Lymphatic System Flashcards
The tonsilar capsule is lined tightly by a lateral structure which functions to do what?
Protect deep structures of pharynx/neck (e.g. nerves)
What general actions are T cells responsible for?
Destorying antigens, activating B cells
What two type of lymphoid material are present in the body?
Tissue and organs
What are the three types of lymphoid tissue present in the body?
Loose, dense and nodular
What are the two subtypes of nodular lymphoid tissue?
Solitary and aggregate nodular lymphoid tissue
What is the main distinguising factor between loose and dense lymphoid tissue?
Few (loose) and many (dense) lymphocytes present
What mechanism is behind a germinal center’s pale appearance?
Proliferating B cells expand, creating more space between nuclei (leading to more pale appearance)
T/F: Germinal centers are not present in the thymus
True
Explain the structures present to create the blood-thymus barrier
Supportive thymic epithelial reticular cells, desmosomes, continuous blood vessels
What is the name of the unique structure found in the thymic medulla?
Hassall corpuscle
What section of the thymus do T cells mature and migrate into the blood?
Medulla
Name the function(s) of lymph nodes
Filter lymph, aid in mounting immune response
T/F: Lymphoid follicles can be found within a lymph node’s cortex
True
Trace lymphatic drainage beginning with afferent lymphatic vessels
Afferent lymphatic vessel > subcapsular sinus > trabecular sinus > medullary sinus > efferent lymphatic vessel
What cells are present in the paracortex?
T cells
Name the function(s) of the spleen
Filter blood, start immune response to blood borne antigen
Splenic white pulp nodules exhibit a peripheral zone around their central arteriole termed what?
Periarterial lymphatic sheath (PALS)
What type of cell resides in PALS?
T cell
What structure resides at the center of PALS?
Central arteriole
What occurs if an RBC cannot re-enter the venous sinusoid?
Destroyed by resident macrophage
What occurs in each splenic circulation theory?
Open - blood vessel terminates in red pulp, closed - vessels are continuous
Name the four tonsils
Tubal, pharyngeal, palantine, lingual
Where do all lymphocytes originate?
Bone marrow
T/F: All lymphocytes reach full maturity and immunocompetency in the bone marrow
False
T/F: Immunocompetent B cells are activated against a specific antigen
True
What are the primary lymphoid organs?
Bone marrow, thymus
What are the secondary lymphoid organs?
Lymph nodes, spleen, tonsil
Lymphatic vessels enter though a lymph node’s (x) and exit through it’s (y)
Afferent lymphatic vessel, efferent lymphatic vessel
What structures are present between follicles in the outer cortex of a lymph node?
T cells, reticular cells, macrophages, APCs
What type of blood vessels ar present in the deep cortex and lymph node medulla to allow for lymphocytes to enter the blood stream?
High endothelial venule (HEVs)
What types of cells are generally present in lymph node medullary cords?
B cells, plasma cells, macrophages
What types of cells are generally present in lymph node medullary sinuses?
Macrophages, reticular cells, granulocytes (during infection)
PALS occurs in which pulp?
White
What two general structures are present in splenic red pulp?
Splenic cords (of Billroth), splenis (venous) sinuses
What structures do natural killer cells attack?
Virally infected cells, cancerous cells
What cell gives rise to a pluripotent stem cell?
Yolk sac cells
What cells are present in the cortex of the thymus?
Lymphocytes, supportive reticular cells
What cells are present in the medulla of the thymus?
Mature/Immunocompetent T cells, remnants of ERCs
Lymphatic nodules are primarily made of what type of cell?
B cells
What phenomenon can be described as a lymphocyte being retained by it’s chosen lymph node?
Homing
In general, what is the function of the lymph node medullary sinus?
Retard lymph flow to enhance filtration
What type of cell resides within germinal centers?
B cells
What two theories are presented regarding splenic circulation?
Open, closed
What subclassifications of lymphocytes are present in the lymphatic system?
T cell, B cell, natural killer cell
What is an alias for nodular lymphoid tissue?
Follicular lymphoid tissue
Name an example of an aggregate nodular lymphoid tissue
Peyer’s patches (GIT)
List some characteristics of loose lymphoid tissue
Initial immune response, no capsule
List some characteristics of dense lymphoid tissue
Contained in meshwork, no capsule
T/F: Primary lymphoid follicles possess germinal centers
False
From what embryological origin does the thymus come from?
Third pharyngeal pouch
T/F: The thymus possesses afferent lymphatic vessels
False
T/F: The blood-thymus barrier is found in the thymic medulla
False
Physically, what is a Hassall corpuscle?
Spherical, degenerative masses of epithelial reticular cells
What two general structures can be found in the lymph node medulla?
Medullary cords and sinuses
What is an alias for trabecular sinus?
Radial sinus
Name the aliases for the lymph node paracortex
Deep cortex, inner cortex
What is the largest lymph organ?
Spleen
The splenic capsule possesses what unique cell types?
Myofibroblast
What cell types are present in splenic red pulp cords?
Reticular fibers, RBCs, lymphocytes, plasma cells, macrophages, granulocytes
What type of capilaries are found in splenic red pulp sinuses?
Sinusoidal
What type of cells line splenic venous sinuses?
Tall endothelial cells
T/F: The tonsils are part of GALT
True
T/F: Lymph nodes can serve as site of metastases for cancerous cells
True
What is represented by the swelling of lymph nodes?
Lymphocyte response to antigens, proliferating of germinal center
Why is the swelling of lymph nodes painful?
Capsule distension leads to nervous signaling to CNS
If the spleen is removed via splenectomy, which organ likely takes over the spleen’s functions?
Liver
Why are children more vulnerable for infection after a splenectomy?
Few antibodies/plasma/memory cells present, more prone to infection
If food/debris is caught in tonsilar crypts, what may occur?
Infection
Infected pharyngeal tonsils are termed what?
Adenoids
What symptom do children with swollen adenoids present with?
Difficulty breathing (pharynx obstruction)
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What are the subclassifications of lymphoid organs?
Primary and secondary
What type of cellular structure is present to create a blood-tissue barrier in the thymus?
Tight junctions
What type of tissue is present within subcapsular sinuses?
Loose reticular cells and fibers
A medullary cord is composed of what kind of lymphoid tissue?
Dense lymphoid
What type of epithelium covers the spleen?
Mesothelium (simple squamous epithelium, visceral peritoneum)
What is the main purpose of the lymphatic system?
Protect body against pathogens/antigens
Approximately what percentage of circulating lymphocytes are T cells?
60-70%
In what organ do T cells mature and reach immunocompetency?
Thymus
In what organ do B cells mature and reach immunocompetency?
Bone marrow
What structure do activated B cells become?
Plasma cells
What is the main product of plasma cells?
Antibodies
T/F: Innate immunity responses can be classified as fast and nonspecific
True
T/F: Adaptive immunity responses can be classified as not producing memory cells
False
Where can loose lymphoid tissue be found?
GALT, MALT
Where can dense lymphoid tissue be found?
Walls of GIT, genitourinary tract, respiratory tract
T/F: Neither loose, dense or nodular lymhphoid tissue possess capsules
True
What are the three main compartments of the thymus?
Cortex (outer), paracortex (middle), medulla (inner)
What shape are thymic epithelial reticular cells?
Stellate
After puberty, the thymus is said to undergo what process?
Involution
T/F: Lymph nodes do not have capsules
False
The capsule of the spleen is made of what type of tissue?
Dense CT
When lymphocytes proliferate within germinal centers, what occurs with regards to the location of PALS?
PALS is pushed towards the periphery
What is the main function of splenic red pulp?
Filtration of blood
T/F: The basal lamina of splenic venous sinuses are considered somplete
False
T/F: Macrophages may insert their processes into splenic sinuses to check for circulating antigens
True
Invaginations located within tonsils are termed what?
Tonsilar crypts
Tonsilar crypts are lined by what type of epithelium?
Stratified squamous non-keratinized
The pharyngeal tonsil is covered by what type of epiethlium?
Ciliated pseudostratified columnar epithelium