Don't have a nucleus, which means more space for hemoglobin and oxygen
Shaped like a biconcave disc, which gives them a large surface area for absorbing oxygen
White blood cells
An essential part of the immune system, which defends against infection
How white blood cells defend against pathogens
Phagocytosis (engulfing and consuming microorganisms)
Producing antibodies that bind to and help destroy pathogens
Producing antitoxins that neutralize toxins produced by pathogens
Platelets
Small fragments of cells that float in the blood and rush to wounds to help stop bleeding and prevent infection
Plasma
The pale, straw-colored liquid part of the blood that carries various substances, including red blood cells, white blood cells, and platelets
Most adults have about 5 liters of blood flowing through their circulatory system at any one time
Artificial blood
A blood substitute that consists mainly of salt water, which can add volume to the circulatory system but does not contain red blood cells to transport oxygen
Blood transfusion
Giving a person real blood that has been donated, which contains red blood cells to help survive blood loss
