Structure and Function of RBCs

Question 1

What is the stain used for a basic blood smear?

Answer 1

Wright-Giemsa stain.

Question 2

What stops collected blood from clotting?

Answer 2

EDTA in the collection tube.

Question 3

How does EDTA work?

Answer 3

Chelates calcium

Question 4

Acidic Aromatic stain?

Answer 4

Eosin

Question 5

What does Eosin stain?

Answer 5

Hydrophobic basic macro-molecules (Haemoglobin and some other proteins)

Question 6

Which cell does Eosin stain particularly well?

Answer 6

Eosinophil

Question 7

What percentage of blood is made up of Eosinophils?

Answer 7

Less than 5%

Question 8

Functions of Eosinophils

Answer 8

Mediators of innate immunity

Increase in context of allergic and parasitic infections

Question 9

Aromatic Basic stain?

Answer 9

Methylene Blue

Question 10

What does Methelene Blue stain adhere to?

Answer 10

Hydrophobic acidic macro-molecules such as Nucleic Acids

Question 11

What cells does methelene Blue predominantly stain?

Answer 11

Basophils

Question 12

What percentage of Blood cells are Basophils?

Answer 12

Less than 1%

Question 13

Functions of Basophils

Answer 13

Degranulation during allergic reactions

Related to tissue mast cells

Question 14

Which cells stain with a little of either dyes?

Answer 14

Neutrophils

Question 15

Lifespan of Neutrophils

Answer 15

1 day

Question 16

Neutrophils make up what percentage of Leukocytes?

Answer 16

40-70%

Question 17

When do Leukocytes increase their numbers? (up to 10 fold?)

Answer 17

During Bacterial and Fungal infections.

Question 18

How do Neutrophils do their duty?

Answer 18

Phagocytosis
Degranulation
Formation of extracellular traps

Question 19

Defining features of Monocytes?

Answer 19

Few or no cytoplasmic granules

Question 20

What percentage of blood leukocytes are Monocytes?

Answer 20

3-8%

Question 21

Functions of Monocytes?

Answer 21

Phagocytes that present antigen on MHC class II
Macrophages are derived from Monocytes.
Numbers increase in wide variety of diseases.

Question 22

Lymphocytes life span?

Answer 22

Days to years.

Question 23

What is different about reactive forms of lymphocytes?

Answer 23

Have more cytoplasm and more prominent nucleoli

Question 24

What is the structure of platelets?

Answer 24

Small anucleate fragments

Question 25

Functions of Platelets

Answer 25

1. Primary Hemostatic plug via aggregation 2. Stimulate coagulation cascade 3. Stimulate wound healing (secretion of PDGF which recruits fibroblasts) 4. Present Antigen

Question 26

How are Bands morphologically different from mature neutrophils?

Answer 26

Horseshoe shaped nuclei Bean shaped nuclei in even less mature neutrophils (metamyelocytes) Round nuclei in myelocytes

Question 27

What is different about neutrophil appearance during bacterial infection?

Answer 27

Increased cytoplasmic toxic granules.

Question 28

Describe the red cell design

Answer 28

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)

Question 29

Effect of Oxidants on Haemoglobin

Answer 29

Radicals damage Haemoglobin leading to formation of inter and intra di-sulfide bonds which further leads to precipitation and or denaturation of haemoglobin.

Question 30

What protects red cells from oxidants?

Answer 30

The Glutathione system

Question 31

What is required for efficient operation of the Glutathione

Answer 31

NADPH and The enzyme Gluthathione reductase.

Question 32

What does Iron oxidized to the Fe3+ state produce?

Answer 32

Methemoglobin

Question 33

How is Methemoglobin reduced?

Answer 33

Via cytochrome b5 reductase

Question 34

What is required for reduction of Methemoglobin by cytochrome B5 reductase.

Answer 34

NADH

Question 35

What are 2 of the essential metabolic processes of RBCs?

Answer 35

Glycolysis to make ATP and NADH | Pentose shunt to make NADPH

Question 36

What is the first enzyme of the pentose phosphate shunt?

Answer 36

G-6-PD

Question 37

What is the most common cause of NONSPHEROCTIC HEMOLYTIC ANEMIA?

Answer 37

Pyruvate Kinase deficiency.

Question 38

When is NONSPHEROCTIC HEMOLYTIC ANEMIA first diagnosed?

Answer 38

In Neonates (available screening test)

Question 39

Facts about PK deficiency?

Answer 39

``` Autosomal recessive Over 100 possible mutations Causes right shift in O2 dissociation curve Increased intracellular 2,3-DPG Depleted ATP formation ```

Question 40

Clinical features of PK deficiency

Answer 40

Marked aniso-and poikilocytosis Red cell Fragments Xerocytes High reticulocyte count >30-40%

Question 41

How do RBCs protect themself from complement?

Answer 41

DAF and CD55

Question 42

Lack of DAF results in?

Answer 42

PMH Paroxysmal Nocturnal Hemoglobinuria

Question 43

Terms decribing insufficient Haemoglobin in red cells?

Answer 43

Hypochromic and/or microcytic

Question 44

What is meant by Aniscytosis?

Answer 44

RBC morphology characterized by highly varied RBC sizes/volume

Question 45

What is Poikilocytosis

Answer 45

RBC Morphology characterized by highly varied Shape

Question 46

What is Polychromasia?

Answer 46

Appearance of residual mRNA in RBCs, usually associated with accelerated production. (Basophilic staining in center of the RBC)

Question 47

What are the causes of Heinz-Bodies? (Precipitated Haemoglobin in RBCs)

Answer 47

1. Due to genetic defect in haemoglobin structure (haemoglobinopathy) 2. Failure of antioxidant systems can lead to precipitation of haemoglobin.

Question 48

Results of Heinz body formations?

Answer 48

1. Cell shape can be altered i.e sickling 2. Tissue based Phagocytes can do damage to repair on oxidized haemogolbin removing chunks of the RBC creating bite cells.

Question 49

What are Schistocytes?

Answer 49

Red cell fragments.

Question 50

How are schistocytes formed?

Answer 50

1. Mechanical lysis (artificial valves) | 2. Microangiopathic processes