Ch 9.3 -- Mechanical Events of the Cardiac Cycle -- VTPP 435

Ch 9.3 -- Mechanical Events of the Cardiac Cycle -- VTPP 435

Cardiac Cycle

-one period of systole & diastole in ventricle

Systole

period of cardiac contraction & emptying

Diastole

period of cardiac relaxation & filling

End-Diastolic Volume (EDV)

-volume of blood in ventricle at end of diastole
-when filling is complete
-max blood in ventricle

Isovolumetric Ventricular Contraction

no blood leaves ventricles and pressure in ventricles rises and fiber stays same length

Stroke Volume

volume of blood pumped out of each ventricle with each contraction or beat of heart

End-Systolic Volume (ESV)

-volume of blood in ventricle at end of systole
-when emptying is complete

Steps for Cardiac Cycle

1) AV valve is open
2) Passive Ventricular filling occurs; volume & pressure increase
3) Atrial contraction completes ventricular filling; EDV reached
4) AV Valve closes
5) Isovolumetric ventricular contraction occurs; volume same and pressure rises
6) Aortic Valve opens
7) Blood leaves ventricle, volume drops, pressure peaks and ESV is reached;
8) Aortic Valve Closes
9) Isovolumetric ventricular relaxation occurs; volume is same and pressure falls

First Heart Sound

-low pitched soft and long
-"lub" sound
-closure of AV valves
-ventricle systole onset

Second Heart Sound

-higher pitch, shorter, & sharper
-"dup" sound
-closure of Semilunar Valves
-ventricular diastole onset

Murmurs

abnormal sounds made by blood circulation

Stenotic Valve

-stiff narrowed valve that does not open completely
-high velocity flow
-produces whistling sound from turbulence from big force

Insufficient or Incompetent Valve or Leaky Valve

-valve that does not close completely because valve edges do not fit together properly
-blood flows backward
-swishing or gurgling murmur

Rheumatic Fever

-autoimmune disease triggered by streptococcus bacterial infection
-antibodies form against toxins that cause immunological damage
-causes valvular stenosis & leaky

Systolic Murmur

murmur between 1st & 2nd heart sounds

Diastolic Murmur

murmur between 2nd & 1st heart sounds

Location of Murmur

helps tell which valve is involved

Timing of Murmur

refers to which part of cardiac cycle murmur is heard