heart valves and cardiac cycle + pace makers and action potentials Flashcards
S1 sound is closure of which valves
AV valves (Tricuspid and mitral)
S2 sound is closure of
aortic and pulmonic valves
S3 occurs when in diastole and why
early, from a sudden deceleration of blood flow into left ventricle from the left atrium
S4 late or early in diastole
late diastole,
Occurs in ventricular non-compliance
stenosis = late in diastole
regurgitation = early in diastole
both are characterized by
stenosis = narrowing/thinning of the valves
regurgitation = valve can not close properly, allowing for blood flow
stroke volume =
volume of blood pumped out of the L ventricle during systolic cardiac contraction
3 factors that affect stroke volume
contractility, afterload, and preload
increase with contractility and preload
decrease with afterload
Which ions increase contractility (SV)
o Catecholamine stimulation via B1 receptor (-> Ca2+ release)
o Intracellular [Ca2+]
o Intracellular [Na+] (due to activity of Na+/Ca2+ exchanger)
Contractility decreases with
o Extracellular [Na+] (due to activity of Na+/Ca2+ exchanger)
o B1-blockade
o HF with systolic dysfunction
o Acidosis
o Hypoxemia/hypercapnia
preload depends on which 2 factors
venous tone
circulating volume
afterload depends on which 2 things
wall tension (more wall tension = more afterload)
hypertension
myocardial oxygen demand depends on: contractility, afterload, and what else (2 more)
HR
Ventricular wall tension
cardiac output =
= SV + HR
name the phases of the cardiac cell cycle (7)
- Atrial contraction
Systole - Isovolumetric contraction
- Rapid ventricular ejection
- Reduced ventricular ejection
Diastole - Isovolumetric ventricular relaxation
- Rapid ventricular filling
- Reduced ventricular filling
atrial contraction = SA node or AV node firing
starts with SA node firing
atrial contraction = which wave on ECG
P wave
atrial contraction = contraction of both L and R atria T or F
T