Cells + Tissues Of Lymhatic System Flashcards
What is the lymphatic system made of?
Lymph (fluid)
Lymphatic vessels
Lymphoid tissues and organs
The cells contained within the tissues and organs
What is lymph?
A thin fluid resembling plasma (pH 7.4). However it has lower amounts of protein than plasma
How is lymph in the umbilical region different? What’s its name?
It’s called CHyle
It arises in the GI tract
It’s white and cloudy because it contains fats and dissolved lipids - chylomicrons +fat soluble vitamins (A+E+K)
Through what is the lymph transported around the body?
In lymph vessels
There’s are capillaries, trunks, ducts and viens (size order)
They are blunt ended.
The lymph flows unidirectionally
What are the openings in lymphatic capillaries?
Bit like a valve
Forced open by the oncotic pressure of the lymph and so lymph is forced out through them
How does lymph flow around the body?
Lymph vessels a re arranged into superficial and deep (deep-deep fascia), the lymph flows from superficial to deep.
In the limbs, deep lymphactics pass though the muscles where contraction aids movement.
Larger vessels (duct + trunks), contain smooth muscle cells in their walls, their contraction contributes to lymph flow.
Where in the body is lymph never found?
The CNS and brain
How do lymphatic capillaries compare to veins (blood)?
Similar as low pressure and valves but lymph doesn’t contain cells.
Lymphangion compression by local veins and arteries propels the lymph. (When nearby veins are full of blood they stretch taking more room, and so squish lymph capillaries, this pushes the lymph through.
Describe lymphatic trunks and ducts.
Equivalent to larger viens
Large fibrocartilaginous valves
Rely on skeletal muscle and organ movement for flow
What is the Cisterna Chyli?
A large container of chyle from the GI tract, before it joins rest of lymph system
Where does the lymph drain from/to?
The bodies UPPER RIGHT QUADRANT drains into right subclavian vein and internal jugular vein
The REST OF THE BODY drains into the left subclavical vein and internal jugular vein (including the cisterna chyli from GI tract)
What are the most clinically important lymph nodes?
Neck-cervical nodes
Groin-inguinal nodes
Armpit-axillae nodes
What are lymph nodes structure?
Shaped like kidney
Each node has multiple afforestation lymph vesssels (enter via convex surface)
Each node has a single efferent lymph vessel (leaves via concave hilum)
Each has a feeding artery and draining vein that come via the hilum.
Multiple follicles-nodules containing immune cells
Main connective tissue is reticulin (collagen 3)
What do lymph nodes do?
Filter lymph as it percolates on its way to vascular system.
Germinal centres in the nodules in “cortex” of nodes contain the immune cells that do this (macrophages, dendritic and B and T cells)
What are/is role of Follicular Dendritic cells?
They’re located in the terminal centres of nodules.
Antigen antibody complexes adhere to their dendritic processes and the cell can retain the antigen for months
Follicular dendritic Coll’s cause proliferation of B cells, esp memory B cells (give basis of immunity, can last 20 years)
How do lymph nodes aid the immune system?
Dendritic cells bring bacteria from infected tissue into the nodule. Here it’s engulfed y a macrophage, and the dendritic cell artists a T cell. The T helper cell then activates a B cell. The B cell makes antibodies complementary to the bacteria and this leaves the node with the lymph via the efferent vessel to then circulate the body.
What’s the difference between B and T cells in terms of antigen recognition?
B lymphocytes recognise antigens themselves.
T lymphocytes need to be presented to an antigen to bind they don’t do so alone as they don’t recognise them (use of dendritic cell)
How do the majority of lymphocytes enter and leave the lymph nodes?
Enter Via the feeding artery (a few in lymph)
Leave in the efferent lymphatic
Why so lymph nodes enlarge?
As it fight infection, the germinal centres fill with increasing number of lymphocytes causing the nodes to swell, can cause pain.
Cancers can also cause swelling ad they metastasise to lymph nodes via the afferent lymphatics.
What is the medical term for enlarged lymph nodes?
Lymphadenopathy
Where can lymphadenopathy occur?
In all the nodal regions or affect lymphatic organs
What is lymphoma and hw does it often present?
=malignancy of the lymphoid tissue itself
Often presets with lymphadenopathy
Eg-Hodgkin’s and non-Hodgkin’s lymphoma
What are the lymphatic organs?
Thymus Spleen Tonsils Appendix Payers patches_(small intestine)
What is the location, structure and function of the Thymus?
Location=superior mediastinum, fully formed + functional at birth, involutes after puberty
Structure=similar to lymph node (but no hilum straight into blood stream)
Function=maturation of bone marrow derived stem cells into immunocompetent T cells. Called-thymic cell education
What is the location, structure and function of the Spleen?
Location=inferior to diaphragm,posterior to stomach, fully formed + functional at birth, grows at same rate as person
Structure=similar to Lymph node but separated into white (immune) and red (heam) pulp.
Function=filters blood the way lymph nodes filter lymph, has function in both the immune (remove debris) and heamopoietic (kill debris) systems
Descrieb the 2 functions of the spleen in more detail.
Immune=antigen presentation by APC’s, activation + [proliferation of B+T lymphocytes, production of antibodies, removal of macro molecular antigens (charcoal+carbon) from the blood.
Haemopoietic=removal and destruction of old, damaged/abnormal erythrocytes +platelets, retrieval of iron from erythrocytes heamoglobin, erythrocyte storage (released If >10% blood lost)
What happens if a spleen ruptures?
Has very rich blood supply and is relatively fragile-oh no
A ruptured spleen can lead to death through exsanguination (blood loss). Surgeons often remove the damaged spleen.
What happens after a SPlenectomy?
The liver and bone marrow can take over emoval and destruction of RBC’s.
However, splenectomy increases the risk of infection by encapsulated bacteria (cant be caught by liver, ie meningococcus) and malaria.
What is splenomagaly?
The spleen engages in response to localised infection (like lymph nodes) or enlarges in response to systemic infection. Especially glandular fever, malaria and septicaemia. It can enlarge to 10x its normal size! (Could then squish liver)
What is the location, structure and function of th tonsils?
3 types=Pharyngeal, Palatine and Lingual
Location=Oropharynx and nasopharynx, fully formed+functioning at birth, mostly affected in childhood, together constitute Waldeyer’s Ring
Structure=Nodules reside inferior to surface invaginations (in crypts) to increase SA
Function=prevent pathogen ingress through oral/nasal routes, prevent pathogen through aural route (pharyngeal tonsil), crypts increase SA
What happens to tonsils clinically?
The surface epithelial have numerous microfold (M-Cells), they present antigens to underlying immune cells. This causes swelling due to B cell and T cell proliferation
What is the location, structure and function of the vermiform appendix?
Location=inferior to and attached to caecum
Structure=Nodules reside inferior to surface invaginations (crypts), many M-fold cells in epithelial surface
Function=Prevents pathogen ingress through GI routes, prevents pathogen ingress arriving from ileum, Crypts increase SA
What is the location, structure and function of the Payer’s Pathces?
Location=inferior to and attached to side of ileum
Structure=Nodules reside inferior to surface domes, many M-fold cells in epithelial surface
Function=prevent pathogen ingress through digestion
Summarise the 4 main functions of the lymphatic system
1) Fluid Balance (interstitial fluid returned to circulation)
2) Transport of fats+fat-soluble vitamins (Fastest way to send lipid soluble from digestive system to venous circulation)
3) Defense against pathogen/disease (nodes+organs filter lymph to remove danger, visiting T/B cells + macrophages)
4) Storage and destruction of aged erythrocytes (spleen mainly but liver can if spleen damaged/removed)
How can cancer cells travel in metastatic disease?
Through newly produced vasculature (made by the tumour itself)
Through interstitial space
Through lymph (myeloid cell Enters sentinel node, here it recruits tumour cells + produces matrix factors to make the environment more favourable for invasion, then melanoma cells are recruited, deposited and grow in the node)
Why/how are Sentinel Lymph nodes used in cancer detection?
The first set of lymph nodes to swell in cancer
Axilla or pectoral cells looked at in breast cancer, prescience of malignant cells leads to mastectomy.
Old method of malignancy cell detection -take frozen section whilst in theatre then decide whether whole mastectomy or not
New method=use flurography, the radioactivity shows up exactly where the rapidly dividing cancer cells are so everything is removed, sometimes the lymph itself is infected.
What are some key causes of secondary lymphodeama?
Surgery-either node involvement or accidental damage
Infections=
Cellulitis-obstruction of a vessel leads to blocking bacteria so its allowed to grow and then damages the tissue as stuck there
Filariasis-a parasitic worm that invades + survives in vessels again blocking them
