The cardiovascular system is part of the circulatory system which circulates blood around the body transporting gases, nutrients, hormones, plasma protein etc. The blood, heart and blood vessels make up the cardiovascular system.
Blood consists of red blood cells, white blood cells and platelets which are little cell fragments. All of which are suspended in a fluid called plasma which is a pale yellow colour. Blood has many functions including: transporting gases, nutrients, waste products, etc around the body; maintains body temperature, keeps pH levels between 6.8 to 7.4, removes toxins from the body via kidneys and regulates body fluid electrolytes. The composition of blood plasma is 92% water, 6-8% proteins, 0.8% salts, 0.6 lipids and 0.1% glucose. Red blood cells (RBCs) aka erythrocytes “are the primary cells in human blood. They are biconcave discs, having a depressed center on both sides. These depressed centers allow the cells to have more cell membrane surface which can be exposed to diffusing oxygen while transiting the lungs. This structure also allows them to be more flexible when negotiating tight passages. RBCs are about 7.8 micrometers in diameter (A micrometer is 1/1,000,000 of a meter). They have a flexible nature that allows them to bend and bounce back their original shape. This comes in handy when they must squeeze through the minute capillary alleyways between cells in the tissues” [ (Pendleton 2008) ]. White blood cells (WBC’s) are also known as leukocytes. They defend the body against bacterial and fungal infections, defends against parasitic infections, take care of allergic responses, provide immunity and act as the clean-up crew. Without haemoglobin WBC’s are colourless. It has an irregular shape and contains a nucleus and bigger than RBC’s. WBC’s can squeeze through the walls of the blood vessels into the inter-cellular spaces by easily changing their shape. Platelets function in the clotting of the blood..