3 Blood Components
Learn how plasma, red blood cells, white blood cells, and platelets carry substances, protect against infection, and help limit blood loss.
Blood’s four components
Blood consists of a liquid portion, , and three formed elements: , , and . Together, these components transport materials, protect against infection, and help prevent blood loss.
carries dissolved substances
is the straw-colored liquid portion of blood and is mostly water. It carries proteins, salts (electrolytes), nutrients, hormones, waste products, and blood cells through the body.
proteins help maintain fluid balance, and some are involved in blood clotting. For example, carries nutrients absorbed from the digestive system to tissues and transports some waste products toward organs that remove them.
transport gases
contain , the protein that gives blood its red color. carries oxygen from the lungs to body tissues. also transport some carbon dioxide from tissues back toward the lungs to be exhaled.
During exercise, deliver oxygen to working muscles.
support defense
, also called leukocytes, help defend the body against infection and other threats. Different types perform different immune functions, including recognizing or attacking harmful organisms. During an infection, help the immune system respond to the cause of illness.
help limit bleeding
, also called thrombocytes, are small cell fragments that help stop bleeding. When a blood vessel is injured, gather at the damaged area and help form an initial plug. Clotting proteins then help strengthen the clot.
After a small cut, collect at the break in the vessel wall and help limit blood loss.