The function of the lymphatic system is to keep fluids out of the interstitium and connective tissue by returning it to the blood. Fluid leaks out of capillaries because of their thin walls. The lymphatic vessels collect this fluid and return it to the heart. When the lymphatic system is impaired, this fluid can accumulate in the tissue and cause swelling, known as edema.

Most of the lymph re-enters the venous circulation through the thoracic duct, and the volume is somewhere around a liter to a liter and a half per day.

Blood flows back to the heart through the pulmonary veins after being oxygenated in the lungs and re-enters the heart through the left atrium. The blood then passes into the left ventricle, which pumps an enormous volume of blood via the aorta to the rest of the body. This chamber of the heart is under a lot of pressure since the heart must pump blood through the many miles of vessels and arteries; therefore, the left ventricle wall must be thicker to withstand the force of these contractions.

The cardiac cycle consists of the filling of the right atrium with venous blood (oxygen-poor blood that has returned from the body to now be pumped into the lungs for oxygenation), and opening of the tricuspid valve to allow transfer of blood to the the right ventricle. The right atrium contracts to do this. Then, the tricuspid valve closes and the right ventricle contracts to pump the blood through the pulmonary valve into the pulmonary arteries, which carry oxygen-poor blood into the lungs to be oxygenated. Pulmonary veins carry oxygen-rich blood from the lungs into the left atrium. The mitral valve opens to allow the flow of blood from the left atrium into the left ventricle, the left atrium contracts to help. The mitral valve closes and the left ventricle contracts, pumping blood through the aortic valve into the aorta, through which oxygen-rich blood is transferred to the whole body.

The function of the lymphatic system is to keep fluids out of the interstitium and connective tissue by returning it to the blood. Fluid leaks out of capillaries because of their thin walls. The lymphatic vessels collect this fluid and return it to the heart. When the lymphatic system is impaired, this fluid can accumulate in the tissue and cause swelling, known as edema.

Most of the lymph re-enters the venous circulation through the thoracic duct, and the volume is somewhere around a liter to a liter and a half per day.

Blood flows back to the heart through the pulmonary veins after being oxygenated in the lungs and re-enters the heart through the left atrium. The blood then passes into the left ventricle, which pumps an enormous volume of blood via the aorta to the rest of the body. This chamber of the heart is under a lot of pressure since the heart must pump blood through the many miles of vessels and arteries; therefore, the left ventricle wall must be thicker to withstand the force of these contractions.

The cardiac cycle consists of the filling of the right atrium with venous blood (oxygen-poor blood that has returned from the body to now be pumped into the lungs for oxygenation), and opening of the tricuspid valve to allow transfer of blood to the the right ventricle. The right atrium contracts to do this. Then, the tricuspid valve closes and the right ventricle contracts to pump the blood through the pulmonary valve into the pulmonary arteries, which carry oxygen-poor blood into the lungs to be oxygenated. Pulmonary veins carry oxygen-rich blood from the lungs into the left atrium. The mitral valve opens to allow the flow of blood from the left atrium into the left ventricle, the left atrium contracts to help. The mitral valve closes and the left ventricle contracts, pumping blood through the aortic valve into the aorta, through which oxygen-rich blood is transferred to the whole body.

The ejection fraction of a healthy heart is about 70% of its 100ml volume, or 70ml per stroke.

At a heart rate of 70 beats per minute, then approximately 5 liters is pumped by EACH side of the heart each minute.

Both the right and left sides of the heart must pump the same volumes since all blood from the right side returns to the left side after passing through the lungs.

Veins are the only circulatory vessels that contain valves. These structures contain valves because much of the pumping pressure that originated in the heart has been reduced by the time blood reaches veins, which return deoxygenated blood to the heart. The reduction of force can cause the blood to pool or move very slowly. Since veins rely mostly on gravity, blood flow force (originating from the heart), and muscular contractions to squeeze blood through them, it makes sense for them to have valves to keep blood from flowing backwards in between muscular contractions.

The ejection fraction of a healthy heart is about 70% of its 100ml volume, or 70ml per stroke.

At a heart rate of 70 beats per minute, then approximately 5 liters is pumped by EACH side of the heart each minute.

Both the right and left sides of the heart must pump the same volumes since all blood from the right side returns to the left side after passing through the lungs.

Veins are the only circulatory vessels that contain valves. These structures contain valves because much of the pumping pressure that originated in the heart has been reduced by the time blood reaches veins, which return deoxygenated blood to the heart. The reduction of force can cause the blood to pool or move very slowly. Since veins rely mostly on gravity, blood flow force (originating from the heart), and muscular contractions to squeeze blood through them, it makes sense for them to have valves to keep blood from flowing backwards in between muscular contractions.