Lymphatic System Flashcards
when does the lymphatic system begin to develop?
by week 5 of embryonic development
How does the lymphatic system arise?
arise as lymph sacs from developing veins
jugular lymph sacs arise to form …
right lymphatic duct and thoracic duct
where do all the lymphatic organs (except thymus) arise from?
the mesoderm
6 lymph sacs from which the lymphatic vessels are derived
jugular (paired
posterior lymph (paired)
retroperitoneal
cisterna chyli
cisterna chyli
abdominal origin of thoracic duct
about T11 or T12
formed by the union of 2 lumbar trunks and the intestinal trunk
all lymphoid organs (except thymus) develop from what cells?
mesodermal mesenchymal cells
poorly developed at birth T/F?
true
function of lymphatic system
fluid balance-returns excess fluid back to the venous system.
immune surveillance in fighting pathogens.
3 parts of the lymphatic system
network of lymphatic vessels
lymph: fluid in vessels
lymph nodes: cleanse lymph
lymphoid organs and tissues provide structural basis of immune system by…
housing phagocytic cells and lymphocytes
structures of the lymphatic system
spleen, thymus, tonsils, lymph nodes, other lymphatic tissues
circulation in lymphatic system
3L of interstitial fluid per day
75% via thoracic duct
25% via right lymphatic duct
what is the largest lymphatic vessel?
the thoracic duct
when does interstitial fluid become lymph
when it has entered the lymphatics (lymphatic capillary)
lymph fluid
proteins, water, lymphocytes, waste products of cell activity, foreign substances like cancer cells, and fats (cholesterol, vit A, D, E)
transport system
fluid comes into lymphatic capillaries and travels through body up through venous system
is the lymphatic system one way or two way?
one way: lymphatic vessles up toward heart
blind ended tubes
closed on one end
lymphatic capillaries
smallest of lymphatic vessels
absorb interstitial fluid
absent in bone, teeth, and bone marrow
larger and more permeable than blood capillaries
can take up larger molecules
has minivalves
lacteals
specialized lymph capillaries present in intestinal mucosa
absorb digested fat and deliver fatty lymph (chyle) to the blood
chyle
fatty lymph
white color bc it is lymph mixed with digestive fats
minivalves
capillary flaps overlap, filaments get stretched as fluid builds up, open flaps, and fluid comes into the capillaries and becomes lymph
collecting lymphatic vessels
larger lymphatic vessels
similar to veins with thinner walls
larger lymphatic vessels
consist of vessels, trunks, and ducts
lymphatic trunks
formed by union of largest collecting vessels
drain large areas of the body
paired lumbar trunks
paired bronchomediastinal
trunks
paired subclavian trunks
paired jugular trunks
single interstitial trunk
fluid movement
capillaries–> collecting vessels–>trunks–> ducts
muscle role in lymphatic flow
pulsation from arteries to deep muscles help move lymph as well
paired lumbar trunks
lymph from the lower extremities, lower body quadrants, external genitalia
paired bronchomediastinal trunks
lymph from the lungs, heart, trachea and mammary glands.
paired subclavian trunks
lymph from the upper extremities, upper body quadrants, shoulder region, mammary glands
paired jugular trunks
lymph from head and neck
single intestinal trunk
lymph from stomach and digestive system, liver and pancreas
right lymphatic duct
25% of lymphatic circulation
drains right upper arm and right side of head and thorax
thoracic duct
largest lymphatic vessel in the body
75% of lymphatic circulation
drains the rest of the body (right and left lower quadrants, left upper quadrant, left head and neck
lymphagitis
condition in which lymphatic vessels appear as painful red lines under the skin; inflammed lymph vessels
can lead to septicemia
lymph transport
low pressure
propelled by milking action of skeletal muscles, pressure changes in the thorax during breathing, valves, pulsation of nearby arteries, contractions of smooth muscle in walls of lymphatics, and physical activity
lymphedema
severe localized edema
abnormal accumulation of protein rich fluid usually in extremities (proteins draw in water=swelling)
progresses if left untreated
treatment=complete decongestive therapy
common causes: parasite, breast cancer surgery/radiation, primary lymphedema (infants)
stage 1 lymphedema
bad towards night, better in the morning (system catches up overnight)
stage 2 lymphedema
doesn’t always go away
stage 3 lymphedema
contours of the leg start to disappear
stage 4 lymphedema
lost contours, some skin changes
immune system cells
lymphocytes (T and B cells), macrophages, and dendritic cells
T lymphocyte cells
manage immune response, and some also attack and destroy infected cells (involved directly in cell-to-cell contact)
mature in the thymus
B lymphocyte cells
produce plasma cells, which secrete antibodies
antibodies mark antigens for destruction by phagocytosis or other means
macrophages
phagocytize foreign substances and help activate T cells
dendritic cells
capture antigens and deliver them to lymph nodes; also help activate T cells
supporting lymphoid cell
reticular cells produce reticular fibers (stroma-scaffolding of immune cells) in lymphoid organs
main functions of lymphoid tissue
houses and provides proliferation sites for lymphocytes
offers surveillance vantage points for lymphocytes and macrophages as they filter through lymph
largely composed of reticular connective tissue (type of loose connective tissue)
macrophages live on what fibers?
reticular fibers
2 main types of lymphoid tissues
diffuse lymphoid tissue and lymphoid follicles (nodules)
diffuse lymphoid tissue
loose arrangement of lymphoid cells and some reticular fibers
in almost every organ
lymphoid follicles (nodules)
solid, spherical bodies consisting of tightly packed lymphoid cells and reticular fibers
contain germinal centers of proliferating B cells
primary lymphoid organs
areas where T and B cells mature—red bone marrow and thymus
–> T and B cells originate in bone marrow, but only B cells matures there; T cells mature in thymus
where the lymphocytes originate
secondary lymphoid organs
areas where mature lymphocytes first encounter their antigen and become activated
nodes, spleen, MALT (mucosa-associated lymphoid tissue) and diffuse lymphoid tissues
MALT
tonsils, Peyer’s Patches, and appendix
lymph nodes
principal secondary lymphoid organs of body (not primary bc B and T cells don’t come from here)
humans have set number at birth
swollen and painful=likely a microorganism
swollen and not painful=likely cancerous
2 main function of lymph nodes
- cleansing the lymph: act as lymph “filters”
–> Macrophages remove and destroy microorganisms and debris that enter lymph
–> Prevent unwanted substances from being delivered to blood
- immune system activation: offer a place for lymphocytes to become activated and mount an attack against antigens
structure of lymph nodes
bean shaped, surrounded by external fibrous capsule (extends inward as trabeculae)
regions of nodes
cortex
medulla
cortex
superficial area of cortex contains follicles with germinal centers that are heavy with dividing B cells
deep cortex houses T cells in transit
medulla
medullary cords extend inward from cortex and contain B cells, T cells, and plasma cells
lymph sinuses are found throughout node
–> consist of large lymphatic capillaries spanned by crisscrossing reticular fibers.
–> macrophages reside on fibers, checking for and phagocytizing any foreign matter.
lymph enters convex side of node via…
afferent lymphatic vessels
circulation in lymph nodes
enters convex side of node via afferent lymphatic vessels, travels through large subscapular sinus into smaller sinuses found throughout cortex and medulla, then enters medullary sinuses, and finally enters concave side at hilum via efferent lymphatic vessel.
centinal node
first node lymph goes through
usually removed in the case of cancer
buboes
inflamed, swollen, tender lymph nodes that result when nodes are overwhelmed by what they are trying to destroy
bubonic plague
painful swollen lymph nodes in groin and armpits; oozing pus and blood; damage to skin and underlying surfaces; dark blotches-acral necrosis
lymphadenopathy
enlargement of superficial lymph nodes; from typical cold.
What is the largest lymphoid organ?
the spleen
functions of the spleen
site of lymphocyte proliferation and immune surveillance and response
cleanses blood of aged blood cells and platelets; macrophages remove debris
site of lymphocyte proliferation
the spleen
additional functions of the spleen
- stores breakdown products of RBCs (e.g., iron) for later reuse
- stores blood platelets and monocytes for release into blood when needed
- may be site of fetal erythrocyte production
white pulp of the spleen
immune system here
most lymphocytes here
mostly lymphocytes on reticular fibers
found around central arteries
red pulp of the spleen
around central arteries
site where old blood cells and bloodborne pathogens are destroyed
rich in RBCs and macrophages
composed of splenic cords separating blood-filled splenic sinusoids
splenectomy
surgical removal of ruptured spleen
What organs take over if the spleen must be removed?
liver and bone marrow
tonsils
simplest lymphoid organ
lymphatic tissue around the pharynx
gather and remove pathogens from food and air
palatine tonsils
posterior oral cavity
most often infected
largest tonsils
lingual tonsils
base of tongue
pharyngeal tonsil
posterior nasopharynx
also called adenoids
tubal tonsils
surround openings of auditory tubes into pharynx
Peyer’s patches
also called aggregated lymphoid nodules
clusters of lymphoid follicles in wall of distal portion of small intestine
peak at age 15-25
destroy bacteria, preventing them from breaching intestinal wall
generate “memory” lymphocytes
appendix
offshoot of the first part of the large intestine
destroy bacteria, preventing them from breaching intestinal wall
generate “memory” lymphocytes
thymus
bilobed lymphoid organ found in inferior neck
where t cells mature
largest during childhood
thymus cortex
rapidly dividing lymphocytes
thymus medulla
regulatory t cells develop in thymic corpuscles
regulatory t cells
help body identify what are antigens and what are good self particles.
thymus differs from other lymphoid organs in what important ways?
- no follicles bc it lacks b cells
- doesn’t directly fight antigens
- stroma is made up of epithelial cells, not reticular fibers
blood thymus barrier
keeps immature T lymphocytes isolated from any antigens to prevent premature activation
prevents particles from getting into the thalamus and premature activation of T cells.
