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Questions and Answers
What is the primary component of blood that constitutes 55% of its volume?
What is the primary component of blood that constitutes 55% of its volume?
Which of the following abnormal red blood cell shapes is associated with increased fragility and hemolysis?
Which of the following abnormal red blood cell shapes is associated with increased fragility and hemolysis?
What is the average diameter of a normal red blood cell?
What is the average diameter of a normal red blood cell?
Which staining procedure is utilized to create a blood film for examination?
Which staining procedure is utilized to create a blood film for examination?
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What phenomenon describes the presence of red blood cells of varying sizes?
What phenomenon describes the presence of red blood cells of varying sizes?
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What is the primary component of red blood cells responsible for carrying oxygen?
What is the primary component of red blood cells responsible for carrying oxygen?
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In which organ are old red blood cells primarily phagocytosed?
In which organ are old red blood cells primarily phagocytosed?
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What happens to red blood cells in a hypotonic solution?
What happens to red blood cells in a hypotonic solution?
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What is the average lifespan of a red blood cell?
What is the average lifespan of a red blood cell?
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Anemia is characterized by a red blood cell count of:
Anemia is characterized by a red blood cell count of:
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What is one physiological cause of polycythemia?
What is one physiological cause of polycythemia?
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Which cytoskeletal components help maintain the shape and stability of red blood cells?
Which cytoskeletal components help maintain the shape and stability of red blood cells?
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What feature of the biconcave shape of red blood cells primarily aids in gas exchange?
What feature of the biconcave shape of red blood cells primarily aids in gas exchange?
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Which of the following characteristics is NOT associated with leukocytes?
Which of the following characteristics is NOT associated with leukocytes?
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What are the types of granular leukocytes categorized by?
What are the types of granular leukocytes categorized by?
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What condition is characterized by a total leukocytic count exceeding 11,000/mm3?
What condition is characterized by a total leukocytic count exceeding 11,000/mm3?
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Which enzyme is specifically mentioned as being found in red blood cells?
Which enzyme is specifically mentioned as being found in red blood cells?
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How is the differential leukocytic count determined?
How is the differential leukocytic count determined?
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What distinguishes non-granular leucocytes from granular leucocytes?
What distinguishes non-granular leucocytes from granular leucocytes?
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What is a typical life span for granular leucocytes?
What is a typical life span for granular leucocytes?
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Which type of leukocyte is characterized as being motile and spherical, with a function in defense?
Which type of leukocyte is characterized as being motile and spherical, with a function in defense?
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Which type of granules in neutrophils are primarily responsible for defense against bacteria and viruses?
Which type of granules in neutrophils are primarily responsible for defense against bacteria and viruses?
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What characterizes the nucleus of neutrophils?
What characterizes the nucleus of neutrophils?
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What role does lactoferrin play in the function of neutrophils?
What role does lactoferrin play in the function of neutrophils?
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During which process do neutrophils migrate between endothelial cells?
During which process do neutrophils migrate between endothelial cells?
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Which type of neutrophil granules contains enzymes like lysozyme and collagenase?
Which type of neutrophil granules contains enzymes like lysozyme and collagenase?
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What is the lifespan of neutrophils in circulation?
What is the lifespan of neutrophils in circulation?
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What is formed from dead neutrophils during an infection?
What is formed from dead neutrophils during an infection?
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Which feature of neutrophils aids in their movement through connective tissue?
Which feature of neutrophils aids in their movement through connective tissue?
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What effect does pus have on the body's temperature regulation?
What effect does pus have on the body's temperature regulation?
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Study Notes
Faculty of Medicine, Academic Year, and Module Information
- Academic year: 2024-2025
- Year: 1
- Semester: 1
- Module: Blood and Body Fluids (BLF) 103
Histology of Blood Cells I
- Professor: Safinaz Salah Eldin
- Department: Histology
- Faculty of Medicine, Cairo University
Objectives
- Recognize different blood elements
- Describe the histological characteristics of RBCs, leucocytes (granular, non-granular), and platelets at light and electron microscopy levels
- Correlate normal RBCs structural adaptation for proper function
- Relate RBCs structural abnormalities to clinical conditions (e.g., hemolytic anemia)
- Differentiate between RBCs and WBCs
- Recall normal RBCs, leucocytic, and platelet counts
- Correlate the ultrastructure components of platelets to their function
- Discriminate different types of WBCs from each other in various blood films
- Point out abnormal variations in RBC count and shape
- Identify deviation in WBCs and platelet counts and some of their causes
- Interpret alterations in RBC, WBC, and platelet count and relate them to possible clinical conditions
- Define the total and differential leucocytic count
- Describe the histological organization and sites of the bone marrow
- Identify types of bone marrow
- Recognize the histological structure of the cells involved in various stages of hemopoiesis
Blood Composition
- Blood is a specialized type of connective tissue
- Blood elements (45%): red blood corpuscles, leucocytes, platelets
- Plasma (55%): the fluid portion of blood
Blood Examination
- Blood film
- Leishman's stain (neutral stain)
- Acidic stain (eosin)
- Basic stain (methylene blue)
- Dissolved in methyl alcohol (fixative)
Blood Smear Preparation
- Withdraw blood using a micropipette
- Place a drop of blood on a slide
- Use a second slide to spread the blood thinly
- Apply stain, rinse, and place a coverslip
Red Blood Corpuscles (RBCs) - Erythrocytes
-
Light Microscopy (LM):
- Shape: biconcave discs (side view), rounded (top view)
- Size: 6-9 µm diameter (average 7.5 µm). Edge 2.2 µm, center 0.8 µm
- Abnormal sizes: Microcytes (< 6 µm), Macrocytes (> 9 µm). Anisocytosis (different sizes)
- In unstained blood film: Color due to hemoglobin (Hb). Rounded, non-nucleated. Acidophilic (Hb is a basic protein), pale center (1/3 of diameter) = Normochromic
-
Electron Microscopy (EM):
- No nucleus or organelles
- Hb appears electron-dense & homogenous
- Flexible cell membrane
- Cytoskeleton (actin & spectrin) maintains shape and stability
- Glycocalyx includes antigenic sites for blood groups and Rh factor
- Life span: 120 days
- Fate: phagocytosed by macrophages in liver, bone marrow, and spleen. Excreted as bile pigments. Iron reused for new RBCs production
Histologic Features of Osmotic Fragility
- Plasma (isotonic solution 0.9% saline): Normal shape
- Hypertonic solution: Cells shrink and show notches
- Hypotonic solution: Cells swell, burst, and leak hemoglobin
RBC Number
- Determined by hemocytometer or electronic instruments
- Average normal adult male: 5-5.5 million/mm³
- Average normal adult female: 4.5-5 million/mm³
- Stimulatory effects of male hormones on the bone marrow
RBC Abnormalities in Number
- Anemia: < 4 million/mm³ (oligocythemia) and/or decreased hemoglobin concentration
- Polycythemia: > 6 million/mm³, due to hypoxia (physiological e.g., high altitudes; pathological e.g., chronic lung and heart diseases)
Adaptation to Function
- Plasmalemma: Flexible, Lipoproteins squeeze inside narrow capillaries, highly selective for gas exchange
- Shape: Biconcave ++++ surface area for gas exchange, Rounded edges—easy passage in branched vessels
- Content: No nucleus, no organelles ++++ space Hb, Enzymes: Hb reductase, Carbonic anhydrase
White Blood Cells (Leucocytes)
- Types: Granular (e.g., neutrophils, eosinophils, basophils) and Non-granular leucocytes (e.g., lymphocytes, monocytes)
- General characteristics: Five types of cells, contain nuclei and organelles, total count 4000-11000 mm³, lifespan - days to years. spherical, 6-20um
- Leucocytic count: 4000 to 11000/mm³
- Abnormalities: Leukocytosis (> 11,000/mm³) due to infections (acute or chronic); Leukopenia (< 4000/mm³) due to X-ray, irradiation, typhoid fever, influenza, excessive use of antibiotics
Granular Leucocytes (e.g., Neutrophils)
- Short lifespan (few days)
- Single, condensed nucleus (segmented) with peripheral heterochromatin and central euchromatin
- Few organelles (Golgi apparatus, mitochondria, rER)
- Contain non-specific (azurophilic) and specific granules
- Azurophilic granules bind to azure dye
Specific Granules
- Bind basic or acidic stains
- Have specific functions
Neutrophils (Polymorphonuclear leucocytes)
- 60-70%, 10-12 µm diameter
- Life span: Few days
- LM: Cytoplasm contains specific granules (numerous fine, pale granules). Azurophil granules (few, large, stain purple with azure dye)
- Nucleus: Single segmented nucleus, 2-5 lobes connected by thin chromatin threads. Shape various. Barr body (inactive X chromosome) in females (3-6% of cells)
- EM: Nucleus—peripheral heterochromatin & small central euchromatin, Cytoplasm—pseudopodia, few organelles (more glycogen). Granules—primary (azurophilic) and secondary (specific)
- Primary granules: Large, few, dark, considered as 1ry lysosomes. Contain Myeloperoxidase defenses against bacteria & viruses
- Secondary granules/Specific granules: Small, many, and pale. Contain Collagenase, Phagocytin, Lysozyme, Lactoferrin
- Functions: 1st line of defense (non-specific), diapedesis, become motile, microphages; phagocytose bacteria; lactoferrin binds to iron, phagocytin kills bacteria, lysozyme destroys bacterial proteins; collagenase destroys collagen, myeloperoxidase kills bacteria
- Dead neutrophils form pus cells; pus increases body temperature to stimulate heat regulation center in brain. Attracts monocytes to clean infection site. Stimulates bone marrow for more neutrophils. Secretes trephone substances for wound healing
Neutrophil Abnormalities
- Neutrophilia (> 75%): acute pyogenic infection (e.g., tonsillitis, appendicitis, abscess)
- Neutropenia (< 60%): typhoid fever, tuberculosis, viral infections (e.g., influenza)
- Band cells (immature neutrophils): Large amounts indicate bacterial infections
Eosinophils
- 1-4%, 10-14 µm diameter.
- Life span: Few days
- LM: Nucleus: bilobed, horse-shoe shaped connected by thick chromatin threads. Cytoplasm: Large acidophilic granules (specific)
- EM: Nucleus –peripheral heterochromatin with central euchromatin. Cytoplasm –few organelles & two types of granules: azurophil (=lysosomes). Specific –oval, electron-dense core (internum) & less dense periphery (externum)
- Functions: Terminate allergy (sulphate to destroy histamine & heparin; phagocytose antigen-antibody complexes). Defend against parasites (cytotoxic effect of internum; neurotoxins disrupt function of parasites)
- Eosinophilia (>5%): allergic diseases (urticaria, eczema, asthma), parasites (bilharziasis)
- Eosinopenia (<1%): corticosteroids inhibit their release from bone marrow
Basophils
- 0-1%, 10-12 µm diameter.
- Life span: Few days
- LM: Nucleus: irregular segmented, S-shaped. Cytoplasm: Coarse basophilic granules obscure nucleus. Metachromatically stained by toluidine blue.
- EM: Nucleus - peripheral heterochromatin with central euchromatin. Cell membrane shows receptors for IgE. Cytoplasm –few organelles, & two types of granules: azurophil (=lysosomes), specific - large, rounded, electron dense & contain: histamine, heparin, eosinophil chemotactic factor, leukotrienes
- Functions: Secretes heparin (anticoagulant, promotes allergy). Secretes histamine (vasodilation, sudden decrease in blood pressure during anaphylaxis). Attract eosinophils to site of allergy by ECF. Leukotrienes cause bronchospasm and asthma. Limited phagocytic powers
- Basophilia (>2%): allergic diseases, viral infections (chicken pox), liver cirrhosis
Summary
- RBCs: LM, count, size/shape, color, adaptation
- WBCs: Types, total and differential leucocytic count, granular & non-granular, neutrophils, eosinophils, basophils
References
- Junqueira's Basic Histology: Text and Atlas (2018), 15th edition by Anthony Mescher, chapter 12, pp 248
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Description
Test your knowledge on the essential components of blood, focusing on red blood cells, their structure, functions, and lifespan. This quiz covers questions related to blood composition, disorders like anemia, and physiological phenomena affecting blood cells. Perfect for students of human physiology and related fields.
