Phase of Cardiac Cycle Flashcards
understanding how the ventricles fill and release
what is (4) phases are occurring during a Cardiac cycle? total time on average heart beat for one cycle is 0.8 sec.
- ventricles filling phase-when pressure in atria is greater than the pressure in the ventricles, the AV valves open. 2. Isovolumetric contraction- all (4) valves are closed, and the ventricles contract increasing pressure with no change in volume early (Systole). 3. Ventricular ejection- when the pressure inthe ventricles is greater than the pressure in the major vessel ( aorta or pulmonary artey ) then the semilunar valves open into great vessels. 4 Isovolumetric relaxation- All (4) chambers are relaxing and all (4) valves are shut.
What is auscultation?
the act of listening to sounds within the body.
what are the (4) heart sounds? 2 (loud) 2 (quieter)
the heart is best heard above a valve.
S1- the first sound is the turbulence from the closing of AV valves. a (lubb) sound
S2- the second sound is turbulence from the closing of the semilunar (SL) valves, a (dubb) sound
S3- rapid ventricular filling
S4- atrial contraction
what does a heart murmur sound like?
a heart murmur sound is a abnormal heart sound usually before or in between heart sounds. They are often a result of a valve abnormality.
what are the some common causes of heart murmurs?
Stenosis- a narrowing of the valvular opening front scarring or a birth defect.
Valvular insufficiency- valve doesn’t close right so there is back flow into the cavity just before the valve.
MVP (mitral valve prolapse)- when a portion of the valve is pushed up or into the atrium when ventricles contract.
What is Cardiac Output (CO) ?
CO = the volume of blood ejected from either right or left ventricle in one minute.
SV ( stroke volume) - the volume of blood ejected in one contraction of a ventricle.
EDV ( end diastolic volume)- the end volume in the ventricle after ventricular diastole.
ESV ( end systolic volume) - the volume in ventricle after ventricular systole.
what are the (3) factors that regulate stroke volume? sympathetic nervous system
Preload- the stretch of the heart before contraction which is the EVD (venous return) is the primary factor that affects preload.
Contractility- the forcefulness of the contraction will increase (SV) stroke volume, (can be increased with regular cardiovascular conditiong)
afterload- the threshold pressure that must be reached to open the (SL) valves and eject the blood out of the ventricles.
what is the Frank-starling law of the heart?
the heart has its own autoregulation that alters the force of contraction to prevent blood from pooling in the ventricles.
What is Congestive Heart Failure (CHF) ?
congestive heart failure is a limit to the increase of preload in the hearts stroke volume. when the heart has to compensate for the increase of preload the heart will streatch more and weaken it. If the left side of the heart fails, blood will pool in the pulmonary circuit and bring edema into the lungs making it impossible to breath. If the right side is failing peripheral edema occurs around the heart.
What is the heart Regulated by?
The cardiovascular center of the medulla plays a role in altering the rate ( increase or decrease) of output to match demands of the body.
what Receptors are needed to detects the changes in demand in the hearts rate?
Chemoreceptors- monitor the blood composition, pH, oxygen, hormones, calcium, potassium.
Baroreceptors- monitor blood pressure in major arteries by monitoring the changes in diameter.
Sympathetic division of the ANS in the cardiovascular center - Nerves travel to the SA node and release norepinephrine.
what are 2 of the effects of norepinephrine?
Increases the rate of depolarization an increase of HR also, an influx of calcium therfore increasing the force of contraction and SV to a point.
what is the effect of the Parasympathetic division of the ANS in the cardioinhibitory center?
The Vagus nerve releases acetylcholine which slows the rate of depolarization.
Other factors that can affect heart rate are?
Age- infants have higher heart rates, heart rate decreases with age and gender too. Males have larger hearts, and a slower heart rates. Conditioning the heart can also decrease your resting heart rate due to increased efficiency of the heart.
Temperature, Chrontropic- factor (time) effects heart rate.
inotropic- factor (force) that effects contraction.
How would sodium affect your heart rate?
Hypernatremia- too much sodium, can lead into blood volume increase and heart rate increase. (extreme cases) (asymptomatic)
Hyponatremia- Too low sodium, in exteme cases brain swelling by increased plasma. (asymptomatic)
