Thymus And Lymph Node Flashcards
What is the Thymus?
This is an organ responsible for the production and maturation of immune cells.
Which cells make up the main component of the thymus?
T- Lymphocytes
What are the other components of the thymus?
3rd pair of pharyngeal pouches, Dense in the cortex, Loose in the medulla- Hassall corpuscles.
What is the overall function of the Thymus?
Development of self tolerance to antigens
What is hyperplasia?
This refers to the enlargement of a tissue and or organ due to an increase in cell production.
What is agenesis?
The failure of a particular organ or tissue to develop during embryonic growth.
What is Hypoplasia?
The incomplete development of an organ/tissue, lack of cell growth.
What is Neoplasia?
This is the uncontrolled, abnormal growth of a tissue or cells in the body.
What is Atrophy?
Arrested development or loss in matter of cells/ tissues resulting in a decrease in size. Due to degradation.
What are the developmental pathologies of the thymus?
Agenesis and Hypoplasia
What are the acquired pathologies of the thymus?
Atrophy, Neoplasia and Hyperplasia.
Agenesis vis Hypoplasia
Agenesis is the failure of an organ/tissue (absence) to be developed while Hypoplasia refers to the underdevelopment of an organ or tissue.
Causes of Thymic Atrophy?
Age, Malnutrition, Stress, Terminal illness, Cytotoxic drugs (cancer drugs)
What thymic hyperplasia linked to?
Myasthenia Gravis, Graves’ disease, Addison disease, Lupus, Scleroderma and Rheumatoid Arthritis.
What is Myasthenia Gravis?
This is a neuromuscular disorder causing weakness in muscles due to the damage of receptors resulting in defective signal transmission.
What are some thymic Neoplasms?
Thymomas (epithelial) , Lymphomas (Lymphoid)
What is Lymphadenopathy?
Lymph node enlargement
What are some causes of Lymphadenopathy?
Acute and Chronic Reactive Hyperplasia as well as Neoplasia
What happens overall in reactive hyperplasia?
Antigen processing by macrophages, activation of resting lymphocytes, morphological changes such as size, cytoplasm etc… secretion of cytokines, recruitment of other cells, elimination of a pathogen.
What triggers reactive hyperplasia?
Foreign material, cell debris as well as microbes.
Features of Acute reactive hyperplasia?..
It is usually microbial and where there is direct drainage of the infection it can be seen in the tonsils, Inguinal? And Enteric as well as Generalized - Viral infections, Bacteraemia and septicaemia.
Effects of Acute Reactive Hyperplasia on a general/gross level?
Painful and tender, on the gross level can be red-grey its capsule is intact with perinodal extension
What are the microscopic effects/morphology of the lymph nodes during acute reactive hyperplasia?
Follicular Hyperplasia, Sinusoidal Congestion, Polymorphs something about necrosis unclear.??
