5.1. Hematopoiesis. The composition of the blood. The human blood group systems. Flashcards
- What is the Normal value of blood?
60 – 80 mL/kg
70kg adult has 5L of blood
- What are the Main functions of blood
- Transport
- O2, CO2
- Metabolites, nutrients and waste products
- Hormones
- Heat - Regulation
- Salt-water balance
- Osmotic concentration
- Acid-base balance
- Body temperature - Protection
- Immune defense (pathogen, cancer cells)
- Hemostasis (blood clotting)
- Composition of blood
a/ What is the general composition of the blood plasma?
90% water
8% plasma proteins
2% other organic compounds
- Composition of blood
b/ What are the cellular elements of the blood plasma?
RBCs
WBCs
Platelets
- Composition of blood
a/ What is the general composition of the blood plasma?
90% water
8% plasma proteins
2% other organic compounds
- Composition of blood
c/ What is the formula and normal value of hematocrit?
Hematocrit = Height of RBCs/ Total height
Normal value: 0.42 – 0.46
- Composition of blood
d1/ Describe the permeability of capillaries to proteins? What can you conclude about the role of of proteins in blood?
Capillaries have low permeability to proteins
=> Proteins are responsible for the osmotic pressure gradient between intravascular and interstitial compartments
- Composition of blood
d2/ What are the principal plasma proteins? What are their percentages?
Albumin: app. 80% - A major contributor to the colloid pressure
Globulins: app. 20%
Fibrinogen: app 0%
- Composition of blood
d3/ What is the role of principal plasma proteins?
distribution of the total colloid osmotic pressure
- Composition of blood
d3/ Where are principal plasma proteins produced?
Produced by liver (majority) and B-lymphocytes (immunoglobulins
- Composition of blood
e1/ What is the normal value and life span of RBCs?
NV: 4.5 – 5 million/ µl
LS: 120 days
- Composition of blood
e2/ What is the normal value and life span of Platelets?
NV: 300 000/ µl
LS: 7 – 10 days
- Composition of blood
e3/ What is the normal value and life span of WBCs?
NV: 7000/ µl
LS: From 8 hours to years
- Composition of blood
e4/ What are the 5 types of WBCs?
1/ Neutrophil granulocyte
2/ Lymphocyte
3/ Monocyte
4/ Eosinophil
5/ Basophil
- Composition of blood
e5/ What is the normal value of Neutrophil granulocyte?
4000/ µl
- Composition of blood
e6/ What is the normal value of Lymphocyte?
2000/ µl
- Composition of blood
e7/ What is the normal value of Monocyte
?
500/ µl
- Composition of blood
e7/ What is the normal value of Eosinophil?
200/ µl
- Composition of blood
e8/ What is the normal value of Basophil?
50/ µl
- HEMATOPOIESIS A
a/ Definition of hematopoiesis
the production of all the cellular components of the blood and blood plasma
- HEMATOPOIESIS A
b/ What are the 2 types of hematopoiesis
1/ Constitutive (steady-state)
2/ Stress-induced
- HEMATOPOIESIS A
c/ Location of hematopoiesis
Hematopoiesis takes place at different locations in a fetus and an adult
1/ Intrauterine (within uterus)
- Yolk sac -> Liver, spleen -> Bone marrow
2/ Extrauterine (forming outside the uterus; adult)
- Exclusively in red bone marrow within axial skeleton (pelvis, sternum, vertebrae) and long bones
- Lymphocytes in spleen and lymph nodes
- HEMATOPOIESIS A
d/ Definition and role of Constitutive hematopoiesis
- Definition: Continuous replenishment of blood cells throughout lifetime
- Role: Maintain the balance (used up + produce new ones)
- HEMATOPOIESIS A
e/ Definition of Stress-induced hematopoiesis
Increased output of certain blood cells induced by a stress signal
- HEMATOPOIESIS A
f/ 2 examples of Stress-induced hematopoiesis
1/ Hypoxia will lead to increased production of RBCs
2/ Infection will lead to increased production of granulocytes (WBC)
- HEMATOPOIESIS A
g1/ Structure of bone marrow
The bone marrow contains yellow and red bone marrow
- HEMATOPOIESIS A
g2/ Characteristics of Yellow bone marrow
Yellow bone marrow contain inactive, mainly fat cells
- HEMATOPOIESIS A
g3/ Characteristics of Red bone marrow
Red bone marrow contains actively producing RBCs
- Also contains hematopoietic cells, stromal cells and hematopoietic stem cells (HSC)
- Stromal cells serve as structural support, signaling and control of hematopoietic cell maturation
- HEMATOPOIESIS B
h/ What is definition of Hematopoietic stem cells?
HSCs cells are cells in which all the cells of the circulating blood are derived from
- HEMATOPOIESIS B
i/ What are the characteristics of Hematopoietic stem cells?
1/ Uncommitted
2/ Asymmetric division
3/ Self-renewal capacity
4/ Pluri/multipotency (able to differentiate other cells)
5/ Don’t have specific morphology (cell surface markers)
- HEMATOPOIESIS B
j/ Role of surface markers
the determination of mature cells or stem cells which can be used to measure or count different types of cells
- HEMATOPOIESIS B
k/ What are the 2 examples of surfaces markers
1/ CD34+ = (CD = cluster of differentiation)
- A cell migration/adhesion regulator that may help stem cells bind to marrow matrix
2/ C-kit is a receptor tyrosine kinase which binds “stem cell factor”
- HEMATOPOIESIS B
L/ How can you find evidence for the presence of Hematopoietic stem cells (HSCs)?
You can find evidence of hematopoietic stem cells in bone marrow
- HEMATOPOIESIS B
m/ What are the 3 types of Hematopoietic stem cells (HSCs)?
1/ LT – HSC (long term)
- Pluripotent
2/ ST – HSC (short term)
- Multipotent
3/ MPP (Multipotent progenitor)
- HEMATOPOIESIS B
n/ What are the locations of Hematopoietic stem cells (HSCs)?
1/ Mainly in red bone marrow
2/ Peripheral blood (chord blood)
- HEMATOPOIESIS B
o/ What is a Pluripotent cell?
It is a stem cell that can develop into many different types of cells or tissues in the body
- Embryonic stem cells are considered as pluripotent
- HEMATOPOIESIS B
o/ What is a Multipotent cell?
- Multipotent cell is a stem cell that can differentiate into particular cells types associated with multiple cell lineages (more limited than pluripotent)
-> Adult stem cells are considered as multipotent
- HEMATOPOIESIS C
a/ What are the phases of hematopoiesis
1/ Hematopoiesis begins with HSCs and then steadily differentiate
2/ HSCs (LT-HSCs and ST-HSCs) first become MPP (multipotent progenitor cells
3/ MPP cannot self-renew, but their daughter cells will differentiate into 2 types of oligopotent progenitors which are CMP (common myeloid progenitor) and CLP (common lymphoid progenitor)
- CMP can differentiate into MEP (megakaryocytic erythroid progenitors) and GMP (granulocyte monocyte progenitor)
4/ Oligopotent progenitors will then differentiate into unipotent progenitors
5/ Unipotent progenitors will differentiate into differentiated cells
- HEMATOPOIESIS C
b/ Make a Hierarchy map of hematopoiesis
1/ T-cell progenitor will differentiate and complete their development into T-cells in thymus
2/ Note for the diagram
Green: pluri/multipotent cells
Blue: oligopotent
Red: unipotent
Black: differentiated/ specific cells
- HEMATOPOIESIS C
c/ What are the factors involved in regulation of hematopoiesis?
1/ Local humoral factors
- From developing blood cells, stromal cells
- E.g, cytokines, Hematopoietic growth factors (GFs)
2/ Local cell-cell interactions
- Bone marrow “niche”
3/ General humoral factors
- From blood steam
- E.g, hormone, cytokines, Hematopoietic growth factors (GFs)
- HEMATOPOIESIS C
d1/ How do regulatory factors involve in hematopoiesis in early phases?
1/ There are many regulatory factors with overlapping effects
2/ Regulatory factors involved:
- IL-3 (solute) (Interleukin 3)
- GMCSF (solute) (Granulocyte-macrophage colony-stimulating factor)
- CSF
+) Solute + cell surface
+) Receptor: C-kit
- HEMATOPOIESIS C
d2/ How do regulatory factors involve in hematopoiesis in later phases?
1/ There is few or 1 regulatory factors with no overlapping effects
2/ Examples of regulatory factors
- EPO (Erythropoietin)
- G– CSF (Granulocyte colony-stimulating factor (G-CSF))
- M – CSF
- Thrombopoietin (TPO)
- IL – 7 (lymphoid)
- HEMATOPOIESIS C
e/ How does Hematopoietic niche participate in Regulation of hematopoiesis ?
1/ The environment of the cell (cell-to-cell connections) is important in the differentiation of blood cells in the bone marrow
2/ Cells will take on certain differentiation routes (an area dedicated to a certain function like this = niche), therefore chemokines exist in the bone marrow to induce cell movement to different parts in the bone marrow (via chemotaxis)
3/ Niche = area in which stem cells are present in (1) an undifferentiated state and (2) a self-renewable state
- Divisional asymmetry: only a certain type divide, hence limited number of production
- Environmental asymmetry: some niches produce a certain type of cells more than the others
- HEMATOPOIESIS C
f1/ The definition and role of cytokines
1/ Definition: Glycoproteins (EC signal protein) which affects cells
2/ Their function is usually overlapping and can work for several cells (mast cells, B-cells, stem cells, etc.)
3/ Acts as local mediator in cell-cell communication (induce movement, vision)
- HEMATOPOIESIS C
f2/ Examples of cytokines
1/ Erythropoietin (EPO)
- Secreted by kidney in response to cellular hypoxia
2/ Granulocyte-colony stimulating factor (G-CSF) which stimulate WBCs production
- HEMATOPOIESIS C
g1/ The role of CSF (colony-stimulating factor)
Stimulating committed progenitor to proliferate in vitro
- HEMATOPOIESIS C
g2/ The examples of CSF (colony-stimulating factor)
E.g, M-CSF, G-CSF
-> Form colony of specific lineages
-> Form CFU (colony-forming unit)
-> E.g, CFU – GEMM, CFU – E
- HEMATOPOIESIS D
a/ definition of Erythropoiesis
Definition: erythropoiesis the the development from erythropoietic stem cell to mature RBCs
- Erythropoiesis
a/ definition of Erythropoiesis
Definition: erythropoiesis the the development from erythropoietic stem cell to mature RBCs
- Erythropoiesis
b/ Process of Erythropoiesis
1/ 7 to 10 days RBC production process occurs in erythropoietic islands
2/ Form from the myeloid lineage -> proerythroblasts-> erythroblasts
3/ Slowly gain more hemoglobin and their nuclei shrink -> orthochromatic erythroblasts
4/ A macrophage absorbs the nucleus of the erythroblast and then becomes reticulocyte, which is anuclear and also without mitochondria
- Erythropoiesis
c/ What is the location for erythropoiesis?
BM erythroblastic islands (IBM) which are embedded in EBI macrophages
*Note:
- Erythroblastic islands (EBIs)
- Erythropoiesis
d/ Which mechanisms are involved in erythropoiesis?
1/ Control of erythropoiesis – the erythropoietin
2/ ON-OFF regulation of EPO synthesis in renal EPO producing (REP) cells
3/ O2 sensing mechanism
- Erythropoiesis
d1/ How does erythropoietin participate in Regulation of erythropoiesis?
1/ Erythrocyte production is regulated by erythropoietin (EPO), which is mainly produced in the kidney by interstitial fibroblasts (90%).
2/ Erythropoietin (EPO) can also be produced by hepatocytes in liver (10%)
- Erythropoiesis
d2/ Definition of ON-OFF regulation of EPO synthesis in renal EPO producing (REP) cells
Definition: Production of EPO is a negative feedback mechanism that is regulated by O2- concentration in the kidney
- Erythropoiesis
d2/ Mechanism of ON-OFF regulation of EPO synthesis in renal EPO producing (REP) cells
- Hypoxia: Low O2 content in kidneys causes hypoxia-inducible factor (HIF) to activate, causing production of EPO which leads to increased erythrocytes and then increased O2-content of kidney
- This will lead to normoxia which in turn inhibit the synthesis of EPO
- Erythropoiesis
d3/ Characteristics of O2 sensing mechanism
1/ HIF-⍺ is a transcription factor that regulates the expression of EPO
2/ At the normal level, HIF-⍺ levels are low, where as HIF-⍺ levels increases in hypoxia
- Erythropoiesis
d3/ Describe O2 sensing mechanism in case of normoxia
1/ O2 activates proxyl hydrolyase which will then hydroxylate HIF-⍺
2/ This hydroxylation stimulates the interaction of HIF-⍺ with VHL (Von Hippel-Lindau disease tumor surpressor protein), leading to ubiquination by Ubiquitin ligase
3/ Leads to degradation of HIF-⍺ (by proteasomal degradation)
- Erythropoiesis
d3/ Describe O2 sensing mechanism in case of hypoxia
1/ proxyl hydrolyase are inactivated
2/ HIF-⍺ accumulates in nucleus and then interacts with hypoxia response element and form a complex with HIF-β
3/ EPO gene expression increases abnormally
- Erythropoiesis
e/ What are Dietary requirements for normal erythropoiesis?
1/ Amino acids
2/ Vitamin B6
3/ Iron
4/ Vitamin B12
5/ Folic acid
- Erythropoiesis
f/ Cause of Anemias
Deficiency in dietary requirements for normal erythropoiesis
- Erythropoiesis
g/ What are the 3 types of Anemias
1/ Normocytic
2/ Microcytic
3/ Macrocytic
- RBCs parameters
a/ what is the normal count value?
4.5 – 5 million/µl
- RBCs parameters
b/ What is the normal Hematocrit value?
0.42 – 0.46
- RBCs parameters
c/ What is the normal Amount of hemoglobin?
2.2 – 2.5 mM (tetramer)
- RBCs parameters
d/ What is the normal value of Mean corpuscular hemoglobin (MCH)?
0.5 fmol/ cell
(Note: fmol mean femtomole (1fmol = 10-15 moles))
- RBCs parameters
e/ What is the normal value of Mean corpuscular hemoglobin concentration (MCHC)?
5 mM
- RBCs parameters
f/ What is the normal value of Mean corpuscular volume (MCV)?
90 fL
- How does Breakdown of RBCs by macrophages occur?
- Thrombopoiesis
a/ Definition of Thrombopoiesis
Thrombopoiesis is the formation of platelets in blood
- Thrombopoiesis
b/ Process of Thrombopoiesis
Formed from the myeloid erythrocyte progenitor
-> promegakaryoblast
-> Promegakaryocyte
-> megakaryocyte
-> immigration towards the BM sinusoids
-> shedding of platelets
- Thrombopoiesis
c/ Characteristics of megakaryoblats
1/ Undergo endoreduplication (replication of genome in absence of mitosis) (32n)
2/ Extremely large diameter (60μm), hold lots of duplicated DNA
3/ Lobulated nucleus
4/ Their processes extend into blood vessels and
disintegrate to become ~104 platelets
- Thrombopoiesis
d/ How is Thrombopoiesis regulated?
- By using TPO (thrombopoietin) which is produced mainly in the liver (+ kidney)
- Thrombopoietin receptor is c-mpl on megakaryocytes and platelets
1/ If the number of platelets increases, TPO level will decreases
2/ If the number of platelets decreases, TPO level will increases
-> It will then bind to receptors and cause platelet production (only with megakaryocytes) along with TPO degradation (for balance)
- How does Development of monocytes, macrophages, dendritic cells and osteoclast occur?
1/ They all develop from GMP (granulocyte-monocyte progenitors)
2/ Monoblasts can form either osteoclasts, macrophages or dendritic cells (6 days)
3/ Granulocytes take 9 to 12 days to mature, but can be sped up to 2 days in cases of infection (thanks to cytokines)
4/ Mature granulocytes exit the bone marrow and either freely circulate or they attach to the endothelial cells of blood vessels
- Blood group
a/ Characteristics of blood group
1/ They have genetically determined antigens (Ag) on the surface
2/ Glycoproteins, glycolipids and integral membrane proteins
3/ There are about 30 blood group system
4/ There are about 300 antigens
- Blood group
b/ Characteristics of ABO system
1/ Antigen is composed of glycosphingolipids
2/ Codominant inheritance
3/ Ag gene codes for monosaccharide transferase enzymes
- Blood group
c/ The role of Ag genes
1/ H-gene -> fucosyltransferase => H-antigen
=> Core structure
2/ O – gene -> inactive enzyme => H-antigen
3/ A-gene -> GalNac transferase => A-antigen
4/ B-gene -> Gal transferase => B-antigen
- Blood group
d/ Describe Phenotype of ABO system
1/ Type O: neither A nor B antigens are present.
- O is recessive
2/ Type A: only type A antigen is present
3/ Type B: only type B antigen is present
4/ Type AB: both A and B antigens are present
- Co-dominance
- Blood group
e/ The characteristics and role of antibodies ABO system?
1/ Characteristics: IgM type immunoglobulins (5 x 2 binding sites for antigens)
2/ Role:
- They are present in the blood
- Naturally against non-self ABO antigens
- Blood group
f/ What is Landsteiner’s rule?
- If an antigen is present on RBCs of an individual, the corresponding antibody must be absent in the plasma. (Self-tolerance)
- If an antigen is absent on RBCs of an individual, the corresponding antibody must be present in the plasma.
- Blood group
g/ Explain Antigen-antibody reaction in ABO system
1/ If an antigen is present on RBCs of an individual, the corresponding antibody present
=> There will be agglutination
2/ If an antigen is absent on RBCs of an individual, the corresponding antibody is absent
=> There will be no reaction
- Blood group
h/ Characteristics of The Rhesus (Rh) system
1/ There are 6 common types of Rh antigens, but the type D antigen is widely prevalent and more antigenic than other Rh antigens.
2/ Anyone who has the type D antigen is said to be Rh positive, and a person without it is Rh negative.
- Blood group
I/ Describe the phenomenon of The Rhesus (Rh) incompatibility
1/ When the mother is Rh – and the father is Rh +, the baby inherits Rh+.
2/ The mother develops anti-Rh antibodies from exposure to the fetus’s Rh antigen.
3/ Then, the mother’s antibodies diffuse through the placenta into the fetus and cause RBC agglutination.
4/ The incidence rises progressively with subsequent pregnancies.
- Blood group
L/ What are the 2 types of Hemolytic transfusion reactions?
1/ Acute (IgM-mediated)
2/ Delayed (IgG-mediated)
- Blood group
L/ What are the characteristics of Acute (IgM-mediated) hemolytic transfusion reactions?
Complement activation
- Hemolysis
- Proinflammatory mediator release
- Disseminated intravascular coagulation
- Blood group
m/ What are the characteristics of Delayed (IgG-mediated) hemolytic transfusion reactions?
Incomplete complement activation
- Splenic & hepatic erythrophagocytosis
- Anemia
- Jaundice