Blood Histology

Question 1

Components of Blood

Answer 1

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

Question 2

Hematocrit

Answer 2

Hematocrit: packed RBC volume

men: 40-50%
women: 35-45%
newborns: 45-60%

Question 3

Platelets

Answer 3

anucleated
7-10 day lifespan
produced by megakaryocytes from cytoplasm

Question 4

Lymphocytes

Answer 4

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

Question 5

Monocytes

Answer 5

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

Question 6

Mononuclear Phagocytic System

Answer 6

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

Question 7

Agranulocytes

Answer 7

Monocytes and Lymphocytes

contain only non-specific granules such as lysosomes with typical hydrolytic enzymes

Question 8

Granulocytes

Answer 8

Neutrophils, Eosinophils, and Basophils
contain lysosomes + respective specific granules
live a few days and do most of their work in CT and organs

Question 9

Neutrophils

Answer 9

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

Question 10

Neutrophil Granules

Answer 10

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

Question 11

WBC Count Highest to Lowest

Answer 11

Neutrophils, Lymphocytes, Monocytes, Eosinophils, and Basophils
Never Let Monkeys Eat Bananas

Question 12

Neutrophilic Phagocytosis

Answer 12

Enhanced if coated with IgG or complement = opsonization
Specific granules fuse with phagosome and pH lowers via proton pumps

Bacteria killed by:

1. High reactive superoxide anions produced by initial O2 burst
2. Lysozyme destroys cell wall of gram + bacteria
3. Lactoferrin binds iron to deprive bacteria of nutrient source

Question 13

Eosinophils

Answer 13

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

Question 14

Eosinophil Granules

Answer 14

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

Question 15

Basophil Granules

Answer 15

basophilic
Heparin: anticoagulant
Histamine and Heparin Sulfate: vasodilators
Leukotrienes: constrict smooth muscle of pulmonary airways and maintain inflammation

Question 16

Erythrocytes

Answer 16

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%)

Question 17

Anisocytosis, Hypo/Hyperchromic, and Poikilocytosis

Answer 17

Anisocytosis: variable in size
Hypochromic: low Hb than normal
Hyperchromic: high Hb than normal
Poikilocytosis: varies in shape

Question 18

RBC Cytoskeleton

Answer 18

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

Question 19

Protein Defects

Answer 19

result in fragile or deformed RBCs
Spherocytosis: spectrin gene mutation
Elliptocytosis: band 4.1 gene mutation

Question 20

Bone Marrow

Answer 20

With age, red marrow is replaced by fat = yellow marrow

At middle age, most appendicular skeletal has yellow marrow

Question 21

Sites of Hematopoiesis

Answer 21

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

Question 22

Hematopoiesis

Answer 22

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

Question 23

First and Second Erythropoiesis Stage

Answer 23

1. 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
2. Basophilic erythroblast – smaller than a proerythroblast; nucleoli generally not seen; cytoplasm still basophilic due to many free ribosomes (polyribosomes).

Question 24

Third and Fourth Erythropoiesis Stage

Answer 24

3. 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
4. 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

Question 25

Final Erythropoiesis Stage

Answer 25

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

Question 26

Timeline of RBCs

Answer 26

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

Question 27

Erythropoietin

Answer 27

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)

Question 28

Basophils

Answer 28

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