CHAPTER 20: LYMPHATIC SYSTEM Flashcards
WHAT IS THE FUNCTION OF THE LYMPHATIC SYSTEM? IS IT 1 WAY OR 2 WAY? WHAT DIRECTION DOES IT GO IN?
- Returns leaked fluid from the blood vessels back into the blood.
- It is a 1 way system ensuring lymph only moves towards the heart
WHAT ARE THE THREE MAJOR/BROAD PARTS OF THE LYMPHATIC SYSTEM?
Lymph: fluid in the lymphatic vessel
lymph node: cleanses the lymph
network of lymphtaic vessels
WHAT ARE LYMPHOID ORGANS AND TISSUES? WHAT IS THEIR FUNCTION?
they are organs of the lymphatic system.
provide a structural basis of immune system by housing phagocytic cells and lymphocytes
WHAT ARE SOME EXAMPLES OF LYMPHOID ORGANS/TISSUES
spleen, thymus, tonsils, lymph nodes, other lymphoid tissues
WHAT ARE LYMPHATIC VESSELS
they are an elaborate netwrok of drainage vessels, they circulate around 3L of fluid per day.
WHAT ARE THE 2 TYPES OF LYMPHATIC VESSELS
1) lymphatic capillaries
2) Larger lymphatic vessels
WHAT ARE LYMPHATIC CAPILLARIES? HOW ARE THEY DIFFERENT TO BLOOD CAPILLARIES?
what they are:They are blind ended (closed at one end) vessels that weave between tissue cells and blood capillaries.
difference: they are more permebale, so they can take in larger molecules and particles that blood capillaries cannot.
- ex. Proteins, cell debris, pathogens, and cancer cells
^^ this means they can act as a route for pathogens and cancer cells :(
WHERE ARE LYMPHATIC CAPILLARIES NOT LOCATED
teeth, bones, bone marrow, central nervous system (circulates CSF using it’s own system)
WHAT IS ANOTHER NAME FOR LARGER LYMPHATIC VESSELS? WHAT ARE THE THREE TYPES OF THEM?
collecting lymphatic vessels
three types include: vessels, trunks, and ducts
COMPARE AND CONTRAST LARGER COLLECTING VESSELS AND BLOOD VESSELS
Compare: have structures and tunics similar to veins
contrast:thinner walls, more internal valves, and asastomose (split apart) more frequently
collecting vessels in skin travel w/ superficial veins
Deeper ones travel w/ deep veins
WHAT ARE THE 2 TYPES OF LYMPHATIC DUCTS? WHERE DO THEY DRAIN THEIR LYMPH FROM? WHERE IS THE LYMPH DRAINED TO?
Right lymphatic duct: drains lymph from the right upper arm and right side of head and thorax
thoracic duct: drains from the rest of the body
both ducts will drain the fluid into venous circulation into the junction of the subclavian and jugular veins (on their respective side)
IS THE LYMPHATIC SYSTEM HIGH OR LOW PRESSURE? HOW IS LYMPH PROPELLED?
HINT: similar to blood
LOW PRESSURE
1) milking action of skeletal muscle
2) pressure changes in thorax while breathing
3) valves to prevent backflow
4) pulsation of nearby arteries
5) contraction of smooth muscle in the walls of lymphatics
WHAT ORDER DOES LYMPH TRAVEL IN?
Lymph flows successively: lymphatic capillaries -> collecting lymphatic vessels -> lymphatic trunks -> lymphatic ducts
HOW DOES EXERCISE PROMOTE FASTER HEALING
it increases the flow of lymph, this causes immobilization of the affected area and keeps neccessary inflammatory material in the area, thus faster healing.
WHAT ARE THE 2 TYPES OF LYMPHOID CELLS? WHAT DO THEY DO?
IMMUNE CELLS
- Lymphocytes:
T-lymphocytes: manage the immune response, some destory and atack infected cells
B-lymphocytes: produce plasma cells which secrete antibodies (mark antigens for destruction by phagocytosis or other means)
macrophages: phagocytize foreign substances and help activate T-cells
SUPPORTING LYMPHOID CELLS: produce fibers in lymphoid organs that makes a network-like support to act as scaffolding for immune cells
WHAT ARE THE MAIN FUNCTIONS OF LYMPHOID TISSUE? WHAT IS IT COMPOSED OF?
- houses and provides proliferation sites for lymphocytes
- gives surveilance vantage points for lymphocytesand macrophages as they filter through lymph
it is largely composed of reticular connective tissue, this is where macrophages live, spaces between reticular tissue offers a place for lymphocytes to occupy when they return from patrolling body (kind of like a safe space)
WHAT ARE THE 2 TYPES OF LYMPHOID TISSUE?
diffuse lymphoid tissue: loose arangement of lymphoid cells and some supporting fibers. (found in every body organ)
Lymphoid follicles (nodules): solid spherical bodies cosisting of lighly packed lymphoid cells and reticular fibers. contains proliferating B cells and may form parts of larger lymphoid organs (nodes)
WHAT ARE THE TWO TYPES OF LYMPHOID ORGANS? WHICH ORGANS ARE INCLUDED IN THEM?
PRIMARY LYMPHOID ORGANS: Is where T and B cells mature. includes red bone marrow and thymus.
- note: both B and T cells are made in the red bone marrow, but B cells mature in bone marrow and T cells mature in the thymus
**SECONDARY LYMPHOID ORGANS **: Areas where mature lymphocytes are first exposed to their antigens and become activated. includes lymph nodes, spleen, MALTS(mucosa-associated lymphoid tissue –> tonsils, peyer’s patches, and appendix)
WHAT ARE LYMPH NODES? FUNCTION?
WHAT: Princible secondary lymphoid organ of the body, hundreds are found throughout the body.
FUNCTION
1) Cleanse the lymph and act as filters. done mainly by macrophages destorying microorganisms and debris. also prevent unwanted substances frome entering blood
2) immune system activation: offer a place for lymphocytes to activate and attack antigens.
WHAT IS THE STRUCTURE OF A LYMPH NODE>?
they vary in shape and size and are smaller than an inch.
- surounded by fibrous capsule
- capsule extends inwards as trabeculae that divides into 2 compartments
**medulla: ** is the deeper compartment, houses T and B cells and antibody secreting plasma cells
cortex: is the moste superficial compartment. contains follicles which centers are heavy with dividng B cells. Deep cortex houses T cells in trasnit
lymph sinuses: are found throughout the node and contain large lymphatic capillaries that are spanned by criss crossing fibers. macrophages live on those fibers and and check for and phagocytize foriegn matter.
HOW DOES LYMPH ENTER AND EXIT A LYMPH NODE
it enters from the convex side via affarent lymphatic vessels, and leaves through the concave side at hilum through the efferent lymphatic vessels
WHAT IS THE SPLEEN? WHAT IS IT’S FUNCTIONS
**WHAT: **it is the largest lymphoid organ and is around the size of a fist. It is served by the splenic artery and vein which enter and exit at the hilum.
FUNCTIONS:
1) site for lymphocyte proliferation and immune surveilance and response
2) cleanses blood of old blood cells and platelets, macrophages remove debris
additional functions include
1) stores breakdown products of RBC’s (iron)
2) stores platelets and monocytes and release them when needed
3) may be site of fetal RBC production
WHAT IS THE STRUCTURE OF THE SPLEEN
encased by fibrous capsule and also has trabeculae.
has 2 components
1) white pulp: site where immune function occurs. contains mostly lymphocytes and supporting fibers. appear as islands of white in a sea of red pulp
2) red pulp:: sitr where old RNC and bloodborne pathogens are destroyed, is rich in RBC’s and macrophages that engulf them
WHAT ARE MALT’S (mucosa-associated lymphoid tissue)? FUNCTION?
what: they are lymphoid tissue in mucous membranes throughout the body. found in mucosa of respiratory tract, digestive tract, genitourinary organs, largets collections of MALT are found in:
1) tonsils
2) peyer’s patches
3) appendix
Function: protet from pathogens trying to enter the body.
WHAT ARE TONSILS? FUNCTION?
WHAT: simplets lymphoid organ. form rings of lymphatic tissue around pharynx and appear as swellings of the mucosa.
FUNCTION:
- gather and remove pathogens in food or air.
- contain follicles with B cells in the center and scattered lymphocytes
- bacteria enters crypts where they are trapped and destroyed, its risky but allows immune system activation.
WHAT IS THE STRCUTURE OF TONSILS?
they are named according to location
1) palatine tonsils: posterior end of oral cavity, are the largest and most commonly infected
2) lingual tonsils: lumpy collection of follicles on base of tounge
3) pharyngeal tonsil: also called adenoids, located in posterior wall of nasopharynx.
they are not fully encapsulatedm overlying epithelium invanginates forming tonsillar crypts.
WHAT ARE PEYER’S PATCHES? FUNCTION? STRUCTURE?
WHAT: clusters of lymphoid follicles od the distal portio of the small intestine
STRUCTURE: similar to tonsils
FUNCTION:
1) destory bacteria, prevent them from breaching intestinal wall
2) generate “memory” lymphocytes
WHAT IS THE APPENDIX? FUNCTION? STRUCTURE?
**WHAT: **it is the offshoot part of the large intestine
STRUCTURE: contains a large number of lymphoid follicles, its location is complementary to it’s function (like Peyer’s patches)
FUNCTION:
1) destroy bacteria, preventing them from breaching intestinal wall
2) generate “memory” lymphocytes
WHAT IS THE THYMUS? FUNCTION? STRCUTURE?
WHAT: is a bilobed organ found in the inferior neck
FUNCTION: functions as a lymphoid organ where T cells mature.
- it is most active and largest in size during childhood
- stops growing during adolescence, then gradually atrophies
- still produces imunocompetent cells, just slower
STRUCTURE: differs from other lymphoid organs, contains no follicles because it lacks B cells.
- does not directly fight antigens, functions to strictly in T cell maturation
