bone marrow

Question 1

discuss the life spans of RBCs and platelets

Answer 1

RBC- 120 days

platelet- 10 days

Question 2

where does hematopoiesis take place in the 3rd week of development?

Answer 2

in the blood islands of the yolk sac

Question 3

where does hematopoiesis take place in the 2nd trimester of development?

Answer 3

major- liver

minor- spleen

Question 4

when does the bone marrow begin to participate in hematopoiesis?

Answer 4

beginning in the 2nd trimester and persisting though adulthood

Question 5

what are blood cells derived from?

Answer 5

pleuripotent hemopoetic stem cells (HSC)

Question 6

where can HSC cells be isolated from? (4)

Answer 6

umbilical cord blood, fetal liver, fetal and adult bone marrow

Question 7

what are the 2 cell types that HSCs can differentiate into?

Answer 7

1- common myeloid progenitor

2- common lymphoid progenitor

Question 8

what cells arise from common myeloid progenitor cells?

Answer 8

neutrophils, mast cells, macrophages, platelets and erythrocytes

Question 9

what cells arise from common lymphoid progenitor cells?

Answer 9

natural killer cell, T cells and plasma cells

Question 10

describe the formation of a mature erythrocyte (10)

Answer 10

1- HSC
2- common myeloid progenitor cell
3- erythrocyte/megakaryocyte progenitor
4- erythrocyte progenitor
5- proerythroblast
6- basophilic erythroblast
7- polychromatophilic erythroblast
8- orthochromatophilic erythroblast/normoblast
9- reticulocyte
10- mature RBC

Question 11

describe a proerythroblast

Answer 11

large cell with 3-5 nucleoli, lacking hemoglobin, lots of free ribosomes that give cytoplasm blue color

Question 12

what forms when proerythroblast undergoes mitosis?

Answer 12

basophilic erythroblast

Question 13

describe a basophilic erythroblast

Answer 13

blue cytoplasm 2/2 ribosomes synthesizing hemoglobin, coarse chromatin

Question 14

what forms when basophilic erythroblast undergoes mitosis?

Answer 14

polychromatophilic erythroblast

Question 15

describe a polychromatophilic erythroblast

Answer 15

checkerboard pattern of nucleus 2/2 clumping chromatin

Question 16

what forms when a polychromatophilic erythroblast undergoes mitosis?

Answer 16

orthochromatophilic erythroblast

Question 17

describe an orthochromatophiic erythroblast

Answer 17

high amounts of hemoglobin, dark and condensed nucleus,(that will soon be extruded)

Question 18

how does a reticulocyte form?

Answer 18

nucleus of an orthochromatophilic erythroblast is extruded

Question 19

what is another name for an orthochromatophilic erythroblast ?

Answer 19

normoblast

Question 20

what is high retic count? what do high reticulocyte counts indicate?

Answer 20

over 1-2%, blood loss

Question 21

what type of stain can be used to identify reticulocytes?

Answer 21

supravital stain

Question 22

what is another name for reticulocyte?

Answer 22

polychromatophilic erythrocyte

Question 23

what hormone controls erythrocyte formation?

Answer 23

EPO

Question 24

where is EPO synthesized?

Answer 24

kidneys

Question 25

bonus- who used EPO (procrit) as a performance enhancing drug?

Answer 25

Lance Armstrong

Question 26

what causes the kidney to release EPO?

Answer 26

EPO is released in response to low blood oxygen concentration

Question 27

what happens to old RBCs?

Answer 27

they are phagocytized by macrophages n the spleen, bone marrow and liver

Question 28

what happens to the bilirubin from heme after the RBC is destroyed?

Answer 28

conjugated in the liver and secrete in bile (makes feces brown), white feces = bad

Question 29

what hormone controls platelet formation?

Answer 29

thrombopoietin from the liver and kidneys

Question 30

describe the formation of a platelet (7)

Answer 30

``` 1- HSC 2- common myeloid progenitor cell 3- megakaryocyte/erythrocyte progenitor cell 4- megakaryocyte-committed progenitor 5- megakaryoblast 6- megakaryocyte 7- platelets ```

Question 31

describe a megakaryoblast

Answer 31

large, non-lobed nucelus, participates in endomitosis to reach ploidy of 8n-64n

Question 32

what is endomitosis?

Answer 32

reproduction of nuclear elements without cytoplasmic division or chromosome movements

Question 33

describe a megakaryocyte

Answer 33

larger than a megakaryoblast, multi-lobed nucleus, platelets seen in peripheral fields

Question 34

describe thrombocytopenia

Answer 34

decreased platelets that put pt at increased risk of bleeding

Question 35

below what platelet threshold can spontaneous bleeding occur?

Answer 35

20,000

Question 36

describe the general events in week 1 and week 2 of granulopoiesis

Answer 36

week 1- mitotic (proliferative phase), stops at late myelocyte week 2- post-mitotic (differentiation) phase, metamyelocyte to mature myelocyte

Question 37

where are neutrophils stored?

Answer 37

bone marrow and vascular reserve (circulating pool)

Question 38

what causes increase in circulating neutrophils?

Answer 38

infection, inflammation, strenuous exercise

Question 39

describe the formation of a granulocyte (9)

Answer 39

``` 1- HSC 2- common myeloid progenitor 3- granulocyte/monocyte progenitor 4- myeloblast 5- promyelocyte 6- myelocyte 7- metamyelocyte 8- band/stab cell 9- neutrophil ```

Question 40

describe a promyelocyte

Answer 40

round nucleus nucleolus present basophilic cytoplasm with azurophilic granules

Question 41

describe a myelocyte

Answer 41

flattened nucelus

Question 42

what will differentiate between neutrophil, eosinophil and basophil?

Answer 42

granules present

Question 43

describe a metamyelocyte

Answer 43

kidney bean nucleus | specific granules now outnumber azurophilic granules, increasingly pale cytoplasm

Question 44

describe a band cell

Answer 44

horseshoe nucleus

Question 45

when will increased band cells be present?

Answer 45

in the setting of inflammation or infection

Question 46

describe a mature neutrophil

Answer 46

distinct, multi-lobed nucleus, fine granules +- barr body

Question 47

where is red bone marrow found?

Answer 47

medullary cavity of young long bones and spaces of spongy bone

Question 48

what cell cords are contained in red marrow? (4)

Answer 48

hemopoietic cells, macrophages, mast cells and adipose cells

Question 49

where are megakaryocytes located in the bone marrow?

Answer 49

next to the sinusoid wall, discharge platelets directly into sinusoids

Question 50

describe the structure and function of sinusoids

Answer 50

sinusoids are specialized blood vessels that separate the marrow cavity from the peripheral circulation, located between artery and vein

Question 51

what do sinusoids contain?

Answer 51

endothelia, basal lamina, and adventitial cells

Question 52

described adventitial cells

Answer 52

send sheet-like extensions into the hemopoietic cords to provide support for developing cells

Question 53

what is another term for adventitial cells?

Answer 53

reticular cells

Question 54

how do newly formed cells exit the marrow?

Answer 54

penetrate the endothelia

Question 55

is the bone marrow considered open or closed?

Answer 55

closed

Question 56

what is the primary composition of yellow marrow?

Answer 56

adipose tissue

Question 57

in what members of the population is yellow marrow more prevalent?

Answer 57

adults

Question 58

can yellow marrow conduct hemopoiesis?

Answer 58

it is not active, but retains the potential for activity

Question 59

what disease occurs when too much marrow is replaced with fat?

Answer 59

aplastic anemia

Question 60

what equation can be used to calculate the expected decrease in bone marrow cellularity with age?

Answer 60

(100-Age) +/- 10%

Question 61

practice question- what is the expected bone marrow cellularity for a 30 year old?

Answer 61

(100-30) +/- 10% = 60-80%

Question 62

in what condition is the marrow hypercellular?

Answer 62

acute myeloid leukemia

Question 63

through which bone are bone marrow biopsies typically extracted?

Answer 63

iliac crest (avoiding sinusoids)