Nat Sci 179 The Heart And The Cardiac Cycle

Front 1

Review of heart anatomy

Back 1

-chambers
-valves: 2 AV, 2 semilunar
-major vessels: aorta, pulm. trunk, vena cavae

Front 2

Review of double-loop system

Back 2

-one loop to pulmonary circulation (right heart)
-one loop to systemic circulation (left heart)

Front 3

Pathway of blood through heart

Back 3

sup. & inf. vena cavae -> R atrium -> tricuspid V -> R vent. -> pulm. V -> pulm. trunk -> pulm. circulation -> L atrium -> bicuspid V -> L vent. -> aortic valve -> aorta -> systemic circ. -> sup. & inf. vena cavae

Front 4

Brief version of cardiac cycle:

Back 4

1) atria contract; ventricles are relaxed
2) ventricles contract; atria relax
3) all chambers relax

Front 5

Relation of cardiac cycle to ECG

Back 5

P wave, QRS complex, T wave

Front 6

Phases of the cardiac cycle:
1) ventricular filling

Back 6

1)-ventricular diastole; ventricles are relaxed
-pressure in ventricles drops, AV valves open
-atria contract
-ventricles fill

Front 7

Phases of the cardiac cycle:

2) isovolumetric contraction

Back 7

2) isovolumetric contraction
-atria are relaxed
-ventricles contract but do not eject blood yet (isovolumetric)
-AV valves close
-note; all four valves are briefly closed at same time

Front 8

Phases of the cardiac cycle:

3) ventricular ejection

Back 8

3) ventricular ejection
-semilunar valves open when P inside vents. is great enough
-blood ejected from ventricles
-note: not all blood is ejected (about 54%)
-more is ejected during exercise (as high as 90%)
-a diseased heart may eject less than 50%
-stroke volume = amt. of blood in ml ejected per beat

Front 9

Phases of the cardiac cycle:

4) isovolumetric relaxation

Back 9

4) isovolumetric relaxation
-ventricular diastole; vents. relax
-semilunar valves close
-all four valves are briefly closed
-vents. not yet filled, so is an isovolumetric relaxation
-as soon as AV valves open, step one has begun again