Transcript red blood cells

Blood
and
hemopoiesis
Lecture, 26.4.2012
Blood
structure and function
•
•
•
•
•
•
•
•
•
•
„connective tissue“ (cells and ECM )
blood cells and plasma
erythrocytes (red blood cells)
leukocytes (white blood cells)
platelets
serum – differs from plasma by the
absence of factors (oraganic and
anorganic), which leave plasma during
coagulation (has been involved in clot)
hematocrit - the volume of combined
formed elements in the blood after
centrifugation
erythrocytes – 43%
leukocytes and paltelets (buffy coat) 1%
40-50% male
30-40% female
Blood
structure and function
• total volume 5,5L
• transport : oxygen, CO2, nutrients, waste products,
hormones…
• maintaining of acid/base and osmotic balance, body
temperature
• plasma: water, proteins (albumin, globulins, clotting
proteins, complement, lipoproteins), inorganic salts, ions,
nitrogenous compounds, nutrients, gases
Formed elements
Erythrocytes
red blood cells








biconcave-shaped discs without nuclei
size: 7,5 x 2,6 μm (in the middle only 0,8 μm)
shape provides the cell with larger surface area thus enhancing its
capability for the exchange of gases
number: 3,9 – 5,5 milions in 1μL
it depends on age, gender, race and other factors as diet,altitude ect. Therefore,
every country has to determinate and statistically calculate reference values.
plasmalemma (integral proteins: glycophorins, ion channels, anion
transporters), subplasmalemmal cytoskeleton (spectrin, actin
tetramers).. hemoglobin (33%), enzymes: glycolysis, hexosemonophosphate shunt
they survive 120 days in circulation
oligosacharides on the surface, that acts like antigen – AB0 system
determination
Clinical applications






anemia
polycythemia – physiological adaptation or haemoblastosis – it
increases blood viscosity
anisocytosis – higher variability in size
macrocytes – greater – impairment of maturation (deficiency of vit.
B12)
microcytes – smaller (defeiciency of iron)
sicle cell disease/thallasemia – point mutation in the gene for
hemoglobin – HBS shape – abnormal/crescent shape of RBC (red
blood cell) – anemia, small vessels/venules obstruction
Leukocytes – white blood cells
granulocytes a agranulocytes
neutrophil
eosinophil
basophill
lymphocyte
monocytes
• granulocytes
• neutrophils (polymorphonuclear
leucocytes)
• eosinophils
• basophils
• agranulocytes/
mononuclear – see mononuclear
phagocyte system
• lymphocytes , B, T
• monocytes
Leukocytes function
• number 6500 – 10,000 in 1μL
• do not function in blood stream, but use it for transport to
connective tissue, where perform their function
• diapedesis – active migration from blood stream do CT
Granulocytes



content of two granule types:
 specific with specific function for particular
garnulocyrte type
 nonspecific/azurophilic (lysosomes)
all granulocytes in periferal blood are terminal postmitotic
stages of the cell development – cells do not divide. They
survive only few days in peripheral blood
nuclei are divided in two or more lobes
Neutrophilic granulocytes



60-70% of lekocytes
size: 12-15 μm (in smear)
nucleus is divides in two or three lobes that are connected by
chromatin bridges;
(small appendage to the nucleus inactive second X chromosome – Barr body in
females´neutrophiles good indentified)




specific granules – small, near the limit of resolution in LM lysosomes
azurophilic granules – 0,5 μm
glycogen – source of energy – anaerobic metabolism
phagocytosis, oxidative burst – (H2O2) and oxygen radicals
Neutrophil
• chemoattraction to sites of
microorganism invasion
• phagocytosis of microorganisms
- phagosome
• release of hydrolytic enzymes
and by reactive oxidative
compounds in phagosome
(superoxide, hydrogen peroxide,
hypochlorous acid (oxidative
stress)
• only once perform a
phagocytosis and die (pus)
Eosinophilic granulocytes
2-4%
 size: 12-15 μm
 bilobed nucleus
 specific granules: crystalline
core (internum) – major
basic protein
matrix (externum) - lighter
 allergy, parasitic infections
 modulation of inflamation
(inactivation of leukotrienes
and histamine)

Basophilic granulocytes





less that 1%
size 12-15 μm
nucleus is divided in irregular
lobes, but it is not distinct
because it is covered by
granules
specific granules –
metachromatic, content of
heparine and histamine –
liberation of granules –
degranulation - after binding
of certain antigens.
similarity between basophil and
mast cell
Lymphocytes





on the basis of size:
small (6-8μm), medium-sized
and large (up to 18μm).
small lymphocytes prevail in
blood – memory cells
large round nucleus,
chromatin is condensed,
nucleolus
thin rim of cytoplasm,
ribosomes, azurophilic
granules
Lymphocyte function




T and B lymphocytes – specific immunity (T lymphocytes
prevail in peripheral blood: 65% - 75% )
B lymphocytes – humoral – differentiation in plasma cells
– production of antibodies
T lymphocytes – cytotoxic CD8 (induce apoptosis) , helper
CD4 (cooperate with B-lymphocytes and macrophages)
NK (natural killers) medium-sized lymphocytes – 10-15%
in peripheral blood – nonspecific - innate immune
response
Monocytes




size: 12 -20μm
oval, horseshoe or kidney
shaped nucleus,
excentrically placed
basophilic cytoplasm,
azurophilic granules
(lysosomes), RER,
polyribosomes,
mitochondria, Golgi
complex
monocytes differentiate
into macrophages (antigen
presenting cells)
Leukocytes - differential white cell count: the distribution of
the diffrent types of white cells present in circulating blood

6 000 -10 000 in 1μL

granulocytes


neutrophiles 60 -70%, 3500-7500
eosinophiles 2-4%,
150 - 400

basophiles 0-1%
agranulocytes
lymphocytes 20-30%

monocytes 3-8%


50-100
1500-2500
200-800
Platelets - thrombocytes








nonnucleated, disc-like cell fragments of megakaryocytes
size - 2-4 μm
200 000– 400 000 in uL
central zone containing granules – granulomera and peripheral
lighter zone - hyalomera
hyalomera: open canalicular system – invagination of superficial
plasmalemma, marginal bundle of microtubules, actin and myosin –
contractile
granulomera: mitochondria, glycogen, granules (δ - dense bodies –
ATP and serotonin; α – platelet-specific proteins: fibrinogen, PdGF,
FGF, von Willebrandt factor, platelet-specific factor IV; λ lysosomes)
hemophilia – inherited deficiency of factor VIII or IX
Von Willebrand disease – the most frequent bleeding disorder, hereditary disease with
abnormal or defect of von Willebrand factor
Platelets
Hemopoeisis
Chick embryo – blood islands, 2ED
• mesoderm of yolk sac
•(3 week)
• intraembryonic splanchnic
mesoderm (3week – 6week)
• liver
• spleen (hepato-lineal period)
•bone marrow (from8week)
Hemopoeisis


hemopoiesis is a result of simultaneous
proliferation and differentiation
hemopoetic stem cells – types and terms:
pluripotent stem cell – self-renewal – low mitotic activity
multipotent stem cell – lymphoid and myeloid stem cells
unipotent - progenitor cells - colony forming cells - self-renewing
– high mitotic activity
precursor cells (blasts) – not self-renewing (lymphoblast,
erythroblast....)
mature cells – (cytes) (lymphocyte, erythrocyte)
Development of blood cells
regulation


microenvironment – cells of
stroma, extracellular matrix
growth factors:

growth factors –
stimulation of mitotic
activity

colony-stimulating factors
(CSF)

hematopoietins
(erythropoietin – synthesis
in kidney, thrombopoeitin
- synthesis in liver)
Red bone marrow




stroma: hematopoietic cords and sinusoids
stroma – reticular connective tissue (reticular cells and
reticular fibres – (collagen type 1 and 3, fibronectin,
laminin and proteoglycans)
sinusoids – capillaries with discontinuous endothelium
stem cells – they can differentiate also in other cellular
types that blood cells – appropriate stimulation is
necessary
Haemopoiesis
Erythropoiesis






Proerythroblast – large cell with loose chromatin, nucleoli and
basophilic cytoplasm
Basophilic erythroblast – condensed nucleus, basophilic
cytoplasm - polyribosomes
Polychromatophilic erythroblast – polyribosomes decrease,
hemoglobin appears
Orthochromatophilic erythroblast – eosinophilic cytoplasmhemoglobin, maximally condensed nucleus – nucleus
expulsion
Reticulocyte – rest of ribosomes – substantia reticulofilamentosa – 1% in peripheral blood
Erythrocyte
Erythropoiesis






erythropoietin, iron, folic acid, cyancobalamin (vit B12)
3 - 5 division from proerythroblast to erythrocyte
approximately 7 days from proerythroblast to reticulocyte
decrease of the cell volume
condensation of chromatin (pycnotic nucleus) and its
expulsion
synthesis of hemoglobin and successive loss of basophilia
(polyribosomes)
Granulopoiesis






Gardual synthesis of azurophilic and later also specific
granules
Myeloblast – finely dispersed chromatin, no granules
Promyelocyte – basophilic cytoplasm, Golgi complex and
azurophilic granules
neutrophilic, basophilic and eosinophilic myelocytes –
condensation of nucleus, appearance of specific granules
neutrophilic metamyelocyte – band cell –
mature granulocyte
Maturation of lymphocytes



no specific morphologic differences
stem cells - progenitors in bone marrow –– they do not
have antigens specific for B and T lymphocytes
maturation in thymus (precursors T- lymphoblasts –
differentiate in mature lymphocytes) or in bone marrow
(B – lymphoblasts, lymphocytes), they may divide in
periphery in lymphoid organs (spleen, lymph node, tonsil)
Maturation of monocytes





monoblast – identical with myeloblast
promonocyte – large cell – up to 18μm; basophilic
cytoplasm, large slightly indented nucleus, large amount
of RER, large Golgi complex
formation of azurophilic granules – lysosomes
in blood, they circulate approximately 8 hours
they survive in periphery for several months –
macrophages - antigen presenting cells
Origin of platelets




megakaryoblast – 15 - 50 μm, large ovoid nucleus,
numerous nucleoli. Polyploid cell - up to 30 sets of
chromosomes (reflecting its size)
megakaryocyte – giant cell - 35 – 150 μm.
irregular nucleus, numerous mitochondria, welldeveloped RER and extensive Golgi complex. Formation of
granules. Invagination of plasmalemma – demarcation
membranes – they surround areas – processes –
fragmentation – release of platelets into the blood
after dessintegration of cytoplasm into the platelets,
megakaryocyte die by apoptosis