Lecture 2

Question 1

What is a differential white blood cell count?
What is the total differentiated wbc count?
What are the two main types of wbcs? And give examples under each as well as the percentage of the examples in the wbcs.

Answer 1

A count that looks at the different components of the WBCS.

What is do the wbcs under granulocytes plus monocytes have in common?
They are all from the mixed myeloid progenitor.
The unit of WBCS is per litre of blood. So the normal differentiated wbc count in total is 4800-10,800/litre

The two main types of wbcs are granulocytes (neutrophils (50-70%),eosinophils(2-4%),basophils(0.5-1%)) and agranulocytes(lyphocytes(25-45%),monocytes(3-8%)

Question 2

What is do the wbcs under granulocytes plus monocytes have in common?
Which cell is differentiated into t and b lymphocytes which are agranulocytes?

Answer 2

They are all from the mixed myeloid progenitor lineage

Lymphoid progenitor differentiates into T and B lymphocytes

Question 3

Which part of granulocytes stain specifically with weights stain?
State three other characteristics of granulocytes

Answer 3

Cytoplasmic granules of the granulocytes stain with wrights stain. Cytoplasmic granules of granulocytes (neutrophils, eosinophils, and basophils) stain with Wright’s stain due to their specific chemical composition and affinity for the stain components. Wright’s stain is a combination of eosin (an acidic dye) and methylene blue (a basic dye), which allows it to differentiate various cellular components based on their chemical properties.

Here’s why the granules stain as they do:

1. Neutrophils: Their granules contain neutral substances that take up both eosin and methylene blue, resulting in a lilac or light pink color.
2. Eosinophils: Their granules are rich in proteins that have a high affinity for eosin, an acidic dye. As a result, the granules stain a bright red or orange color.
3. Basophils: Their granules contain heparin and histamine, which have a high affinity for methylene blue, a basic dye. Consequently, the granules stain dark purple or blue.

Wright’s stain exploits these affinities, allowing for the clear differentiation of granulocytes based on the color of their cytoplasmic granules. This differential staining is essential for identifying and studying different types of blood cells under a microscope.

Other characteristics: they are larger and shorter lived than RBCS
THEY have a lobed nuclei
They are phagocytic

Question 4

What is the wrights stain?
How are rbcs,wbcs and platelets viewed under the microscope when they are stained using the weights stain?

Answer 4

Wright’s stain is a type of histologic stain used primarily in hematology to differentiate blood cell types and to diagnose various blood disorders. It is a modification of the Romanowsky stain and contains a combination of eosin (an acidic dye) and methylene blue (a basic dye), which together help to visualize different components of blood cells.

• Red Blood Cells (RBCs): Appear pink to orange.
• White Blood Cells (WBCs): Nuclei stain purple to blue, while the cytoplasm varies depending on the cell type (e.g., eosinophils stain pink-red due to eosinophilic granules).
• Platelets: Appear as small purple granules.

Wright’s stain is crucial for routine blood examination and plays an essential role in clinical pathology and hematological studies.

1. Components: The stain typically contains eosin Y (which stains cytoplasm and other acidic components pink to red) and methylene blue (which stains nuclei and other basic components blue to purple).
2. Applications: Wright’s stain is commonly used to stain peripheral blood smears and bone marrow aspirates. It helps in identifying and differentiating various blood cell types, including red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).
3. Diagnostic Use: It is widely used in the diagnosis of blood disorders such as anemia, leukemia, infections, and other hematological abnormalities.

1. Sample Preparation: A drop of blood is spread on a glass slide to create a thin smear.
2. Fixation: The smear is usually air-dried and then fixed with methanol.
3. Staining: The slide is stained with Wright’s stain for a specific duration, allowing the dyes to interact with the cellular components.
4. Rinsing and Drying: The slide is then rinsed with distilled water or buffer solution and allowed to air dry.
5. Microscopy: The stained slide is examined under a microscope for detailed cellular analysis.

Question 5

Which of the WBCS is the most abundant or numerous?
What are they sometimes referred to as?
The fine granules of this type of wbcs take up both acidic and basic dyes true or false?
What do the granules of this type contain?
This type of wbcs give the cytoplasm a lilac color and are very very phagocytic “bacteria slayers” true or false

Answer 5

Neutrophils.

They are sometimes called polymorphonuclear leukocytes (PMN). The neutrophils have 3-5lobes usually that’s why they are called polymorphonuclear . Poly for many, morpho for their morphology and nuclear as in their nucleus

You are correct in noting that the different components of neutrophils pick up different stains. Here’s a more precise explanation:

• Granules: The fine granules of neutrophils take up both acidic (eosin) and basic (methylene blue) dyes, which combine to give the granules a neutral lilac or light pink color. This dual affinity is why they appear lilac when stained with Wright’s stain.
• Nucleus: The nucleus of neutrophils picks up the basic dye (methylene blue), which stains the nucleus a dark blue or purple color.

So, while the granules of neutrophils are neutral and take up both dyes, the nucleus specifically picks up the basic dye, resulting in a darker color. This staining pattern helps differentiate the cellular components under the microscope.

Neutrophils are the most abundant type of white blood cells (WBCs).

• What are they sometimes referred to as?
  They are sometimes referred to as polymorphonuclear leukocytes (PMNs) or polys due to their multi-lobed nucleus.
• The fine granules of this type of WBCs take up both acidic and basic dyes: true or false?
  True. The fine granules of neutrophils take up both acidic (eosin) and basic (methylene blue) dyes, giving them a lilac or light pink color.
• What do the granules of this type contain?
  The granules of neutrophils contain enzymes and antimicrobial proteins, such as:
  
  • Myeloperoxidase
  • Lysozyme
  • Defensins
  • Lactoferrin
• This type of WBCs gives the cytoplasm a lilac color and is very phagocytic “bacteria slayers”: true or false?
  True. Neutrophils give the cytoplasm a lilac color due to their granules taking up both acidic and basic dyes, and they are very phagocytic, often referred to as “bacteria slayers” due to their role in engulfing and destroying bacteria.

Question 6

Eosinophils digest which type of organisms? And why? What type of granules do they have?
What type of nuclei do they have? What color do they pick up when they are stained?

Answer 6

Digest parasitic worms that are too large to be phagocytized.
They have a bilobed nuclei
Are stained red in H and E staining. The eo in the eosinophils is for the red color. (Hematoxylins and eosin (H&E) staining is one of the most widely used techniques in histology and pathology for examining the detailed structure and morphology of tissues. This staining method provides excellent contrast, making it easier to differentiate between various tissue components.)
They have lysosome like granules(like neutrophils do but basophils don’t have such granules )

They are red to crimson(acidophilic) coarse
They are modulators of the immune response

Eosinophils can be stained with both Wright’s stain (which includes methylene blue and eosin) and H&E stain (hematoxylin and eosin). Here’s why and how they stain differently with each:

1. Wright’s Stain (Methylene Blue and Eosin):
   
   • Methylene Blue: This is a basic dye that stains acidic components, such as nucleic acids, blue.
   • Eosin: This is an acidic dye that stains basic components, such as proteins in the granules, red or pink.
   • Eosinophils: The granules in eosinophils have a strong affinity for eosin because they are basic (contain proteins that are positively charged). Therefore, when stained with Wright’s stain, the granules take up eosin and appear bright red or orange. The nucleus, being acidic, takes up the methylene blue and stains dark blue or purple.
2. H&E Stain (Hematoxylin and Eosin):
   
   • Hematoxylin: This is a basic dye that binds to acidic structures, staining them blue to purple.
   • Eosin: This is the same acidic dye used in Wright’s stain and stains basic structures pink to red.
   • Eosinophils: The same principle applies here: the granules in eosinophils have an affinity for eosin and thus stain bright red or orange, while the nucleus stains blue to purple with hematoxylin.

Why Eosinophils Aren’t Exclusively Stained with One Type:
- Wright’s Stain: It is commonly used in blood smears and differentially stains all types of blood cells, including eosinophils, allowing for identification and differentiation based on the staining characteristics of their granules and nuclei.
- H&E Stain: It is widely used in histology for tissue sections, providing clear differentiation between different tissue structures and cell types, including eosinophils.

Both staining methods can effectively highlight eosinophils, but they are used in different contexts (blood smears vs. tissue sections) and leverage different dye combinations to achieve similar results for these particular cells.

Question 7

Explain the parts of the cell that the H and E stain in H and E staining

Answer 7

1. Hematoxylin:
   
   • Function: Stains cell nuclei.
   • Color: Blue to purple.
   • Mechanism: Hematoxylin is a basic dye that binds to acidic components of the cell, particularly nucleic acids in the cell nucleus, resulting in blue or purple staining.
2. Eosin:
   
   • Function: Stains the cytoplasm and extracellular matrix.
   • Color: Pink to red.
   • Mechanism: Eosin is an acidic dye that binds to basic components of the cell, such as proteins in the cytoplasm and extracellular matrix, resulting in pink to red staining.

Question 8

Which of the WBCS are the rarest?

Answer 8

Basophils

Question 9

Which of the Wbcs are functionally similar to mast cells

Answer 9

Basophils.

Mast cells release histamine for vasodilation. So example of cells that release histamine for vasodilation are basophils and mast cells
Mast cells have many many granules about 1000s and are usually found in tissues. They also contain heparin. Are involved in formation of blood vessels or angiogenesis and are involved in hypersensitivity reactions

Basophils are found in circulating blood cells and have lower granules number and also contain heparin plus histamine but are not involved in angiogenesis. Just inflammation

Basophils also contain granules, but their composition and function are distinct from those of neutrophils and eosinophils. The granules in basophils are:

1. Large Basophilic Granules: These granules stain dark blue to purple with basic dyes (such as methylene blue in Wright’s stain) due to their high content of acidic substances. The main components of these granules include:
   
   • Histamine: A vasoactive amine that plays a key role in inflammatory responses, particularly in allergic reactions. It causes vasodilation and increased vascular permeability.
   • Heparin: An anticoagulant that helps to prevent blood clotting.
   • Various Enzymes: Such as proteases that contribute to the breakdown of proteins and other substrates during immune responses.

These granules do not have the same lysosome-like properties as the granules in neutrophils or eosinophils, but they are crucial for basophils’ role in mediating allergic reactions and inflammation. Basophils are less involved in direct pathogen destruction and more in the regulation of immune responses through the release of their granule contents.

Both basophils and eosinophils are involved in hypersensitivity reactions, but they play different roles:

1. Basophils:
   
   • Basophils are closely associated with Type I hypersensitivity reactions (immediate hypersensitivity), which include allergic reactions such as asthma, hay fever, and anaphylaxis.
   • They release histamine and other mediators from their granules in response to the binding of allergens to IgE antibodies on their surface. This release contributes to the symptoms of allergic reactions, such as vasodilation, increased vascular permeability, and smooth muscle contraction.
2. Eosinophils:
   
   • Eosinophils are involved in late-phase reactions of Type I hypersensitivity and are also important in Type II hypersensitivity reactions (antibody-dependent cellular cytotoxicity) and Type IV hypersensitivity reactions (delayed-type hypersensitivity).
   • They play a key role in responding to parasitic infections and are recruited to sites of allergic inflammation. Eosinophils release cytotoxic granule proteins, such as major basic protein and eosinophil cationic protein, which can damage tissues and contribute to inflammation.
   • Eosinophils help modulate the immune response by releasing cytokines and chemokines that can influence other immune cells.

In summary, basophils are primarily associated with the immediate phase of hypersensitivity reactions, particularly in allergies, while eosinophils are involved in the later stages of allergic reactions and play a broader role in various types of hypersensitivity reactions and in defense against parasitic infections.

Question 10

Which of the wbcs have large,purplish black or blue or deep purple granules that contain histamine

Answer 10

Basophils

Histamine is an inflammatory chemical that acts as a vasodilator and attracts other wbcs to inflamed sites

Platelets granules are smallish and purple but not deep purple

Question 11

Which type of cell has two lobed nuclei with cytoplasmic granules staining red?
Which type is a multilobed nucleus?
Which type has a bilobed nucleus with purplish black cytoplasm granules

Answer 11

Eosinophils
Neutrophils
Basophils

Band cells are also bilobed
Bilobed nucleus you can think of landline telephone. One side of it is a lobe of the nucleus and the other is another lobe

Question 12

Why are agranulocytes called so?
What is the shape of their nuclei?

Answer 12

Called so because they lack visible cytoplasmic granules.

They have spherical or kidney shaped nuclei
Spherical for lymphocytes and kidney for monocytes

Question 13

Which cells have a large dark purple circular nuclei with a thin rim of blue cytoplasm?

Answer 13

Lymphocytes

In an MCQ setting, you should pick lymphocytes.

Lymphocytes are characterized by their large, dark purple circular nucleus that occupies most of the cell, with only a thin rim of blue cytoplasm visible.

Basophils, on the other hand, have a bilobed or S-shaped nucleus that is often obscured by their large, dark purple granules in the cytoplasm, giving them a more granular appearance rather than the distinct large nucleus with a thin cytoplasmic rim seen in lymphocytes.

While eosinophils have red cytoplasm

Question 14

Where are lymphocytes usually found?
What are the two types of lymphocytes and state their functions
Which are cytotoxic and what MHC class does this type of lymphocyte interact with?

Answer 14

In the lymphoid tissue. Few circulate in the blood.

That’s correct:

• Basophils: These are primarily found in the circulation (bloodstream). They make up a very small percentage of circulating white blood cells (less than 1%). Basophils play a role in allergic reactions and inflammatory responses, but they are not as commonly found in tissues.
• Lymphocytes: These are more commonly found in lymphoid tissues such as the lymph nodes, spleen, tonsils, and mucosa-associated lymphoid tissues (MALT). However, they do circulate in the blood as well. Lymphocytes are crucial for adaptive immunity, including the production of antibodies and cell-mediated immunity.

So, in the context of where they are most commonly found, basophils are more prevalent in the circulation, while lymphocytes are more abundant in lymphoid tissues.

Two types
•T cells act against virus-infected cells and tumor cells. (We have cd8 T cells which are cytotoxic and then cd4 cells which are helper cells. CD8 T cells are cytotoxic and directly kill infected or malignant cells by recognizing MHC Class I molecules.
• CD4 T cells are helper cells that orchestrate the immune response by interacting with MHC Class II molecules on antigen-presenting cells and assisting other immune cells like B cells, CD8 T cells, and macrophages.)
•B cells give rise to plasma cells, which produce antibodies

Question 15

Which cells are the largest leukocytes?

Answer 15

Monocytes

Question 16

Which cells have dark purple standing in with U or B or kidney shaped or horseshoe nuclei?

Answer 16

Monocytes

Small lymphocytes generally have large spherical nucleus
The shape of the monocytes nucleus can also be used as a unique identifier for mature monocytes

Question 17

Which cells have abundant pale blue cytoplasms

Answer 17

Monocytes

Correct, no part of the monocytes typically stains red with standard stains like Wright’s or Giemsa stain.

Monocytes are a type of white blood cell characterized by:

• Nucleus: The nucleus of a monocyte is large, often kidney-shaped or horseshoe-shaped, and stains a bluish or purple color with basic dyes (like methylene blue).
• Cytoplasm: The cytoplasm of monocytes typically stains pale blue or gray and may contain fine azurophilic granules, which are lysosomes, but these do not stain red. The granules can sometimes give the cytoplasm a slightly grainy appearance.

Red staining is usually associated with acidic dyes like eosin, which stains eosinophilic structures (like eosinophil granules) a red or pink color. Monocytes, however, do not have components that take up the acidic stain to appear red.

Question 18

Which cells leave circulation,enter tissues and differentiate into macrophages?

Answer 18

Monocytes

Macrophages in circulation are monocytes. Once the monocytes enter tissues and differentiate, they become macrophages. So macrophages are differentiated monocytes

Question 19

What are the functions of monocytes?

Answer 19

Actively phagocytic cells; crucial against viruses, intracellular bacterial parasites, and chronic infections(so neutrophils,eosinophils and monocytes(and macrophages which are differentiated monocytes) are phagocytic)
•they Activate lymphocytes to mount an immune response

Question 20

What is leukopoiesis?
What stimulates this process?
Which interleukins play a role in this process?
What stem cells do leukocytes originate from?

Answer 20

Production of WBCs
•Stimulated by chemical messengers from bone marrow and mature WBCs:
-Interleukins (e.g., IL-5,IL-3)
-Colony-stimulating factors (CSFs) named for the WBC type they stimulate (e.g., granulocyte-CSF stimulates granulocytes)
•All leukocytes originate from Hemocytoblasts or hematopoietic stem cells

Or

Granulocyte-Colony Stimulating Factor (G-CSF)
• Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF)
• Interleukin-3 (IL-3)
• Interleukin-5 (IL-5)

Question 21

What is leukopenia?
What is leukemia?
What are the two types of leukemia?
Which group of people does acute leukemia usually affect?
Which group does chronic leukemia usually affect?

Answer 21

Leukopenia
• Abnormally low WBC count—drug induced
•Leukemias:
Cancerous conditions involving WBCs
•Named according to the abnormal WBC clone involved
•Myelocytic leukemia involves myeloblasts
•Lymphocytic leukemia involves lymphocytes
•Acute leukemia involves blast-type cells and primarily affects children
•Chronic leukemia is more prevalent in older people

Leukemias are indeed cancers of the white blood cells (WBCs) and are named based on the specific type of WBC that is abnormally proliferating. While leukemias primarily involve WBCs, they can also affect red blood cells (RBCs) and platelets indirectly due to the impact on bone marrow function.

Leukemias and Their Naming:

Leukemias are classified based on two main criteria:

1.	Cell Lineage (Myeloid or Lymphoid): Leukemias are named based on whether the cancer originates from the myeloid or lymphoid cell lines.
•	Myeloid Leukemias: Arise from myeloid precursors, which can differentiate into RBCs, platelets, neutrophils, eosinophils, basophils, or monocytes.
•	Lymphoid Leukemias: Arise from lymphoid precursors, which can differentiate into B cells, T cells, or natural killer (NK) cells

Question 22

Explain the process of leukopoiesis

Which of the following is the correct pathway for the differentiation of a monocyte?
• A) Myeloid progenitor → Monoblast → Promonocyte → Monocyte
• B) Lymphoid progenitor → Monoblast → Promonocyte → Monocyte
• C) Myeloid progenitor → Myeloblast → Monoblast → Monocyte
• D) Myeloid progenitor → Lymphoblast → Promonocyte → Monocyte

Which of the following is the correct pathway for the differentiation of a granulocyte?

• A) Myeloid progenitor → Myeloblast → Promyelocyte → Myelocyte → Metamyelocyte → Granulocyte (e.g., Neutrophil)
• B) Lymphoid progenitor → Myeloblast → Promyelocyte → Myelocyte → Metamyelocyte → Granulocyte (e.g., Neutrophil)
• C) Myeloid progenitor → Monoblast → Promyelocyte → Myelocyte → Metamyelocyte → Granulocyte (e.g., Neutrophil)
• D) Lymphoid progenitor → Monoblast → Promyelocyte → Myelocyte → Metamyelocyte → Granulocyte (e.g., Neutrophil)

**
### MCQ for Lymphocytes

Which of the following is the correct pathway for the differentiation of a lymphocyte?

• A) Lymphoid progenitor → Lymphoblast → Prolymphocyte → Lymphocyte (e.g., T cell, B cell)
• B) Myeloid progenitor → Lymphoblast → Prolymphocyte → Lymphocyte (e.g., T cell, B cell)
• C) Lymphoid progenitor → Monoblast → Prolymphocyte → Lymphocyte (e.g., T cell, B cell)
• D) Lymphoid progenitor → Myeloblast → Prolymphocyte → Lymphocyte (e.g., T cell, B cell)

Answer 22

Leukopoiesis is the process by which white blood cells (leukocytes) are produced from hematopoietic stem cells (HSCs) in the bone marrow.
Which of the following is the correct pathway for the differentiation of a monocyte?
• A) Myeloid progenitor → Monoblast → Promonocyte → Monocyte
• B) Lymphoid progenitor → Monoblast → Promonocyte → Monocyte
• C) Myeloid progenitor → Myeloblast → Monoblast → Monocyte
• D) Myeloid progenitor → Lymphoblast → Promonocyte → Monocyte
• Answer: A) Myeloid progenitor → Monoblast → Promonocyte → Monocyte

Here are similar MCQs for granulocytes and lymphocytes:

Which of the following is the correct pathway for the differentiation of a granulocyte?

• A) Myeloid progenitor → Myeloblast → Promyelocyte → Myelocyte → Metamyelocyte → Granulocyte (e.g., Neutrophil)
• B) Lymphoid progenitor → Myeloblast → Promyelocyte → Myelocyte → Metamyelocyte → Granulocyte (e.g., Neutrophil)
• C) Myeloid progenitor → Monoblast → Promyelocyte → Myelocyte → Metamyelocyte → Granulocyte (e.g., Neutrophil)
• D) Lymphoid progenitor → Monoblast → Promyelocyte → Myelocyte → Metamyelocyte → Granulocyte (e.g., Neutrophil)

Answer: A) Myeloid progenitor → Myeloblast → Promyelocyte → Myelocyte → Metamyelocyte → Granulocyte (e.g., Neutrophil)

Which of the following is the correct pathway for the differentiation of a lymphocyte?

• A) Lymphoid progenitor → Lymphoblast → Prolymphocyte → Lymphocyte (e.g., T cell, B cell)
• B) Myeloid progenitor → Lymphoblast → Prolymphocyte → Lymphocyte (e.g., T cell, B cell)
• C) Lymphoid progenitor → Monoblast → Prolymphocyte → Lymphocyte (e.g., T cell, B cell)
• D) Lymphoid progenitor → Myeloblast → Prolymphocyte → Lymphocyte (e.g., T cell, B cell)

Answer: A) Lymphoid progenitor → Lymphoblast → Prolymphocyte → Lymphocyte (e.g., T cell, B cell)

This process involves several stages of differentiation and maturation, leading to the formation of various types of leukocytes, including granulocytes, monocytes, lymphocytes, and others. Here’s a brief overview of leukopoiesis:

• Origin: All blood cells originate from multipotent hematopoietic stem cells in the bone marrow.
• Differentiation: HSCs have the potential to differentiate into all blood cell lineages through a series of intermediate progenitor cells.

• Common Myeloid Progenitor (CMP): Differentiates into myeloid cells, giving rise to granulocytes (neutrophils, eosinophils, basophils), monocytes, erythrocytes, and megakaryocytes (platelet precursors).
• Common Lymphoid Progenitor (CLP): Differentiates into lymphoid cells, giving rise to B cells, T cells, and natural killer (NK) cells.

• Myeloblast: The first committed myeloid precursor cell that differentiates into granulocytes.
• Promyelocyte: Develops from the myeloblast and begins to accumulate granules.
• Myelocyte: Further differentiation with more specific granule formation.
• Metamyelocyte: Immature granulocyte with a kidney-shaped nucleus.
• Band Cell: Precursor to mature granulocytes with a horseshoe-shaped nucleus.
• Mature Granulocytes: Fully differentiated neutrophils, eosinophils, and basophils.

• Monoblast: The first committed precursor in the monocyte lineage.
• Promonocyte: Develops from the monoblast and undergoes further differentiation.
• Monocyte: Mature monocytes are released into the bloodstream, where they can migrate into tissues and differentiate into macrophages or dendritic cells.

• Lymphoblast: The first committed precursor in the lymphoid lineage.
• Prolymphocyte: Intermediate stage of lymphocyte development.
• B Lymphocytes (B Cells): Mature in the bone marrow and migrate to peripheral lymphoid organs (e.g., spleen, lymph nodes) where they can differentiate into plasma cells and produce antibodies.
• T Lymphocytes (T Cells): Mature in the thymus and migrate to peripheral lymphoid organs, where they participate in cell-mediated immunity.
• Natural Killer (NK) Cells: Develop from CLPs and play a role in innate immunity by targeting infected or cancerous cells.

Leukopoiesis is a complex process involving the differentiation of hematopoietic stem cells into various types of white blood cells through distinct myeloid and lymphoid lineages. This process ensures the continuous production of leukocytes required for immune defense and homeostasis.

So in summary:
Hematopoietic stem cells differentiate into myeloid and lymphoid stem cells. The myeloid go on to form myeloblasts and lymphoid go to form lymphoblasts. At this point, they are both committed to becoming the cells that they have to become.
The myeloblasts become promyelocytes and promonocytes. The promyelocytes go on to form neutrophils,basophils and eosinophils while the promonocytes go on to form the monocytes.
The promyelocytes become neutrophilic myelocytes ,basophilic myelocytes and eosinophilia myelocytes then they become neutrophilic band cells ,basophilic band cells and eosinophilia band cells before they finally become neutrophils basophils and eosinophils.
Promonocytes just go straight to be monocytes.

For lymphoblasts, they move on to become pro lymphocytes and then to become lymphocytes

Question 23

What are platelets?
What regulates its formation?

Answer 23

Platelets
•Small fragments of megakaryocytes
•Formation is regulated by thrombopoietin
•

Question 24

Which cells have blue staining in their outer region and have purple granules

Answer 24

Platelets

Question 25

Platelet granules contain what components

Answer 25

Blue-staining outer region, purple granules •Granules contain serotonin, Ca2+, enzymes, ADP, and platelet-derived growth factor (PDGF)

Question 26

What is the use of platelets What comes to stabilize the platelets after it has come to do its initial work? Circulating platelets are kept inactive and mobile by what two things?

Answer 26

Form a temporary mechanical platelet plug that helps seal breaks in blood vessels during the hemostatic response to vascular injury. fibrin forms a more stable and permanent clot following the initial platelet plug. Here’s how it works: 1. Platelet Plug: When a blood vessel is injured, platelets quickly adhere to the site and to each other, forming a temporary “platelet plug” that helps stop initial bleeding. 2. Fibrin Clot: The coagulation cascade is then activated, leading to the conversion of fibrinogen into fibrin. Fibrin strands weave through the platelet plug, reinforcing and stabilizing it. This creates a stronger, Durable clot that effectively seals the wound until the vessel can be repaired •Circulating platelets are kept inactive and mobile by NO and prostacyclin from endothelial cells of blood vessels Nitric oxide and prostacyclin are vasodilators

Question 27

Which of the following is not part of the most important parts of the platelet? A. Glycoproteins B.lysosomes C.Granules (alpha and dense) D. Mesh Adhesion of platelets to collagen is facilitated by what glycoproteins?

Answer 27

1.Glycoproteins; they are on the surface coat and are important in platelet reactions of adhesion and aggregation which are initial events leading to platelet plug formation during haemostasis. Adhesion to collagen is facilitated by glycoprotein 1a or GP1a 2.Two types of storage granules: Alpha granules are specific and contain fribrinogen,factor V, VWF,fibronectin,heparin antagonist PF4, PDGF Dense granules contain nucleotides ADP,Calcium and serotonin(for vasoconstriction) 3.Lysosomes

Question 28

How are platelets formed from stem cells? When megakaryocytes form, how do they form platelets ? How do megakaryocytes mature ? Mature megakaryocytes have how many lobes in their nucleus? Do they have a high or a low nuclear:cytoplasmic ratio?

Answer 28

Formed from Hemocytoblasts stem cells in bone marrow, then move on to become megakaryoblasts and move on to become promegakaryotes and then megakaryocytes and then the megakaryocytes form platelets by endomitotic release or fragmentation. Megakaryocytes mature by endomitotic synchronous replication Mature Megakaryocytes are extremely large with a single lobulated nucleus and a low nuclear:cytoplasmic ratio Endomitotic release is a process in which a cell undergoes chromosome replication without completing mitosis, resulting in a cell with multiple copies of its genome.

Question 29

What are the three major platelet functions

Answer 29

Adhesion Aggregation Release reactions and amplification

Question 30

What is a potent inhibitor of platelet aggregation and prevents the deposition of platelets on normal vascular endothelium

Answer 30

Prostacyclin (PGI2)

Question 31

Which chemicals are responsible for platelet aggregation? And which are responsible for vasoconstriction?

Answer 31

thromboxane A2 and ADP for platelet aggregation which leads to primary hemostatic plug and then serotonin plus the same thromboxane A2 and ADP for vasoconstriction

Question 32

What is Hemostasis ? Note that this is different from homeostasis What are the three main components of hemostasis

Answer 32

H emostasis •Fast series of reactions for stoppage of bleeding 1.Vascular spasm- • Smooth muscle contracts, causing vasoconstriction. 2.Platelet plug formation-Injury to lining of vessel exposes collagen fibers; platelets adhere. • Platelets release chemicals that make nearby platelets sticky; platelet plug forms. 3.Coagulation (blood clotting)- • Fibrin forms a mesh that traps red blood cells and platelets, forming the clot.

Question 33

What are vascular spasms in hemostasis and what triggers these spasms(state three)

Answer 33

Vascular Spasm •Vasoconstriction of damaged blood vessel •Triggers 1.Direct injury 2.Chemicals released by endothelial cells and platelets 3.Pain reflexes

Question 34

How are platelet plugs formed What factor helps platelets to stick to exposed collagen fibers at the site of blood vessel injury ADP is from dense granules in the platelets (not the alpha granules). What is the role of ADP in platelet plug formation What is the role of serotonin and thromboxane in platelet plug formation

Answer 34

Platelet Plug Formation •Positive feedback cycle 1.At site of blood vessel injury, platelets •Stick to exposed collagen fibers with the help of von Willebrand factor, a plasma protein. von Willebrand factor (vWF) is a protein involved in platelet adhesion and stabilization of Factor VIII. vWF is a glycoprotein involved in hemostasis, specifically in platelet adhesion and protecting Factor VIII from degradation, but it does not belong to the numbered series of clotting factors. Its primary role is to help platelets stick to the site of injury and stabilize Factor VIII, an essential clotting factor. •Swell, become spiked and sticky, and release chemical messengers •ADP from dense granules causes more platelets to stick and release their contents •Serotonin and thromboxane A2 enhance vascular spasm and more platelet aggregation

Question 35

What is coagulation

Answer 35

Coagulation •A set of reactions in which blood is transformed from a liquid to a gel •Reinforces the platelet plug with fibrin threads

Question 36

State the three phases of coagulation Factor X complexes with what three things to form prothrombin activator? What catalyzes the joining of fibrinogen to form a fibrin mesh

Answer 36

Coagulation •Three phases of coagulation 1.Prothrombin activator is formed (intrinsic and extrinsic pathways)- In an MCQ setting, if the question is: **"Prothrombin activator is formed via intrinsic and extrinsic pathways."** You should pick **False** because the precise statement would be that the prothrombin activator is formed in the **common pathway** after the intrinsic and extrinsic pathways converge. The intrinsic and extrinsic pathways contribute to the formation of the prothrombin activator, but they themselves do not directly produce it. Coagulation Phase 1: Two Pathways to Prothrombin Activator •Initiated by either the intrinsic or extrinsic pathway (usually both) •Triggered by tissue-damaging events •Involves a series of procoagulants •Each pathway cascades toward factor X •Factor X complexes with Ca2+, PF3, and factor V to form prothrombin activator 2.Prothrombin is converted into thrombin 3.Thrombin catalyzes the joining of fibrinogen to form a fibrin mesh

Question 37

What are the types of pathways in coagulation

Answer 37

Intrinsic Extrinsic Common (where factor X comes into play is at the common pathway)

Question 38

Under coagulation factors, what is factor I and what is its active form?

Answer 38

Fibrinogen with its active form as fibrin subunit

Question 39

Under coagulation factors, what is factor II and what is its active form?

Answer 39

Prothrombin Active form: thrombin which is a serine protease Yes, you are correct. Thrombin (Factor IIa) is indeed a serine protease. Serine proteases are a type of enzyme that has a serine residue in their active site, which is essential for their enzymatic activity. Thrombin’s role as a serine protease involves cleaving fibrinogen to form fibrin, activating other clotting factors, and facilitating platelet aggregation. This protease activity is crucial for effective blood clot formation.

Question 40

Under coagulation factors, what is factor III and what is its active form?

Answer 40

Tissue factor Active form: receptor/cofactor. It is active without proteolytic modification

Question 41

Under coagulation factors, what is factor IV?

Answer 41

Calcium ions

Question 42

Under coagulation factors, what is factor V and what is its active form?

Answer 42

Labile factor Active form: cofactor

Question 43

Under coagulation factors, what is factor V and what is its active form?

Answer 43

Labile factor or proaccelerin Active form: cofactor

Question 44

Under coagulation factors, what is factor VI and what is its active form?

Answer 44

Unassigned

Question 45

Under coagulation factors, what is factor VII and what is its active form?

Answer 45

Pro convertin (a before c so accelerin is V and convertin us VII) factor or stable factor Active: serine protease

Question 46

Under coagulation factors, what is factor IX and X and what are their active form?

Answer 46

IX-Christmas factor Serine protease X-Stuart-Prower factor Serine protease

Question 47

Under coagulation factors, what is factor VIII and what is its active form?

Answer 47

Antihaemophilic factor Active: cofactor

Question 48

Under coagulation factors, what is factor XI and XII and what are their active forms?

Answer 48

XI-Plasma thromboplastin antecedent Serine protease XII-Hageman (contact) factor Serine protease

Question 49

Under coagulation factors; what is factor XIII and its active form

Answer 49

XIII-Fibrin-stabilizing factor Active form -Transglutaminase or Prekallikrein (Fletcher factor) Active form - Serine protease or HMWK (Fitzgerald factor) Active form- Cofactor* HMWK, high molecular weight kininogen.

Question 50

Which clotting factors are responsible for intrinsic pathway in order of the one that starts to the end

Answer 50

The intrinsic pathway of the coagulation cascade involves several coagulation factors, including factors XII,XI(Factor XI, also known as Plasma Thromboplastin Antecedent (PTA)),IX,VIII How to remember factors for intrinsic pathway: It’s descending order: So from factor 12 next is 11 next is 9 and then 8. Not 10 because ten is the factor in the common pathway

Question 51

Why is the intrinsic pathway important?

Answer 51

. It provides a mechanism for the body to initiate the clotting process in response to internal damage or injury to blood vessels. By activating factors within the blood itself, the intrinsic pathway helps ensure that blood clotting can occur even in the absence of external factors.

Question 52

Explain how the intrinsic pathway works

Answer 52

The intrinsic pathway is one of the two main pathways in the coagulation cascade. It begins with the activation of factor XII (also known as Hageman factor) by contact with subendothelial surfaces when blood vessels endothelium are damaged and underlying tissues example collagen are exposed. The platelets cling and their surfaces provide sites for mobilization of the factors. Factor XII becomes factor XIIa(the activated form of XII) then factor XIIa activates factor XI. Factor XI along with calcium ions activates factor IX. Factor IX activates factor VIII. Factor IX, along with its cofactor factor VIII, forms IX/VIII complex and activates factor X. This leads to the common pathway, where factor X converts prothrombin to thrombin, ultimately resulting in the formation of fibrin and the formation of a blood clot. The intrinsic pathway is named as such because the factors involved are present within the blood itself. Then later The conversion of prothrombin to thrombin and the subsequent conversion of fibrinogen to fibrin are central steps in the clotting process: 1. **Prothrombin to Thrombin**: - **Prothrombin** (Factor II) is converted to **thrombin** (Factor IIa) by the prothrombinase complex, which includes Factor Xa, Factor Va, calcium ions, and phospholipids. 2. **Thrombin's Role**: - **Thrombin** acts on **fibrinogen** (Factor I), a soluble plasma protein. 3. **Conversion of Fibrinogen to Fibrin**: - Thrombin cleaves **fibrinogen** to produce **fibrin**. This process involves: - Cleaving fibrinogen into fibrin monomers. - The fibrin monomers then spontaneously polymerize (self-assemble) into long, insoluble fibrin strands. - These fibrin strands form a mesh that traps red blood cells and platelets, forming a stable blood clot. The fibrin clot provides a physical barrier to blood flow, facilitating wound healing and stopping further bleeding.

Question 53

Which coagulation factors are in the extrinsic pathway

Answer 53

Tissue factor,calcium,VII How to remember the factors that form extrinsic: factor 3 plus factor 7 gives you factor ten which starts the common pathway

Question 54

What is the difference between intrinsic and extrinsic pathway

Answer 54

The extrinsic pathway is the other main pathway in the coagulation cascade. Unlike the intrinsic pathway, which is initiated by factors present within the blood, the extrinsic pathway is triggered by external factors, particularly tissue factor (TF), which is released by damaged tissues outside of blood vessels. TF forms a complex with factor VII, activating it. Activated factor VII then activates factor X, leading to the common pathway of the coagulation cascade. In summary, the main difference between the extrinsic and intrinsic pathways lies in their initiation: the extrinsic pathway is triggered by external factors (tissue factor), while the intrinsic pathway is initiated by factors present within the blood itself. Both pathways converge at factor X, ultimately leading to the formation of fibrin and blood clotting. Even taking blood sample and putting it in the blood collection tube, the pathway that will occur for clot to form is the extrinsic pathway not the intrinsic pathway

Question 55

Which coagulation factor comes in after the common pathway ? What is the importance of cross linking process?

Answer 55

Factor XIII It is the fibrin stabilizing factor The fibrin stabilizing factor, also known as factor XIII, is a crucial enzyme in the final stages of the coagulation cascade. Once fibrinogen has been converted to fibrin, factor XIII cross-links fibrin molecules, strengthening and stabilizing the clot. This cross-linking process helps prevent the premature breakdown of the clot and contributes to the formation of a stable blood clot, essential for effective wound healing and hemostasis.

Question 56

Explain the common pathway Which factor is the labile factor? Another name for the labile factor is? Which factor is the stable factor? Another name for the stable factor is?

Answer 56

In the common pathway of the coagulation cascade, the primary event is the conversion of prothrombin to thrombin. Thrombin is a key enzyme that plays a central role in blood clot formation. Prothrombin activator which is gotten from the common pathway catalyzes the transformation of prothrombin to the active enzyme thrombin. Factor VII is known as Proconvertin or the Stable Factor. • Factor V is known as Proaccelerin or the Labile Factor. Factor X, also known as Stuart-Prower factor or prothrombinase, is a protein involved in the coagulation cascade. It plays a central role in the common pathway of blood clot formation. Factor X is activated by either the intrinsic or extrinsic pathways, ultimately leading to the conversion of prothrombin to thrombin. Factor X is activated and it activates factor V which converts factor X to prothrombin activator Factor X is not directly converted into thrombin; instead, it is converted into its active form, **Factor Xa**, which then plays a crucial role in the conversion of prothrombin (Factor II) into thrombin (Factor IIa). Here's how it works: 1. **Factor X Activation**: - Factor X is converted to **Factor Xa** by either the intrinsic or extrinsic pathways. In the intrinsic pathway, the conversion is facilitated by the tenase complex (comprising activated Factors VIIIa and IXa along with calcium and phospholipids). In the extrinsic pathway, it’s done by the tissue factor (Factor III) and Factor VIIa complex. 2. **Prothrombin to Thrombin**: - **Factor Xa** then combines with Factor Va (which is activated Factor V), calcium, and phospholipids to form the **prothrombinase complex**. - This complex converts **prothrombin (Factor II)** into **thrombin (Factor IIa)**. So, Factor Xa, along with the prothrombinase complex, is responsible for the conversion of prothrombin into thrombin.

Question 57

What happens in phase 2 and 3 of coagulation? (Intrinsic extrinsic and common pathways are in phase 1) Which factor is responsible for cross linking of mesh fibers Which is soluble in the blood? Fibrin or fibrinogen State two uses of fibrin in clot formation

Answer 57

Phase 2-prothrombin activator converts prothrombin (factor II) to thrombin(activated factor II. So factor IIa) Prothrombin activator catalyzes the transformation of prothrombin to the active enzyme thrombin In phase 3 thrombin converts fibrinogen (which is soluble in the blood) to fibrin(which is an insoluble polymer) Then calcium (factor VI)activates factor XIII to cross link the fibrin to form a cross linked fibrin mesh Or Coagulation Phase 3: Common Pathway to the Fibrin Mesh •Thrombin converts soluble fibrinogen into fibrin •Fibrin strands form the structural basis of a clot •Fibrin causes plasma to become a gel-like trap for formed elements •Thrombin (with Ca2+) activates factor XIII which: 1.Cross-links fibrin 2.Strengthens and stabilizes the clot

Question 58

Heparin enhances the activity of what anticoagulant?

Answer 58

Heparin works primarily by enhancing the activity of antithrombin III (ATIII), a natural anticoagulant in the body. Antithrombin III inhibits several coagulation factors, including factor Xa and thrombin (factor IIa). Heparin binds to antithrombin III and causes a conformational change that greatly accelerates its ability to inhibit these coagulation factors. By inhibiting factor Xa and thrombin, heparin effectively prevents the formation of blood clots. This mechanism of action makes heparin a commonly used anticoagulant medication in preventing and treating thromboembolic disorders, such as deep vein thrombosis and pulmonary embolism.

Question 59

Disorders of hemostasis are grouped into two main name them Haemophilia a is due to a problem with which factor? Haemophilia b is due to a problem with which factor?

Answer 59

Thromboembolytic disorders- undesirable clot formation Bleeding disorders-abnormalities that prevent normal clot formation Bleeding disorders example is haemophilia(haemophilia a is problem with factor 8 and haemophilia b is problem with factor 9)

Question 60

What triggers intrinsic and extrinsic pathways? Which of them is faster?

Answer 60

Intrinsic pathway • Is triggered by negatively charged surfaces (activated platelets, collagen, glass). Intrinsic Pathway: Triggered by collagen exposure, leading to the activation of Factor XII. • Extrinsic Pathway: (Collagen exposure is linked with tissue damage that exposes tissue factor, which then activates the extrinsic pathway.Collagen exposure from damaged tissues can thus contribute to the activation of both pathways.) That’s why blood collection in a tube is more likely to cause clotting through the intrinsic pathway. So intrinsic pathway is usually assessed by the Activated Partial Thromboplastin Time (aPTT). This is done by bringing the blood into contact with negatively charged surface such as glass with silica or kaolin •Uses factors present within the blood (intrinsic) 1.Extrinsic pathway •Is triggered by exposure to tissue factor (TF) or factor III (an extrinsic factor) •Bypasses several steps of the intrinsic pathway, so is faster. This pathway plus common pathway is assessed using the Prothrombin time or Pt time. The blood is collected and a tissue activator is added to it to make the extrinsic pathway occur to see how long it takes for the blood to clot. To assess the extrinsic pathway, tissue factor (also known as thromboplastin) is added to the blood sample. Tissue factor is not present in the standard blood collection tubes but is added in the PT test.

Question 61

What causes clot retraction?

Answer 61

Clot Retraction •Actin and myosin in platelets contract within 30–60 minutes •Platelets pull on the fibrin strands, squeezing serum from the clot

Question 62

After how many days does fibrinolysis occurs? How does it occur? What is plasmin?

Answer 62

Fibrinolysis •Begins within two days •Plasminogen in clot is converted to plasmin by tissue plasminogen activator (tPA), factor XII and thrombin •Plasmin is a fibrin-digesting enzyme

Question 63

After how many days does fibrinolysis occurs? How does it occur? What is plasmin? What three things cause the conversion of plasmin from its previous form

Answer 63

Fibrinolysis •Begins within two days •Plasminogen in clot is converted to plasmin by tissue plasminogen activator (tPA), factor XII(Hageman factor) and thrombin •Plasmin is a fibrin-digesting enzyme

Question 64

Transfusions •Whole-blood transfusions are used when blood loss is substantial •Packed red cells (plasma removed) are used to restore oxygen-carrying capacity •Transfusion of incompatible blood can be fatal True or false

Answer 64

True

Question 65

Difference between clot retraction and fibrinolysis

Answer 65

Clot retraction and fibrinolysis are two distinct processes that occur after the formation of a blood clot: 1. **Clot Retraction**: This process involves the contraction of the blood clot, which leads to the squeezing out of serum (the liquid component of blood) from the clot. It is mediated by platelets and their contraction, which pull the edges of the wound together, reducing the size of the clot. Clot retraction helps to reinforce and consolidate the clot, making it more stable and promoting wound healing. 2. **Fibrinolysis**: Fibrinolysis is the process by which the blood clot is dissolved. It involves the enzymatic breakdown of fibrin, the protein that forms the mesh-like structure of the clot, by an enzyme called plasmin. Plasminogen, an inactive precursor of plasmin, is activated to plasmin, which then cleaves fibrin into smaller fragments, ultimately dissolving the clot. Fibrinolysis is essential for preventing excessive clot formation and ensuring proper blood flow once the injury is healed. In summary, clot retraction involves the physical contraction of the clot, while fibrinolysis involves the enzymatic breakdown of fibrin within the clot. Both processes are important for effective wound healing and the restoration of normal blood flow.