12 Questions
What is the primary function of lymphocytes?
To provide specificity and memory in adaptive immune responses
Where are lymphocytes typically found in the body?
Scattered within tissues, aggregated across lymph nodes, or circulating in the blood
What is the role of T cells in the immune system?
To impart cell-mediated immunity by recognizing antigens associated with the cells of the host organism
What distinguishes B cells from other lymphocytes?
They have the ability to produce antibodies and confer humoral immunity
What is the primary function of natural killer (NK) cells?
To limit the spread of infections and tumors, but without true antigen specificity and memory
Where is the thymus located in the body?
Between the lungs in the superior and anterior part of the inferior mediastinum, posterior to the manubrium
Which of the following statements about the thymus is correct?
It produces T cells with unique receptors for foreign antigens.
What is the primary function of hematopoiesis?
To produce mature blood cells from undifferentiated stem cells.
Which of the following cells are primarily responsible for cell-mediated immunity?
T cells
What is the primary function of neutrophils?
To travel to the site of infection and destroy microorganisms by phagocytosis.
Which of the following cells are responsible for humoral immunity?
B cells
What is the primary function of eosinophils?
To defend against parasitic helminths and modulate inflammatory processes.
Study Notes
Lymphocytes
- Lymphocytes are a type of leukocytes (white blood cells) responsible for specificity and memory in adaptive immune responses
- They recognize antigens to help the organism fight infection and disease
- Lymphocytes are found scattered within tissues, aggregated across lymph nodes, or circulating in the blood
Types of Lymphocytes
- T Cells: have T-cell antigen receptors (TCRs), impart cell-mediated immunity by recognizing antigens associated with the cells of the host organism
- B Cells: have surface immunoglobulins B-cell antigen receptors (BCRs), produce antibodies, conferring humoral immunity
- Natural Killer (NK) Cells: limit the spread of infections and tumors, do not have true antigen specificity and memory
Thymus
- Located between the lungs, in the superior mediastinum and the anterior part of the inferior mediastinum, posterior to the manubrium
- A primary lymphoid gland where the development of T cells occurs
- Selects T cells for survival to minimize the chance of an auto-immune response
Bone Marrow and Hematopoiesis
- Hematopoiesis is the lifelong process of producing mature blood cells from undifferentiated hematopoietic stem cells (HSC)
- A continuous formation of cellular components of the blood leads to a balanced state of producing and losing mature blood cells
- Hematopoiesis occurs to meet the everyday demands in producing and turning over blood cells, as well as to respond to increased demand (e.g., by infection, injury)
Functions of Lymphocytes
-
T Cells: impart cell-mediated immunity by recognizing antigens associated with host cells
- Helper T lymphocytes activate macrophages, T cells, and B cells via release of cytokines to facilitate immune responses
- Cytotoxic T lymphocytes eliminate the reservoirs of infection and kill infected cells
- B Cells: impart humoral immunity by the elimination of extracellular microbes, and the production of memory B cells and plasma cells, leading to the generation of antibodies
- Natural Killer (NK) Cells: limit the spread of tumors and microbial infections, preventing subsequent tissue damage
-
Granulocytes:
- Neutrophils: travel to the site of infection, destroying microorganisms by phagocytosis and subsequent release of enzymes
- Eosinophils: involve as host defense against parasitic helminths and modulate inflammatory processes within the cell
- Basophils: release histamine, mediate inflammation, and prevent the formation of blood clots to improve flow of blood
- Monocytes: generate mononuclear-phagocyte system cells in tissues, induce phagocytosis, and digest
Test your knowledge on the anatomy and function of the thymus gland located above the heart. Learn about the development of T cells and the production of unique T-cell receptors in this primary lymphoid gland.
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