Our Blood

Red Blood Cell - The primary function of red blood cells is to transport oxygen to body cells and deliver carbon dioxide to the lungs. 

Red blood cells have a unique structure. Their flexible disc shape helps increase the surface area-to-volume ratio of these extremely small cells. This enables oxygen and carbon dioxide to diffuse across the red blood cell's plasma membrane more readily. A red blood cell has what is known as a biconcave shape. This shape also aids in a red blood cell's ability to maneuver through tiny blood vessels to deliver oxygen to organs and tissues. 

Red Blood Cells, also called erythrocytes, are tiny biconcave disc-shaped cells. They do not have a nucleus or mitochondria. Their cytoplasm is rich in haemoglobin. O₂binds to the iron in haemoglobin. Red blood cells are made in the bone marrow. They survive for about four months. They are destroyed and recycled by the liver and spleen. They are destroyed because they have to constantly change shape to pass through narrow blood vessels. When they die the haemoglobin is stored in the liver and used to make new blood cells in the bone marrow. They are very small. There are about 5 million red blood cells in 1 cc. of blood. The rest that is not stored is converted into bile pigments.

White Blood Cells – White Blood Cells are colourless cells and possess a nucleus. They function in defending the body against pathogens. Some ‘feed’ on pathogens by phagocytosis. These white blood cells are called phagocytes. Others, the lymphocytes produce antibodies, the specific defense proteins. They are made by the bone marrow and lymphatic tissue.

Platelets - also called thrombocytes, are tiny fragments of large bone marrow cells. They carry specialised blood clotting chemicals. The clotting chemicals are released where blood and lymph vessels are injured. A nucleus is not present in platelets.

Blood plays an important role in regulating the body's systems and maintaining homeostasis.

Other functions include supplying oxygen and nutrients to tissues, removing waste, transporting hormones and other signals throughout the body, and regulating body pH and core body temperature.

Blood is composed of plasma, red blood cells, white blood cells, and platelets.

Blood platelets play a role in coagulation (the clotting of blood to stop bleed from an open wound); white blood cells play an important role in the immune system; red blood cells transport oxygen and carbon dioxide.

Blood is considered a type of connective tissue because it is made in the bones.