Blood in Humans
4-6 liters per adult
8% of body weight
Functions of blood
Components of Blood
red blood cells are produced in
red bone marrow
Erythropoietin
hormone that stimulates cells of the bone marrow to increase the production of red blood cells
RBC count
normally between 4 - 6.5 million rbc/ml
Polycythemia
increase in red blood cells, causes blood to be thicker and more dense; excessive blood cells than plasma
Hematocrit
Hemoglobin
carries oxygen to the body
Neutrophils
55%; elevated in bacterial infections (most numerous of all the WBCs)
Eosinophils
3%; elevated in asthma, allergic reactions and parasite infections
Basophils
1%; release histamine and heparin, promote inflammation
Lymphocytes
make antibodies, increased in viral infections (AIDS); T cells, B cells
Monocytes
Platelets
thrombocytes; needed for the clotting process
Normal count of platelets
130,000 to 360,000 per cubic millimeter of blood
Thrombocytosis
high platelet levels
Thrombocytopenia
low platelet levels
Plasma
serum after centrifugation
components of plasma
Hemostasis
control of bleeding, stopping of a flow of blood
Coagulation
process of clotting, formation of a blood clot
Thrombus
stationary clot
Embolus
traveling clot