Lymphatic System Flashcards
The lymphatic system carries out the immune response through a network of lymphatic vessels that collect _________ from the body’s interstitial spaces, filters the fluids through the _______________ and returns it to the _______________.
Lymph
Lymph nodes
Bloodstream
What’s the difference between interstitial fluid and lymph?
Not much, just location.
When the fluid leaves the interstitial space and enters the lymphatic vessels, it becomes the lymph.
What are lacteals?
Specialized lymphatic capillaries
Where are lacteals and what do they do?
These specialized lymphatic capillaries are in the lining of the small intestine (fingerlike projections) and they absorb lipids from the intestinal tract
When lymph is in the lacteals, what is it called?
Chyle.
Creamy white in color
3 functions of the lymphatic system
- Drains excess interstitial fluid from tissue spaces
- Transports dietary lipids form the GI tract to the blood
- Protects against invasion through the immune responses
Besides lymph, the lymphatic system consists of:
Lymphatic capillaries
Lymphatic vessels
Agranular leukocytes called lymphocytes (t,b,natural killer)
Thymus and spleen
Lymph nodes
Lymphoid nodules (peyers patches, tonsils, appendix)
Lymphatic vessels begin as…
Closed ended vessels called lymphatic capillaries in spaces between tissues
If lymphatic vessels are in the viscera, they run along…
Arteries
If lymphatic vessels are in the subcutaneous tissue, they run along…
Veins
Where are lymphatic vessels absent from?
CNS
Bone marrow
Teeth
Avascular tissues (cornea, epidermis, hyaline cartilage)
What are the lymphatic vessel valves for?
To prevent the backward flow of the lymph
How are lymphatic vessels similar to veins?
They both have valves to prevent backflow
Consist of the same 3 tunics, but calls are thinner and poorly defined in lymph vessels
Lymphatic vessels receive nutrients from…
Vasa vasorum
What has a larger diameter, lymph vessels or veins?
Lymph vessels
Collagenous type fibers extending from the endothelial cells of lymphatic capillaries to surrounding tissue space
Anchoring filaments
Flow pattern of lymph
Interstitial spaces (as interstitial fluid) To Lymph capillaries (as lymph) To Lymphatic vessels (as lymph) To Lymphatic trunks (as lymph) To Lymphatic ducts (as lymph) To Subclavian veins (as blood plasma) To Arteries (as blood plasma) To Blood capillaries (as blood plasma)
What is a lymphatic trunk? How many are there?
Where the lymphatic vessels merge.
9
What are the nine major lymphatic trunks?
Pairs: Lumbar Jugular Subclavian Bronchomediastinal
Single:
Intestinal trunk
What’s another name for the thoracic duct?
Left lymphatic duct
What makes up the cisterna chyli?
Intestinal trunk + right lumbar trunk + left lumbar trunk
Thoracic duct and right lymphatic duct drains lymph into the…
Right and left subclavian veins
The flow of lymph from tissue spaces is maintained by…..(2)
- Primarily by the contraction of skeletal muscles
2. One-way valves
Primary lymphatic structures of the body
Red bone marrow and the thymus gland
Because they produce T-cells, B-cells and Natural killer cells
Major secondary lymphatic structures
Lymph nodes, spleen, and lymphatic nodules
Where most immune responses occur
Agranular leukocytes
Lymphocytes
T-cells, b-cells, and natural killer cells
Lymphocytes that attack fungi, transplanted cells, and cancer cells
T-cells
Lymphocytes that destroy bacteria
B-cells
Lymphocytes that attack certain spontaneously arising tumor cells
Natural killer cells
Thymus
Does NOT provide a filtering function, like lymph nodes, since there are NO afferent lymphatic vessels leading into the thymus.
Afferent = arrive Efferent = exiting
Function of thymus
Promote the maturation of t-cells (they migrate from the red bone marrow to the thymus cortex, then to thymus medulla)
Secretes thymosin (assists in promotion and maturation of T-cells)
Why does the spleen not provide a filtering function? Like the thymus
There are not afferent lymphatic vessels leading into the spleen
2 areas of the spleen
- White pulp (mostly b-cells)
2. Red pulp (venous sinuses filled with blood, and splenic/Billroth’s cords that lie between sinuses)
Function of white pulp in spleen
The site of B-cell proliferation into plasma cells
Function of red-pulp in spleen
Carries out the main function of the spleen which is phagocytosis of bacteria and worn out or damaged red blood cells and platelets
Also functions as reservoir for blood platelets
Where the lymph nodes heavily concentrated
Inguinal, axillary, and mammary
Lymph nodes are specialized into 2 regions
Cortex = outer region, t cells and immature b cells
Medulla = inner region of mature b cells
Germinal centers in lymph nodes
Contain masses of actively proliferating lymphocytes
Medullary cords of lymph nodes
Thin inward extension, from the cortex toward the hilum, of t cells, b cells, and macrophages
Afferent lymphatic vessels
Carry lymph from tissues to the lymph nodes
Enter the convex side of the node
ARRIVING
Efferent lymphatic vessels
Carry lymph from the hilum (concave side of a node) to venous circulation
EXITING
Where is the subcapsular sinus?
Between the capsule and cortex of the lymph nodes
Direction of lymph flow in lymph nodes
From subcapsular sinus Through cortex via cortical sinuses Through medulla via medullary cords Into hilum Exit lymph node via efferent lymph vessels
What are the functions of the lymph nodes?
ONLY lymphatic tissue that filters lymph
Foreign substances are filtered from lymph before it passes back to blood (due to macrophages by phagocytosis of immune response)
plasma cells and t cells that have proliferated within a lymph node also leave and circulate to other parts of the body
Lymphatic nodules
Are NOT surrounded by a capsule
Clusters that guard in all mucous membranes
MALT (mucosa-associated lymphoid tissue)
Example of lymphatic nodules:
Peyers Patches.
In mucosa lining the lieu of the small intestine
Other examples of lymphatic nodules
Paryngeal tonsil/adenoid, two palatine tonsils, and two lingual tonsils
Lymphatic nodules and the large intestine
Contains a large grouping of lymphatic nodules (located in lamina propria of mucosa)
