Blood is made up of solid particles and fluid. The solid particles are red blood cells , white blood cells , and platelets , and are commonly called the formed elements . Red blood cells White blood cells Platelets
Red blood cells (RBC) = erythrocytes White blood cells (WBC) = leukocytes Platelets = thrombocytes Remember!!! These are the FORMED ELEMENTS
Red blood cells carry O 2 & CO 2 White blood cells help fight infection Platelets help to clot the blood Remember!!! These are the functions of the FORMED ELEMENTS
The average volume of blood for a man is approximately 5 liters or 10 to12 pints . The average volume of blood for a woman is approximately 4.5 liters or 9 to 11 pints .
The formed elements can be separated from the fluid portion (or plasma) by centrifugation . When blood is spun at high speeds, it separates into three layers. plasma leukocytes & platelets erythrocytes
These three layers, from the top, are the liquid portion or plasma , the “ buffy coat ” which contains white blood cells and platelets , and the packed red cells which is all the red blood cells packed together. (***note the percentages of total volume for each) Buffy coat Packed red cells Liquid portion (Formed elements)
The percentage of the total volume that these packed red cells occupy is called the hematocrit . The normal hematocrit percentage ranges from 42 to 48% within both genders with an average of 45% . Females can go as low as 39% and males as high as 50% and still be within the “norm”. This is an important health indicator and is often ordered as a laboratory test to determine the effect of various diseases or drugs. Packed red cells 45%
Question: Why are the platelets and the white blood cells on “top” of the red cells? 55% 45% < 1% The buffy coat occupies less than 1% of the total volume of the blood.
Plasma Buffy coat Packed red cells lipids (fats), amino acids, dissolved gasses, hormones, vitamins, and metabolic waste products all dissolved in water. The last portion of this centrifuged blood is the plasma layer. Plasma is actually a very complex mixture of many components. It contains dissolved salts (giving it a composition similar to diluted seawater), non-nutrient proteins, glucose, the blood minus the RBC , WBC , and platelets . It is a straw-colored fluid which is
These solutes and colloids together make up about 8 to 10 % of the volume of plasma. A more detailed summary of the composition of plasma will follow. Plasma Buffy coat Packed red cells