Red blood cells (RBC) also known as erythrocytes are the most abundant cells in the blood. RBC’s are 7.8 micrometers in diameter, has a life span of 120 days and makes up about 45 percent of the blood volume. The primary function of red blood cells is to transport oxygen from the lungs to the other cells of the body and removes carbon dioxide and other waste materials that form in the cells. RBC contains a protein known as hemoglobin that carries oxygen plays a significant role in the part of a red blood cell which is essentially the functional component of a cell. RBC’s are bi-concave disc in shape and have no nucleus. The structure has a depressed center on both sides of the cell and this allow the cells to have more cell membrane surface and be more flexible when they pass through tiny passages.
Red blood cell reacts to solutions of having different tonicity. In a hypertonic solution, the concentration of water is greater in the cell than in the solution, so water leaves the cell and therefore moves towards the greater solute concentration. When a red blood cell is placed in a hypertonic solution, the cell shrinks. In an isotonic solution, the concentration inside the cell is equal to the solution. So water molecules move into and out of the cell. When a cell is placed in an isotonic solution, there is no effect, since the system is at equilibrium. In a hypotonic solution, the concentration of water is less in the cell than in the solution, so water enters the cell. When a red blood cell is placed in a hypotonic solution, the cell would burst and swell.