Cells + Tissues Of Lymhatic System

Question 1

What is the lymphatic system made of?

Answer 1

Lymph (fluid)
Lymphatic vessels
Lymphoid tissues and organs
The cells contained within the tissues and organs

Question 2

What is lymph?

Answer 2

A thin fluid resembling plasma (pH 7.4). However it has lower amounts of protein than plasma

Question 3

How is lymph in the umbilical region different? What’s its name?

Answer 3

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)

Question 4

Through what is the lymph transported around the body?

Answer 4

In lymph vessels
There’s are capillaries, trunks, ducts and viens (size order)
They are blunt ended.
The lymph flows unidirectionally

Question 5

What are the openings in lymphatic capillaries?

Answer 5

Bit like a valve

Forced open by the oncotic pressure of the lymph and so lymph is forced out through them

Question 6

How does lymph flow around the body?

Answer 6

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.

Question 7

Where in the body is lymph never found?

Answer 7

The CNS and brain

Question 8

How do lymphatic capillaries compare to veins (blood)?

Answer 8

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.

Question 9

Describe lymphatic trunks and ducts.

Answer 9

Equivalent to larger viens
Large fibrocartilaginous valves
Rely on skeletal muscle and organ movement for flow

Question 10

What is the Cisterna Chyli?

Answer 10

A large container of chyle from the GI tract, before it joins rest of lymph system

Question 11

Where does the lymph drain from/to?

Answer 11

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)

Question 12

What are the most clinically important lymph nodes?

Answer 12

Neck-cervical nodes
Groin-inguinal nodes
Armpit-axillae nodes

Question 13

What are lymph nodes structure?

Answer 13

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)

Question 14

What do lymph nodes do?

Answer 14

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)

Question 15

What are/is role of Follicular Dendritic cells?

Answer 15

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)

Question 16

How do lymph nodes aid the immune system?

Answer 16

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.

Question 17

What’s the difference between B and T cells in terms of antigen recognition?

Answer 17

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)

Question 18

How do the majority of lymphocytes enter and leave the lymph nodes?

Answer 18

Enter Via the feeding artery (a few in lymph)

Leave in the efferent lymphatic

Question 19

Why so lymph nodes enlarge?

Answer 19

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.

Question 20

What is the medical term for enlarged lymph nodes?

Answer 20

Lymphadenopathy

Question 21

Where can lymphadenopathy occur?

Answer 21

In all the nodal regions or affect lymphatic organs

Question 22

What is lymphoma and hw does it often present?

Answer 22

=malignancy of the lymphoid tissue itself
Often presets with lymphadenopathy

Eg-Hodgkin’s and non-Hodgkin’s lymphoma

Question 23

What are the lymphatic organs?

Answer 23

Thymus 
Spleen 
Tonsils 
Appendix
Payers patches_(small intestine)

Question 24

What is the location, structure and function of the Thymus?

Answer 24

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

Question 25

What is the location, structure and function of the Spleen?

Answer 25

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

Question 26

Descrieb the 2 functions of the spleen in more detail.

Answer 26

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)

Question 27

What happens if a spleen ruptures?

Answer 27

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.

Question 28

What happens after a SPlenectomy?

Answer 28

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.

Question 29

What is splenomagaly?

Answer 29

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)

Question 30

What is the location, structure and function of th tonsils?

Answer 30

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

Question 31

What happens to tonsils clinically?

Answer 31

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

Question 32

What is the location, structure and function of the vermiform appendix?

Answer 32

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

Question 33

What is the location, structure and function of the Payer’s Pathces?

Answer 33

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

Question 34

Summarise the 4 main functions of the lymphatic system

Answer 34

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)

Question 35

How can cancer cells travel in metastatic disease?

Answer 35

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)

Question 36

Why/how are Sentinel Lymph nodes used in cancer detection?

Answer 36

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.

Question 37

What are some key causes of secondary lymphodeama?

Answer 37

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