objective 2 pt 1 Flashcards
returns fluids leaked from BV back to blood; defends against invading organisms and disease
lymphatic system
what does the lymphatic system consist of?
lymphatic vessels
lymph
lymph nodes
provide structural basis of immune system by housing phagocytic cells and lymphocytes
lymphoid organs and tissues
returns interstitial fluid and leaked plasma proteins back to blood via lymphatic vessels
lymphatic system
circulates ~3L interstitial fluid per day
lymphatic vessels
what do lymphatic vessels offer?
one-way system, ensuring lymph flows only toward heart
Blind-ended vessels (a sealed end) that weave between tissue cells and
blood capillaries
Absent from bones, teeth, bone marrow, and restricted to limited locations in
the meninges of the CNS
Similar to blood capillaries, but exceptionally permeable
Can take up larger molecules and particles that blood capillaries cannot
lymphatic capillaries
lymphatic capillaries have increased permeability due to two specialized structures which are?
one-way mini-valves
mini-valves are anchored by collagen, allows mini-valves to open easily
specialized lymph capillaries present in intestinal mucosa
absorb digested fat and deliver fatty lymph to the blood
lacteals
lymph capillaries drain into increasingly larger vessels
collecting lymphatic vessels
Consist of collecting vessels, trunks, and ducts
Have structures and tunics similar to veins, except:
Have thinner walls, with more internal valves
Link together more frequently
Collecting vessels in skin travel with superficial veins, but deep vessels of the
trunk travel with arteries
larger lymphatic vessels
formed by union of largest collecting vessels, drain large areas of body
lymphatic trunks
what are the two large lymphatic ducts that lymph is delivered into?
right lymphatic duct
thoracic duct
drains right upper arm and right side of upper body
right lymphatic duct
drains rest of the body
thoracic duct
empty lymph into venous circulation at junction of internal jugular and
subclavian veins in the neck to superior vena cava then right atrium of heart to
enter systemic circulation
ducts
a low-pressure system like venous system; slow flow
lymph system
what is the flow of lymphatic fluid maintained by?
skeletal muscle contraction
Pressure changes in thorax during breathing
Contractions of lymphatic vessels
Valves prevent back flow
what do lymph cells consist of?
immune system cells
supporting cells
mature into one of two main types for adaptive immunity
lymphocytes
what are the main functions of lymphoid tissue?
houses and provides production sites for lymphocytes
offers surveillance for lymphocytes and macrophages as they filter lymph
largely composed of reticular connective tissue
macrophages live here
lymphoid tissue
grouped into two functional categories
lymphoid organs
what are the 2 groups of lymphoid organs?
primary lymphoid organs
secondary lymphoid organs
T and B cells originate in bone marrow, but only B cells mature there; T cells mature in thymus
primary lymphoid organs
areas where mature lymphocytes first encounter their antigen and become activated
secondary lymphoid organs
most important secondary lymphoid organs of body
lymph nodes
what are the two main types of lymph nodes?
cleansing the lymph
activate the immune system
macrophages remove and destroy microorganisms and debris
prevent unwanted substances from being delivered to blood
cleansing the lymph
after a place for lymphocytes to become activated and amount an attack against antigens
activate the immune system
vary in shape and size but most are bean shaped
surrounded by external fibrous capsule from which connective tissues strands call trabeculae extend inward to divide node into compartments
lymph node
what are the 2 distinct regions of a node?
cortex
medulla
contains mostly inactivated B cells
T cells are housed in transit
abundant numbers of dendritic cells are found here
cortex
consists of medullary cords
contains both B and T lymphocytes
medulla
where does the lymph enter the nodes
via afferent lymphatic vessels
where does the lymph exit?
via efferent lymphatic vessels
blood-rich organ about size of fist, located in left side of abdominal cavity, just
below stomach
* Largest lymphoid organ (blood reservoir)
* Served by splenic artery and vein, which enter and exit at the hilum
spleen
what are the functions of the spleen
Site of lymphocyte production and immune function
Destroys aged & defective red blood cells and bloodborne pathogens; macrophages
remove debris
Recycles breakdown products of hemoglobin (e.g., iron) for later reuse
2. Stores blood platelets and monocytes for release into blood when
needed
3. May be site of fetal erythrocyte production
what are the two components that the spleen is encased by?
white pulp
red pulp
site where immune function occurs
white pulp
site where old blood cells and blood-borne pathogens are destroyed
red pulp
Protects pathogens in certain areas from penetrating the mucous membrane lining
* Found in mucosa of respiratory tract, genitourinary organs, and digestive tract;
* largest collections of MALT found in
mucosa-associated lymphoid tissue (MALT)
simplest lymphoid organs; function to gather and remove pathogens in food or air
tonsils
destroy bacteria, preventing them from breaching intestinal wall; generates memory lymphocytes
Peyer’s patches/aggregated lymphoid nodules
located off large intestine; contains lymphoid follicles; functions are same Peyer’s patches; prevents bacteria from breaching the intestinal wall, also has “memory”
appendix
at posterior end or oral cavity
largest of tonsils and most often infected
palatine tonsils
lumoy collection of follicles at base of tongue
lingual tonsil
located in posterior wall of nasopharynx; effect voice
pharyngeal tonsil
surround openings of auditory tubes into pharynx
tubal tonsils
bilobed, found in inferior neck
Extends into mediastinum and partially overlies heart
T cells mature & become immunocompetent
Most active and largest in size during childhood
Stops growing during adolescence, then gradually atrophies
Still produces immunocompetent cells, though more slowly
thymus
what are the ways that the thymus differs from other lymphoid organs?
Lacks B cells (no follicles)
2. Does not directly fight antigens
A. Functions strictly in T lymphocyte maturation site
B. Contains blood thymus barrier: keeps immature T lymphocytes
isolated from any antigens to prevent premature activation
3. Stroma of Thymus consists of epithelial cells rather than
reticular fibers.
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