Lecture 1 Blood Physiology by Dr. Roomi

8/12/2019 Lecture 1 Blood Physiology by Dr. Roomi

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Physiology of Blood

Definition: Blood is a specializedconnective tissue in which there is aliquid intercellular substance known

as plasma and formed elements. It circulates in a closed system of

blood vessels and chambers of heartby pumping of heart.

Formed elements:Red blood cells-Erythrocytes

White blood cells-Leucocytes

Platelets- Thrombocytes


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Functions of Blood1- Transport function:

A-Respiratory function:Haemoglobin the respiratorypigment present in the Red Blood Cells (RBCS) .It increasesoxygen carrying capacity of blood.O2 & CO2.

B-Nutritive function:glucose, amino acids, fatty acids,vitamins, minerals & water.

C-Excretory function:Urea, uric acid, creatinine throughkidney. Bile pigments through liver. CO2 through lungs.

D:Distribution function:Hormones & hormone bindingproteins towards target tissues & organs.

E: Temperature regulation:Heat produced in active tissues

in the body core is brought to the skin and lungs. It isregulated by the amount of blood flow to these areas. Thewater in plasma has

i) High specific heat-can absorb large amount of heat. ii) High thermal conductivity-distribute heat. iii) High heat of evaporation-heat loss.


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Temperature regulation


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2- Regulatory function: a) Maintenance of ionic balance and internal

environments b/w cells &ICF b) Maintenance of water balance b/w interstitial,

intracellular and vascular compartments.

c) Maintenance of acid base equilibrium.

hemoglobin , plasma proteins are buffers.Bicarbonate buffer system.

d) Regulation of blood volume- Haemostasis

(homeostasis). Excessive blood loss is prevented

by clotting of blood (clot formation) by clottingfactors and platelets.


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3- Defensive function:

Neutrophils and monocytes:Phagocytosis of dead tissues

invading micro-organisms. T lymphocytes:Cellular immunity

B lymphocytes & plasma cells:Humoral immunity

(antibodies).

Eosinophils: Phagocytosis of allergic complex


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4-Functions due to plasma proteins: Proteins exert osmotic pressure (28 mmHg) and

contribute to dynamic distribution of water b/w blood,

lymph and intracellular fluids. Transport function

Nutritive function

Buffer function

Precursor of active substances Hormones

Blood clotting factors

Immunity antibodies


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Composition of blood

Plasma---52-55%

Formed elements(hematocrit)---45-48%

pH 7.35-7.45, Plasma

Liquid 90-92%

Solids 8-10%


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Inorganic constituents in plasma:

Na+ 138--- 142 mEq/L

K+ 4.5---5.5 mEq/L

Ca++ 4.2---4.5 mEq/L

Mg++ 1.2---1.5 mEq/L

Cl- 103 mEq/L

HCO3- 25-27 mEq/L

Phosphate 1-4 mEq/L

SO41

mEq/L


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Organic constituents of plasma

A-Plasma proteins: 6.5-7.5 gm/dl

Albumin 4.5gm/dl

Globulin 2.5gm/dl

Fibrinogen 100---300mg/dl

Prothrombin 10---20mg/dlB-Non-protein nitrogenous substances: 28-48mg/dl

Urea 15-40mg/dl,

Uric acid 4-8mg/dl,

Creatinine 0.2---1.2mg/dl,

Amino acids 40mg/dl

Xanthine, hypoxanthine


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Organic constituents of plasma

C-Nutritive substances in plasma:

Glucose 100mg/dl

lipids 450---500mg/dl Fatty acids 200-400mg/dl

Cholestrol 150-250mg/dl

Triglycerides 100-150mg/dl Very Low Density Lipoprotien (VLDL)

Low Density Lipoprotien (LDL)

High Density Lipoprotien (HDL)

D-Coloured substances

Bilirubin 0.3---1mg/dl

CaroteneE-Other substances

Hormones, enzymes, vitamins,minerals,

Metabolites (Lactic acid, Ketone bodies)


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Plasma proteins

Albumin: 60% 0f total Plasma Proteins

4.55.7gm/dl

Mol.wt 69000

Water soluble

Heat co-aguable

Precipitated by fully saturated solution of

(NH4)2SO4. MCQ Produced by liver cells. MCQ

Responsible for 2/3rdplasma colloidal osmoticpressure (oncotic pressure). MCQ


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Globulin:

30% 0f total Plasma Proteins

1.52.5gm/dl

Mol. Wt.= 80,000---200,000

Types 1, 2 , ,

Insoluble in water but soluble in dilute salt

solution

It is precipitated with half saturation of (NH4)2SO4

Mainly transport function and immunity

Mostly produced by liver, but noy -globulins


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electrophoretic separates the types ofglobulins:

1----carries thyroxine2----- carries copper (Ceruloplasmin),

erythropoietin, prothrombin

---lipoprteins carry lipid, steroids, cholestrol. --- produced by lymphocytes and plasma cells.

Provides Immunity. Called immunoglobulinsinclude IgG (75%), IgA, IgM, IgE, IgD. Also include

blood group antibodies.


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Fibrinogen (Clotting factor I)

5% of total plasma proteins.

300mg/dl

Mol. Wt.= 330, 000 Produced by the liver

It is changed to Fibrinduring blood

coagulation process. Difference between plasma and serum?


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Prothrombin (Clotting factor II)

Serum = Plasma-(fibrinogen+ other clottingfactors).

20mg/dl

Mol. Wt.= 68, 700

Produced by liver in presence of Vitamin K. its

level in blood decreases in liver disease.

In its deficiency prothrombin time isincreased.

It is changed to thrombin in coagulation.


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Functions of plasma proteins

1-Proteins exert osmoticpressureand contributeto dynamic distribution ofwater b/w blood andinterstitial fluids.

With protein conc. 7.5gm/dl albumin exerts 70%(2/3rd)of total osmoticpressure. MCQ

Regulate filtration-absorption of fluid acrossthe capillary membrane.


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2-Proteins perform transport functions:

Albumin----carries bilirubin, calcium, fatty

acids, steroids and drugs etc. ***

1-globulin---- carries thyroxin, polysaccharides

(glyco proteins)

2-globulin----- carries copper (Ceruloplasmin),erythropoietin, prothrombin

-globulins:

Lipoproteins carry lipid, steroids and cholestrol.

Transferrin carries iron (Fe). MCQ


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3-Proteins perform hemostatic functions:

Prothrombin (factor II), fibrinogen, blood clotting factors V,

VII, VIII, IX, X, XI, XII and XIII are proteins which take part inclotting of blood.

Factors II, VII, IX , X are vitamin K dependent factors whichare synthesized in liver. MCQ

4-Proteins perform nutritive functions:

are in a state of dynamic equilibrium with cellularproteins. Undergo constant breakdown to supply rawmaterial to body tissues & constantly beingreplenished by synthesis of new plasma proteins.


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5-Proteins perform immune functions:

Immunoglobulins ( globulins) provide resistance

against infections (antigen antibody reactions). Chemically these are glycoproteins of mol. Wt=

150, 000 -1000,000.

6-plasma Proteins perform buffer functions: At body pH 7.4 act as anions and accept H+ ions.

1/6thof total buffering capacity of blood is due to

plasma proteins.


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7-Plasma Proteins are precursors of active

substances: e.g. Kininogens---- Kinins

Angiotensinogen--- Angiotensin

Erythropoietinogen---Erythrpoieotin

8-Plasma Proteins resposible for viscosity of

plasma and blood pressure:

normal viscosity of blood is 1.05-1.06


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9-Plasma Proteins include proteins of

inflammation:

Gamma globulins

Complement system

Acute phase proteins

C reactive proteins (CRP)

Fibrinogen

Haptoglobins


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10-Plasma Proteins include various enzymes e.g.

amylase, transaminase, dehydrogenase, lipase,

phosphatase.

These enzymes have diagnostic value e.g. Lactate

dehydrogenase (LDH) increases in heart

attack/myocardial infarction (MI).

Lecture 1 Blood Physiology by Dr. Roomi

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