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 inter

stitial 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 substanc

e is equal to 1 osmole. If a substance io

nizes into 2 ions, 0.5 gram mole of the s

ubstance equals 1 osmole.

Osmotic pressure is determined by t

he number of particle, instead of the

mass of the solute. The osmolal conc

entration of a solution is called its os

molality, expressed by osmole perK

g. 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 (hemopoiesi

s)

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 → Orth

ochromatic erythroblast → Reticulocyte

→ erythrocytes

Maturation of red blood cellVitamin 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 t

he 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 bone

marrow

(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 → Orth

ochromatic 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 f

ormed in kidneys, remainder mainly in the li

ver.

Effect of EPO on erythrogenesis.

EPO stimulates production of proerythrobla

sts from hemopoietic stem cells in bone marr

ow. EPO causes these cells to pass more rapi

dly through different erythroblastic stages, s

peeding 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 thrombocytopoiesisPlatelets 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 agents:

ADP, thrombin, collagen ， thromboxane A2

Aggregation

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 s

urrounding area. Release is energy-depen

dent and requires ATP.

Release of contents of dense granule, -gra

nule 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 groupsAgglutinogens: 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 Agglutinins in Plasma Plasma agglutinates

Red Cells of Type

O Anti-A, Anti-B A1,A1B, B, A2B, A2

A1 (A,A1) Anti-B B, A1 B, A2B,

A2 (A) Anti-B, anti A1 B, A1 B, A2 B,

B Anti-A A1, A1B, A2, A2B,

A1B None None

A2 B Anti A1 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 plasma

donor

recipient

Incompatible blood type

Transfusion reactions

Type AB: “universal recipients”

Type O: “universal donors”