Hyoid Bone Anatomy
Components of blood
General Composition of Blood:
Human blood is primarily composed of plasma, red blood cells (erythrocytes), and white blood cells (leukocytes).
- If a tube of blood is left standing or spun briefly in a centrifuge, the components will separate into layers, based on their density.
- The bottom, red-colored layer is made up of red blood cells (RBCs or erythrocytes). Red blood cells normally occupy about 45% of the total blood volume (females = 37-48% & males = 45-52%).
- Above the RBCs is the buffy coat. This narrow, white band is composed of white blood cells (WBCs or leukocytes) and cell fragments called platelets (thrombocytes). Approximately 1% of the blood volume is occupied by these components.
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- Together, the RBCs, WBCs, and platelets are referred to as the blood’s formed elements.
- On top of the formed elements is the blood plasma. This straw-colored fluid makes up approximately 55% of the total blood volume.
- By weight, the composition of plasma is about 91.5% water and 8.5% dissolved solutes. Most of the dissolved solutes are proteins. The remaining solutes are a mixture of nutrients, electrolytes, nitrogenous wastes, respiratory gases, and regulatory compounds.