How Does Blood Function in the Body?
-
Transportation
-
One of the most important roles of blood is to move materials through the body. Blood transports a variety of materials, including oxygen, nutrients, waste, hormones and ions, to and from body tissues. Oxygen is taken in by the lungs and moves into the blood where it attaches to a protein in red blood cells called hemoglobin. This oxygen is then delivered to cells; carbon dioxide is picked up, returned to the lungs and expelled during breathing. The red blood cells that transport oxygen account for 45% of the total blood volume. The remaining 55% of blood is composed of plasma and proteins. Plasma is 90% water, which allows for materials such as salt, fat, sugar and protein to dissolve and move easily. When these items are low in concentration in the blood they move freely into the plasma and are carried to the cells that need them. Urea and other waste products are moved away from tissues and transported to the lungs, kidneys and liver for disposal in the plasma.
Temperature and pH
-
The blood regulates the pH and temperature of the human body. When the body needs to cool down the blood flow near the surface of the skin increases and heat is released from the blood. If the body temperature has to be increased the blood flow at the surface of the skin is decreased and blood is held closer to the body core, allowing necessary heat to be retained.
Blood contains buffers that keep the pH of the body between 7.35 and 7.45. If the blood begins to move outside of the normal pH range, the buffer systems of the body work to increase or decrease the blood pH. Changes in breathing rate, foods in the diet, the process of eating and many illnesses can impact the pH of the blood. The buffer systems work constantly to monitor and adjust the blood pH by adding or removing ions. For example, if the acidity is due to an increase in breathing rate the blood removes hydrogen ions from the body and transports them to the kidneys for disposal.
-
Immunity and Protection
-
The blood contains specialized cells that protect the body from disease. These cells, called white blood cells, are an important part of the body's immune system. When bacteria or viruses enter into the blood stream, the white blood cells launch an attack and devour the foreign invaders. The blood also contains cells named platelets that defend the body in case of injury. The platelets cause the blood to clot in the event that a vessel is cut or damaged. When damage to a vessel occurs, platelets gather and form a barrier between the damaged tissue and the outside world, eventually resulting in a scab. In minor injuries, this clot protects the vessel and surrounding tissues while they are healing and keeps blood from pouring out of the wound.
-
Resources
- Photo Credit stock_xchng - blood (stock photo by datarec) [id 652136]
