Flashcards in The Lymphatic System Deck (97)
Where do HSC arise from?
Foetal liver / post-natal bone marrow
What organ is associated with B cell maturation?
What organ is associated with T cell maturation?
What is the central (primary) lymphoid system composed of?
Bone marrow + thymus
What is the peripheral (secondary) lymphoid tissue composed of?
* Lymph nodes.
* Tonsils (Waldeyer’s ring).
* Epithelio-lymphoid tissues.
* Bone marrow.
In clinic, what do you have to decide about enlarged lymph nodes?
* Localised, more widespread or generalised.
* Peripheral or central (internal).
What is splenomegaly?
What is the function of the lymphatic system?
* Important function in fluid homeostasis
* Prevent excessive accumulation of fluid in the tissues – oedema
What does the lymphoid system permit?
* Cell traffic
* Cell trapping
* Interaction with of cells and “molecules” with cells of the immune system – protective function
Describe the appearance of a lymph node.
Small, oval bodies, measuring up to 2.5cm.
Where are lymph nodes located?
Along lymphatic vessels
What are lymphatic vessels?
Blind-ending vascular channels that collect fluid from tissues and return to the blood stream
What type of movement do lymphatic vessels depend on?
Passive movement of fluid
What ensures the direction of flow through lymphatic vessels?
What drains lymph through the capsule of the lymph node?
Afferent channels – through the capsule in to the peripheral sinus
What leaves from the hilum of the lymph node?
Effect channel - allows lymph to leave the node
What do the efferent vessels of the lymph node drain to?
* cisterna chyli/thoracic duct.
* L jugular, subclavian or bronchomediastinal trunks.
* R jugular, subclavian or bronchomediastinal trunks.
After leaving the lymph node, where does lymph drain to?
The venous system at the junction of the L or R subclavian and jugular veins
Where do arterial and venous vessels serving the node enter/exit?
At the hilum
What happens to lymph, in the lymph node, before it is returned to the circulation?
It is filtered within the node parenchyma
Where would lymph oedema be seen in a patient post-axillary clearance from breast cancer?
Why does axillary surgery for breast cancer cause lymphoedema?
Disrupts the ability of the lymphatics to return fluid back to the circulation
What is chylous ascites?
Main trunk draining lymph back is obstructed or damaged
Accumulation of lipid rich lymph in the peritoneal cavity due to distruption secondary to trauma or obstruction
What is the 2 main functions of the lymphatic system?
* To return lymph to the circulation
* To filter lymph before returning it to the circulation
How does the lymphatic system prevent lymphedema?
By returning lymph to the circulation
The lymphoid system is an important DEFENCE system
How does the lymphoid system act as a defence system?
* Houses cells of the innate immune system
* Traffic of APC’s links innate and adaptive immune responses
* Seat of the adaptive immune response
What are the 3 types of lymphocyte found in lymph nodes?
* B cells
* T cells
* NK cells
What are B cells associated with?
Follicles and germinal centres.