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Questions and Answers
Questions and Answers
Which of the following cell types differentiates from myeloid progenitor cells?
Which of the following cell types differentiates from myeloid progenitor cells?
- T-lymphocytes
- B-lymphocytes
- Natural killer cells
- Megakaryocytes (correct)
Hematopoietic stem cells originate and differentiate exclusively in the bone marrow.
Hematopoietic stem cells originate and differentiate exclusively in the bone marrow.
False (B)
What is the primary function of T-lymphocytes in adaptive immunity?
What is the primary function of T-lymphocytes in adaptive immunity?
Cellular immune response
B-lymphocytes are responsible for producing ______, which are the effectors of humoral immunity.
B-lymphocytes are responsible for producing ______, which are the effectors of humoral immunity.
Match the lymphocyte type with its primary location:
Match the lymphocyte type with its primary location:
Which of the following is the function of the thymus?
Which of the following is the function of the thymus?
The spleen acts as a lymphoid filter in the lymphatic system.
The spleen acts as a lymphoid filter in the lymphatic system.
What percentage range of total leukocytes do lymphocytes typically comprise?
What percentage range of total leukocytes do lymphocytes typically comprise?
Lymphocytes are identified by protein markers on their surface, known as 'cluster of differentiation' or '______' system.
Lymphocytes are identified by protein markers on their surface, known as 'cluster of differentiation' or '______' system.
Match the following lymphoid tissues with their description:
Match the following lymphoid tissues with their description:
Which of the following is the abbreviation of "thymus dependent lymphocyte?"
Which of the following is the abbreviation of "thymus dependent lymphocyte?"
T cells account for 30-40% lymphocytes in peripheral blood
T cells account for 30-40% lymphocytes in peripheral blood
What is the name of the receptor, that is found on the surface of the T-cell?
What is the name of the receptor, that is found on the surface of the T-cell?
Helper T cells are identified by the presence of ______ marker.
Helper T cells are identified by the presence of ______ marker.
Match the T cell with their relevant information:
Match the T cell with their relevant information:
Where do B cells develop and mature?
Where do B cells develop and mature?
Mature B cells have CD3 marker on the surface
Mature B cells have CD3 marker on the surface
List two main functions of B-cells:
List two main functions of B-cells:
B cells can survive 20 years or more ( ______ B cells)
B cells can survive 20 years or more ( ______ B cells)
Match the name with the function for NK cells:
Match the name with the function for NK cells:
Questions and Answers
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Flashcards
Flashcards
Myeloid progenitor cells
Myeloid progenitor cells
Stem cells in bone marrow that differentiate into megakaryocytes, erythroblasts, myeloblasts, and monoblasts.
Lymphoid progenitor cells
Lymphoid progenitor cells
Stem cells that differentiate into T-lymphocytes, B-lymphocytes, and Natural Killer (NK) cells.
Primary lymphoid organs
Primary lymphoid organs
Organs where stem cells migrate to proliferate and differentiate; includes the thymus and bone marrow.
Thymus
Thymus
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Bone marrow
Bone marrow
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Secondary Lymphoid Organs
Secondary Lymphoid Organs
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Lymph nodes
Lymph nodes
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Spleen
Spleen
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MALT
MALT
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GALT
GALT
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Tonsils
Tonsils
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Lymphocytes
Lymphocytes
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Major types of Lymphocytes
Major types of Lymphocytes
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T-Lymphocyte
T-Lymphocyte
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CD4 marker
CD4 marker
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CD8
CD8
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B-Lymphocytes
B-Lymphocytes
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Natural killer cells
Natural killer cells
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Study Notes
Study Notes
- All blood components, including immune cells, originate from hematopoietic stem cells, which differentiate into progenitor cells.
- Hematopoietic stem cells form and develop early in embryonic stages, migrating to the liver, spleen, and differentiating in bone marrow.
Myeloid Progenitor Cells
- Myeloid progenitor cells differentiate into megakaryocytes, which then differentiate into platelets.
- Erythroblasts multiply and differentiate into red blood cells (RBCs).
- Myeloblasts differentiate into neutrophils, eosinophils, and basophils.
- Monoblasts differentiate into monocytes and dendritic cells.
Lymphoid Progenitor Cells
- Lymphoid progenitor cells differentiate into T-lymphocytes, which mediate cellular immune response.
- Lymphoid progenitor cells differentiate into B-lymphocytes, which produce antibodies via humoral immune response.
- Lymphoid progenitor cells differentiate into natural killer cells (NKs).
Lymphoid System
- Stem cells travel to primary lymphoid organs (Thymus and Bone marrow) to proliferate and differentiate.
- The thymus, a small gland in front of the heart and behind the sternum, receives progenitor cells from bone marrow for proliferation, differentiation, and formation of thymus-derived T cells.
- Bone marrow is the source of progenitor cells, and it differentiates progenitor cells into B-lymphocytes.
- Mature T and B lymphocytes migrate from their differentiation sites to peripheral or secondary lymphoid organs.
Lymphoid Organs
- Lymph nodes act as lymphoid filters in the lymphatic system.
- The spleen acts as a lymphatic filter within the blood vascular tree.
- Mucosa-associated lymphoid tissue (MALT) is a collection of cells in the sub-mucosa of different tissues.
- Gut-associated lymphoid tissues (GALT) line the intestinal tract, including lymphoid tissue in the intestines (Peyer's patches), bronchus-associated lymphoid tissue (BALT) lining the respiratory tract, and lymphoid tissue lining the genitourinary tract.
- Tonsils are nodular aggregates of lymphoid tissues that detect and respond to pathogens in the aerodigestive tract.
Lymphocytes
- Lymphocytes are a class of white blood cells derived from stem cells, maturing in bone marrow or thymus.
- Lymphocytes comprise 20-40% of all leukocytes and are distributed into blood, lymph, and lymphoid organs.
- Lymphocytes are small, round cells (5-10µm diameter) with a spherical nucleus, densely compacted nuclear chromatin, and scanty cytoplasm.
- The three major types of lymphocytes are B lymphocytes, T lymphocytes, and NK cells.
- Lymphocytes are identified by protein markers on their surface, known as "cluster of differentiation" or "CD" system, such as CD45 (found in all leukocytes), CD4, and CD8.
T-Lymphocytes
- T-cells, short for "thymus dependent lymphocytes," originate in bone marrow as T-cell precursors and mature in the thymus.
- Maturation involves rearrangements and coding of the variable part of the T Cell Receptor (TCR) by enzymes and hormones.
- T-cells react with antigen receptors, Fc fragment of antibodies, RBC receptors, and virus receptors.
- T cells account for 70-80% of lymphocytes in peripheral blood, 5-10% in bone marrow, 70-80% in lymph nodes, and 30-40% in the spleen.
- Surface markers include two kinds of TCR: TCR 1 and TCR 2, along with other markers/receptors.
- Two major types of T cells are Helper T cells (TH) and Cytotoxic T cells (TC).
Helper T Cells (TH)
- Helper T cells are identified by the presence of CD4 marker.
- Helper T cells recognize antigen when presented with Class II MHC molecules.
- Helper T cells are subdivided into TH1 and TH2 subsets based on the cytokines they produce.
- TH1 cells produce interleukin-2 (IL-2), interferon-gamma (IFNy), and tumor necrosis factor-beta (TNF-ẞ).
- TH2 cells produce IL-4, IL-5, IL-6, IL-10, and TGF-ẞ (Transforming growth factor beta).
- Helper T cells promote differentiation of B-cells and cytotoxic T-cells, activate macrophages, and secrete cytokines.
Cytotoxic T Cells (TC)
- Cytotoxic T cells are identified by the presence of CD8 marker.
- Cytotoxic T cells recognize antigen when presented along with Class I MHC molecules.
- Cytotoxic T cells play a role in down-regulation of immune response and kill infected cells.
B-Lymphocytes
- B cells develop and mature in bone marrow.
- Early stages of B cell maturation occur in the fetal liver and continue in bone marrow throughout life.
- Stages in B cell development: Stem cell → pro-B cell → pre-B cell → immature B cell → mature B cell.
- B cells account for 5-15% of lymphocytes in circulation, 80-90% in bone marrow, 20-30% in lymph nodes, and 50-60% in the spleen.
- Surface markers include CD32 (receptor of Immunoglobulin), CD35 (Receptor for complement component), CD20, CD21, and CD22.
- B cells directly recognize and present antigens.
- B cells secrete large amounts of antibodies after differentiating into plasma cells.
- Memory B cells can survive 20 years or more.
- Two major types of B cells: T-independent cells and T-dependent cells.
Natural Killer Cells
- Natural killer cells (NK cells), also called Large Granular Lymphocytes (LGLs), are large lymphocytes that kill various target cells (such as tumor cells, bacteria/virus-infected cells, and transplanted cells) without MHC participation.
- NK cells account for 10-15% of blood lymphocytes and are rare in lymph nodes, not circulating through lymph.
- Surface markers include CD16 (receptor of Immunoglobulin), CD8, CD56, IL-2R, CD2, ICAM-1, and LFA-1.
- NK cells recognize various target cells.
- NK cells induce cytolysis of target substances and secrete cytokines like IFN-γ.
- NK cells kill antibody-coated target cells via antibody-dependent cell cytotoxicity (ADCC).
- NK cells participate in graft rejection in organ transplants and bone marrow transplantation.
- The cytotoxic capacity of NK cells is enhanced after activation by IL-2.
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