Lymphatic Flashcards
What are the major components that make up the lymphatic system?
Lymphatic vessels
Lymphatic nodes
lymph
Bone marrow
Thymus
What is lymph?
Interstitial fluid that enters the lymphatic vessels is called lymph
What do lymphatic nodes do?
Cleanse lymph
What part do lymphatic organs and tissues play in the lymphatic system?
They provide the structural basis of the immune system by housing phagocytic cells and lymphocytes
Why are lymphatic capillaries more permeable than cardiovascular capillaries?
-one way mini-valves formed by endothelial cells overlapping
- mini-valves are anchored to matrix by collagen filaments
increase in ECF opens valves more, decrease in ECF closes them
What relationship do lacteals have to lymphatic capillaries?
Lacteals are lymph capillaries located in intestinal mucosa. They absorb and digest fat and deliver lymph to blood.
What is chyle and how does it relate to lacteals?
Chyle is fatty lymph delivered to the blood by the lymph capillaries called lacteals
Can you give a brief overview of lymphatic vessel structure
- have Tunics similar to veins except they have thin walls and more valves
- anastomose more frequently
- these vessels have trunks and ducts
as well as collecting vessels
What are collecting vessels and what is their relationship to capillaries?
Collecting vessels are large lymphatic vessels that capillaries drain into. Collecting vessels can be found traveling with veins superficially and deep with arteries.
How do collecting vessels relate to lymphatic trunks?
They are both lymphatic vessels. The union of collecting vessels form lymphatic trunks
What do lymphatic trunks do?
They drain large areas of the body
How do we choose the names for lymphatic trunks?
They are named for the regions of the body they drain
Are you able to name the lymphatic trunks?
Make sure you note paired or single
Hint: there are five
Paired lumbar
Paired bronchomediastinal
Paired subclavian
Paired jugular
Single intestinal trunks
Where does lymph go after leaving the lymphatic trunks?
The lymph drains into one of the two lymphatic ducts
How many lymphatic ducts are there? Can you name them?
There are two lymphatic ducts and their named right lymphatic duct and thoracic duct
What body parts do the right lymphatic duct and thoracic drain?
R drains R upper arm and R side of the head and thorax
T spine drains the rest of the body
Left side of body, thorax and abdomen
What does the right lymphatic duct and thoracic duct have in common?
They both empty lymph into venous circulation at the junction of the internal jugular and subclavian veins
What is the relationship between the thoracic duct and cisterna chyli?
The thoracic duct starts out as an enlarged sac called cisterna chyli in half of individuals.
Now that you know the pathway of lymph, can you describe the system by which it is transported?
-low pressure system
- propelled by milking action of skeletal muscle, valves, pulsations of nearby arteries, contractions of smooth muscle and pressure changes in thorax during breathing
- increased activity will increase the flow of lymph but if you are immobile it gives your body a change to keep material needed for healing
How many calls do lymphoid cells have?
Lymphoid cells have 1 immune system cell found in lymphoid tissue. It also has 2 supporting cells that form lymphoid tissue structures.
Lymphoid cells
Can you name the immune system cells? ( Do not include supporting cell)
Lymphocytes
Macrophages
Dendritic cells
Lymphocytes mature into one of two cells. Can you name those two cells?
T cells and B cells
What do both T and B cells protect against?
Antigens (anything perceived as foreign)
What are the assigned duties for T and B cells
T cells manage immune response
B cells are responsible for producing plasma cells
What do plasma cells (produced by B cell) secrete?
Antibodies
What is the job assigned to macrophages?
Phagocytize foreign substances and help active T cells
What is the job assigned to dendritic cells?
Capture antigens and deliver them to lymph nodes; also helps activate T cells
What is the supporting lymphoid cell called?
Reticular cell
What is the job assigned to reticular cells?
They are responsible for producing stroma in lymphoid organs
Stroma is network-like support that acts as scaffolding for immune cells
What does proliferation mean?
Rapid increase in numbers
What are the main functions of lymphoid tissue?
- houses lymphocytes and provide proliferation sites
- a good surveillance point for lymphocytes and macrophages (immune cells)
What does reticular connective tissue house? And what type of tissue is it?
It makes up most lymphatic tissue. This tissue is loose connective. It offers a place for lymphocytes to chill at. Macrophages like to live on the fibers found here.
What are the two main types of lymphoid tissues?
Diffuse lymphoid tissue
Lymphoid follicles (nodules)
What are the two functional categories lymphoid organs are grouped in?
Primary lymphoid organs and secondary lymphoid organs
Diffuse lymphoid tissue
Loose arrangement of lymphoid cells and some reticular fibers
Found in every organ
Larger collection in lamina propria of mucous membranes
Lymphoid follicles (nodules)
Solid, spherical bodies with tightly packed cells and reticular fibers
Contain germinal centers of proliferating B cells
Peyers patches in appendix (isolated lymphatic nodule)
Primary lymphoid organ
Areas where T and B cells mature -red bone marrow and thymus
Where do T and B cells mature?
Both originate from bone marrow but only B cells mature there. T cells mature in thymus
Secondary lymphoid organ
Areas where mature lymphocytes first encounter their antigen and become activated
Can you give examples of secondary organs
Nodes, spleen, MALT ( mucosa-associated lymphoid tissue) and diffuse lymphoid tissue
What are the two main functions of lymph nodes?
Cleanse lymph and immune system activation-
-offer a place for lymphocytes to become activated and mount attack on antigens
-macrophages destroy debris and microorganisms in lymph
Lymph node structure
Surrounded by external fibrous capsule
The capsule fibers extend inwards as trabeculae
Trabeculae
Capsule fibers that extend inwards that divide nodes into compartments
Cortex
Superficial vs deep
Superficial - follicles with germinal centers heavy with dividing B cells
Deep- houses T cells in transit
Dendritic cells are closely associated with both B and T cells. They play a role in activating lymphocytes.
Medulla
Medullary cords contain B, T and plasma cells
Lymph sinuses
Found throughout the node
Large lymphatic capillaries criss crossed with reticular fibers
Macrophages reside on fibers
What is the circulation of lymph through nodes?
Enters through afferent vessels at the convex surface> travels through subscapular sinus> medullary sinuses> exits at the concave surface where hilumis located via efferent
Where is the spleen located?
Just below the stomach in the left side of the abdominal cavity
Spleen
Largest lymphoid organ
Encased by fibrous capsule and has trabeculae
Splenic artery and vein enter and exit at hilum
What are the functions of the spleen?
Site of lymphocyte proliferation and immune surveillance and response
Cleanses blood of aged cells and platelets; macrophages remove debris
Stores break down products of RBC’s for later use
Stores blood platelets and monocytes for release info blood when needed
Maybe the site of fetal erythrocyte production
Histologically what are the two components of the spleen?
White pulp and red pulp
White pulp
Site where immune function occurs
-contains mostly lymphocytes on reticular fibers
- found around central arteries
Surrounded by red pulp
Red pulp
Site where old blood cells and Bloodborne pathogens are destroyed
-rich in RBC’s and macrophages that engulf them
- composed of splenic cords (reticular tissue) that separates blood filled splenic sinusoids
Splenic cords
Reticular tissue that separates blood filled splenic sinusoids
Where is MALT found?
Mucosa associated lymphoid tissue
Respiratory track, genitourinary organs, digestive track
*Tonsils
*Peters patches
*Appendix
What is the functions of tonsils?
Gather and remove pathogens in for or air
At the posterior end of the oral cavity
Palatine tonsil
Lumpy collection of follicles at base of tongue
Lingual tonsils
Also called adenoids, located posterior wall of nasopharynx
Pharyngeal tonsil
Surround openings of auditory tubes into pharynx
Tubal tonsils
Histology of tonsil
Are not fully encapsulated
Contain follicles with germinal centers and scattered lymphocytes
Overlying epithelium invaginates forming tonsillar crypts
Tonsillar crypts
Trap and destroy bacteria
Allows immune cells to activate and build memory cells against pathogens
