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

• 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

Platelets

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 antibodyGroup B- antigen B,anti- A antibodyGroup AB-antigen AB, no antibodies Group O- has no antigens,has both anti-A &B antibodiesPeople 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 countEG: 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 developmentCauses - 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 incompetentSymptoms • 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