Structure and function of blood Flashcards
erythocytes
red blood cells
Leukocytes
white blood cells
formation of blood components ( red & white blood cells & platelets), from heamatopoietic stem cells ( HSCs)
haematopoiesis
site of haematopoiesis for foetus:
0-2 months- yolk sac
2-7 months- liver & spleen
5-9 months- bone marrow
site of haematopoiesis for infants
bone marrow
site of haematopoiesis for adulthood
axial skeleton ( vertebral bones, ribs & sternum, sacrum, pelvis)
Pluripotent
have the ability to undergo self renewal & to give rise to all cells of tissues of the body
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
formation of red blood cells is called?
erythropoiesis
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
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
As the erythroid cells mature, they become smaller and ?
have more condensed chromatin, lose their nucleoli & their cytoplasm changes from blue to pink
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)
Maturation of erythroid precursors and iron uptake takes how long? and happens where?
3 weeks and in the bone marrow
RBC lifespan takes how long and happens where?
120 days and in the peripheral blood
thrombopoiesis is?
the formation of thrombocytes (blood platelets)
what is the main regulator of thrombopoiesis?
thrombopoietin
process of thrombopoiesis is caused by?
the breakdown of proplatelets
proplatelets is?
mature megakaryocyte membrane pseudopodal projections
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
stem cell to platelets process (short ver. )
stem cell = multipotent progenitor = committed megakaryocyte-progenitor cell = immature megakaryocyte = mature megakaryocyte = platelets
granulopoiesis is ?
fromation of granulocytes
granulocytes and monocytes are formed from?
common precursor cells
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
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
