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
What makes up the red pulp in the spleen?
contains SINUSOIDS (fenestrated, lined by endothelial cells and supported by reticulin)
CORDS containing macrophages and some fibroblasts and cells (RBCs/ WBC/ PC and some CD8+ T cells) in transit
Why should splenic rupture always be considered in abdominal injuries?
- it only has a thin capsule and it is a well-vascularized organ
What is the white pulp of the spleen?
LYMPHATIC tissue of the spleen:
- periarteriole lymphatic sheath (lymphoid organ- T-cells and marcophage)
- marginal zone (macrophages)
- follicles (B-cells)
Describe the circulation of blood within the spleen.
- splenic artery> central arterioles> end arterie s
What % of the spleen makes up 25% of it?
White matter
How does blood return with the venous system in the spleen?
- through the sinus system; found all around the capillaries (which have fevenstrations)
> v.sinus > collecting vein> splenic vein
What % if the spleen is made up by the red pulp?
75%
- resp. to screen for abnormal RBCs, OLD rbc
WHat may be a sign of splenectomy/ hyposplenism?
- presence of abnormal red cells in the peripheries.
(Howell-Joly bodies- remnants of
What is seen in the peri-arteriolar lymphoid sheath?
- CD4+ lymphoid cells
- –PALS is explanded by lymphoid follicles
How does splenomegaly present as?
- LUQ DRAGGIN sensation
- discomfort with EATING
- pain if infarction
- HYPERSPLENISM
What occurs with hypersplenism?
TRIAD
- splenomegaly
- FALL in 1/more cellular components
- correction of CYTOPENIAS by splenectomy
What infection may cause splenomegaly?
EBV TB Malaria Typhoid Brucellosis Leichmaniasis trypanosomiasis
What inflammatory conditions results in splenomegaly?
RA
- SLE
Name congestive causes of splenomegaly.
portal (hepatic cirrhosis/ splenic vein thrombosis. cardiac failure)
Name haematological diseases leading to splenomegaly.
- lymphoma/leukaemia
- Haemolytic anaemia
- ITP
- Myeloproliferative d.o
Storage causes of splenomegaly.
Gaucher’s
Niemann-Pick disease
When may hypersplenism occur?
with conditions a.w splenomegaly
Apart from splenectomy, what are other causes of hyposplenism?
- coeliac disease
- sickle cell disease
- sarcoidosis
- iatrogenic (non-surgical)
Hyposplenism occurs with loss of fxn of which pulp?
RED pulp
