Thymus Anatomy and Function Quiz

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

Description

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.