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THE PHYSIOLOGY OF BLOOD Objectives

1. HEMOGLOBN

2. HEMOSTASIS

Practical tasks Determination of hemoglobin blood content Blood coagulation time determination (Lee White) Determination of bleeding time by Duke Determination of prothrombin time by Quick HEMOGLOBIN – composed of 4 subunits bound together each having HEME molecule combined with long POLYPEPTIDE chain called GLOBIN HEME is made of pyrrole compound in the centre of which is Fe. The oxygen and polypeptide are bound to coordination bonds of the iron atom as molecular O2 Hb DERIVATIVES Depend on gass content or Fe form

OXYHEMOGLOBIN Hb(O2)4

DEOXYHEMOGLOBIN = CARBAMINOHEMOGLOBIN Hb(CO2)4

CARBOXYHEMOGLOBIN Hb(CO)4 METHEMOGLOBIN Fe++ is oxygenized to Fe+++

Hb TYPES Depend on slight variations in aminoacid composition of the polypeptide portion

Hb A – ADULT form of Hb Contains 2alpha and 2 beta chains

Hb A2 – MINOR COMPONENT Contains 2 alpha and 2 delta chains

Hb F – FETAL Hb Contains 2 alpha and 2 gamma Hb loads up with oxygen in lungs and unloads oxygen in the tissue capillaries In both cases oxygen moves according to its diffusion gradient

Calculation of oxygen capacity of blood

The blood normally contains approximately 15 g of hemoglobin for 100 ml = 15% = 150 g per one liter of blood 1g of Hb can bind with maximum 1,34 ml of oxygen

15 . 1.34 = 20.1 ml of oxygen in 100 ml of blood BLOOD CLOTTING INCLUDES THE ROLE OF THREE SUBSYSTEMS 1. PLATELETS ACTIVATION 2. VASOCONSTRICTION 3. PLASMA COAGULATION FACTORS ACTIVATION

In injured vessel collagen of subendothelial connective tissue is exposed to blood – initiation of 3 separate hemostatic mechanisms 1. PLATELET ADHESION TO COLLAGEN mechanical attachment provided by plasma protein Von Willebrandt factor that circulates as a complex with f. VIII 2. PLATELET ACTIVATION (viscous metamorphosis, liberation of ADP, Thromoboxane, Serotonin, platelet f. 3., from cytoplasmic granules) Platelets – disc shaped 3. PLATELET AGGREGATION cells without nuclei, diameter 2-4 micrometers, 4. PLATELET PLUG FORMATION formed in bone marrow 5. BLOOD CLOT includes contraction of platelets and fibrin from megacaryocytes, lifespan 10 days The same time local myogenic spasm occurs in wounded vessel – vasoconstriction, which helps to close the wound Platelet factors promote vasoconstriction PLASMA CLOTTING FACTORS

= plasma proteins present in blood activated by intrinsic or extrinsic pathways Blood in test tube will clot as a result of INTRINSIC PATHWAY Damaged tissues release f.III. that initiates “shortcut” to the formation of fibrin, and That is EXTRINSIC PATHWAY

I. FIBRINOGEN II. PROTHROMBIN III. TISSUE TROMBOPLASTIN IV. CALCIUM IONS V. PROACCELERIN VI. DOES NOT EXIST VII. PROCONVERTIN VIII. ANTIHEMOPHILIC FACTOR IX. PLASMA THROMBOPLASTIN COMPONENT (PTC) CHRISTMAS FACTOR X. STUART-PROWER FACTOR XI. PLASMA THROMBOPLASTIN ANTECEDENT (PTA) XII. HAGEMAN FACTOR XIII. FIBRIN STABILIZING FACTOR

Plasma without clotting factors is called serum a Bleeding Disorders A deficiency of a clotting factor can lead to uncontrolled bleeding. The deficiency may arise because •not enough of the factor is produced or •a mutant version of the factor fails to perform properly. Examples: •von Willebrand disease (the most common) •hemophilia A for factor VIII deficiency •hemophilia B for factor IX deficiency. •hemophilia C for factor XI deficiency In some cases of von Willebrand disease, either a deficient level or a mutant version of the factor eliminates its protective effect on factor 8. SYMPTOMS •Easy Bruising •Frequent nosebleeds that are hard to stop •Bleeding longer than expected following circumcision, surgery, or having a tooth pulled •Bleeding into joints and soft tissues •Women often have heavy bleeding with menstrual periods (menorrhagia) Hemophilia A and B

The genes encoding factors 8 and 9 are on the X chromosome. Thus their inheritance is X - linked Like other X-linked disorders, hemophilia A and B are found almost exclusively in males because they inherit just a single X chromosome, and if the gene for factor 8 (or 9) on it is defective, they will suffer from the disease.

Queen Victoria (1819-1901) of Great Britain had a defective gene for Clotting Factor VIII, which caused "royal hemophilia" in her son Leopold as well as many other of Victoria's numerous royal descendants. Many of Victoria's descendants married into other royal families, spreading the defective gene widely and greatly affecting world history. Today, people with abnormal Factor VIII can use powdered, freeze-dried CF VIII to help them cope with this disorder. Unfortunately, it was originally derived from human donor blood and risks blood-borne disease transmission including hepatitis and HIV. In fact, the HIV epidemic took a huge toll on hemophilia sufferers during the 1980s and 1990s. However, today synthetic (recombinant) sources of CF VIII and other therapies have made hemophilia treatments safer and more effective.