at CO ejected by LV equals the volume it receives in venous return
EDPVR and ESPVR stand for?
EDPVR: end-diastolic pressure-volume relationship
ESPVR: end-systolic pressure-volume relationship
What causes increased afterload?
HTN, increased TPR, aortic stenosis, increased blood viscocity, increased intrathoracic pressure
What causes increased contractility?
Adrenergic stimulation
Compensation when preload/after load changes
After a few heart beats, the other will change to match
Compensation when contractility changes
Changes in preload and afterload occur
Three means of cardiac compensation
- Renal (RAAS)
- Natriuretic peptides
- Symp and parasymp influence
RAAS function for cardiac compensation
Raises blood volume to maintain BP
What occurs with increasing level of BNP?
Risk of death increases
Symp and parasymp effect on CO
Symp: increases contractility
Parasymp: decreases contractility
Symp and parasymp receptors for CO changes
Symp: B-adrenergic receptors
Parasymp: muscarinic receptors
Cascade of effects with symp activation
Phosphorylation of sarcolemma Ca channels + phospholamban + troponin I (inhibits)
Parasymp activation cascade
Decreases inward Ca current during plateau -> + Ach increases outward K current
Which type of work is costlier, volume or pressure work?
Pressure work
Why does LV have to work proportionally harder than RV?
Systemic pressure is greater than pulmonary pressure
How does heart failure cause edema?
Decreased CO + atrial pressure -> increased pulmonary venous and arterial pressures -> edema
What does decreased pO2 cause in heart failure?
Dyspnea, respiratory alkalosis
Two types of heart failure and what happens to EF
HRrER: systolic HF; EF is reduced
HRpER: diastolic HF, EF is unchanged
Which part of the hear commonly fails in HRrEF?
LV
What decreases and increases in HRrEF?
Increases: diastolic volume, BNP
Decreases: contractility
What increases in HRpEF?
LV diastolic pressure, RA pressure
What factors are increased, decreased, and unchanged with aortic stenosis
Increased: afterload
Decreased: SBP, pulse pressure
Unchanged: DBP
What pressure increases in COPD?
Pulmonary mean arterial pressure
What is right sided heart failure associated with?
Lung dysfunction; decreased gas exchange in pulmonary caps
Three systemic effects of right sided heart failure
- Increased systemic venous pressure -> edema
- Liver function decreases
- Decreased renal perfusion
Where does pressure back up in mitral valve stenosis?
Increased pressure in LA -> backs up into pulmonary system
S/S mitral valve stenosis
Pulmonary edema due to fluid in interstitial space, SOA
