Structure and Function of RBCs Flashcards
What is the stain used for a basic blood smear?
Wright-Giemsa stain.
What stops collected blood from clotting?
EDTA in the collection tube.
How does EDTA work?
Chelates calcium
Acidic Aromatic stain?
Eosin
What does Eosin stain?
Hydrophobic basic macro-molecules (Haemoglobin and some other proteins)
Which cell does Eosin stain particularly well?
Eosinophil
What percentage of blood is made up of Eosinophils?
Less than 5%
Functions of Eosinophils
Mediators of innate immunity
Increase in context of allergic and parasitic infections
Aromatic Basic stain?
Methylene Blue
What does Methelene Blue stain adhere to?
Hydrophobic acidic macro-molecules such as Nucleic Acids
What cells does methelene Blue predominantly stain?
Basophils
What percentage of Blood cells are Basophils?
Less than 1%
Functions of Basophils
Degranulation during allergic reactions
Related to tissue mast cells
Which cells stain with a little of either dyes?
Neutrophils
Lifespan of Neutrophils
1 day
Neutrophils make up what percentage of Leukocytes?
40-70%
When do Leukocytes increase their numbers? (up to 10 fold?)
During Bacterial and Fungal infections.
How do Neutrophils do their duty?
Phagocytosis
Degranulation
Formation of extracellular traps
Defining features of Monocytes?
Few or no cytoplasmic granules
What percentage of blood leukocytes are Monocytes?
3-8%
Functions of Monocytes?
Phagocytes that present antigen on MHC class II Macrophages are derived from Monocytes. Numbers increase in wide variety of diseases.
Lymphocytes life span?
Days to years.
What is different about reactive forms of lymphocytes?
Have more cytoplasm and more prominent nucleoli
What is the structure of platelets?
Small anucleate fragments
Functions of Platelets
- Primary Hemostatic plug via aggregation
- Stimulate coagulation cascade
- Stimulate wound healing (secretion of PDGF which recruits fibroblasts)
- Present Antigen
How are Bands morphologically different from mature neutrophils?
Horseshoe shaped nuclei
Bean shaped nuclei in even less mature neutrophils (metamyelocytes)
Round nuclei in myelocytes
What is different about neutrophil appearance during bacterial infection?
Increased cytoplasmic toxic granules.
Describe the red cell design
Flexible shape
Bi-concave disc
Cable reinforce alpha beta spectrin heterodimer anchored to Ankyrin and Band 3
Haemoglobin packed in just short of crystallization concentrations
Na/K ATPase pump maintains osmotic pressure (Failure of ATPase pump results in swelling and bursting)
Effect of Oxidants on Haemoglobin
Radicals damage Haemoglobin leading to formation of inter and intra di-sulfide bonds which further leads to precipitation and or denaturation of haemoglobin.
What protects red cells from oxidants?
The Glutathione system
What is required for efficient operation of the Glutathione
NADPH and The enzyme Gluthathione reductase.
What does Iron oxidized to the Fe3+ state produce?
Methemoglobin
How is Methemoglobin reduced?
Via cytochrome b5 reductase
What is required for reduction of Methemoglobin by cytochrome B5 reductase.
NADH
What are 2 of the essential metabolic processes of RBCs?
Glycolysis to make ATP and NADH
Pentose shunt to make NADPH
What is the first enzyme of the pentose phosphate shunt?
G-6-PD
What is the most common cause of NONSPHEROCTIC HEMOLYTIC ANEMIA?
Pyruvate Kinase deficiency.
When is NONSPHEROCTIC HEMOLYTIC ANEMIA first diagnosed?
In Neonates (available screening test)
Facts about PK deficiency?
Autosomal recessive Over 100 possible mutations Causes right shift in O2 dissociation curve Increased intracellular 2,3-DPG Depleted ATP formation
Clinical features of PK deficiency
Marked aniso-and poikilocytosis
Red cell Fragments
Xerocytes
High reticulocyte count >30-40%
How do RBCs protect themself from complement?
DAF and CD55
Lack of DAF results in?
PMH Paroxysmal Nocturnal Hemoglobinuria
Terms decribing insufficient Haemoglobin in red cells?
Hypochromic and/or microcytic
What is meant by Aniscytosis?
RBC morphology characterized by highly varied RBC sizes/volume
What is Poikilocytosis
RBC Morphology characterized by highly varied Shape
What is Polychromasia?
Appearance of residual mRNA in RBCs, usually associated with accelerated production. (Basophilic staining in center of the RBC)
What are the causes of Heinz-Bodies? (Precipitated Haemoglobin in RBCs)
- Due to genetic defect in haemoglobin structure (haemoglobinopathy)
- Failure of antioxidant systems can lead to precipitation of haemoglobin.
Results of Heinz body formations?
- Cell shape can be altered i.e sickling
- Tissue based Phagocytes can do damage to repair on oxidized haemogolbin removing chunks of the RBC creating bite cells.
What are Schistocytes?
Red cell fragments.
How are schistocytes formed?
- Mechanical lysis (artificial valves)
2. Microangiopathic processes
