ANAT - Lecture 2 Flashcards
What are the 4 components of the Lymphatic system?
- Lymph plasma
- Lymphatic vessels
- Lymphoid tissue
- Red bone marrow
What 3 organs are associated with the lymphatic system?
- Thymus
- Spleen
- Lymph nodes
What are the 2 main functions of the Lymphatic/Immune system?
- Drains excess interstitial fluid
□ Transports lymph back to blood (maintains normal blood volume) - Carries out immune response
□ Produces, maintains and distributes lymphocytes
□ Contain phagocytic and lymphocytes essential for defense against disease
□ Lymphocytes = specialized white blood cells
Interstitial fluid vs Lymph
- After interstitial fluid passes into lymphatic vessels its called “lymph plasma”
- Differ only by locations
- Interstitial fluid is in found between cells, but lymph plasma is located within lymph vessels and lymphatic tissues
How do Lymphatic vessels differ from veins?
Lymphatic vessels have:
- thinner walls
- more valves
- are more permeable
Can lymphatic capillaries absorb large molecules like proteins and lipid?
Yes, lymphatic capillaries can absorb large particles like lipids and proteins
Describe the walls of lymphatic capillaries?
- The wall of lymphatic capillaries are made of overlapping endothelia cells
- The cells are not tightly joined, instead they have loosely overlapping edges which form easily opened flaps
- When the pressure is greater in the interstitial fluid than the lymph plasma, the cells in the wall separate and interstitial fluid enters the capillary
- Anchoring filaments are attached to lymphatic capillaries and they anchor them to surrounding connective tissue.
Why are the anchoring ligaments on lymphatic capillaries important?
Anchoring ligaments are important because if there is an increase in interstitial fluid volume then this increase in pressure will force the overlapping sections apart instead of collapsing them
How much fluid is leaked out into lymphatic vessels daily?
3.6L
Where do lymphatic vessels return fluid?
Lymphatic vessels return fluid back to the systemic circulation of the heart
All lymph plasma returns to the bloodstream through the ________ ____ _____ and various ___ _____
All lymph plasma returns to the bloodstream through the thoracic lymphatic duct and various lymphatic trunks
Describe the flow of lymph
Lymphatic capillaries —> Lymphatic collecting vessels —> Lymphatic trunks —> Lymphatic ducts
Describe the histology of a lymphatic capillary
You can see the nucleuses, but other than than is essentially uniformly pink
How do lymphatic collecting vessels compare to veins?
They are similar, but they have more internal valves
Lymphatic ______ can be superficial or deep?
Lymphatic collecting vessels can be superficial or deep
Define Superficial and Deep Lymphatic Collecting Vessels
Superficial = located in the subcutaneous layer of skin, collect lymph from superficial structures of the body. They tend to follow the venous drainage system. They drain into deep lymphatic vessels
Deep = carry lymph from internal organs
Lymphatic vessels doesn’t have a pump, so how does it move?
Lymph relies solely on muscle contraction to move
What forms lymphatic trunks?
Superficial and deep lymphatic vessels merge to form lymphatic trunks
What forms lymphatic trunks?
Lymphatic collecting vessels leaving lymph nodes unite to form lymphatic trunks
Name the principal lymphatic trunks:
Principle Lymphatic trunks:
1) Broncho mediastinal
2) Lumbar
3) Intestinal
4) Jugular
5) Subclavian
Where do the Principle Lymphatic trunks:
1) Broncho mediastinal
2) Lumbar
3) Intestinal
4) Jugular
5) Subclavian
Drain lymph from?
Principle Lymphatic trunks:
1) Broncho mediastinal - thoracic wall, lungs, heart
2) Lumbar - lower limbs, pelvis, kidneys, abdominal walls
3) Intestinal - stomach, intestine, pancreas, spleen, part of liver
4) Jugular - head and neck
5) Subclavian - upper limbs
Essentially the name implies where they drain from
Where do lymphatic trunks deliver lymph to?
Lymphatic trunks —> Lymphatic ducts
Which area of drainage is larger: the right or left lymphatic duct?
The left lymphatic duct
How are the lymphatic ducts divided?
- Right lymphatic ducts
- Thoracic duct (left)
What 3 lymphatic trunks join to form the right lymphatic duct
- Right jugular trunk
- Right subclavian trunk
- Right bronchomediastinal trunk
Where does the right lymphatic duct collect from?
- the right side of the body above the diaphragm
Where does the right lymphatic duct return venous circulation to?
The right lymphatic duct returns to venous circulation at or near the junction of the right internal jugular vein and the right subclavian vein = Venous angle
Where does the thoracic duct collect from?
- both sides below the diaphragm
- the left side above the diapragm
What is the largest lymphatic vessel
The thoracic duct is the largest lymphatic vessel
Describe the pathway of the thoracic duct?
- Starts at cisterna chyli
- Collects from lumbar trunks and interstitial trunks
- Brings lymph back into venous circulation by travelling up the left side of the spine to the level of the left clavicle
Where does the thoracic duct return lymph to venous circulation?
The thoracic duct returns lymph to circulation at the left subclavian vein near the junction with the left internal jugular vein (venous angle)
Why are the right and left lymphatic ducts divided as they are?
embryological development
What comprises the venous angle?
The subclavian vein and the internal jugular vein
What cells comprise the initial line of defense for the immune system?
Macrophages and Lymphocytes
What do lymphocytes develop from?
Lymphocytes develop from stem cells in red bone marrow
What do lymphocytes differentiate into?
T cells
B cells
NK cells
Where do T cells mature?
T cells migrate from bone to thymus which is where they will mature
Where do B cells mature
B cells stay in red bone marrow and mature and get into blood from there
Which cell is responsible for “cell mediated immunity”
T cells = cell mediated immunity
What are the 4 kinds of T cells and their purpose?
1) Cytotoxic T cells
- can directly attack and destroy antigen
- responsible for cell mediated immunity
2) Helper T cells
- Works with suppresser T cells to regulate immune response
- role in activation and activity of B cells
3) Suppressor T cells
- Work to shut down the cytotoxic T cells
4) Memory cells
- when T lymphocytes are activated by antigens binding their external surface, these cells hide, and if reinvaded these cells are the first to recognize and destroy
What type of cell is responsible for antibody mediated immunity?
B cells
What are the 2 type of B cells - describe
1) Plasma cells
- b cells are activated to differentiate into plasma cells when an antigen binds its receptor
- produce and secrete an antibody to neutralize the antigen that activated it
- requires help of “helper T cell” to promote the b cell to differentiate into plasma cell
- requires help of “suppressor T cell” to shut it down
2) Memory B cells
- same as memory T cells
Describe NK cells
NK cells
- 5% of circulating lymphocytes
- Immunological surveillance cells
- Travel in the body, get in tissue, police for antigen to kill/destroy
What type of connective tissue is lymphoid tissue?
Lymphoid tissue is specialized loose ct, reticular ct
What are the 2 ways lymphoid tissue is packed?
- Diffuse Lymphatic tissue
- mainly in mucus membranes and in lymphatic organs - Lymphatic follicles/nodes
- have germinal center = where B cells become plasma cells, thus indicates presence of antigen
- tightly packed spheres of reticular tissue and cells
Where are lymphoid tissues found?
- Digestive system (GALT)
- Pharynx as tonsils (pharyngeal, palatine, lingual tonsils) (tonsil = neutralize antigens coming in nose/mouth, have crypts to catch)
- Ileum (Peyer’s patches)
- Appendix
What are the 3 lymphoid organs?
- thymus
- lymph nodes
- spleen
