Anatomy: Animals Inside

Circulatory System

What are the main components of human blood?

Blood is considered a complex tissue—a group of similar cells—suspended in a fluid medium for easy transport through blood vessels in many organisms, including humans. The following lists the four main components of human (and many other organisms) blood (for more about cells, see the chapter “Cellular Basics”):

When a blood vessel is damaged and fluids start escaping, platelets in the blood are activated to form fibrin, which traps red blood cells and lymph cells, forming a clot.


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