Hematology: Origins of Blood Cells Flashcards Preview

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Flashcards in Hematology: Origins of Blood Cells Deck (19):
1

Hematopoietic tissue

in embryo: yolk sac

in fetus: liver and spleen

in adult: bone marrow; liver and spleen can make blood cells if needed= extra-medullary hematopoiesis (EMH)

2

Young marrow vs. older marrow

Young= red, active marrow

young animal produces high numbers of blood cells.

older= yellow marrow in middle, with fat and supporting cells. network of reticular cells. 

red marrow still exists at ends of long bones and flat bones

3

Broad overview of commitment of cell lines

Multipotent stem cell--> primitive progenitor cells CMP or CLP

CMP--> committed precursor cells MEP and GM

MEP (erythroid line): platelets and RBCS

GM: monocytes, neutrophils, eosiniphils and basophils

CLP--> committed precursors TNK and BCP

TNK: T-cells and natural killer  cels

BCP: B-cells. 

4

Erythropoiesis

Bone marrow: (proliferating mitotic pool) multipotent stem cell-->unipotential stem cell--> rubriblast/proerythroblast-->prorubricyte/basophilic erythroblast/early normoblast--> rubricyte/polychromatophilic erythroblast

Post-mitotic pool: -->metarubricyte/orthocromatic erythroblast/late normoblast--> reticulocyte-->

in blood: erythrocyte

First recognizable cells: rubriblast/proerythroblast- first cell we can see on a microscope. blue nucleus. nucleus starts to get small and darker.

Normoblast/metarubricyte: shiny black nucleus, can see it poking out of side of cell. 

5

Reticulocyte and normoblast appearances

Normoblast: dark nucleus poking out of side of cell

Reticulocyte: on new methylene blue stain: supervital stain taken up-- dotted blue throughout cell. 

 

 

6

Life of an erthyrocyte

Bone marrow: 3-5d

Reticulocute: maturation in blood for 2 days

Mature RBC: 100 day life span

Aged/damaged rbcs to SPLEEN, liver and BM by macrophages. 

Spleen recycles iron and bilirubin and protein; iron to bone marrow and bilirubin to liver. 

Bilirubin transported to liver by albumin and liver conjugates it to make it water souble; removed in bile. 

Splenic sequestration: horses and some dogs- when stressed, can show up as a transient erythrocytosis- normalizes after 30 mins. 

 

7

RBC life span in circulation: species differences

Dog: 120 days

Horse: 145 days

Cat: 70 days

Cow: 130 days

Mice: 43 days 

8

Erythropoietin

Hormone produced by kidney

disease of kidney affect ability to produce EPO: chronic renal failure-->less able to produce EPO--> unable to replace RBCs

Stimulates proliferation of erythroid progenitors (precursors)

Fundamental stimulus to EPO production is hypoxia--> if levels of O2 in blood decrease, kidney stimulates EPO production, increased blood cell production. 

9

Granulopoiesis-white cells

Bone marrow: multipotential stem cell-->unipotential stem cell-->myeloblast

Myeloblast=first recognizable cells. Big, pinky nucleus; nucleoli, light blue cytoplasm

Myeloblast-->promyelocyte (pink granules)-->myelocyte-->metamyelocyte

Maturational post mitotic pool: metamyelocyte (bean-shaped nucleus)--> band neutrophils (horseshoe shaped nucleus)-->mature neutrophils/segmenters (storage pool). 

10

Life of a neutrophil

6 days to get produced in bone marrow

circulating neutrophil--> marginating neutrophil--> tissues (7-14 hours)

Once in tissues, lost from body surfaces or destroyed by macrophages.

N'phils in 2 pools: 

circulating: central column of blood- that's what we see when we take a blood sample

marginating: creep along blood vessel walls looking for damage triggers (receptors, CKs); squeeze through walls and into tissues. 

No re-entry into circulation occurs after emigration into tissue. 

11

Lives of other leukocytes

eosinophils: take 2-6 days to develop in BM--> 1-24 hours in circulation--> exit to tissue (skin, GI, resp)--> last for 2d to 2weeks

Monocytes: have short transit time in blood-->recruited into tissue where the differentiate into macrophages (lifespan is variable)

12

Lymphocyte kinetics

lymphocytes-lymphopoiesis occurs in BM (B-cells) or thymus (T-cells) 

can keep reycling lymphocytes. 

13

Species differences

Red cell size: dogs>horses>cats>ruminants

No release of immature red cells (reticulocytes) from BM in horses, even when they're anemic. Need to take serial samples in monitoring anemia.

Rouleaux formation: in horses (normal), in cats, sign of inflammation. Negative charge prevents RBCs from sticking. With increased blood viscosity, RBCs stack. In cat inflammation, lots of globulin-->viscous blood.

Breed differences: healthy greyhounds have an increased number of RBCS, greater than other breeds. 

Age: very young animals tend to have lower RBCs than mature adult

Seals have HUGE rbcs, llamas have bery small and elliptical rbs.

with immune-mediated destruction of RBCs, almost impossible to tell difference between a spherocyte and a small RBC. 

14

Cat RBCs and WBCs

eosinophils: more rod shaped granules

basophil: don't see many in dogs and cats, but sometimes looks like nucleus has holes in it

RBC: less obvious areas of central pallor 

15

Cow blood

v. small RBCs

lymphocytes: quite large in circulation

16

Horse blood

Rouleaux formation

eosinophil looks like a raspberry

17

Rabbit blood

tend to see more reticulocytes in lagomorphs and rodents (healthy) likely due to shorter lifespan of RBCs. 

 

18

Reptile and fish blood

reptile (lizard): n'phil equivalent=heterophil. have staining granules

platelets= ragged cytoplasmic edges

nucleated rbcs

fish: nucleated rbcs. 

19

Hematology values

RBC: erythrocyte concentration

Hb: hemoglobin

HCT: hematocrit= PCV (packed cell volume): volume percentage of RBCs in blood

MCV: mean cell volume

MCHC: mean cellular hemoglobin concentration

RDW: red cell distribution width (don't often look at this)

WBC: leukocyte concentration

PLT: platelet concentration

Normoblasts: nucleated red blood cells.