Immunology - Lymphoid Structures Flashcards
What are the functions of the lymph node?
Filtration of lymph by macrophages; storage and activation of B and T cells; production of antibodies
Does a lymph node have more afferent or efferent lymph vessels?
It has many afferent vessels and few efferent vessels
Within a lymph node, what is the site of B-cell localization and proliferation?
The follicle
In lymph nodes, _____ (primary/secondary) follicles have pale central germinal centers and are active, while _____ (primary/secondary) follicles are dense and dormant.
Secondary; primary
Which lymph node area contains cords of closely packed lymphocytes, plasma cells, and sinuses?
The medulla
Which lymph node structures communicate with efferent lymphatics and contain reticular cells and macrophages?
Medullary sinuses
Which lymph node area houses T cells?
The paracortex, which is located between the follicles and the medulla
In lymph nodes, what is the name of the region that contains high endothelial venules through which T and B cells enter the lymph node from the blood?
The paracortex
Which part of the lymph node contains B cells?
Follicles, which are located in the outer cortex
In which genetic syndrome would a lymph node biopsy show an underdeveloped paracortex?
DiGeorge syndrome, due to thymic aplasia and lack of functional T cells
In what part of the lymph node are the follicles (ie, the sites of B cell localization and proliferation) located?
The outer cortex
In lymph nodes, what area becomes greatly enlarged during an extreme cellular immune response and contains high endothelial venules?
The paracortex
Into which lymph vessel does lymph from the right arm and right half of the head drain? What is the lymph drainage for the rest of the body?
Right lymphatic duct; the rest of the body drains to the thoracic duct
What are the primary lymph nodes in the lymphatic drainage of the stomach?
The celiac nodes
What are the primary lymph nodes in the lymphatic drainage of the duodenum, jejunum, and sigmoid colon?
The duodenum and jejunum drain to the superior mesenteric lymph nodes; the primary drainage sites for the sigmoid colon are the inferior mesenteric lymph nodes
Which lymph nodes serve as the primary lymph drainage site for the lower rectum and anal canal (above the pectinate line)?
Internal iliac
What is the primary lymph node drainage site for the scrotum, thigh, and anal canal (below the pectinate line)?
Superficial inguinal nodes
Where does lymph from the testes drain?
The superficial and deep plexuses
Where does the lymph from the lateral side of the dorsum of the foot drain?
Popliteal lymph nodes
In the spleen, what is the name of the long, vascular channels located in the red pulp that contains the fenestrated barrel hoop basement membrane?
The sinusoids
In the spleen, what type of cells are found in the periarterial lymphatic sheath and in the red pulp?
T cells
In the spleen, what type of cells are found in the follicles within the white pulp?
B cells
In a patient with Streptococcus pneumoniae bacteremia, what important immunologic function does the spleen serve?
Macrophages found within the spleen remove encapsulated bacteria from the blood
Name three findings seen on peripheral smear in asplenic patients.
Howell-Jolly bodies, target cells, thrombocytosis
What is the major consequence of asplenia?
Increased susceptibility to infection by encapsulated organisms
Why are asplenic patients more susceptible to encapsulated bacteria?
Asplenic patients have decreased immunoglobulin M secretion, leading to poor complement activation and therefore inhibited phagocytosis
In which encapsulated organ do T cells mature?
The thymus
From which branchial pouch is the thymus derived?
Third branchial pouch
What is the purpose of negative selection of T cells? Positive selection?
Negative selection ensures that T cells are nonreactive to self, and positive selection ensures that T cells are able to recognize major histocompatibility complex molecules
In the thymus, the ______ (cortex/medulla) is dense with immature T cells, whereas the ______ (cortex/medulla) is pale with mature T cells and epithelial reticular cells.
Cortex; medulla
