Leukocytes, Platelets, and Hemostasis Study Guide Flashcards
amount of leukocytes in a microliter (ul) of blood
4,800 to 10,800 (less than erythrocytes)
diapedesis
how leukocytes cross blood vessel walls to travel to areas of need
Positive Chemotaxis
phenomenon in which damaged/infected cells provide a chemical trail for leukocytes to follow
Leukocytosis
elevated number of leukocytes (> 11,000/µl)
Leukopenia
decreased number of leukocytes
5 types of leukocytes in order of abundance
Neutrophils (Most Abundant)
Lymphocytes.
Monocytes.
Eosinophils.
Basophils (Least Abundant)
Agranulocytes
Lymphocytes
Monocytes
Granulocytes
Neutrophils
Eosinophils
Basophils
Lymphocytes
- Account for 25% of all leukocytes
- Often classified by diameter – small, medium, and large
- Largely live in lymphoid tissues – lymph nodes and spleen – versus the bloodstream
- T Lymphocytes (T-Cells): directly fight against virus-infected and tumor cells
- B Lymphocytes (B-Cells): give rise to antibody-producing plasma cells
Monocytes
- Account of 3-8% of all leukocytes
- Are the largest of all leukocytes
- Differentiate into highly mobile macrophages with enormous appetites
- Able to activate lymphocytes to mount an immune response
Neutrophils
- The most numerous type of leukocyte (50-70% of all leukocytes)
- Function as “bacteria-slayers” - very active phagocytes
- Are chemically attracted to inflammation
Eosinophils
- Account for 2-4% of all leukocytes
- Lead the counter-attack against parasitic worms and other things too large to be phagocytized
- Play a role in responding to allergens and modulating the overall immune system response
Basophils
- Rarest leukocytes (0.5-1%)
- Granules contain Histamine – an inflammatory chemical that vasodilates vessels and attracts other leukocytes - and Heparin - an anticoagulant that assists the mobility of other leukocytes
What stimulates the creation of leukocytes?
Chemical messengers called interleukins or colony-stimulating factors (CSFs)
blood cells that differentiate from the myeloid line
monocytes (following monoblast and promonocyte)
blood cells that differentiate from the lymphoid line
Lymphocytes
- T Lymphocyte Precursors give rise to immature T-Cells which mature in the thymus
- B Lymphocyte Precursors give rise to immature B-Cells which mature in the bone marrow