Week 4, Perfect Paragraph

The heart is located at the center of the circulatory system and delivers blood to every part of your body. Before deoxygenated blood coming from veins fills the right atrium, it is assumed that the pressure in the right atrium is 0mmHg at diastole. The blood flowing though the right atrium passively fills the right ventricle as it passes the open atrioventricular (AV) valve. This stage is called diastole because the heart is relaxed and not contracting yet. Systole (contraction) begins when the pressure in the right atrium increases by a small increment to push the rest of its contents into the right ventricle. This causes the pressure in the right ventricle to exceed the pressure of the atrium above it and the AV valve to close shut. The valves close tightly with the aid of the chordae tendineae and papillary muscles. The right ventricle pressure begins to rise. The aortic pressure is the determinant of our blood pressure and has a normal range of 80-120 mmHg. As the ventricle builds up in pressure by isometric contraction, it surpasses the aortic pressure and the aortic valve opens. As the right ventricular pressure begins to decrease after it ejected blood into the aorta, it reaches a pressure below 80 mmHg and the aortic valve closes. The ventricle will cease systole and go into diastole. The ventricle ejects 70 mL of blood into the aorta. The right ventricle's pressure will decrease to a point lower than the pressure in the right atrium, the AV valve will open and the right ventricle will be filled passively once again. This similar process occurs on the left side of the heart as the left atrium fills with oxygenated blood that came from the lungs. This blood vessel network is crucial to survival and any deviation from it can cause serious heart disorders.