Blood Histology Flashcards
What is the composition of blood?
55% blood plasma and 45% blood cells
Blood cells are also referred to as formed blood elements.
How are blood cells counted?
By Hemocytometer or electronic apparatus.
What is a blood film?
A drop of blood spread on a glass slide.
What type of stain is used for blood examination?
Leishman’s stain.
What is the shape of red blood cells (RBCs)?
Acidophilic biconcave discs.
What is the thickness of the periphery and center of RBCs?
Thick periphery: 2 μm; Thin center: 0.8 μm.
What appearance do RBCs show in slow circulation?
Rouleaux appearance.
What causes the Rouleaux appearance of RBCs?
High surface tension causing them to adhere in columns.
What is crenation?
Shrunken RBCs in a hypertonic solution.
What is spherocytosis?
Swollen (spherical) RBCs in a hypotonic solution.
What is poikilocytosis?
Variable shapes of RBCs.
What is the mean diameter of RBCs?
7.5 μm.
What defines a microcyte?
RBCs less than 6 μm.
What defines a macrocyte?
RBCs more than 9 μm.
What is anisocytosis?
Variable diameter of RBCs.
What is the appearance of normochromic RBCs in a stained blood film?
Acidophilic with a pale center.
What are RBCs primarily composed of?
Hemoglobin (Hb).
What is the only organelle in RBCs?
Cell membrane.
What type of membrane proteins are found in RBCs?
Integral membrane proteins.
(Band 3 protein & glycophorin A)
What is the function of band 3 protein in RBCs? mmm
Ion channels.
What covers the outer surface of RBCs?
Carbohydrate-rich glycocalyx.
( Blood group & Rh factor)
What do the antigens in the glycocalyx determine?
Blood groups [ABO] and Rh factor.
What stabilizes the membrane of RBCs?
Peripheral cytoskeleton proteins.
What adaptations do RBCs have for gas exchange?
Cytoskeleton meshwork, selective permeability, biconcave shape, absence of nucleus and organelles.
What enzymes are contained in RBCs?
Hb reductase ( combine with O2)and carbonic anhydrase ( carry CO2)
What is the shape of red blood cells (RBCs)?
Acidophilic biconcave discs
This shape increases the surface area for gas exchange.
What is the thickness of the periphery and center of RBCs?
Thick periphery: 2 μm, Thin center: 0.8 μm
What appearance do RBCs show in slow circulation?
Rouleaux appearance
This is due to high surface tension, causing RBCs to adhere in columns (piles of coins), which is reversible and causes no damage.
What are the causes of abnormal shapes of RBCs?
Changes in cell membrane or Hb content
Define crenation in RBCs.
Shrunken RBCs in hypertonic solution
What happens to RBCs in a hypotonic solution?
They swell (spherocytosis) and may rupture, leaving cell ghosts
What is poikilocytosis?
Variable shapes of RBCs, such as sickle cells and ovalocytes
What is the mean diameter of RBCs?
7.5 μm
What is classified as a microcyte?
RBCs less than 6 μm
What is classified as a macrocyte?
RBCs more than 9 μm
What does anisocytosis refer to?
Variable diameter of RBCs
What is the appearance of normochromic RBCs in a blood film stained with Leishman stain?
Acidophilic with a pale center (about 1/3 of the diameter)
Normochromic RBCs indicate a normal amount of hemoglobin.
What is the structure and composition of RBCs?
Not true cells; non-nucleated sacs filled with hemoglobin (Hb) and no organelles
RBCs primarily consist of hemoglobin, which is responsible for oxygen transport.
What is the only organelle present in RBCs?
Cell membrane
The cell membrane contains important proteins and structures essential for RBC function.
What type of proteins are predominantly found in the RBC membrane?
Integral membrane proteins, including ion channels like band 3 protein and glycophorin A
These proteins play critical roles in ion transport and blood group antigen presentation.
What covers the outer surface of RBC membranes?
Carbohydrate-rich glycocalyx
The glycocalyx is involved in cell recognition and interaction.
What antigens are contained in the glycocalyx of RBCs?
Blood groups [ABO] and Rh factor
These antigens are crucial for blood transfusion compatibility.
What is associated with the inner surface of the RBC membrane?
Peripheral cytoskeleton proteins
These proteins help stabilize the membrane and maintain the biconcave shape of RBCs.
What is the primary function of the cytoskeleton meshwork in RBCs?
Reinforces the membrane and maintains shape and flexibility
This adaptation allows RBCs to navigate through narrow capillaries.
What property of the RBC membrane allows selective permeability?
Selective permeability to O2 and CO2
This property is essential for gas exchange during respiration.
What is the significance of the biconcave shape of RBCs?
Increases surface area for gas exchange
The biconcave shape facilitates efficient oxygen and carbon dioxide transport.
What advantage does the absence of nucleus and organelles provide to RBCs?
More space for hemoglobin
This adaptation enhances the oxygen-carrying capacity of RBCs.
Name two enzymes contained in RBCs.
- Hb reductase
- Carbonic anhydrase
Hb reductase assists in oxygen binding, while carbonic anhydrase helps transport carbon dioxide.
What is the average life span of red blood cells (RBCs)?
About 120 days
Where are old RBCs recognized and phagocytosed?
In the liver, spleen, and bone marrow
What is the average number of RBCs per mm3 in a normal adult male?
5 - 5.5 million/mm3
What is the average number of RBCs per mm3 in adult females?
4.5 - 5 million/mm3
What causes the lower average number of RBCs in adult females?
Menstrual cycle and inhibitory effect of female hormones on bone marrow
What is anemia?
Decreased number of RBCs below 4 million/mm3 and/or decreased hemoglobin concentration
What is polycythemia?
Increased number of RBCs above 6 million/mm3
What stimulates the bone marrow to produce more RBCs in polycythemia?
Hypoxia
What are the physiological causes of polycythemia?
- High altitudes
- Muscular exercise
- Newborns
What are the pathological causes of polycythemia?
- Chronic lung diseases
- Chronic heart diseases
What is pernicious anemia?
Vitamin B12 deficiency anemia due to failed production of intrinsic factor by the stomach
What is hemorrhagic anemia?
Excessive loss of blood due to bleeding nose, piles, or excess menstrual bleeding
What is hemolytic anemia?
Excess destruction of RBCs due to abnormal shape or abnormal Hb content
What characterizes sickle cell anemia?
An abnormal rigid type of Hb that gives a crescent shape to RBCs
What are platelets (thrombocytes)?
Very small non-nucleated, membrane-bound cell fragments
Platelets are not true cells.
What is the origin of platelets?
Cytoplasmic fragmentation of megakaryocyte in bone marrow
What is the normal platelet count range?
150,000-400,000/mm3
What is thrombocytosis?
Increase in platelets number
What is thrombocytopenia?
Decrease in platelets number
What is the lifespan of a platelet?
10 days
Where are old platelets phagocytosed?
By macrophages in the spleen
How are platelets seen in a blood film?
Singly or more commonly as clumps
What is the shape of platelets?
Oval (Biconvex) discs
What is the size of platelets?
2-4 µm in diameter
What are the two zones of a platelet?
Hyalomere and granulomere
What is the outer pale basophilic peripheral zone of a platelet called?
Hyalomere
What is the central dark granular zone of a platelet called?
Granulomere
What is the function of the glycocalyx in platelets?
Helps platelets adhesion & aggregation (platelet plug)
What does the marginal bundle in the hyalomere consist of?
Microtubules rings and actin & myosin microfilaments
What is the role of microtubules in platelets?
Maintaining the discoid form of platelets
What is the role of actin & myosin microfilaments in platelets?
Platelet contraction for motility & blood clot retraction
What are the two membranous tubular systems in the context of platelets?
- Open canalicular system
- Dense tubular system
The open canalicular system facilitates uptake of factors from plasma and rapid degranulation at activation, while the dense tubular system stores Ca2+ ions.
What is the function of the open canalicular system?
Facilitates:
* Uptake of factors from plasma
* Rapid degranulation at activation & Ca2+ release
The open canalicular system is an invagination from the cell membrane.
What does the dense tubular system store?
Ca2+ ions
The dense tubular system consists of remnants of the endoplasmic reticulum of megakaryocytes.
What is contained within the granulomere of platelets?
- Mitochondria
- Ribosomes
- Glycogen
- 3 types of granules
The granulomere is a crucial component of platelets.
What are the three types of granules found in platelets?
- α (alpha) granules
- Delta granules (Dense bodies)
- λ (lambda) granules
Each type of granule has specific contents and functions.
What do α (alpha) granules contain?
- Clotting factors (e.g., fibrinogen)
- Growth factors
- Ca2+
α granules are the majority of granules in platelets.
What is contained in delta granules (Dense bodies)?
- ADP
- ATP
- Serotonin
Delta granules play a role in platelet function and aggregation.
What do λ (lambda) granules contain?
Lysosomes
λ granules are involved in the degradation of substances.
What does purpura indicate?
Thrombocytopenia
Purpura refers to a condition characterized by small purple spots on the skin due to bleeding underneath.
What is the platelet count that indicates thrombocytopenia?
Less than 50,000/mm3
Thrombocytopenia can lead to serious bleeding complications.
What are the two main causes of thrombocytopenia?
- Decreased production (bone marrow depression)
- Increased breakdown (autoimmune disease)
Understanding the causes is critical for treatment.
What are the characteristics of thrombocytopenia?
- Prolonged bleeding time
- Excessive bleeding after minor trauma
These symptoms highlight the risks associated with low platelet counts.
Q: What are the components of the C.T. stroma in bone marrow?
A:
Reticular cells (fibroblast-like)
Reticular fibers (collagen type I)
Macrophages
Fat cell
Q: What are the characteristics of blood sinusoids in bone marrow?
Wide and irregular, supported by reticular fibers
Lined with fenestrated endothelial cells
Discontinuous basement membrane
Surrounded by macrophages
Q: What is found in the hematopoietic cords of bone marrow?
Developing blood cells at different stages
Mesenchymal stem cells that produce tissues in addition to blood cells
Q: What are leucocytes (WBCs)?
A: True cells with a single nucleus and organelles.
Q: How long do leucocytes remain in the blood and connective tissue?
Several hours in blood
Few days in connective tissue
Q: What is the normal range for WBC count in blood?
A: 4,000 to 11,000/mm³
Q: What is leukocytosis, and what are its causes?
:
Leukocytosis: Increase in WBCs > 11,000/mm³
Causes:
Physiological (Transient): Pregnancy, labor, cold bath, exercise
Pathological: Acute or chronic infections
Q: What is leukopenia, and what are its causes?
Leukopenia: Decrease in WBCs < 4,000/mm³
Causes:
X-ray exposure
Irradiation
Typhoid fever
Influenza virus
Excessive use of some antibiotics
Q: What are the two main types of leucocytes, and what distinguishes them?
Granular Leucocytes: Have specific + non-specific granules
Agranulocytes: Have only non-specific granules
Q: What are the percentages of different types of WBCs?
Neutrophils: 60-70%
Eosinophils: 1-4%
Basophils: 0-1%
Lymphocytes: 20-30%
Monocytes: 3-8%
Q: What are granular leucocytes? List their types.
: WBCs with specific and non-specific granules:
Neutrophils
Eosinophils
Basophils
Q: What are agranulocytes? List their types.
WBCs with only non-specific granules:
Lymphocytes
Monocytes
Q: What are neutrophils also known as?
Polymorphonuclear leucocytes (P.M.N.)
Microphages
Q: What is the normal differential count for neutrophils?
A: 60-70%
Q: What is neutrophilia, and what are its causes?
Neutrophilia: Increased neutrophil count
Causes: Acute pyogenic (bacterial) infections such as:
Acute tonsillitis
Acute appendicitis
Abscessخراج
Q: What is neutropenia, and what are its causes?
Neutropenia: Decreased neutrophil count
Causes:
Influenza
Measles
Typhoid
Tuberculosis (T.B.)
Q: What is the diameter of neutrophils?
A: 12-15 µm
Q: Describe the nucleus of neutrophils under L.M. (Light Microscope).
Single but segmented into 2-5 lobes
Lobes connected by thin chromatin threads
Dark and variable in shape (Polymorphonuclear
Q: What is the significance of the Barr body in neutrophils?
Found in 6% of neutrophils in females only
Nucleus has a drumstick appearance
Represents the condensed, inactive X chromosome
Q: Describe the cytoplasm of neutrophils under L.M.
Pale basophilic cytoplasm
Contains numerous granules of two types:
Neutrophilic granules: Specific, fine granules
Azurophilic granules: Non-specific, stain purple with azure dye
Q: What are the electron microscopic features of the nucleus in neutrophils?
Peripheral heterochromatin
Small central euchromatin
Q: What are the features of neutrophil cytoplasm under electron microscopy?
Presence of pseudopodia for movement
Few organelles
High glycogen content for energy
Contains two types of granules:
Specific Neutrophilic granules
Non-specific Azurophilic granules
Q: What are specific neutrophilic granules, and what do they contain?
80% of granules
Small, numerous, membrane-bound granules
Contain:
Phagocytin: Bactericidal
Lactoferrin: Bacteriostatic
Collagenase
Q: What are non-specific azurophilic granules, and what do they contain?
20% of granules
Large, less numerous, electron-dense
They are primary lysosomes containing:
Hydrolytic enzymes
Myeloperoxidase: Acts against bacteria and viruses
Q: What is the main function of neutrophils?
l infection
Steps:
Margination: Neutrophils adhere to vessel walls
Diapedesis: Migrate between endothelial cells
Phagocytosis: Engulf and digest bacteria using granules
Dead neutrophils form pus cells
