Blood Histology Flashcards
Components of Blood
Plasma – the ECM
Plasma is 90% water; remaining 10% are solutes (electrolytes, antibodies, clotting factors)
Serum = plasma w/o clotting factors
Bottom of tube: RBCs
Middle of tube: buffy coat with WBCs and platelets
Top of tube: plasma
RBCs + WBCs+platelets = formed elements
Hematocrit
Hematocrit: packed RBC volume
men: 40-50% women: 35-45% newborns: 45-60%
Platelets
anucleated
7-10 day lifespan
produced by megakaryocytes from cytoplasm
Lymphocytes
20-35% of WBCs
Round, heterochromatic nucleus with little cytoplasm
Recognize and respond to Ag
B cells: produce circulating Ab and mature in bone marrow
T cells: cell mediated immunity and mature in thymus
NK cells: kill virus infected cells and tumor cells
Live several years, but T cells live longest and most numerous compared to B cells
Monocytes
3-8% of WBCs
Largest of all WBCs
indented, C shaped nucleus
stays in circulation for a few days then into CT and differentiate into macrophages
Survive for months
Act as Ag presenting cells, and phagocytose pathogens, tissue debris, and dead PMNs and bacteria
Mononuclear Phagocytic System
Osteoclasts - in bone Microglia - in NS, but not formed from monocytes Macrophage - in CT Langerhans - epidermis Dendritic - lymph nodes and spleen Alveolar Macrophage - lungs Kupfer cells - liver
Agranulocytes
Monocytes and Lymphocytes
contain only non-specific granules such as lysosomes with typical hydrolytic enzymes
Granulocytes
Neutrophils, Eosinophils, and Basophils
contain lysosomes + respective specific granules
live a few days and do most of their work in CT and organs
Neutrophils
Most numerous WBC (60-70%)
Nucleus has 3-5 lobes, which increase with age
Contain Barr bodies (drumstick shape)
Salmon pink cytoplasm
Phagocytosis of bacteria and foreign organisms
Are in the blood for 8-12 hours then CT
First responder and attracted to site of inflammation via chemotaxis
Induce fever via IL-1
After organism digestion, neutrophil dies to form pus
Neutrophil Granules
Azurophilic Primary Lysosomes: contain myeloperoxidase (bleach), defensins (plasma membrane), and other hydrolytic enzymes
Specific Secondary: most abundant containing type IV collagenase (basement membrane), lactoferrin (bind iron), lysozyme (gram + bacteria cell wall)
Tertiary: matric metalloproteinases (MMPs) like collagenase ad gelatinase
WBC Count Highest to Lowest
Neutrophils, Lymphocytes, Monocytes, Eosinophils, and Basophils
Never Let Monkeys Eat Bananas
Neutrophilic Phagocytosis
Enhanced if coated with IgG or complement = opsonization
Specific granules fuse with phagosome and pH lowers via proton pumps
Bacteria killed by:
- High reactive superoxide anions produced by initial O2 burst
- Lysozyme destroys cell wall of gram + bacteria
- Lactoferrin binds iron to deprive bacteria of nutrient source
Eosinophils
2-4% of WBCs
Bi or Tri lobed nucleus with red/pink granules
8-12 days in CT and 3-4 hours in blood
Allergic and inflammatory reactions and parasitic infections
Moderate effects of basophils and mast cells
Often found in chronic inflammation in CT of respiratory, digestive, or vaginal tracts
Eosinophil Granules
highly acidophilic and eosinophilic (- charge)
Neurotoxins: major basic protein and attacks parasites
Histaminase: moderates allergic reactions
Arylsulftase: neutralizes leukotrienes, especially in airways
Eosinophil peroxidase: anti-bacterial and anti-parasitic
Azurophilic (lysosomes): hydrolytic enzymes, anti-parasitic, and phagocytosis of Ag-Ab complexes
Basophil Granules
basophilic
Heparin: anticoagulant
Histamine and Heparin Sulfate: vasodilators
Leukotrienes: constrict smooth muscle of pulmonary airways and maintain inflammation
Erythrocytes
Most numerous blood cell and transport O2 and CO2 via Hb
Only contained in blood unless bleeding occurs
Biconcave for max surface area for gas exchange and highly deformable (flexible cytoskeleton)
Lifespan of 120 days then destroyed by spleen, marrow, and liver macrophages (90%) and intravasculary (10%)
Anisocytosis, Hypo/Hyperchromic, and Poikilocytosis
Anisocytosis: variable in size
Hypochromic: low Hb than normal
Hyperchromic: high Hb than normal
Poikilocytosis: varies in shape
RBC Cytoskeleton
Changes in glycophins with cell age and trigger elimination via macrophages
Band 3 acts anion antiporter by Cl- in and HCO3- out during Cl shift
Extracellular portion where different sugars attach to glycophorins to contribute to blood groups/types
Spectrin: cytoskeletal filaments that determine shape
Protein Defects
result in fragile or deformed RBCs
Spherocytosis: spectrin gene mutation
Elliptocytosis: band 4.1 gene mutation
Bone Marrow
With age, red marrow is replaced by fat = yellow marrow
At middle age, most appendicular skeletal has yellow marrow
Sites of Hematopoiesis
Fetal: 2-6 weeks occurs in blood islands in body stalks and yolk sac, then at 6 weeks liver and spleen are major sites, then 7-9 months bone marrow is primary
4-5 years: red marrow in all bones, then tibia and fibula contain yellow marrow
Adult: red marrow confined to vertebrae, sternum, ribs, skull, pelvis, and proximal ends of long bones
Hematopoiesis
As time goes on the size decreases, the nucleus will condense and eventually come out (extrude), and cytoplasm gets less basophilic
Middle of phase will start the production of Hb until RBC is essentially a sack of Hb
First and Second Erythropoiesis Stage
- Proerythroblast – one or two nucleoli that appear light (opposite to that expected); basophilic cytoplasm (due to many polyribosomes [free ribosomes, NOT rER!]) with a perinuclear Golgi halo
- Basophilic erythroblast – smaller than a proerythroblast; nucleoli generally not seen; cytoplasm still basophilic due to many free ribosomes (polyribosomes).
Third and Fourth Erythropoiesis Stage
- Polychromatophilic erythroblast has muddy gray cytoplasm due to the increased amount of hemoglobin (eosinophilic) mixed with the free ribosomes (basophilic) in the cytoplasm.
Starting to make Hb and will stain with eosin so starts to become pinker
Nucleus is checkered – characteristic - The orthochromatophilic erythroblast is no longer capable of cell division, smaller, and contains even more Hb
Nucleus is more condensed and moving to periphery for extrusion
Final Erythropoiesis Stage
Reticulocytes typically account for about 0.8% of RBCs in the adult circulation. They mature fully within 24 hrs of entering the circulation.
Reticulocytes are also called polychromatophilic erythroCYTES (not to be confused with polychromatophilic erythroBLASTS).
Popped out its nucleus with few ribosomes left and formed in bone marrow, but will then circulate in blood until extrude the rest of the ribosomes to become fully mature, so have few reticulocytes in circulation
Timeline of RBCs
The number of erythrocytes released from bone marrow each day is about the same number destroyed in the spleen.
Macrophages degrade hemoglobin and send the iron to the liver, bone marrow, and spleen via the iron-transporting protein transferrin.
Mature RBCs are not capable of mitosis because no nucleus; only the proerythroblast, basophilic erythroblast, and polychromatophilic erythroblast stages are able to under mitosis
Erythropoietin
EPO: made by endothelial cells in peritubular capillaries in kidney cortex and forms RBCs in response to decreased O2 in blood (in high altitudes, different forms of anemia, or hemorrhage) and this will cause more reticulocytes in the circulation than normal
Downside: blood doping; too much RBCs in the blood can clog the smaller capillaries and cause organ damage to liver and kidneys (more vascularized)
Basophils
Less than 1% of all WBCs
Lobed nucleus, usually obscured by granules
Travels 8 hours in blood
Few or no lysosomes, so little phagocytic activity
