Medical Notes Norway - Histology Exam Series 2024
BLOOD AND HEMOPOIESIS
Blood is composed of:
- Erythrocytes
- Leukocytes
- Platelets
- Plasma
Plasma consist of 90% water, 9% organic compounds and 1% inorganic salts. The main
plasma proteins are Albumin(which helps in transport of metabolites and maintains the
colloid osmo c pressure and blood volume by resis ng the exit of plasma from the
bloodstream), γ-globulin(blood an body), α-globulins and β-globulins(transport metal ions
and lipids), blood-clo ng proteins like brinogen(protein that converts into brin during
blood clo ng), and some complement proteins(C1-C9) which func on in nonspeci c host
defense and ini ate the in ammatory process. Serum is yellow-ish uid that remains a er
blood has clo ed.
Erythrocytes are round, anucleate and biconcave cells. Average lifespan is about 120days
and express oligosaccharides on membrane surface when they are about to be destroyed by
macrophages. Blood group is determined by di erent carbohydrate(an gens) on the
membrane surface of RBC, all are a ached to membrane by transmembrane protein
glycophorins. The di erent groups are determined by enzymes required to add terminal
sugars, presence of these enzymes is gene cally determined.
Type A: N-acetylgalactosamine transferase
Type B: Galactose transferase
A B AB O
An gens on the A-an gen B-an gen A and B-an gen None
surface of RBC
An bodies in An -B An -A None An A and B
the plasma
Universal Universal donor
acceptor
The most important blood type an gen is the D-an gen which can lead to a great
immunogenic response, as erythroblastosis fetalis in newborns. If the d-an gen is expressed
in the membrane of RBC you are Rh-posi ve and if not Rh-nega ve.
Several cytoskeletal proteins maintain the shape of the red blood cells:
- Ankyrin
- Band 4.1
- Band 3
- Spectrin
- Ac n
, Medical Notes Norway - Histology Exam Series 2024
Mature erythrocytes are lled with hemoglobin (Hb), protein composed of four polypep de
chains, where each is linked to a heme-group(containing an iron atom)
Hematocrit value is an es mate of the volume of packed erythrocytes pr unit volume of
blood.
- Adult men 40%-50%
- Adult women 35%-45%
- Children 35%
- Newborns 45%-60%
Transport of CO2 and O2 is carried out by the erythrocytes. Every minute approx. 200ml of
CO2 is formed by the cells, and since the pressure of CO2 in the ssue is higher than pressure
in capillaries, it enters by simple di usion.
- 20ml of CO2 is transported in the plasma
- 40ml binds to Hb (forming carbaminohemoglobin)
- 140ml enters the cytosol of the RBC
CO2 TRANSPORT
1. Inside cytosol, enzyme carbonic anhydrase forms H2CO3 by combining CO2 with H2O.
2. H2CO3 splits and HCO3- leaves the RBC and enters plasma, and therefore Cl- from
plasma enters RBC to maintain electrical equilibrium. This is referred to as chloride
shi .
3. At the same me, since the par al pressure of O2 is greater in the RBC than in the
ssue, O2 is released from Hb and forms deoxyhemoglobin.
O2 TRANSPORT
1. O2 enters the erythrocytes cytosol and binds to heme moiety of the Hb forming a
oxyhemoglobin
2. HCO3- from plasma reenter RBC cytosol, and Cl- leaves (reversal of the chloride shi ).
The bicarbonate is combined with H+ to make H2CO3, which is cleaved to give H20 and
CO2. CO2 leaves through plasma with simple di usion.
CO binds strongly to Hb and can block binding of O2. NO(nitric oxide) is a neurotransmi er
that binds to Hb, in areas of the body that lack oxygen. This will dilate blood vessels in that
areas and make a more e cient replacement of CO2 to O2
Leukocytes possess varying numbers of lysosomes, which again contains di erent types
hydroly c enzymes. Leukocytes are divided into granulocytes (has speci c granules) and
agranulocytes (has no speci c granules). These speci c granules contain cytotoxic molecules,
enzymes and an microbial pep des.
Granulocytes
- Neutrophils – phagocytose, kill and digest bacteria (by use of hydroly c enzymes)
- Eosinophils – control the in ammatory response by inac va on of histamine
- Basophils – mediate in ammatory response, just like mast cells.
BLOOD AND HEMOPOIESIS
Blood is composed of:
- Erythrocytes
- Leukocytes
- Platelets
- Plasma
Plasma consist of 90% water, 9% organic compounds and 1% inorganic salts. The main
plasma proteins are Albumin(which helps in transport of metabolites and maintains the
colloid osmo c pressure and blood volume by resis ng the exit of plasma from the
bloodstream), γ-globulin(blood an body), α-globulins and β-globulins(transport metal ions
and lipids), blood-clo ng proteins like brinogen(protein that converts into brin during
blood clo ng), and some complement proteins(C1-C9) which func on in nonspeci c host
defense and ini ate the in ammatory process. Serum is yellow-ish uid that remains a er
blood has clo ed.
Erythrocytes are round, anucleate and biconcave cells. Average lifespan is about 120days
and express oligosaccharides on membrane surface when they are about to be destroyed by
macrophages. Blood group is determined by di erent carbohydrate(an gens) on the
membrane surface of RBC, all are a ached to membrane by transmembrane protein
glycophorins. The di erent groups are determined by enzymes required to add terminal
sugars, presence of these enzymes is gene cally determined.
Type A: N-acetylgalactosamine transferase
Type B: Galactose transferase
A B AB O
An gens on the A-an gen B-an gen A and B-an gen None
surface of RBC
An bodies in An -B An -A None An A and B
the plasma
Universal Universal donor
acceptor
The most important blood type an gen is the D-an gen which can lead to a great
immunogenic response, as erythroblastosis fetalis in newborns. If the d-an gen is expressed
in the membrane of RBC you are Rh-posi ve and if not Rh-nega ve.
Several cytoskeletal proteins maintain the shape of the red blood cells:
- Ankyrin
- Band 4.1
- Band 3
- Spectrin
- Ac n
, Medical Notes Norway - Histology Exam Series 2024
Mature erythrocytes are lled with hemoglobin (Hb), protein composed of four polypep de
chains, where each is linked to a heme-group(containing an iron atom)
Hematocrit value is an es mate of the volume of packed erythrocytes pr unit volume of
blood.
- Adult men 40%-50%
- Adult women 35%-45%
- Children 35%
- Newborns 45%-60%
Transport of CO2 and O2 is carried out by the erythrocytes. Every minute approx. 200ml of
CO2 is formed by the cells, and since the pressure of CO2 in the ssue is higher than pressure
in capillaries, it enters by simple di usion.
- 20ml of CO2 is transported in the plasma
- 40ml binds to Hb (forming carbaminohemoglobin)
- 140ml enters the cytosol of the RBC
CO2 TRANSPORT
1. Inside cytosol, enzyme carbonic anhydrase forms H2CO3 by combining CO2 with H2O.
2. H2CO3 splits and HCO3- leaves the RBC and enters plasma, and therefore Cl- from
plasma enters RBC to maintain electrical equilibrium. This is referred to as chloride
shi .
3. At the same me, since the par al pressure of O2 is greater in the RBC than in the
ssue, O2 is released from Hb and forms deoxyhemoglobin.
O2 TRANSPORT
1. O2 enters the erythrocytes cytosol and binds to heme moiety of the Hb forming a
oxyhemoglobin
2. HCO3- from plasma reenter RBC cytosol, and Cl- leaves (reversal of the chloride shi ).
The bicarbonate is combined with H+ to make H2CO3, which is cleaved to give H20 and
CO2. CO2 leaves through plasma with simple di usion.
CO binds strongly to Hb and can block binding of O2. NO(nitric oxide) is a neurotransmi er
that binds to Hb, in areas of the body that lack oxygen. This will dilate blood vessels in that
areas and make a more e cient replacement of CO2 to O2
Leukocytes possess varying numbers of lysosomes, which again contains di erent types
hydroly c enzymes. Leukocytes are divided into granulocytes (has speci c granules) and
agranulocytes (has no speci c granules). These speci c granules contain cytotoxic molecules,
enzymes and an microbial pep des.
Granulocytes
- Neutrophils – phagocytose, kill and digest bacteria (by use of hydroly c enzymes)
- Eosinophils – control the in ammatory response by inac va on of histamine
- Basophils – mediate in ammatory response, just like mast cells.
