BLOOD

BLOOD AND ITS ASSOCIATED DISORDERS Blood is a specialized body fluid that circulates in the blood vessels bringing oxygen and nourishment to all the cells and carrying away waste like carbon di oxide. Composition of blood Blood cells (45%) like Erythrocytes(RBC), Leucocytes(WBC) , Platelets(THROMOBOCYTES) All blood cells are produced in the bone marrow (haematopoises) some mature in the lymphoid organs Plasma (55%)– constitutes about 90% of water , remaining 10% contains nutrients, electrolytes, gases, albumin (protein), clotting factors, antibodies, enzymes and hormones . Normal blood volume is 5 ltrs

Erthrocytes (red blood cells) Major function is to carry oxygen to the tissues Oxygen is bound to iron containing pigment called hemoglobin(imparts red color to the blood) RBC are biconcave or disc shaped having no nucleus There are 5 millions RBC per microlitre of blood These cells die after 120 days

Leucocytes White blood cells (WBC) They have a prominent nuclei Types Granulocytes- have visible granules Agranulocytes - do not show any visible granules Three types of granulocytes Neutrophils- also called polymorphs (because of their various shaped nuclei) Eosinophils Basophils Two types of agranulocytes Lymphocytes Monocytes

Relative percentage of WBC Neutrophils- 54-62%- responsible for bulk of immuno response. Main components of pus and responsible for its whitish colour. Eosinophils – 1-3%- mediates allergic reactions, defense against parasites Basophils – less than 1%- mediates allergic reactions Lymphocytes- 25-38%- renders immunity Monocytes – 3-7%- help in immune system. (low monocyte is good and high indicates a problem in the patient) TOTAL WBC COUNT=4500-11000 millions per litre

Platelets One of the process of hemostasis is called coagulation Fragments of small cells called megakaryocytes Formed in the bone marrow Normal count – 150,000 to 350,000 per microliter of blood Plays an important role in hemostasis- (prevention of blood loss) One of the process of hemostasis is called coagulation Platelets form a plug at the site of vessel injury and release some substances that react with coagulation factors and seal the wound Coagulation factors are 12 in number Final reaction in coagulation is conversion of fibrinogen to fibrin threads to form a clot

Blood groups Human blood groups fall into four main groups- A ,B ,AB, O Each group has a specific combination of antigen(on RBC cell membrane) and associated antibodies Antigens are inherited while antibodies are acquired by 6 months of birth Group A –antigen A ,anti-B antibody Group B- antigen B,anti- A antibody Group AB-antigen AB, no antibodies Group O- has no antigens,has both anti-A &B antibodies People with group O are universal donors as they lack antigens, while group AB are universal recipients as they lack antibodies

Clinical aspects of blood I Anaemia It is defined as condition characterised by low amount of hemoglobin in the blood Anaemia can result from decreased RBC count or small cell size or little hemoglobin Different types of anaemia A. Anaemia due to decreased blood count EG: Aplastic anaemia – results from bone marrow destruction causes - Drugs ,Radiation, Viruses ,Toxins, Bone marrow cancers B. Nutritional anaemia (iron deficiency) Results from deficiency of vitamin B12 or folate needed for RBC development Causes - Poor diet ,pregnancy, low iron absorption

C. Pernicious anaemia- results from specific form of Vit B12 deficiency D. Sideroblastic anaemia- results from non utilisation of iron inspite of availability, secondary to any disease E. Hemolytic anaemia- reduction in RBC due to excessive destruction of RBC. Congenital spherocytosis

F. Anaemia due to loss or destruction of RBC Hemorrhagic anaemia – results from excessive blood loss-acute or chronic Thalassemia –(thalassa means sea) occurs in mediterranian population It is a heriditary disorder characterised by production of abnormal hemoglobin G. Sickle cell anaemia- is a mutation altering the hemoglobin molecule resulting in sickle shape of the RBC .

II Hemophilia Hereditary deficiency of clotting factor (factor viii) Sex linked that passes from mother to son There is presence of bleeding in the tissue Can be treated with administration of required fractions of clotting factors

Neoplasms A. Leukaemia – It is the neoplasm of WBC. White cells divide rapidly and accumulate but are incompetent Symptoms Anaemia, fatigue, bleeding,splenomegaly, hepatomegaly B. Multiple myeloma Cancer of blood forming cells in the bone marrow, mainly plasma cells that produce antibodies Patient with multiple myeloma suffers from infections due to immunodeficiency Treated with radiation and chemotherapy