The Circulatory System

• Your body receives the nutrients and substances it needs via the circulatory system, the body's transport system
• It is composed of the heart, blood vessels, and blood
• Cardio refers to heart while, vascular refers to a channel or passage
• The heart is a hollow muscular organ located in the chest
• During an average person's life, the heart beats at least 2,400 million times
• The heart pumps more than 500 million liters of blood
• The heart is enclosed in a protective sac called pericardium
• The heart has four chambers
• The two upper chambers are called atria (singular: atrium) and the two lower chambers called ventricles
• These chambers act as a reservoir for blood that enters the heart
• The atria receives blood while the ventricles pump blood out of the heart
• Valves are flaps of muscles found between the chambers
• The tricuspid valve is between the right atrium and right ventricle
• The bicuspid or mitral valve is between the left atrium and left ventricle
• The pulmonary valve lets blood be pumped from the heart to the lungs
• The aortic valve allows blood to be pumped from the heart to the rest of the body
• Blood vessels are tubes that serve as passageways for blood to reach the different parts of the body
• There are three kinds of blood vessels: The arteries, veins, and capillaries
• Arteries Carry blood away from the heart. All arteries deliver oxygen-rich blood to all body parts, except for the pulmonary artery, which comes oxygen-poor blood to the lungs
• The smallest arteries are called arterioles and they are thinner than a strand of thread
• Veins bring back blood from the different parts of the body back to the heart. The blood carried by veins contain carbon dioxide and other wastes, except for the pulmonary vein which carries oxygen-rich blood from the lungs to the heart. The smallest veins are called venules
• Capillaries these are the smallest blood vessels which connect the arterioles and venules.
• The blood has two parts: the liquid and solid part. The solid part consists of blood cells and platelets while the liquid part consists of plasma. About 45% of the blood consists of the solid part and 55% for the liquid part
• What are the two parts of the blood?

  The liquid part and solid part
• What does the solid part consist?

  The blood cells and platelets
• Plasma is the liquid part of the blood which is straw-yellow in color.
• The solid part of the blood consists of white blood cells, red blood cells, and platelets
• Red blood cells (RBC's) are produced in the red bone marrow. They are also called erythrocytes. Their function is to carry oxygen from the lungs and transport it to the body parts and remove carbon dioxide and other substances. It contains hemoglobin, it gives the red color to the blood and has a lot of iron
• White blood cells (WBC's) are sometimes referred to as leukocytes. They are generally bigger than red blood cells but are fewer in number. There is about one white blood cells for every 500 red blood cells. They are the soldiers of the body.
• Platelets or thrombocytes are fragments that are relatively smaller and are irregular in shape. They play an important role in blood clotting.