Blood Histology PDF

# BLOOD HISTOLOGY Dr. Ahmed Adel ## The Blood Cells **Def:** the fluid of life, contained in the closed circulatory system. ### Blood | Component | Percentage | | ----------------------- | ---------- | | Plasma (Fluid part) | 55% | | Cells | 45% |...

# BLOOD HISTOLOGY Dr. Ahmed Adel ## The Blood Cells **Def:** the fluid of life, contained in the closed circulatory system. ### Blood | Component | Percentage | | ----------------------- | ---------- | | Plasma (Fluid part) | 55% | | Cells | 45% | ### Red Blood Corpuscles (RBCs) (Erythrocytes) **A - Shape** * Biconcave Discs. * In slow blood stream: "Rouleaux". **B - Size** * Normal: 6-9 µm (average 7.5 µm). **C - Colour:** * Single RBC → greenish yellow due to minimal HB. * Drop of blood → red as it contains large number of RBCs. * In stained sections → acidophilic with a pale center **D - Number:** * Males: 5 - 5.5 million /mm3. * Females: 4.5 - 5 million /mm3 (decreased due to menstruation and female sex hormones) **E - Structure & Adaptation to Function:** * Biconcave disc → ↑ surface area for more gas exchange. * Plastic → Squeezed in narrow vessels without rupture. * Selective permeability → Easy exchange of O2 and CO2 but not HB. * Absent Nucleus → More space to HB for gas exchange * Absent organelles → More space to HB for gas exchange. * Carbonic anhydrase → CO2 transportation from tissues to the lung ## Abnormalities of RBCs | Characteristic | Abnormality | | :---------------- | :------------------------------------------------ | | Abnormal Shape | Spherocytosis | | Abnormal Size | Normal: 6-9 µm <br>Microcytic Anemia <br>Macrocytic Anemia | | Abnormal Number | Oligocythemia→ Anemia <br>Polycythemia | | Abnormal Color | Hypochromic <br>Normochromic <br>Hyperchromic | ## White Blood Cells (WBCs) (Leucocytes) **Def:** True nucleated cell **Colour:** Single WBC is colorless but aggregated WBCs appear white. **Count:** (4000 - 11000 / mm3) * Leucopenia < 4000 * leukocytosis > 11000 **white blood cells ~ WBC** | Type | Percentage | | :------------------ | :-------------- | | agranular | | | lymphocytes | 20 - 25% | | monocytes | 3 - 8% | | granular | | | basophils | .5 - 1% | | neutrophils | 60 - 70% | | eosinophils | 2 - 4% | **Total Leucocyte count:** It is the total number of leucocytes in 1 mm3 of blood **Differential leucocyte count:** It is the percentage of each type of leucocytes in blood. ## Granular leukocytes | Feature | Neutrophils | Eosinophils | Basophils | | :------------- | :-------------------------- | :--------------------------- | :---------------------------- | | Percentage | 60-75% | 2-5% | 0.5-1% | | Size | 10-12 μm | 12-15 μm | 10-12 μm | | LM: | | | | | Nucleus | Single, Segmented (2-5 segments) | Bilobed or horse-shoe shaped. | Large, Irregular. | | Cytoplasm | Fine neutrophilic granules. | large acidophilic refractile granules. | Obscured by cytoplasmic granules. | | Function | | | | | | Defense mechanism: | Anti-allergic action through: | | | | As they migrate to the infected area | 1. Phagocytosis of Ag-Ab complex. | Produce histamine & heparin | | | and phagocytose bacteria and foreign | 2. Histaminase & sulphatase → destroy | during allergy. | | | bodies resulting in pus formation (so | excess histamine & other substances | | | | called microphages). | causing allergy. | | ## Non granular leukocytes | Feature | Monocytes | Lymphocytes | | :------------- | :-------------- | :--------------------------- | | Percentage | 3 - 8% | Small (B&T) 25-30% | Medium 10-12 μm | | Diameter | 15 μm | 6-8 μm | | | LM: | | | | | Nucleus | • Large & pale. | • Dark. | • Pale. | | | • Kidney or horse-shoe shaped.| • Rounded. | • Indented. | | Cytoplasm | • Abundant. | • Little rim around nucleus. | • Abundant. | | | | • Pale basophilic. | • More basophilic. | | Function | Phagocytic function as they migrate | Humoral immunity | Cell mediated immunity | | | through the wall of capillaries and venules | | | | | into the surrounding C.T. → macrophages. | | | ## Platelets (Thrombocytes) * **Structure:** Formed of cytoplasm covered with a membrane with no nucleus (not true cells) * **Counts:** 150000 - 400000 / mm3 * **Shape:** oval or rounded discs * **LM:** * Outer pale blue part (hyalomere) * Central granular part (granulomere) * **origin:** megakaryocyte **Function:** → **Stop bleeding (Hemostasis)** 1. **Serotonin → V.C. → ↓blood loss)** 2. **Platelet aggregation (white thrombus):** Platelets adhere to the wall of injured blood vessel 3. **Red thrombus (coagulation):** Platelets secrete Thromboblastin which changes prothrombin into thrombin → change fibrinogen into fibrin network → attraction of RBCs → closes blood vessel and stops bleeding. | Image | Description | | ----- | ----------------------------------------------------------- | | (a) | Vessel injury | | (b) | Platelet plug formation <br> Collagen fibers | | (c) | Fibrin <br> Blood clotting | ## Quiz **Which of the following formed elements do not contain a nucleus?** a. Basophils b. Erythrocytes c. Leukocytes d. Monocytes e. Lymphocytes **Which of the following is a granulocyte?** a. Thrombocyte b. Lymphocyte c. Eosinophil d. Monocyte e. Erythrocyte **The normal total leucocytic count is:** a. 4000 - 11000 / mm3 b. 2000 - 7000 / mm3 c. 1000 - 5000 / mm3 d. 7000 - 11000 / mm3 e. 5000 - 12000 / mm3 **About monocytes : one is true:** a. Their percentage is from 3-8%. b. Their nucleus is segmented. c. They have a role in allergy. d. The cytoplasm has acidophilic granules. e. They can be transformed into plasma cell **Regarding RBCs:** a. True nucleated cells b. Drop of blood appears greenish yellow in color c. Biconcave discs d. Total count is 4000 - 11000 / mm3 e. Cytoplasm has numerous organelles. **Which leukocyte is the most abundant in a peripheral smear of blood?** a. Lymphocytes b. Basophils c. Neutrophil d. Monocytes e. Eosinophils