Cardiac Cycle: Mechanical Events Flashcards
what is systole?
contraction
diastole is what ?
relaxation
what is the normal duration of the cardiac cycle?
0.8 sec. resulting in a resting heart rate of 72 beats/min
systole/contraction = 0.3 sec
diastole/relaxation = 0.5 sec
if you shorten the diastole time what happens?
you have less blood filling into the ventricle - therefore you have less blood available to the body - therefore you have less blood flow profusing the heart = vicious cycle
- the heart pumps everywhere including to the heart -
what portion of the heart is responsible for the unidirectional flow of the heart?
the heart valves
the mitral valve connects which two chambers?
mitral valve is between the left atrium and left ventricle
when the atriums fill with blood, what valve is closed?
the AV valves are closed
when the ventricles are filled, what valves are closed?
the semi-lunar vavles are closed (to the aorta or pulmonary arteries)
pressure on what side of the heart is higher?
the pressure on the left side of the heart is higher than the right side
the 1st and second heart sounds are associated with what events?
first = AV valve closure (tricuspid/mitral)
second = outflow valve closure (pulmonary /aortic)
What is associated with the 3rd anf fourth heart sounds?
third= filling of ventricles - benign in youth, some trained athletes, and pregnancies - though sometimes it can be indicative of a pathology
4th = atrial contraction
what is a murmer?
most common cause is an aortic regurgitation and mitral stenosis
regurgitation = valvular incompetence
stenosis = valvular narrowing
when in the heart sound does a murmer occur?
depends on type of murmer
diastolic murmur = occurs after S2 and before S1 - due to aortic regurgitation/mitral stenosis
systolic murmur= occurs between S1 and S2 - due to mitral regurgitation/aorticc stenosis- or non-pathological reasons
what is a cystolic murmer?
quite common - often “innocent functional” flow murmurs
- common pathological cuasese are mitral regurgitation, aortic stenosis, and tricuspid regurgitation
REVIEW THE LEFT VENTRICULAR PRESSURE VOLUME RELATIONSHIP GRAPH
What is the left ventricular en diastolic pressure?
left ventricular pressure just before onset of left ventricular systolic indicative of haemodynamic health of left ventricle - normally less than 12 mmHg
what is the ejection fraction?
it is the percentage of blood that is ejected by the ventricle relative to its end
what is a normal ejection fraction?
55-70%
during exercise it could increase to more than 90%
explain what occurs at each indicated letter in this jugular venous pressure wave form
c= rise in atrial pressure- right vent. contraction causes tricuspid valve to bulge towards the right atrium
x= fall in atrial pressure- atrial relaxation and rapid atrial filling due to low pressure
v= rise in atrial pressure- venous filling when the tricuspid valve is closed
y = fall in atrial pressure- rapid emptying of the atrium into the ventricle following the opening of the tricupsid valve
