1. starts with haematopoietic stem cell which differentiates into a common myeloid progenitor & then into mega karyocyte-erythroid progenitor 2. Further differentiation results in commitment to the erythroid lineage. 3. As the erythroid cells mature, they become smaller, have more condensed chromatin, lose their nucleoli & their cytoplasm changes from blue to pink 4. Eventually, the nucleus is extruded, resulting in a reticulocyte. Most of the process takes places in the bone marrow over 3 weeks 5. the resulting reticulocyte retains some ribosomal RNA to make heamoglobin & after 1-2 days in the bone marrow, it enters the peripheral blood where RNA is lost after 1-2 days resulting in a mature RBC

1. The first cell that starts to resemble a granulocyte is myeloblast. 2. Next developmental stage, a promyelocyte, still has a large oval nucleus, but there is more cytoplasm in the cell at this point, also cytoplasmic granules are beginning to form 3. Development stage continues with next stage, myelocyte. Nucleus starts to shrink 4. At the stage of a metamyelocyte, the cell nucleus is becoming kidney-shaped & it becomes even more bent in the stage of a band cell 5. The maturation is finished with the emergence of a segmented nucleus that is specific for a mature granulocyte

Structure and function of blood Flashcards by Rosemary Ndara

erythocytes

red blood cells

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Leukocytes

white blood cells

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formation of blood components ( red & white blood cells & platelets), from heamatopoietic stem cells ( HSCs)

haematopoiesis

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site of haematopoiesis for foetus:

0-2 months- yolk sac
2-7 months- liver & spleen
5-9 months- bone marrow

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site of haematopoiesis for infants

bone marrow

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site of haematopoiesis for adulthood

axial skeleton ( vertebral bones, ribs & sternum, sacrum, pelvis)

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Pluripotent

have the ability to undergo self renewal & to give rise to all cells of tissues of the body

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multipotent

can develop into more than one cell type; they demonstrate the ability to self-renew or to differentiate into specialised cell types present in a specific tissue or organ

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formation of red blood cells is called?

erythropoiesis

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eryrhropoiesis steps

starts with haematopoietic stem cell which differentiates into a common myeloid progenitor & then into mega karyocyte-erythroid progenitor
Further differentiation results in commitment to the erythroid lineage.
As the erythroid cells mature, they become smaller, have more condensed chromatin, lose their nucleoli & their cytoplasm changes from blue to pink
Eventually, the nucleus is extruded, resulting in a reticulocyte. Most of the process takes places in the bone marrow over 3 weeks
the resulting reticulocyte retains some ribosomal RNA to make heamoglobin & after 1-2 days in the bone marrow, it enters the peripheral

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eryrhropoiesis steps

starts with haematopoietic stem cell which differentiates into a common myeloid progenitor & then into mega karyocyte-erythroid progenitor
Further differentiation results in commitment to the erythroid lineage.
As the erythroid cells mature, they become smaller, have more condensed chromatin, lose their nucleoli & their cytoplasm changes from blue to pink
Eventually, the nucleus is extruded, resulting in a reticulocyte. Most of the process takes places in the bone marrow over 3 weeks
the resulting reticulocyte retains some ribosomal RNA to make heamoglobin & after 1-2 days in the bone marrow, it enters the peripheral blood where RNA is lost after 1-2 days resulting in a mature RBC

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As the erythroid cells mature, they become smaller and ?

have more condensed chromatin, lose their nucleoli & their cytoplasm changes from blue to pink

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erythroid lineage

The proerythroblast is the earliest morphologically identifiable bone marrow red cell precursor characterised by a large cell with high nuclear to cytoplasmic ratio, prominent nucleoli & blue cytoplasm (presence of RNA)

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Maturation of erythroid precursors and iron uptake takes how long? and happens where?

3 weeks and in the bone marrow

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RBC lifespan takes how long and happens where?

120 days and in the peripheral blood

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thrombopoiesis is?

the formation of thrombocytes (blood platelets)

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what is the main regulator of thrombopoiesis?

thrombopoietin

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process of thrombopoiesis is caused by?

the breakdown of proplatelets

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proplatelets is?

mature megakaryocyte membrane pseudopodal projections

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thrombopoiesis affcets most aspects of the production of platelets , including?

self-renewal & expansion of hematopoietic stem cells, stimulating the increase of megakaryocyte progenitor cells & support, & supporting these cells so they mature to become platelet-producing cells

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stem cell to platelets process (short ver. )

stem cell = multipotent progenitor = committed megakaryocyte-progenitor cell = immature megakaryocyte = mature megakaryocyte = platelets

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granulopoiesis is ?

fromation of granulocytes

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granulocytes and monocytes are formed from?

common precursor cells

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granulopoiesis steps

The first cell that starts to resemble a granulocyte is myeloblast.
Next developmental stage, a promyelocyte, still has a large oval nucleus, but there is more cytoplasm in the cell at this point, also cytoplasmic granules are beginning to form
Development stage continues with next stage, myelocyte. Nucleus starts to shrink
At the stage of a metamyelocyte, the cell nucleus is becoming kidney-shaped & it becomes even more bent in the stage of a band cell
The maturation is finished with the emergence of a segmented nucleus that is specific for a mature granulocyte

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myeloblast is charaterised by?

a large oval nucleus that takes up most of the space in the cell & very little cytoplasm

Lymphopoiesis is?

generation of lymphocytes (type of wbc)

Lymphocytes include:

T cells (subdivided into helper, memory & cytotoxic T cells) B cells ( subdivided into plasma cells & memory B cells) and NKs

Haematopoietic growth factors bind where? and stimulate?

to cell surface transmembrane receptors, stimulate growth & survival of progenitors

Haematopoietic growth factors: Some stimulate early progenitors example

IL-3, Stem cell factor ( SCF)

Haematopoietic growth factors: Some stimulate late progenitors example

M-CSF ( monocyte- CSF)

Haematopoietic growth factors: Some specific to one lineage e.g.:

erythropoietin - others stimulate several different lineages

structure of rbcs (erythrocytes)

bioncave dics no nucleus & dont contain DNA,RNA or mitochondria

major constituent of RBCs is?

Haemoglobin (Hb)

structure of Hb

protein tetramer made up of 4 polypeptide chains Adult Hb has 2 alpha & 2 beta globin chains Each globin chain carries a haem molecules The haem holds a feerous ( Fe2+) iron atom Oxygen binds reversibly to the iron atom

list types of leukocytes

neutrophils, eosinophils, basophils =(granulocytes)+ lymphocytes, monocytes

agranulocytes are?

mononuclear cells : wbc that simply lack any granules within their cytoplasm

granulocytes are?

type of wbc- prominent cytoplasmic granules

characteristics of platelets (thrombocytes)

-membrane bound cytoplasmic fragments no nucleus contains granules

3 functions of blood

transport defence homeostasis

role of RBCs:

transport oxygen bound to Hb from lungs to body tissues + help in removal of CO2 from body tissues- lungs

role of neutrophils

phagocytose & kill bacteria & fungi main mediators of innate immunity

role of lymphocytes

main mediators of adaptive (acquired) immunity produce antibodies kill virus infected cells

eosinophils function

kill parasites involved in allergic responses

basophils

kill parasites involved in allergic responses involved in inflammation

monocytes (macrohges)

phagocytose dead cells & pathogens

total wbc count is important for?

diagnosing infection

defence role of platelets

-major role = primary haemostasis recognise damage at blood vessel wall form a platelet prevent/stop bleeding

one Hb can bind to how many o2 molecules?

4 - lesss than 0.01 sec required for oxygenation

role of 2,3-DPG when 02 is unloaded?

substance made in RBCs & it controls the movement of oxygen from RBCs to body tissues-- lower affinity of O2

when are beta chains in Hb pulled apart?

when o2 is unloaded

what happens when Hb is oxygenated?

2,3-DPG is pushed out; beta chains move closer

O2 amount bound to Hb & released to tissues depends on;

PO2 PCO2 Afiinity of Hb for O2

oxygen affinity determines?

proportion of O2 released to tissues or loaded onto the cell at a given oxygen pressure

increased oxygen affinity means? O2

binds more & strongly

decresed oxygen affinity means? O2

O2 is released

Hb that is fully saturated with 02 is called?

oxyhaemoglobin - bright red

Hb that has lost all O2 is called?

deoxyhaemoglobin - dark red

pulse oximetry measures?

colour of Hb- determines if patient is hypoxic

pulse oximetry is based on the principle that O2Hb?

absorbs more near-infared light than HHb, & HHb absorbs more red light than O2Hb

fluid component of whole blood that transports cells

plasma

plasma consists of?

water- 90% plasma proteins 6-8% electrolytes ( Na+, Cl-) other components: glucose, amino acids, hormones (thyroxine, cortisol), waste (urea), blood gases (e.g. CO2)

role of albumin in plasma

- made by liver; helps keep fluid in your bloodstream so it doesnt leak into other tissues & also carries various substances throughout your body including hormones, vitamins & enzymes)

fluid left after blood clotting

serum

examples of tests that work better with serum than plasma

LFT( liver function test), U & Es (urea & electrolytes)

some blood tests require unclotted blood so use?

anticoagulants e.g. EDTA

role of globulins in plasma transport

(alpha & beta) include carrier proteins to transport metal ions (e.g. Ca2+, Fe2+, Cu2+) - transferring transports iron

role of plasma in transport

- plasma & proteins transport nutrients - removes nitrogenous waste products -TO KIDNEY/LUNGS FOR EXCRETION -transports respiratory gases e.g.C02

Co2 is dissolved in plasma or ?

converted to HC03-

Plasma in defence- immunity

delta-globulin: immunoglobulin (Ig) - made by B lymphocyctes- act as body's defence Complement proteins: kill bacteria & other pathogens + cooperate with Ig & wbcs

role of plasma defence - heamostasis:

coagulation factors: fibrinogen plays major role in blood clotting Fibrinlgen is converted to fibrin, forms blood clot fibrin clot reinforces primary platelet plug

Homeostasis is

keeping the internal body environment constant

regulation of acid-base balance is achieved how?

plasma proteins through buffering action, mainting pH at 7.4

regulation of body temp is achieved how?

balance between heat loss and heat gain in the body

coloidal osmotic pressure (COP)

the osmotic pressure exerted by large molecules, serves to hold water within the vascular space. normally created by plasma proteins, that dont diffuse readily across the capillary membrane

COP is maintained at around?

25 mmHg by plasma proteins

Hb concentration units:

g/L

overall concentration of Hb in blood is used to ?

diagnose anaemia

full blood count (FBC)includes:

Hb concentration Mean (red) cell volume (MCV): size of RBCs Mean (red) cell haemoglobin content(MCHC) :how much Hb in each red cell Hamatocrit (Ht or Hc)

polycythaemia also known as? means?

erythrcytosis means having high concentration of RBCs in your blood