Connective and supporting tissues

Blood

• is a liquid tissue circulating along the blood vessels; its volume is about 5.0-5.5 liters
• consists of the plasma (55-60% of total blood volume) and formed elements (40-45%)
• exerts the transport, trophic, respiratory, and protective functions; it participates in heat exchange as well as in maintaining osmotic and acid-base balance

Plasma

• is an intercellular substance of the blood; it is liquid (normally has no fibers but acquires fibrin strands in blood coagulation)
• contains 90-95% of water and 7-10% of dry residue comprising 6.6-8.5% of proteins and 1.5-3.5% of other organic and mineral substances

Formed elements

• these are red blood cells, platelets (thrombocytes), and white blood cells
• are formed in the red bone marrow (lymphocytic differentiation proceeds in the lymphoid organs)
• upon migration from the red bone marrow into the blood stream, they circulate in the peripheral blood, though the duration of this circulation may be different (white blood cells then move to the loose connective tissue)

Formed elements of blood

Quantitative and qualitative blood content parameters (blood test) are defined by such terms as complete blood count and white blood cell differential

The complete blood count involves data on the number of formed elements per unit of blood volume (liter or microliter), on hemoglobin content, osmotic resistance of red blood cells, sedimentation rate (ESR), etc.

The white blood cell differential reflects a proportion between various white blood cell types in the blood (percentage of the total number)

Blood smears are used to study the morphology of formed elements

Blood smear of an adult. Red blood cells and platelets

Blood smear of an adult person: reticulocytes

Blood smear of an adult person: granulocytes

Blood smear of an adult person: agranulocytes

Blood smear from a child