Lymphoid system Flashcards
What are lymph nodes?
- small, oval bodies (2.5cm)
- found along the COURSE of lymphatic vessels
What do LNs do?
- blind-ending vascular channels COLLECT fluid from TISSUES and returns to blood stream
- PASSIVE movement of fluid
- valves
LNs found in the intestinal wall are called ______
PEYER’s PATCHES
What is the function of lymph nodes?
- filter blood
2. assist the immune system in building an immune response
Describe the flow of lymph through the lymph nodes.
- the AFFERENT channels drain lymph through the CAPSULE into the PERIPHERAL sinus
> lymph then moves towards the HILUM of the lymph node
> concave area in the node that drains lymph into the EFFERENT channels = FILTERED lymph
Name the lymphatic trunks.
- 2 lumbar trunks
- 2 bronchomediastinal trunks
- 2 jugular trunks
- 2 subclavian trunks
- 1 intestinal trunk
What are the 2 major ducts of the lymphatic system?
- Thoracic Duct
2. Right lymphatic duct - drains lymph from the Right arm, right side of HEAD and chest
What does the right lymphatic duct then do?
- drain blood into the jxn of the RIGHT JUGULAR vein and the RIGHT subclavian vein
Where does the thoracic duct dump lymph into?
- same jxn on the left side of body
- —–jxn of the Left subclavian and left jugular vein
What cells does the lymphoid system house?
- cells of the INNATE immune system
1. Lymphocytes: B-cells/ T-cells/ NK-cells
- Mononuclear phagocytes (macrophages/ Antigen presenting cells and dendritic cells)
- endothelial cells
Where are the plasma cells located in the lymph node?
- in the MEDULLA
What are forms of lymphadenopathy?
- local inflammation
- systemic inflammation
- malignancy
- others: Sarcoidosis/ catslemans disease/ IgG4-related disease
What are causes of local inflammation?
- infection (TB or Toxoplasma)
2. vaccination/ dermatopathic
What are causes of systemic inflammation?
- viral infections
2. autoimmune
WHat is sarcoidosis?
- a granulomatous condition
- WIDE DDX; no histological dx
- –may mask malignancy in a LN
what is lymphangitis?
- superficial infection (RED lines EXTENDING form an inflamed lesion)
What may be the first sign of UNDERLYING malignancy?
- superficial lymphadenopathy
What could it be if pt presents with GENERALIZED lymphadenopathy?
- inflammatory process
- widespread malignancy (lymphoma/ leukaemia) —FBC check!
Name a IIary lymphoid organ.
SPLEEN
(normally 150-200g) —usually NOT palpable !
What is contact with the spleen’s visceral surface?
- left kidney
- gastric fundus
- tail of pancreas
- splenic flexure of colon
What is the spleen supplied by?
splenic artery (br. of the coeliac axis) ---drained by the splenic vein ----SMV forms the portal vein
What is a diseased spleen prone to ?
RUPTURE
- why it’s an emergency
What is the fxn of the spleen?
FILTER for the blood
- detects, retains and eliminates UNWANTED, foreign/ damaged material
- facilitates immune responses to blood borne antigens!
Describe the morphology of the spleen.
-encapsulated organ with parenchyma, including RED PULP and WHITE pulp