Cardiac Cycle Flashcards
-Explain how a drug that slows conduction through the AV node could reduce ventricular response rate and increase cardiac output during atrial fibrillation. -Explain why tachyarrhythmias, such as atrial fibrillation with rapid ventricular response, often result in reduced cardiac output.
7 periods of cardiac cycle
1) atrial systole=atria contract
2) isovolumetric contraction=ventricular contraction
3) rapid ejection=ventricular contraction
4) reduced ejection=Still ventricles contracting?
5) isovolumetric relaxation= All relax
6) rapid ventricular filling= all relax
7) reduced ventricular filling = all relax
A-wave:
-reflects the increase in pressure of the atria as the contract. A-wave/contraction of atria begins just after the atria depolarize (P-wave on ECG).
C-wave
- rise in pressure of atria - due to A-V valve getting pushed up INTO the artium (bc the contraction of the septum which brings the apex closer toward the base and hence the A-V valve toward the base and into the artium)
- decrease in pressure of atria - due to the contraction of the ventricular walls from inside to outside which effectively elongates the heart (apex and base move downward) and this pulls the A-V valves OUT of the atria decreasing the inside
- OVERALL–> RESULTS FROM VENTRICULAR CONTRACTION
Reduced ejection- which # in cycle? valves doing what?
- # 4
- Aortic and Pulmonic valves REMAIN OPEN
- Mitral and tricuspid CLOSED
Rapid ejection- which # in cycle? valves doing what?
- # 3
- Aortic valves OPEN - due to “momentum” of blood (pressure gradient reversed but TOTAL energy of blood coming from ventricle is still higher than total energy of blood in aorta
- STAGE MARKED BY CLOSURE OF AORTIC AND PULMONIC VALVES
- Mitral and tricuspid valves CLOSED
isovolumetric contraction- which # in cycle? valves doing what?
- # 2
- ALL VALVES ARE CLOSED
atrial systole-which # in cycle? valves doing what?
- # 1
- A-V valves OPEN which contraction of atria
- Pulmonic-Aortic valves closed
isovolumetric relaxation- which # in cycle? valves doing what?
- # 5
- ALL VALVES ARE CLOSED AT FIRST
- When pressure in ventricules falls below atrial pressure–> AV valves OPEN and ventricular filling begins
V-wave
- increase in pressure of atria due to increased venous return coming into atria (while AV valves closed)
- decrease in pressure marked when the AV valves open due to pressure in atria being greater than pressure in ventricles
repid ventricular filling- which # in cycle? valves doing what?
-#6
-AV valves OPEN due to pressure (V-Wave)
-Pulmonic and Aortic CLOSED
-stage lasts until the VENTRICLES HAVE PASSIVELY EXPANDED TO THEIR MAX
(DUE TO NEGATIVE PRESSURE)
reduced ventricular filling-which # in cycle? valves doing what?
- # 7
- FILLING DUE TO POSITIVE PRESSURE FROM SVC and IVC
- OPEN AV-VALVES
- CLOSED pulmonic/aortic valves
increased heartrate which portions of cardiac cycle are most reduced?
MOST DECREASE SEEN IN VENTRICULAR DIASTOLE PERIODS
aortic pressure response slope: factors
risistnace of ciruclation - if the arteriolar diameter got larger the slope of aortic pressure reponse would get steeper downward
(alpha 1 stimulation = less steep)
arteriolar diameter controled by?
- local metabolic byproducts - CO2 for vasodialation
- autonomic innervation
SA node receptors, actions, response
M2 - decreased freq of depol –> dec HR
Beta1 - increase HR –> inc Cardiac output
Ventricular muscle receptors, actions, response
beta1 - increase force –> inc cardiac output
Arterioles receptors, actions, responses
- M3 - inc dialation –> decrease resistance
- Alpha1 - inc constriction in skin, kidney, mesentary –> inc resistance
- Beta2 - inc dialation —> dec resistance
Left Ventricular End Diastolic Volume
represents the maximum ventricular volume of the cardiac cycle.
stroke volume=
difference between LVEDV and LVESV
First heart sound=
LUB S1 = CLOSURE OF MITRAL AND TRICUSPID VALVES
Second heart sounds=
DUB S2 = end of cardiac ejection AND closure of aortic and pulmonic valves
does the aortic or pulmonic valve close first/
aortic is first
Opening Snap Heart Sound (OS):
- you hear the valve OPEN (abnormal)
- mitral stenosis - fibrous bridging across the valvular commisures w/ calcification = produces OS