lymphoid system Flashcards
classification of lymphoid organs
Encapsulated – LN, thymus & spleen
Partially encapsulated - tonsils
Non-encapsulated – Peyer’s patches
composed of non-encapsulated, localized lymphocyte infiltration and lymphoid nodules in the mucosa of the GIT, respiratory & urinary tract.
MALT (mucosa-associated lymphoid tissue)
Distribution of lymphoid organs and lymphatic vessels in the body.
Found throughout the body along the course of lymphatic vessels that carry lymph into the thoracic and right lymphatic duct.
lymph nodes
lymph nodes location
Located in the mesentery, axilla, groin, along the great vessels of the neck & in the thoraco-abdominal cavities
lymph circulation
Afferent lymphatic vessels
Systems of lymph sinuses within the node
Efferent lymph vessels
path of lymph circulation
Afferent lymph vessels - marginal sinus -cortical sinus paracortical sinus -medullary sinus-efferent
lymphatic vessels
functions of the lymph node
Production of lymphocytes
Production of antibodies
Important role in the phagocytosis of foreign materials
lymph node
The only lymph organ located in the course of lymphatic vessels
With both efferent & afferent lymphatic vessels
Only lymph organ with lymph sinuses & filters lymph
Dense accumulation of lymphatic tissues in the tunica propria of the oral cavity and pharynx
Partially encapsulated
Lymphoid Ring of Waldeyer
Lymphocyte & anti-body production
tonsils
Lined by stratified squamous epithelium
With tonsillar crypts
Salivary corpuscles
palatine tonsils
Lined by pseudostrat. ciliated col. epith w/ patches of stratified squamous epithelium
With shallow infoldings (pleats)
Adenoids
pharyngeal tonsils
Found in the upper portion of the tongue behind the circumvallate papillae
W/ deep & wide-mouth crypt
Lined with stratified col. epithelium
lingual tonsils
Found in the tunica propria of the ileum
Lined by simple col. epithelium w/ striated border
peyer’s patches
are there villi over peyer’s patches?
no
With few or absent intestinal glands
Most prominent in children
Affected in TB of the intestines & Typhoid fever
peyer’s patches
Major lymphatic organ
Located in the anterior mediastinum
Capsulated
Undergoes “age involution”
thymus
No germinal centers
Abundant lymphocytes
Few endodermal reticular cells / thymic epithelial reticular cells
cortex
Structures separating blood from the cortical tissues
Endothelial cells joined by occluding junction
Basal lamina of the capillary endothelium
Perivascular space
Basal lamina of the epithelial reticular cells
Thymic epithelial reticular cells (epithelial barrier)
More epithelial reticular cells
Less lymphocytes
Hassall’s body / thymic corpuscles
medulla
functions of hassall’s body
Lymphopoiesis
Important role in immune mechanism
* rejection of grafts / transplants
* Myesthenia Gravis
Largest lymphoid organ
Found in the course of blood vessels
W/ a fibroelastic capsule with smooth muscles
Distensible
spleen
Billroth cord / Pulp cord
Venous sinuses
Atypical type
red pulp
receives the incoming arterial blood; first to come into contact with particulate matters and blood borne cells
Marginal zone
theories
Open / Slow circulation theory
Closed / Rapid circulation theory
Compromise theory
(combination of open & close theories)
