⭐ Module 1: The Hematopoietic System Review Questions

What are the three main components of blood, and what percentage of total blood volume does each component constitute?

45% Plasma

1% Platelets

55% Red Blood Cells

Differentiate between serum and plasma in terms of composition and function.

Plasma is the liquid component of blood that contains water, ions, proteins, nutrients, hormones, and waste products. It is separated from the blood after anticoagulation.

Serum is the liquid that remains after blood has clotted. It lacks coagulation factors like fibrinogen, which are used up during the clotting process.

What are the three main cellular components of blood, and what is the primary function of each?

Erythrocytes (RBCs): Transport oxygen from the lungs to tissues and carry carbon dioxide back to the lungs for exhalation.

Leukocytes (WBCs): Defend the body against infections and foreign materials.

Platelets: Help in blood clotting and wound healing by forming a plug at injury sites.

Reference intervals define the range of normal laboratory test values for a given population. List fourphysiological factors that can influence these normal values.

Age: Newborns may have different reference intervals compared to adults.

Sex: Males and females may have different values, especially in RBC count, hemoglobin, and hematocrit.

Geographic location: Altitude can affect RBC count due to oxygen availability.

Health: Diseases or conditions can alter normal blood values.

Describe the three key processes of cellular homeostasis and explain their importance in maintainingtissue function

Proliferation: The process of cell division and multiplication, essential for tissue growth and repair.

Differentiation: The process by which cells become specialized to perform specific functions.

Apoptosis: Programmed cell death, removing damaged or aged cells to maintain healthy tissue

Compare euchromatin and heterochromatin in terms of function, appearance, and role in gene expression

Euchromatin: Loosely packed chromatin, transcriptionally active, and involved in gene expression.

Heterochromatin: Tightly packed chromatin, transcriptionally inactive, and typically associated with gene silencing.

Identify the stages of the mammalian cell cycle and describe key events occurring in each phase

G1: Cell growth and preparation for DNA replication.

S phase: DNA replication.

G2: Preparation for mitosis, checks for DNA errors.

M phase: Mitosis, division of the cell into two daughter cells.

What are the three cell cycle checkpoints, and how do they help maintain genomic integrity?

G1/S checkpoint: Ensures that the cell is ready to replicate DNA.

G2/M checkpoint: Ensures DNA replication is complete and correct.

Mitotic spindle checkpoint: Ensures chromosomes are properly aligned before division

Compare the intrinsic and extrinsic pathways of apoptosis, including their triggers and key initiators.

Intrinsic pathway: Triggered by internal cellular stress, like DNA damage, and involves mitochondrial release of cytochrome c.

Extrinsic pathway: Triggered by external signals such as binding to death receptors (e.g., Fas or TNF receptors).

Explain the role of apoptosis in hematopoiesis and why it is essential for maintaining blood cellhomeostasis

Apoptosis ensures the elimination of damaged or unnecessary cells during hematopoiesis, such as when excessive WBCs need to be removed after an infection or when abnormal cells are identified.

Differentiate between lysosomal and proteasomal degradation of proteins, including their mechanismsand biological significance

Lysosomal degradation: Involves autophagy or endocytosis and is used to degrade larger, whole proteins and organelles.

Proteasomal degradation: Involves ubiquitin-tagging and is responsible for degrading damaged or unneeded proteins into smaller peptides.

List the four major sites of hematopoiesis during development from fetus to adulthood and explain therole of each site

Yolk sac: Early site of hematopoiesis, producing primitive RBCs and macrophages.

AGM (Aorta-Gonad-Mesonephros): Formation of hematopoietic stem cells.

Liver: Major site of hematopoiesis during fetal development.

Bone marrow: Dominant site of hematopoiesis from the 7th month onward and continues throughout adulthood.

Compare and contrast primary and secondary lymphoid tissues in terms of function and examples.

Primary lymphoid tissues: Sites where lymphocytes are produced and matured (e.g., bone marrow, thymus).

Secondary lymphoid tissues: Sites where mature lymphocytes are activated by antigens (e.g., lymph nodes, spleen, MALT).

Describe the two major compartments of the bone marrow and explain their roles in hematopoiesis.

Vascular compartment: Contains blood vessels, stromal cells, and hematopoietic cells.

Endosteal compartment: Houses HSC niches and is involved in bone remodeling.

What are the primary functions of macrophages in the bone marrow and how do they contribute to hematopoiesis?

Macrophages provide cytokines that regulate hematopoiesis and remove dead or dysfunctional cells.

Differentiate between the functions of splenic white pulp and red pulp.

White pulp: initiates immune response to blood-borne pathogens and is involved in T- and B-cell activation

Red pulp: site of erythrocyte destruction and platelet storage.

Explain the process of T cell selection in the thymus and why it is critical for immune function.

Positive selection ensures T cells can bind MHC molecules.

Negative selection eliminates T cells that bind self-antigens, preventing autoimmune responses.

Define extramedullary hematopoiesis, specify the tissues involved, and discuss its clinical significance.

Hematopoiesis occurring outside the bone marrow, typically in the liver and spleen, when bone marrow cannot meet blood cell demands (e.g., in severe anemia).

How do lymph nodes function in immune defense?

Lymph nodes filter lymph and activate immune cells (T and B cells) to respond to pathogens.

What is mucosa-associated lymphoid tissue (MALT), and how does it contribute to immune defense?

MALT is lymphoid tissue found in mucosal areas (e.g., intestines, tonsils) that protects against pathogens that enter through mucosal surfaces.

Identify the three major categories of hematopoietic precursor cells and describe how they differ in function and differentiation potential.

Hematopoietic stem cells (HSCs): Multipotent, can differentiate into all blood cells.

Common myeloid progenitors (CMPs): Differentiate into myeloid cells like RBCs, platelets, and granulocytes.

Common lymphoid progenitors (CLPs): Differentiate into lymphoid cells like T cells, B cells, and NK cells.

Explain the difference between paracrine, autocrine, and juxtacrine regulation in hematopoiesis.

Paracrine: Signaling between nearby cells.

Autocrine: A cell signals itself.

Juxtacrine: Signaling via direct cell-to-cell contact.

Describe the role of cytokines in hematopoiesis and name two key cytokines involved in lineage-specific differentiation

Cytokines regulate survival, proliferation, and differentiation of blood cells. Key cytokines include Erythropoietin (EPO) and Thrombopoietin (TPO).

Outline the steps of the JAK-STAT signaling pathway and explain its importance in hematopoiesis.

Cytokine binds receptor → JAKs activate STATs → STATs enter the nucleus and regulate gene expression, important for hematopoiesis and immune response.

Compare and contrast the immune functions of the common myeloid progenitor (CMP) and common lymphoid progenitor (CLP)

CMP gives rise to granulocytes, monocytes, and RBCs; involved in innate immunity.

CLP gives rise to T cells, B cells, and NK cells; involved in adaptive immunity.

Explain why the bone marrow microenvironment is essential for hematopoiesis. Include the roles of stromal cells, the osteoblastic, and the vascular niche in your response

The bone marrow microenvironment is crucial for hematopoiesis as it supports hematopoietic stem cells (HSCs) and regulates their proliferation and differentiation.

Stromal cells provide structural support and secrete cytokines that guide HSC development.

Osteoblastic niche helps maintain HSC quiescence and self-renewal.

Vascular niche promotes HSC activation and the release of mature blood cells into circulation.