Week 13- PP
As blood enters the right side of the heart it enters the right atrium where blood is able to flow without any additional help through the atrioventricular valve and into the ventricle. Eventually the atrium contracts (becomes systole however this term is usually only applied to the ventricle) forcing the rest of the blood still present in the atria into the ventricle. Once blood has built up in the right ventricle it contracts, becoming systole while the atrioventricular valve (AV valve) closes as pressure is now greater in the ventricle than in the right atria. Once enough pressure has built up in the ventricle the semilunar, pulmonary valve opens, allowing blood to flow out of the ventricle and into arties that in the case of the right hear carry the blood to the pulmonary circuit where blood that lacks oxygenation is oxygenated. The left side of the heart follows a very similar process however it’s semilunar valve is called the aortic valve and blood is sent to the systemic circuit where organs use oxygen and nutrients from the oxygenated blood.