n WHAT IS SICKLE CELL DISEASE? Sickle cell disease is an inherited blood disorder that affects the ability of red blood cells to carry oxygen throughout the body. Normally, red blood cells are round and flexible. Sickle cell disease causes red blood cells to change into a curved, or sickle, shape. These sickle-shaped red blood cells stick together, blocking blood flow to the hands, feet, joints, bones, and major organs. When blood flow to these areas decreases, the tissues do not get enough oxygen, causing pain and other problems. To understand how sickle cell disease affects the body, it helps to understand a little more about blood.
n WHAT IS BLOOD? Blood is a mixture of cells, proteins, and a watery substance called plasma. The cells in blood are made in our bone marrow, the sponge-like center of the bones in our skull, spine, pelvis, and ribs. Like water being pumped through a hose, our blood is pumped by our heart through small tubes called blood vessels. There are two types of blood vessels: arteries and veins. The arteries carry blood away from the heart and bring oxygen to the body’s tissues. After delivering the oxygen to the tissues, the blood is returned to the heart through the veins.
Blood has many functions. It carries nutrients and gases throughout the body and carries waste away from the tissues and organs. Blood also helps fight infections and heal wounds. Blood has four major components: • White blood cells are the fighter cells, known as leukocytes. White blood cells, which are part of the immune system, protect the body from infection and disease. • Platelets help stop bleeding. Platelets form a scab after skin or tissue has been injured. • Red blood cells make up most of the cells in our blood. These small cells, known as erythrocytes, are slightly flattened, so they look like a doughnut with the hole filled in. The function of red blood cells is to carry oxygen, carbon dioxide, and nutrients throughout the body. Red blood cells contain a protein called hemoglobin, which carries oxygen throughout the body. The cells of the tissues use the oxygen and create carbon dioxide, a waste product. After red blood cells drop off oxygen at the tissues, they pick up carbon dioxide and carry it back to the lungs to be exhaled from the body. • Plasma is a yellowish liquid consisting mostly of water. Plasma acts as a river, helping the white blood cells, red blood cells, and platelets flow freely through the blood vessels.
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