Lymphatic System Flashcards
Carries out the immune through a network of lymphatic vessels that collect excess fluid (lymph) from the body’s interstitial spaces, filters the fluid through lymph nodes then returns it to the bloodstream.
Lymphatic system
After the fluid leaves the interstitial spaces then enters the lymphatic vessels, it is called
Lymph
What color is lymph usually?
-transparent, watery, and slightly yellow
What occurs in the fingerlike projections (villi) of the small intestinal lining
Lacteals
What absorbs lipids from the intestinal tract
Lacteals
The lymp in lacteals is called _______
Chyle
What color is chyle
Creamy-white in color
Functions of the lymphatic system
- drains excess interstitial fluid from tissue spaces
- Transports dietary lipids from the GI tract to the blood (lacteals)
- Protects against invasion through the immune responses
What do the lymph, lymphatic system consist of?
- lymphatic capillaries
- lymphatic vessels
- agranular leukocytes called lymphocytes (T cells, B cells and natural killer cells)
- thymus and spleen
- lymph nodes
- lymphoid nodules (Peyer’s patches, tonsils and appendix)
Lymphatic vessels being as closed-ended vessels called _____________ in spaces between tissue cells
Lymphatic capillaries
Where do lymphatic vessels occur along arteries?
In the viscera
Where do lymphatic vessels occur alongside veins?
In the subcutaneous tissue
Where are lymphatic vessels absent?
- CNS
- bone marrow
- teeth
- avascular tissues such as cornea, epidermis, hyaline cartilage.
Similarities of lymphatic vessels to veins
- valves
- three tunics
- receive nutrients from vasa vasorum
- thin walls
Differences of lymphatic vessels and veins
- LV are closed ended
- LV have larger diameters
- LV have thinner tunics
- LV have anchoring filaments
- ends of the endothelial cells making up the wall of lymphatic capillaries overlap
Anchoring filaments
Collagenous type fibers extending from the endothelial cells of lymphatic capillaries to surrounding tissue space
-situated at right angles from vessels, pressure pulls on these and opens up and allows interstitial fluid in
Flow pattern of lymph
Interstitial space—-lymphatic capillaries——lymphatic vessels—–lymphatic trunk——lymphatic ducts——subclavian veins——arteries——blood capillaries
When does interstitial fluid become lymph
When it goes from interstitial spaces to lymphatic capillaries
When does lymph change to blood plasma?
From lymphatic ducts to subclavian veins
Lymph passes from __________ into __________ which merge to form ____________.
- lymphatic capillaries
- lymphatic vessels
- lymphatic trunks
How many trunks ar there?
9, 4 paired, one unpaired
What is the unpaired lymphatic trunk?
Intestinal trunk
What are the paired lymphatic trunks?
- lumbar
- jugular
- subclavian
- bronchomediastinal
The nine major trunks pass their lymph into what two main channels?
Thoracic duct (left lymphatic duct) and right lymphatic duct
When does lymph go to venous blood?
From the lymphatic trunks to the thoracic duct (left lymphatic duct) and right lymphatic duct
What dumbs into the subclavian
Ducts
Which duct is longer? right or left?
Left lymphatic duct (thoracic duct)
How long is the thoracic duct?
15-18’ in length
How does the thoracic (left lymphatic duct) begin?
- L2
- begins as enlarged region of the lymphatic vessel called the cisterna chyli
Intestinal trunk + right lumbar trunk + left lumbar trunk equals what?
Cisterna chyli
Is the left or right lymphatic duct shorter?
Right
Where does the thoracic duct and right lymphatic duct drain into the left and right subclavian veins?
At their junctures with the internal jugular veins
What drains into the left and right subclavian veins
Thoracic duct and right lymphatic duct
Right lymphatic duct receives lymph from where?
- upper right side of the body
- upper right limb
- right region of the chest
- right region of the head
- right region of the neck
Thoracic duct receives lymph from what?
- left side of head
- left side of neck
- left side of chest
- the left upper limb
- the entire body inferior to the ribs
What is the flow of lymph from tissue spaces maintained by?
- contraction of skeletal muscle
- One way valves
- Respiratory pump (for abdominal region)
What is the primary lymphatic/lymphoid structures?
The body of the red bone marrow and the thymus gland
Why are red bone marrow and thymus gland termed primary lymphatic structures
Because they produce T cells, B cells, and natural killer cells which are lymphocytes that carry out immune responses
Major secondary lymphatic structures
Lymph nodes, spleen, plus the lymphatic nodules
Most responses occur in _________________
Secondary lymphatic structures
What are the lymphocytes?
- T cells
- B cells
- natural killer cells
T cells
Lymphocytes (agranulocytes) that attack fungi, transplanted cells, and cancer cells
B cells
Lymphocyte (agrnanular) that destroy bacteria
Natural killer cells
Lymphocytes (agranulocytes) that attack certain spontaneously arising tumor cells
2 lobed gland lying between the sternum and base of the heart in the superior and a bit of the anterior Mediastinum
Thymus
When does the thymus reach maximum size of 40 grams (and peak of function)
At 10-12 yo
Atrophy of the thymus at 65 yo
About 6 grams
Why is it easier for kids to fight infection and not elderly?
Thymus is at its peak in size and function at 10-12 yo, and atrophies as you age, also reducing function
Afferent
Bringing something to a structure (arriving)
Efferent
Exiting, away from a structure
Thymus and spleen filtering
There is NO filtering of lymph here
Why do the thymus and spleen not filter lymph?
There are no afferent lymphatic vessels leading to these structures
What is each lobe of the thymus surrounded by?
Capsule of dense fibrous connective tissue
What do the inward extensions from the capsule do? (Septa, trabeculae)
Divide the lobes into smaller lobules
Function of thymus
Promote the maturation of T lymphocytes/T cells
T cells formation and maturation
Formed in the red bone marrow, matured in the thymus
What does each lobe of the thymus consist of?
Outer cortex, and a central medulla
Migration of T cells in the thymus
T cells from red bone marrow to the thymus cortex where they multiply and mature. T cells migrate into the thymus medulla where they leave the thymus by medullary blood vessels
What hormone does the thymus secrete?
Thymosin
Produced in medulla
What does thymosin do?
Assist in promoting the proliferation and maturation of T cells
The splenic blood vessels and lymphatic vessels pass through the ____ of the spleen
Hilum
What is the spleen surrounded by?
Capsule of dense fibrous connective tissue that gives inward extensions called trabeculae
What are the two areas of the spleen?
- White pulp
2. Red pulp
White pulp of spleen
Mostly B cells arranged around central arteries
Red pulp of spleen
Consist of venous sinuses filled with blood and splenic/billroths cords tha lie between the sinuses
Function of the white pulp in spleen
B cell proliferation into plasma cells, form antibodies
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 a reservoir for blood platelets
Where are lymph nodes located?
Along the length of the lymphatic vessels and embedded in connective tissue
Where are the lymph nodes heavily concentrated?
In the inguinal, axillary, and mammary gland areas
What are lymph nodes surrounded by?
Capsule of dense fibrous connective tissue
Inward projections of the capsule of the lymph node
Trabeculae that divides the node into compartments, provids the framework support, and convey blood vessels into the interior of a node
Specialized regions of lymph nodes
Cortex and medulla
Outer region of lymph node that is densely packed with T cells and immature B cells?
Cortex
The inner region of mature B cells
Medulla
Masses of actively proliferating lymphocytes in lymph nodes
Germinal centers
Thin inward extension, from the cortex toward the hilum of the T cells, B cells, and macrophages of lymph nodes
Medullary cords
______________ carry lymph from tissues to the lymph node; the vessels enter the convex side of the node. Contain valves that open toward the node so lymph is directed inward
Afferent lymphatic vessels
Carry lymph from the hilum (concave side of a node) to venous circulation. Contain valves that open away from the node to convey lymph out of the node
Efferent lymphatic vessels
Why is there a lot more afferent than efferent?
It takes a long time to get fluid out, more efficient cleaning of lymph
Lymph enters the lymph node via ________ lymphatic vessels?
Afferent
Lymph flows through lymph node in a _______________
Network of sinuses
Flow of lymph through the sinuses in the lymph node
Subcapsular sinus —-cortex via cortical sinuses—–through medulla via medullary cords—–into hilum—exit via efferent lymphatic vessels
What is the only lymphatic tissue that filters lymph?
Lymph nodes
How does the lymph get filtered before it passes through to the blood stream?
Macrophages destroy foreign substances by phagocytosis while other lymphocytes destroy foreign substances via immune responses
What else other than lymph leave the lymph node and circulate to other parts of the body?
Plasma cells and T cells that have proliferated within a lymph node
What is the only lymphatic tissue that is not surrounded by a capsule
Lymphatic nodules
Clusters of lymphocytes that stand guard in all mucous membranes that protect against bacteria and other pathogens that may enter the GI, respiratory, reproductive, and urinary tract
Lymphatic nodules
What are lymphatic nodules referred to as?
Mucosa associated lymphoid tissue (MALT)
What is an example of lymphatic nodules
Peyers pathches in the ileum of small intestine
Tonsils
Appendix
Where are peyers patches located within the ileum of the small intestine?
Mucosa lining
What do Peyers patches contain
Macrophages that capture and destroy bacteria thereby preventing microbes from breaching the intestinal wall
Tonsils create a ring of lymph tissue around the entrance of the ___________
Pharynx
Function of tonsils
Gather and remove many pathogens entering the pharynx
Types of tonsils
- 1 pharyngeal tonsil/adenoid
- 2 palatine tonsils
- 2 lingual tonsils
Where is the pharyngeal tonsil/adenoid located?
Embedded in the posterior wall of the nasopharynx
Where are the two tonsils located
Lie at the posterior region of the oral cavity
Where are the two lingual tonsils located
Located at the base of the tongue
The _______ contains large groupings of lymphatic nodules located in the lamina proprietary of mucosa and a bit in the submucosa
Appendix
