Lab Report: Exercise 5: Cardiovascular Physiology
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Activity 1: Heart Sounds
What is the cardiac cycle?
The cardiac cycle is one complete heart beat. During the cycle each atrium and ventricle will contract and relax once. THe contraction of the chamber is called systole and the relaxation is called diastole. The average heart has approximately 70-75 heartbeats per minute, each cycle lasting just under a second. 2.
Explain the steps of a cardiac cycle.
Ventricular filling: Happens during diastole, when the ventricles expand. Their pressure drops below the atria, the AV valse will open and the blood flows into the ventricles. The filling happens in three phases:
1. rapid ventricle filling, blood enters quickly.
2. Diatasis, slower filling of blood and P wave will occur at the end
3. Atrial systole, atria contracts
Isovolumetric Contraction: the atria depolarizes and relaxes, it will remain in diastole for the rest of the cycle. The ventricles depolarize and create the QRS complex, they begin to contract. The AV valves close as the ventricular blood surges back against the cusps. The cardiocytes exert forve, but with all four valves closed the blood cannot go anywhere. Even though the ventricles contract they do not eject blood. Ventricule Ejection: The ventricular pressure exceeds arterial pressure and forces the semilunar valves to open. The rapid eject occurs with the blood spurts out of each ventricle rapidly. Reduced ejection is when the blood comes out slower due to reduced press. Stroke volume is at about 70 mL of the 130 mL of blood is ejected. the end systolic volume is about 60 mL of blood left. Isovolumetric Relaxation: Early ventricular diastole, when the T wave ends and the ventricles begin to expand. ***** SLIDE 48!
What do the “lubb” and “dupp” heard through...
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