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Transcript
Chapter 3 Blood
Section 1
Blood components and its properties
生理教研室:潘敬运 教授
Functions of blood
1. Place of exchange of substances between
interstitial fluid and external environment
2. Transport
3. Buffer function
4. To keep body temperature relatively constant
5. Hemostasis
6. Defense function
1. Components of blood
plasma
blood cells:
red blood cells (erythrocytes)
white blood cells
platelets
Blood volume: 70-80ml/Kg, 7-8% of body
weight
Hematocrit
men is about 40~50%,
women is about 37~48%.
2. Physical and chemical properties
of blood
(1) Specific gravity
blood: 1.050~1.060. RBC number
plasma: 1.025~1.030. Content of
plasma proteins
RBC:1.090 ~1.092. hemoglobin
(2) Viscosity
Viscosity of plasma is 1.2-1.3 times
that of water, viscosity of whole
blood is 2.4 times of plasma.
Factors of affecting viscosity
a. hemotocrit
b. Shear rate
Shear is a ratio of velocity difference
of adjacent layers to distance
between two fluid layers in laminar
flow.
(3) plasma osmolality — 313 mOsm/Kg
H20.
1 gram mole of non-ionizable
substance is equal to 1 osmole. If a
substance ionizes into 2 ions, 0.5 gram
mole of the substance equals 1 osmole.
Osmotic pressure is determined by
the number of particle, instead of
the mass of the solute. The osmolal
concentration of a solution is called
its osmolality, expressed by osmole
perKg. H20.
At 37℃, 1 osmolality will cause
19300 mmHg osmotic pressure.
Plasma osmolality is 0.313Osm
/Kg. H20
0.313×19300 = 5330 mmHg
Colloid osmotic pressure:
maintain intra-and extracapillary water
equilibrium
Crystal osmotic pressure:
maintain intra-and extracellular water
equilibrium
Isoosmotic solution
hyperosmotic solution
hypoosmotic solution
Isotonic solution
4. RBC fragility.
0.42% NaCl solution--begin
hemolysis
0.35%NaCl solution--complete
hemolysis
5. Plasma pH 7.35-7.45
Section 2 Genesis of blood cells
A. Genesis of blood cells (hemopoiesis)
Section 3 Physiology of red blood
cell
1. Number and shape of RBC.
men, 5.0×1012 /L women 4.2×1012 /L
Hemoglobin: men 150g/L women 140g/L
Function of RBC: transport oxygen and
carbon dioxide .
2. Physiologic characteristics of RBC
(1) Permeability of RBC membrane
(2) Flexibility of RBC
(3) Suspension stability of RBC
Rouleaux formation
Erythrocyte sedimentation rate (ESR)
men: 0-15mm/h
woman: 0-20mm/h.
ESR: fibrinogen, globulins,
cholesterone
ESR: albumin, lecithin.
3. Genesis and regulation of red
blood cells
CFU-GEMM
BFU-E
CFU-E
Proerythroblast→ Basophil erythroblast
→Polythromatophil erythroblast →
Orthochromatic erythroblast →
Reticulocyte → erythrocytes
Maturation of red blood cell
Vitamin B12 and folic acid are essential for
the synthesis of DNA. Lack of either
vitamin B12 or folic acid causes diminished
DNA synthesis and consequently failure of
nuclear maturation and division.
Materials needed to production of RBC
(1) Absorption of vitamin B12
Intrinsic factor combines with vitamin B12 in
the following way:
1)The intrinsic factor binds to vitamin B12
2) intrinsic factor binds to specific receptor
of ileal entocyte
3) Vitamin B12 is transported into blood.
B12 binds to transcobalamine II
marrow
bone
(2). Absorption of folic acid
蝶酰多谷氨酸
Pteroypolyglutamate (PteGlun)
蝶酰单谷氨酸
pteroyglutamate (PteGlu)
二氢叶酸还原酶
dihydrofolate reductase
刷毛缘水解酶
Brush border hydrolase
(3) Iron
Required amount 20-30mg/d
Absorb 1mg iron from iron-containing
food.
95% of required iron is from iron
recycling.
Fe excreted—0.6mg, 0.7mg in menses
Iron-deficiency anemia or
Microcytic hypochromic anemia
Hemochromatosis
5. Regulation of RBC production
CFU-GEMM
BFU-E
CFU-E
Proerythroblast→ Basophil erythroblast
→Polythromatophil erythroblast →
Orthochromatic erythroblast →
Reticulocyte → erythrocytes
(1) Burst promoting activator (BPA)
BFU-E
BPA
Go
S
(2) Deficiency oxygen increases the rate of RBC
production.
Erythropoietin(EPO): Glycoprotein.
Site of formation of EPO: 80 to 90% EPO is
formed in kidneys, remainder mainly in the
liver.
Effect of EPO on erythrogenesis.
EPO stimulates production of
proerythroblasts from hemopoietic stem cells
in bone marrow. EPO causes these cells to
pass more rapidly through different
erythroblastic stages, speeding up
production of new cells.
4. Destruction of red blood cells
Life time 120 days
Intravascular and extravascular Destruction.
Hemolysis
hemoglobin release
Release iron
bile pigment-bilirubin.
C. Platelet
Function:
(1) Maintain integrity of vessel wall
(2) Platelet activation and homeostasis
Regulation of thrombocytopoiesis
Platelets are formed from megakaryocytes
in the bone marrow.
normal value: 100 — 300X109/L.
Half-life: 8 to 12 days.
Receptor: Mpl, Proto-oncogen mpl
Ligand: thrombopoietin TPO
Effect: proloferation, differentiation,
muturation and release
Platelet contents:
Dense granule: ADP, ATP, 5-HT, Ca2+
-granule: clotting factor, PDGF,
fibrin- stabilizing factor, vW
factor, fibrinogen
contractile protein: Actin, myosin and
thrombomsthenin
Store of Ca2+ in endoplasmic reticulum
Enzymes: synthesize PGs, phospholipase
Membrane of platelets: glycoproteins,
phospholipids, platelet factor 3
(PF3).
Physical and chemical
characteristics of platelets:
Adhesion
Aggregation
Aggregation agents:
ADP, thrombin, collagen,
thromboxane A2
Primary aggregation: revesible
Secondary aggregation: irreversible
cAMP, IP3, Ca2+ , cGMP
1) ADP
Dose dependent
Primary agregation
Secondary agregation
ATP, Ca2+, fibrinogen
2)Thromboxane A2 (TXA2)
Strong aggregation agent and
vasoconstricyion
Prostacyclin (PGI)
Anti-aggregation and vasodilation
细胞膜磷脂 membrane phospholipids
磷脂酶A2 phosphlipase A2
花生四烯酸 arachidomic acid
环氧化酶 cyclooxygenase
前列环素合成酶 prostacyclin synthetase
血栓素合成酶 thromboxane synthetase
3) Collagen
Secondary aggregation
Release of ADP, TXA2
4) Thrombin
Similar to ADP action, but no
need of fibrinogen
Release
Platelets discharge granule contents into
surrounding area. Release is energydependent and requires ATP.
Release of contents of dense granule, granule and lysosome
D. Events in homeostasis
1. Vascular constriction
2. Formation of platelet plug
3. Blood coagulation in ruptured
vessel. Formation of blood clot.
4. Fibrous organization or dissolution of
blood clot.
Section 3 Blood groups and
transfusion
ABO blood groups
Agglutinogens: Glycoprotein,
A and B
4 major blood types:
types A, B, AB and O.
Agglutinins: natural body, IgM
Anti-A
Anti-B
Summary of ABO blood system.
Blood type
O
A1 (A,A1)
A2 (A)
B
A1B
A2 B
Agglutinins in Plasma
Anti-A, Anti-B
Anti-B
Anti-B, anti A1
Anti-A
None
Anti A1
Plasma agglutinates
Red Cells of Type
A1,A1B, B, A2B, A2
B, A1 B, A2B,
B, A1 B, A2 B,
A1, A1B, A2, A2B,
None
A1, A1B
Rh group
Rh factor named for rhesus monkey
Antigen D, Rh-positive
Anti-Rh agglutinin,
immune antibody, IgG
Blood typing
across-matching
RBC
donor
recipient
plasma
Incompatible blood type
Transfusion reactions
Type AB: “universal recipients”
Type O: “universal donors”