The aorta is the largest artery in the human body. The aorta originates from the left ventricle of the heart. It carries oxygenated blood from the heart to all parts of the body.

The spleen does not produce blood platelets. It has four main functions as follows.
1. It produces red blood corpuscles.
2. It destroys worn-out red blood corpuscles.
3. It produces lymphocytes.
4. It stores blood.

The aorta originates from the left ventricle of the heart. It carries oxygenated blood from the heart to all parts of the body.

The spleen is located in the abdominal cavity, behind the stomach, and above the left kidney.

The spleen is a lymphatic organ. This is so because it produces lymphocytes.

Blood (a part of the circulatory system) aids in regulating the body temperature.

Pericardium is the double-walled membranous covering that protects the heart. It contains the pericardial fluid that helps in lubrication. In other words, it decreases friction during the heartbeat, and protects it from mechanical damage.

The coronary arteries originate from the base of the aorta.

There are four kinds of valves in the heart. They are:
1. left auriculo-ventricular valve
2. right auriculo-ventricular valve
3. aortic semilunar valves
4. pulmonary semilunar valves

A portal vein begins in the form of capillaries and ends in the form of capillaries too.

The pulse rate increases during strenuous physical work and also during emotional stress.

The word 'pulse' is related to arteries during the ventricular systole.

Blood pressure is exerted by the blood flowing through the arteries on the walls of the arteries.

'Systolic pressure' is the term that indicates the upper limit of blood pressure. 'Diastolic pressure' is the term that indicates the lower limit of blood pressure.

The auricles of the heart have thinner walls than the ventricles. This is so because the chief function of the auricles is to receive blood from all parts of the body and pump this blood into the ventricles just below.