Lymphatic system Flashcards
What does the lymphatic system act as?
Secondary defense system
What are the 3 ways the lymphatic system acts as a defense system?
Humoral immune system
cell mediated immune system
Filtration of lymph & blood
What is the difference between humoral & cell mediated immune systems?
Humoral: B lymphocyte antibodies
Cell mediated: T lymphocytes
What are the 2 types of lymphatic tissue?
Diffuse
Dense
Where is diffuse lymphatic tissue often found?
Lamina propria of
G.I. tract
Where is dense lymphatic tissue often found?
submucosa of G.I. tract
Are lymph nodules made of dense or diffuse lymphatic tissue?
dense
What are peyer’s patches?
accumulation of nodules
In what tissue can lymphocytes be seen invading epithelium?
Tonsils
What are the structural components of a lymph node?
Capsule
Stroma
What is the stroma?
Trabeculae that arise from the capsule and divide the parenchyma
What is the cortex of a lymph node?
Outer region of parenchyma
Where are lymph nodules located?
In cortex
What is the difference between a primary and secondary nodule?
Primary has homogenous appearance and secondary have a germinal center due to previous antigenic exposure (active lymphocytes)
What does the paracortex contain?
T lymphocytes
Why is the paracortex considered a thymus dependent zone?
T lymphocytes are produced in the thymus
What are high endothelial venules?
Vessels that transport T lymphocytes from the thymus to the paracortex
What is different about pigs and elephants in regards to lymph nodes?
Medulla is on outside
Cortex is on inside
What are medullary cords?
Lymphocytes, plasma cells, macrophages and reticular cells located in the medulla
What is the subcapsular sinus?
Space between capsule and lymphatic nodule
What are the medullary sinuses?
Lymph sinuses between medullary cords
Describe lymph flow
Afferent vessels drain to subcapsular and trabecular sinuses (nodules)
Lymph travels from cortical sinuses to medullary sinuses
Efferent vessels transport lymph out
What happens to B cells after being presented with an antigen by a dendritic cell?
B cell becomes activated & divides
Some B cells become plasma cells & some move to medullary cords to secrete antibodies
What are hemal nodes?
Lymphatic organs that filter blood
