Histology BLOOD 2 (WBCs & Blood platelets) PDF

Faculty of Physical therapy lecture 2 BLOOD (WBCs + platelets) By Dr. Dr Doaa Khaled Lecturer of HISTOLOGY & CYTOLOGY, Faculty of Medicine , Helwan University Leucocytes  Are true spherical cells , they have nuclei & organelles Cytoplasm: 1-the cytopla...

Faculty of Physical therapy lecture 2 BLOOD (WBCs + platelets) By Dr. Dr Doaa Khaled Lecturer of HISTOLOGY & CYTOLOGY, Faculty of Medicine , Helwan University Leucocytes  Are true spherical cells , they have nuclei & organelles Cytoplasm: 1-the cytoplasm is mild basophilic & contain all cell organoids and cell inclusions. 2- According to the presence or absence of granules seen by LM in this cytoplasm, leucocyte are classified into: Granular leucocytes 1- Neutrophils 2- Eosinophils 3- Basophils Non-granular leucocytes 1- Lymphocytes 2- Monocytes Number of leucocytes They vary in number from 4000 to 11,000 per cubic millimeter. Leucocytosis It is the increase in number of leucocytes above normal. Leucocytosis occur in: some infectious dis and leukemia (up to 100,000cmm). Leucopenia: It is the decrease in number of leucocytes below 4,000 per cubic millimeter.  The granulocytes are further subdivided into three type according to the staining properties of their granules, namely;  1-Neutrophils: whose granules are neutral.  2-Eosinophils: whose granules are stained by acidic dyes (e.g. Eosin).  3-Basophils: whose granules are stained by basic dyes.  The non-granular leucocytes (agranulocytes) are subdivided according to some morphological and functional characters into:  1- Lymphocytes  2- Monocyte Function : are involved in defense mechanism of the body against foreign materials.  Granular Leucocytes Neutrophil General appearane A- Spherical cell. B- 10-12 diameter. C- 50-70% of the total number of WBCs Neutrophilia Neutrophilia = increased number of neutrophils > 70%. This occurs in acute infections as in tonsillitis, appendicitis and in any abscess formation. Neutropenia It is the decrease in the number of neutrophils< 50% It occurs in typhoid fever, T.B. Influenza and in severe poisoning. Nucleus: Single segmented nucleus having 3-5 lobes. The cytoplasm “ mildly basophilic, heavily populated with granules which are (2 types). a. Azurophilic Granules. b. Specific granules. Neutrophilic granules Azurophilic granules (specific) Numerous (80%) Less numerous (20%) Not seen by L/M Seen by L/M Smaller diameter, less than 0.3 Larger diameter Contain alkaline phosphatase, They are lysosomes & contain collagenase, lactoferrin which has at least 6 hydrolytic enzymes bacteriostatic function (killing the bacteria) a) Neutrophils play an important role in the body defence mechanism in cases of acute inflammations (especially those caused by bacteria). b) Neutrophilia indication of bacterial infection General appearance ▪ Their diameter varies from 12-14 microns. ▪ Eosinophilia = increase in the percentage of Eosinophils which occurs in: 1- Allergic diseases: as urticaria & bronchial asthma 2. Parasitic diseases: as ascaris, Bilharzia & ankylostoma. Eosinopenia = decrease in number of Eosinophils which occurs during treatment with cortisone nucleus : bilobed, horse shoe-shaped nucleus.  3- the cytoplasm - The cytoplasm is mildly basophilic. - They contain numerous, large eosinophilic granules. - These granules are lysosomes that contain large amounts of Histaminase enzyme. Functions of Eosinophils 1. They can destroy parasites by lysosomal enzymes. 2. Eosinophils play an important role in controlling allergic reaction. Gen appearance: - Diameter varies from 10-12microns. Basophilia = An increase in the percentage of basophils. Occurs in: - Liver cirrhosis - small pox and - in allergic dis.. Nucleus : They have irregular S-shaped nuclei. Cytoplasm : They are rich in large basophilic granules that obscure the nucleus. The granules are similar to those of the mast cells where they contain heparin, histamine. they can be stained metachromatically by toluidine blue Functions of basophils: 1. Production and carriage of histamine and heparin. 2. They play a role in allergic (hypersensitivity reaction).  Eosinophil 1-4% Neutrophil 50-70% Basophil 0.5-1%  Lymphocyte 20-40% Monocyte 3-8% General appearance: 1-Shape: spherical cells 2- Percentage: varies from 20% - 40% of blood WBCs 3- Nucleus : The nucleus is single, central, rounded deeply- stained, by a very thin rim of cytoplasm  Lymphocytosis Increase in the percentage of lymphocytes in the circulating blood Causes of Lymphocytosis 1- Lymphocytosis occurs normally in children. Lymphocytosis occurs 2- in chronic diseases as in: - viral infection - T.B. (Tuberculosis) lymphopenia: decreased number of lymphocyte in the blood There are 2 main types of lymphocytes: a. T-lymphocytes b. B-lymphocytes C. Null cells  Stem cells in the bone marrow Stay in the bone Migrate to the Pass to the blood marrow thymus Null-cells B-lymphocytes T-lymphocytes (natural killer cells B-lymphocytes T-lymphocytes Differentiate in the bone - Differentiate in the thymus marrow. represent about 15% of - represent about the circulating small 80% of the circulating lymphocytes. small lymphocytes activation leads them to - activation leads them to differentiate into plasma cells differentiate into many subsets, which secrete the antibodies. each has a role in dealing with the antigen They are responsible for - They are responsible for cell humoral immunity mediate immunity.  Functions of B-lymphocytes 1. B-lymphocytes are responsible for the development of humoral immunity, as follows: If any antigen enters the body,  a programmed B-lymphocyte is firstly activated by first contact with the specific antigen.  It will proliferate into numerous daughter cells carrying the same program of the mother cell. some of these daughter cells will differentiate into 2 types of cells a. Plasma cells which secrete immune bodies directly in the blood (Anti-bodies) forming Humoral immunity. This process is called primary immune response. b. B-memory cells which produce secondary immune response when they are exposed once again in the future to the same types of antigens.  the “secondary immune response” which is more rapid and extensive  - Activation of the programmed B-lymphocyte by its specific antigen needs the help of a T- helper factor released by a T-helper cell. 1- When a programmed T-lymphocyte is activated by contact with its specific antigen. 2- it will proliferate into numerous daughter cells carrying the same program of the mother cell. 3- There are many subsets of T-lymphocytes, each has  a characteristic function, i.e. each subset has its characteristic different role in dealing with the foreign antigen:  a) T-killer cell (cytotoxic T-lymphocytes).  b) T-helper cells.  c) T-suppressor cells.  d) T-amplifier cells.  e) T-memory cells. General apperance: Shape: spherical cells which have a diameter of 12 to 20 microns (largest blood cell). Monocytosis = increase number of monocytes as in chronic infections as in malaria, T.B., syphilis Nucleus: The nucleus is single, eccentric & large kidney shaped Cytoplasm HasFrosted glass appearance The cytoplasm is rich in lysosomes Function of Monocytes: 1. They are highly phagocytic cells in the connective tissue. 2. They can be transformed into macrophage cells all over the body tissues and organs  Lymphocyte 20-40% Monocyte 3-8% Origin & life span: originate in the red bone marrow as cytoplasmic fragments of a giant haematopoietic cell called “megakaryocyte” General appearance Shape: Blood platelets are not cells, small oval biconvex disks non nucleated bodies similar to plates, has 2-5 microns Number: of blood platelets varies from 250,000 to 350,000 per cubic millimeter. 1- Decrease in number of blood platelets------ thrombocytopenia---- cause hemorrhagic blood disease “(purpura)”. Purpura: It is a congenital disease which results from a decrease in the number of blood platelets. The bleeding time is prolonged in this disease. 2- Thrompocytosis ----- after splenectomy By LM it is formed of 2 ill-defined region : Each platelet is formed of a peripheral pale clear part called Hyalomere, and a central granular basophilic part called Granulomere (contain azurophilic granules. Functions of blood platelets 1- Haemostasis (stop bleeding) 2- Blood platelets release serotonin which is a vasoconstrictor substance to B.V. Which of the following is Characteristic to neutrophil? A-Has horse shoe shaped nucleus b- Has acidophilic cytoplasm c- has specific granules only D- represent 60-70 % in circulating blood Which of the following is Characteristic to basophil? A- Contain histaminase enzyme B- its specific granules contain lactoferrin &collagenase C- increase in bacterial infection D- increase in allergic diseases