Lesson 11 Flashcards
immune system is not an organ system but
a cell population that inhabits all organs
what is the function of the immune system
defends the body from agents of disease
the lymphoid system
immune cells concentrated in true organs system
what is the lymphoid system
network of organs and vein-like vessels that recover fluid
what are the functions of the lymphoid system? (3)
- inspect it for disease agents
- activate immune responses
- return fluid to the bloodstream
lymphatic system
lymphatic vessels that penetrate nearly every tissue and a collection of lymphoid tissues and organs that produce immune cells
fluid recovery in the lymphatic system
fluid continually filters from the blood capillaries into the tissue spaces
blood capillaries reabsorb ____ of fluid
85%
where does the rest of the fluid recovered go? how much is it?
- lymphatic vessels
- 15%
lymphedema
swelling due to interference in lymphatic drainage
immune surveillance in the lymphatic system
excess filtered fluid picks up foreign cells and chemical from the tissues pass through lymph nodes
what happens in the lymph nodes
immune cells stand guard against foreign matter
what happens when foreign materials pass through lymph nodes?
activates a protective immune response
lipid absorption in the lymphatic system
lacteals in small intestine absorb dietary lipids that are not absorbed by the blood capillaries
components of the lymphoid system?
- lymph
- lymphatic vessels
- lymphoid tissue
- lymphoid organs
lymphatic vessels
transport lymph
lymphoid tissues
aggregates of lymphocytes and macrophages that populate many organs of the body
lymphoid organs
- organs where lymphoid cells are concentrated
- surrounded by connective tissue capsules
lymph
- clear colorless fluid similar to plasma but low in protein
- recovered fluid
lymph originates as ___ and is then taken up by lymphatic vessels
tissue fluid
does chemical composition vary in different places in the body?
yes
lymph collected from the intestine
look milky
why does intestinal lymph look milky
high lipid content
when is lymph collected
after lymph nodes have high amounts of lymphocytes
lymphatic capillaries
microscopic vessels that penetrate nearly every tissue of the body
lymphatic vessels are absent in
cartilage, cornea, bone, and bone marrow
lymphatic capillary wall
endothelial cells overlapping each other like roof shingles
lymphatic capillaries are ___ at one end
closed
anchoring filaments
anchor the cells of lymphatic vessels to surrounding tissue
intercellular clefts
gaps between cells that are large enough to allow bacteria and cells to enter lymphatic capillary
endothelial cells in lymphatic capillaries create what?
valve-like flaps that open and close with interstitial fluid pressure
when are the flaps in lymphatic capillaries open?
when interstitial fluid pressure is high
when are flaps in lymphatic capillaries closed?
when interstitial fluid pressure is low
as tissues swell with fluid it causes what to occur?
the overlapping edges of the endothelial cells to pry apart and drain the fluid into the lymphatic capillary
what are the three layers of larger lymphatic vessels?
- tunica interna
- tunica media
- tunica externa
lymphatic capillaries merge to form
collecting vessels
collecting vessels converge to form
lymphatic trunks
lymphatic trunks do what?
drain a major portion of the body of lymph
what are the two collecting ducts
- right lymphatic duct
- thoracic duct
right lymphatic duct receives lymph from
- right arm
- right side of head and thorax
where does the right thoracic duct empty into
right subclavian vein
thoracic duct receives lymph from
- below diaphragm
- left arm
- left side of head, neck, and thorax
which lymphatic duct is longer and larger?
thoracic duct
thoracic duct begins as
sac in abdomen
what is the sac that starts the thoracic duct called?
cisterna chyli
where does the thoracic duct empty
left subclavian vein
path from the tissue fluid back to bloodstream (8)
- lymphatic capillaries
- collecting vessels
- 11 lymphatic trunks
- two collecting ducts
- subclavian veins
- brachiocephalic veins
- superior vena cava
- right atrium
characteristics of lymph flow compared to venous return
- forces similar to venous return but no pump
- flows at low pressure and slower speed than venous blood
what stims the contraction of lymph vessels
stretching of vessels
what moves lymph along in lymph vessels (5)
- rhythmic contractions of lymph vessels
- squeezing of skeletal muscles
- rhythmic pulsations of nearby arteries
- thoracic pump
- rapidly flowing blood in subclavian vein drawing lymph to it
cells associated with the lymphoid system
- neutrophils
- natural killer cells
- T cells
- B cells
- macrophages
- dendritic cells
neutrophils
antibacterial
natural killer cells
- NK
- lymphocytes that attack and destroy infected host cells and cancerous cells
T cells
- T lymphocytes
- mature in thymus
B cells
- B lymphocytes
- activation causes proliferation and differentiation into plasma cells and produce antibodies
macrophages aka
antigen-presenting cells
macrophages
- large phagocytic cells
- display antigens on surface to alert other immune cells
dendritic cells
antigen-presenting cells found in skin, mucous membranes, and lymphoid organs
lymphoid tissue
aggregations of lymphocytes in the connective tissues of mucous membranes and various organs
diffuse lymphoid tissue
- lymphocytes are scattered
- not densely clustered
where is diffuse lymphoid tissue most prevalent
body passages open to the exterior (respiratory, digestive, urinary, and reproductive)
when in mucous membranes diffuse lymphoid tissues are called
mucosa-associated lymphoid tissue (MALT)
lymphoid nodules (follicles)
- lymphocytes and macrophages gather in dense masses
- may be temporary or permanent
aggregated lymphoid nodules
- Peyer patches
- large clusters of nodules in small intestine
lymphatic organs have connective tissue capsule that does what?
separates lymphatic tissue from neighboring tissues
primary lymphoid organs include
red bone marrow and thymus
why are red bone marrow and thymus primary lymphoid organs
sits where T and B cells are immunocompetent
immunocompetent
able to recognize and respond to antigens
secondary lymphoid organs include
tonsils, lymph nodes, and spleen
why are lymph nodes, spleen, and tonsils secondary lymphoid organs
locations where immunocompetent cells migrate and populate
red bone marrow
soft, loosely organized, highly vascular material separated from osseous tissue by endosteum of bone
red bone marrow involved in
hematopoiesis and immunity
what happens in blood-forming cells
secrete colony stim factors that stim stem cells to produce the formed elements
blood forming cells attached to ____ and _____
- reticular cells
- other elements of marrow stroma
as blood cells mature what do they do?
push their way through the reticular and endothelial cells to enter sinus and flow away in bloodstream
thymus
bilobed organ located in the superior mediastinum between sternum and aortic arch
thymus is apart of which organ systems?
- endocrine
- lymphoid
- immune
the thymus houses ____ and secretes ____
- developing T cells
- hormones regulating the activity of T cells
with age the thymus exhibits large degree of
involution
involution
degeneration or shrinkage
by age 65 what happens to the thymus
unable to make new T cells
what is it called when thymus can’t make T cells anymore
immunosenescence
immunosenescence does what to older people
leaves older people vulnerable to infections and cancer
fibrous capsule gives off ___ that divides gland into nodes
trabeculae
lobes of the thymus have ___ and ___ populated by T cells
cortex and medulla
thymic epithelial cells are involved in
T cell development
what do thymic epithelial cells secrete? (5)
signaling molecules thymosin, thymopoietin, thymulin, interleukins, and interferons
cortical epithelial cells
along with pericytes surround capillaries to form blood thymus barrier
lymph nodes
bean-shaped structures that cleanse lymph and are sites of lymphocyte activation
what is the most numerous lymph organ?
lymph nodes
how many lymph nodes are in a typical young adult?
450
lymph nodes are enclosed with
fibrous capsule with trabeculae that divide interior into compartments
parenchyma of lymph node divided into ___ and ___
cortex and medulla
germinal centers in cortex
where B cells multiply and differentiate into plasma cells
several afferent vessels lead into node along
convex surface
lymph leaves node though ___
efferent lymphatic vessels
how many efferent lymph vessels are there usually
1-3
where do efferent lymph vessels leave from
hilum
what are all locations where lymph nodes are concentrated? (7)
- cervical
- axillary
- thoracic
- abdominal
- intestinal and mesenteric
- inguinal
- popliteal
where are the thoracic lymph nodes mostly located in the thoracic cavity?
mediastinum
where are abdominal lymph nodes located?
posterior abdominopelvic wall
where are intestinal and mesenteric lymph nodes located
mesenteries and near appendix and intestines
lymphadenitis
swollen, painful lymph node responding to foreign antigen
lymphadenopathy
collective term for all lymph node diseases
metastasis
cancerous cells break free from original primary tumor travel to other sites in the body and establish new tumors
metastasizing cells ____ enter lymphatic cells
easily
what tends to happen when cancer metastisizes in lymph node?
lodge in the first one they encounter, multiply there, and eventually destroy node
cancerous nodes are
swollen, firm, and painless
treatments of breast cancer
lumpectomy, mastectomy, removal of nearby axillary nodes
tonsils
patches of lymphoid tissue located at entrance to the pharynx
what do tonsils do?
guard against ingested or inhaled pathogens
tonsils are covered with ___ and have ____
- epithelium
- deep pits
tonsillar crypts
deep pits in tonsils covered by lymphoid nodules
tonsils have ___ fibrous capsule
incomplete
tonsilitis
acute inflammation of palatine tonsils
what is the largest lymph organ
spleen
location of the spleen
inferior to diaphragm and posterolateral to stomach
what two tissue types does parenchyma of liver exhibit
- red pulp
- white pulp
red pulp
sinuses filled with erythrocytes
white pulp
lymphocytes, macrophages surrounding small branches of splenic artery
what is the function of the spleen?
- erythrocyte graveyard
- blood cell production in fetus
- maintains army of monocytes for release when needed
- stabilize blood volume through plasma transfer to lymph system
spleen is
highly vascular and vulnerable to trauma and infection
w rupture spleen requires a
splenectomy
what happens when someone gets a splenectomy
leaves person susceptible to future infections and premature death
what maintains army of monocytes for release when needed
lymphocytes, macrophages of white pulp monitoring blood for foreign antigens
