Zhikal O. Khudhur/Assist lecturer_____________________________________________Hematology– 3rd Stage /1st Semester
[email protected] https://tiu.edu.iq/
2021 - 2022
TIU - Faculty of ScienceMedical Analysis Department
Lec. 4: Hemoglobin Distruction
Erythrocyte membrane
• RBC plasmalemma is trilaminar–
–
–
Outermost layer: glycolipids, glycoproteins
Central layer: cholesterol, phospholipids
Inner layer: cytoskeleton
– spectrin»
»
Composed of alpha & beta chains
Join to form a matrix which strengthens the
sheer force and controls biconcave shapemembrane against
• ankyrin
Importance of Hb within RBC
• Intra RBC environment is a little more acidicthan plasma for capable respiration
Hb is removed from metabolic pool, preventing its rapid turn over.
•
•
•
•
Half-Life for Hb in
Half-Life for Hb inHb chemical stateabsolutely.
RBC is months,plasma is only 3 hrs.
is required for O2 transport
• Each Saturated gram of Hb can carries 1.3 mloxygen
Destruction of erythrocytes
Cell decrease deformability in microcirculationassociated with;
is
1.
2.
3.
4.
increase in red cell rigidity
increase in blood viscosity,
impeded blood flow
cell fragmentation
The changes inMaintenance of
Normal internal
deformability depends on
cell geometry or biconcave shape
or hemoglobin fluidity Intrinsic
membrane deformability or visco-elastic properties
---------�"'.Agod. abnormal,
M<icropnagetn �preenor hver
or damagoderyttir ocytoi.
\ "']"�Heme
t
• •l r y throcytos
� E,ythropo1es1s
Red bonemarrow
enuubin excreted
Into ,ote$1tne a:. part ol btle
...
S.11 rubin convert
ad into pgmont<11
that ore pan 01
leces
HemoglobinMolecules of hemoglobin account for 95% of the proteinsin RBCs
Hemoglobin is a globular protein, formed from two pairs of
•
•
polypeptide subunits
– Each subunit contains a molecule of heme which reversibly binds an oxygen molecule
Damaged or dead RBCs are recycled by phagocytes•
Structure4 polypeptide
Subunits
Heme group
Porphyrin ring
Ferrous iron
Globin chain
2 Alpha Chains
2 Beta chains
of Hemoglobin
Heme has a variety of functions. As a cofactor
•
•
•
•
•
Oxygen transport in hemoglobin
Storage in myoglobin
A prosthetic group for cytochrome p450 enzymes
A reservoir of iron
Electron shuttle of enzymes in the electron transport chain
Cellular respiration
Signal transduction-heme regulates the antioxidantresponse to circadian rhythms, microRNA processing
Cellular differentiation and proliferation
•
•
•
Difference between oxygenation
and oxidation of Hemoglobin
• IRON(Fe +2) INFERROUS STATE
CARRIER OF OXYGEN
• IRON(Fe +3) IN FERRICSTATE
OXYGEN CARRYING CAPACITY IS LOST
• •
OXYGENATION OXIDATION
Functions of Hemoglobin
• Oxygen delivery to the tissues
• Reaction of Hb & oxygen
• Oxygenation not oxidation
• One Hb can bind to four O2 molecules
• Less than 0.01 sec required foroxygenation
• When oxygenated 2,3-DPG is pushed out
Normal Hemoglobin Function
When fully saturated, each gram ofhemoglobin binds 1.34 ml of oxygen.
The relation between oxygen tension and hemoglobin oxygen saturation is described by the oxygen-dissociation curve of hemoglobin.The characteristics of this curve are relatedpH, temperature, ionic strength, and
•
•
• to
concentration of phosphorylatedcompounds, especially 2,3-diphosphoglycerate (2,3-DPG).
Interstitial fluid
c o 2 - - - • c o , (dissolved In
plasma)
� B i n d s t oroteins( plasma p
HBO2 98.5 %O2 Dissolved in
Plasma 1.5%
WC0 C02 + H20 Slow H2C0 3 - HC0 3- +2
Tissue cell
tt.COa- HCOa-+Clrbonlc
CO2 in plasma 5-7%bicarbonate buffersystem 85% CO2 Dissolved in Plasma 10%
8nhydreseC02 -
C02 -lllll!l�-111111!! (C• rbamlno•
hlmoglobln)
Blood plasma02 (dissolved In
plasma)(a) Oxygen release and carbon dioxide pickup at the t issues
co2 •------..Alveolus Fused basement membranes• - - - - - - c o2 (d isso lved In
plasma)
HC01Reverse
C0 +--- - - - ""!""""!'- - - - - - C0 2 + H20 - H2C0 3 - HC0 3- + W
Slow
2
3
chloride
....,..---,- c l- shit !
Blood plasma02 (dissolved In
plasma)(b) Oxygen pickup and carbon dioxide release In the lungs
Hb-oxygen dissociation curve
is a curve thatplots theproportion ofhemoglobin inits saturated(oxygen-laden)form on thevertical axisagainst theprevailingoxygen tensionon the horizontalaxis
RBC life span and circulation
Replaced at a rate of approximately 3 million new•blood cells entering the circulation per second.
••
Replaced before they hemolyzeComponents of hemoglobin individually recycled– Heme stripped of iron and converted to biliverdin, then
bilirubin
Iron is recycled by being stored in phagocytes, or transported throughout the blood stream bound to transferrinRBC life span 120 days only, short because of the lack
•
•
of nuclei• RBC is soft colloid to change shape in various sized
vessels
Red
MACROPHAGE
Blood Cell Turnover1- - - .....;:i....�Fe2+
Amino acids
BONE
MARROW
RBCfonnation
transported in circulation by transferrln
BLOODPLASMA New RBCs
released Into circulation
- - - - 9 0% � 1:\-_.....i,""1Old and I �
10%
L _ _ _ J
Macrophages in spleen, liver, bone marrow
damagedRBCs Hem.o.l,ysi
s
��
.- - - - - - - - - - - -1-..... Bilirubin
, - - - - - ----1 Bilirubin-derivedproductsLIVER
Excreted Absorbed intoEliminated
in urinein bile'r:;:::� ==::::::±t-h.e.._c_r::u:l::io:n:::
_.ll.::::::::::: Bilirubin-derived 1--. l urobilinsSMALL
INTESTINE products Stercobilins
Eliminatedin fecesLARGE
INTESTINE