Lymphatic System A&P 2
Which of the following is a role of lymph nodes?
-Cleansing the lymph: act as lymph "filters"(have a capsule and medullary chords and sinuses that serve to filter lymph fluid) :Macrophages remove and destroy microorganisms and debris that enter lymph ; Prevent unwanted substances from being delivered to blood and spreading -Immune system activation: offer a place for lymphocytes to encounter antigens and become activated to mount an attack against them Lymph nodes are rich with macrophages, B cells, and T
What is the function of lymphoid tissue?
-Houses and provides a proliferation site for lymphocytes -Furnishes a surveillance vantage point
what is the purpose of peyer's patches AND the appendix?
-To prevent intestinal bacteria from breaching intestinal wall -Generate "memory" lymphocytes for long-term immunity
What are the two types of lymphoid tissues?
-diffuse lymphoid tissue (Found in virtually every body organ with larger collections in lamina propria of mucous membranes) -lymphoid follicles/nodules (Contain germinal centers of proliferating B cells May form part of larger lymphoid organs (Ex: nodes) Isolated aggregations occur in intestinal wall as Peyer's patches and in appendix)
Thymus
-site of T cell maturation and is larger in children and adolescents. -Still produces immunocompetent cells, though more slowly -Cortex contains rapidly dividing lymphocytes (most of thymic cells) and scattered macrophages -Medulla contains fewer lymphocytes plus thymic corpuscles that create regulatory t cells; Type of T cell that helps to prevent autoimmune responses different from other organs b/c.. -Has no follicles because it lacks B cells -Does not directly fight antigens; instead it contains a blood thymus barrier (preventing premature maturation) -Stroma is made up of epithelial cells, not reticular fibers to promote immunocompetence)
Which of the following lymphoid organs is NOT matched with its function?
A. bone marrow: form lymphocytes B. thymus: site of T cell maturation C. Peyer's patches: site of B cell maturation D. spleen: remove old red blood cells C-B cells mature in primary lymphocytes, and Peyer's patches are in the small intestines. (MALT)
Which of the following mechanisms is NOT used to propel lymph through lymphatic vessels?
A. the milking action of muscles B. pulmonary motion C. small, heart-like pumps D. gravity C small, heart like pumps...There is no direct pumping action in the lymphatic system. Movement of fluid depends on factors such as gravity and body movement.
Which lymphoid cells produce antibodies?
Activated B cells, called plasma cells, are responsible for producing antibodies.
your patient has had her spleen removed after it was ruptured in a motorcycle accident. Which of the following is your greatest concern for her future health status?
After splenectomy, your patient has a markedly increased risk of overwhelming bacterial infection. You will help to minimize the risk by educating her and by insuring that she receives specific immunizations recommended for patients after splenectomy.
The spleen is a unique lymphoid organ that filters blood, rather than lymph. Following splenectomy (surgical removal of the spleen) in an adult, which of the following splenic functions would be performed by the bone marrow or liver?
Although the spleen is the main site of red removal from the blood of old and damaged red blood cells, macrophages in the bone marrow and liver are able to perform this function.
Where do B and T lymphocytes mature?
B - bone marrow and T - thymus
Macrophages
Found within the lymph nodes, they are phagocytes that destroy bacteria, cancer cells, and other foreign matter in the lymphatic stream.
Once collected, lymph is ultimately transported into __________.
From the terminal lymphatic ducts, lymph rejoins venous circulation via the subclavian veins.
Where do nutrients come from for large vessels?
Like blood vessels, larger lymphatics receive their nutrients from branching vasa vasorum
Chyle
Liquefied fat that is carried by lacteals from the small intestine to the blood stream.
Which statement correctly describes the origin of lymph fluid?
Lymph is excess tissue fluid formed from plasma that has leaked from capillaries - As blood circulates through the body, nutrients, wastes, and gases are exchanged between the blood and the interstitial fluid. The hydrostatic and colloid osmotic pressures operating at capillary beds force fluid (plasma) out of the blood at the arterial ends of the beds and cause most of it to be reabsorbed at the venous ends. The fluid that remains behind in the tissue spaces, as much as 3 L daily, becomes part of the interstitial fluid. The lymphatic vessels collect this excess interstitial fluid (now called lymph) and return it to the bloodstream.
Collections of lymphoid tissues, called MALT, are strategically placed throughout the respiratory, digestive, and genitourinary systems. Which one of these is located at the end of the small intestine?
Peyer's patches-they guard against bacteria from the large intestine. (appendix is located at the end of the LARGE intestine)
What is the name of the enlarged sac to which the lumbar trunks and the intestinal trunk return lymph?
The cisterna chyli passes lymph from the entire body below the diaphragm into the thoracic duct for return to the heart.
What region of the lymph node contains follicles filled with dividing B cells?
The lymphoid follicles of the cortex contain germinal centers dominated by B cells, which produce antibodies against antigenic agents.
Where are the three large clusters of superficial lymph nodes?
The neck, inguinal area, and armpits have large clusters of lymph nodes to protect major areas of the body. They are located where collecting lymphatic vessels converge to form trunks.
A patient's deep hand laceration was sutured at your clinic yesterday. When you make a follow-up call today, the patient reports "some red streaks on my forearm." Why are you concerned?
The red streaks suggest lymphangitis, which occurs when the blood vessels that supply inflamed lymphatic vessels (vasa vasorum) become congested with blood. You are concerned that the patient's wound is infected by bacteria.
Which lymphoid organ extracts aged and defective blood cells and platelets from the blood in addition to storing some of the breakdown products for later reuse?
The spleen harbors macrophages that ingest and recycle materials from erythrocytes that have aged or become damaged.
Which part of the spleen is its primary site of immune function?
The white pulp of the spleen contains reticular fibers with suspended lymphocytes. These lymphocytes cleanse blood and are an important part of immunological surveillance and response.
lymphatics
Vessels that collect excess tissue fluid and return it to the blood stream
What is another name for peyers patches?
aggregated lymphoid nodules
What are the secondary lymphoid organs?
areas where mature lymphocytes first encounter their antigen and become activated (lymph nodes, spleen, MALT...diffuse lymphoid tissues)
Where do lymphocytes cycle?
between circulatory vessels, lymphoid tissues, and loose connective tissues of the body
Which of the following are primary lymphoid organs?
bone marrow and thymus
Which areas of the body DO NOT have lymphatic capillaries?
bones, teeth, and bone marrow...and only located in the meninges of the CNS
Where in the lymph node do the T cells first encounter antigens presented by dendritic cells?
deep in the cortex (outer area of lymphnodes)
medullary cords
extend from the cortex and contain B cells, T cells, and plasma cells
Tonsils
form a protective circle of lymphatic tissue around the entrance to the respiratory system (pharynx)to prevent pathogens either ingested or inhaled; contain tonsilar crypts to trap and destroy. *simplest organ each named for location... Palatine-back of the throat (most often infected)(largest) Lingual-tip of tongue Pharyngeal-adenoids (wall of nasopharynx) Tubal-auditory opening
dendritic cells
have many appendages like tree branches, and collect antigens to deliver to lymph nodes for recognition by immune cells (they patrol searching for antigens that produce infections)
Which of the following promotes closure of the minivalves associated with lymph capillaries?
increasing pressure inside the lymph capillary
Which direction do the lymphatic vessels travel?
it is a one-way system, ensuring lymph flows only toward heart
Pathway of circulation for lymph
lymph ENTERS convex side of node via afferent lymphatic vessels -> large subcapsular sinus -> smaller sinuses found throughout cortex and medulla -> medullary sinuses -> EXITS concave side at hilum via efferent lymphatic vessels Presence of fewer efferent vessels causes flow to somewhat stagnate BUT allows lymphocytes and macrophages time to function **Lymph travels through several nodes before completely cleansed**
What is the unique structural modification in lymphatic capillaries that increases their permeability?
minivalves
MALT
mucosa-associated lymphoid tissue Largest collections of MALT found in -Tonsils -Peyer's patches -Appendix •Also found in mucosa of respiratory tract, genitourinary organs, and digestive tract protecting pathogens from entering the body
Stroma
network-like support that acts as scaffolding for immune cells
What are the lymphatic organs?
red bone marrow, thymus, lymph nodes, tonsils, spleen, appendix, peyer's patches, MALT.
Difference between collecting lymphatic vessels and veins?
similar structures and tunics, BUT have thinner walls, with more internal valves and they anastomose more frequently (superficial ones travel with veins, deep travel with arteries)
spleen function
the largest lymphatic organ in the body; serves as a blood reservoir (also platelets and monocytes), disintegrates old red blood cells (releasing them into bloodstream for liver to process), may be the site of fetal erythrocyte production, lymphocyte proliferation, macrophages present for immune surveillance , and can store iron.
If cancer goes through a lymph node...
the lymph node can become a secondary cancer site to metastasizing cancer
There is a decrease in our ability to fight infection as we age. Which lymphoid organ may have a role in this decline?
the relative size of the Thymus as well as its function decreases with age. Thymic atrophy may be one reason the elderly are more susceptible to infection
Lymph from what regions of the body is drained into the right lymphatic duct?
the right lymphatic duct, drains the upper right portion of the body (above the diaphragm), returning lymph to the bloodstream via the right subclavian vein. The other trunk, the thoracic duct, drains the rest of the body into the left subclavian vein
What is a lymphatic trunk?
they are drains formed of large unions of collecting vessels
What makes lymphatic capillaries different from blood capillaries?
they are more permeable and can take up larger particles/debris (downside -Can act as route for pathogens or cancer cells to travel throughout body)
Effects on lymph nodes
they can become overwhelmed by bacteria causing inflammation/swollen glands (lymphadenopathy), tenderness, infection, pus-filled = buboes.
Which of the following areas in a secondary lymphoid organ allows intimate contact between blood and the lymphocytes?
white pulp of the spleen (immune functions) (red pulp is involved in RBC destruction)