—low WBC count: below 5,000 WBCs/mL
–Causes: radiation, poisons, infectious disease
–Effects: elevated risk of infection
Leukopenia
—high WBC count: above 10,000 WBCs/mL
–Causes: infection, allergy, disease
Leukocytosis
—cancer of hemopoietic tissue that
usually produces an extraordinary high number of circulating leukocytes and
their precursors
Leukemia
What are the four kinds of leukemia? What are teh effects?
–Myeloid leukemia: uncontrolled granulocyte production
–Lymphoid leukemia: uncontrolled lymphocyte or monocyte production
–Acute leukemia: appears suddenly, progresses rapidly, death within months
–Chronic leukemia: undetected for months, survival time 3 years
–Effects: normal cell percentages disrupted; impaired clotting; opportunistic infections
—the cessation of bleeding
–Stopping potentially fatal leaks
–Hemorrhage: excessive bleeding
Hemostasis
•Three hemostatic mechanisms
–Vascular spasm
–Platelet plug formation
–Blood clotting (coagulation)
—small fragments of megakaryocyte cells
Platelets
–Stem cells (that develop receptors for thrombopoietin) become megakaryoblasts
•Thrombopoiesis
–Repeatedly replicate DNA without
dividing
–Form gigantic cells called
megakaryocytes with a multilobed nucleus
•100 mm in diameter, remains in bone
marrow
•Megakaryoblasts
—live in bone marrow adjacent to blood sinusoids
–Long tendrils of cytoplasm (proplatelets)
protrude into the blood sinusoids: blood flow splits off fragments called
platelets
–Circulate freely for 10 days
–40% are stored in spleen
Megakaryocytes
•Clot retraction occurs within __ minutes
30
—dissolution of a clot
–Factor XII speeds up formation of kallikrein enzyme
–Kallikrein converts plasminogen
into plasmin, a fibrin-dissolving enzyme that breaks up the clot
Fibrinolysis
—abnormal clotting in unbroken vessel
Thrombosis
–clot
•Most likely to occur in leg veins
of inactive people
Thrombus
–clot may break free, travel from veins to lungs
Pulmonary embolism
—anything that can travel in the blood and block blood vessels
Embolus
(tissue death) may occur if clot blocks blood supply to an organ (MI or stroke)
–650,000 Americans die annually of
thromboembolism (traveling blood clots)
Infarction