Test 4 Lymphatic and Imune system Flashcards
lymphatic system
a network of conduits that carry a clear fluid
called lymph…the fluid that has escaped from the blood vessels
lymphatic function
returns lymph back to the bloodstream
main structures of the lymphatic system are?
lymphatic vessels
lymphatic vessels
Which transport fluid and proteins that has escaped from
capillaries back to the heart
-Provide a means by which disease organisms and diseased cells
travel throughout the body
-Carries absorbed fat from the intestine to blood
Main components of the immune system are:
lymphocytes, lymphoid tissue, and lymphoid
organs (spleen, thymus, lymph nodes, tonsils,
and appendix)
immune system function
-Function is to contain and destroy diseased
organisms
Lymphatic vessels
collect lymph from the loose C.T. around blood capillaries. -Carry fluid to great veins in the neck then back to the heart -Fluid flows only toward the heart
Orders of lymphatic vessels
lymph capillaries lymphatic collecting vessels lymph nodes lymph trunks lymph ducts
lymph capillaries
smallest; first
receive lymph
lymphatic collecting vessels
collect
lymph from capillaries; have valves
lymph nodes
: scattered along
collecting vessels
lymph trunks
collect lymph from
collecting vessels
lymph ducts
empty into veins of the
neck
Lymph nodes
bean-shaped organs located along lymphatic collecting
vessels that cleanse the lymph of pathogens
Human body contains approximately how many lymph nodes
500
lymph nodes are organized in?
clusters: cervical, axillary, and
inguinal regions
Lymph nodes surrounded by
a fibrous capsule of dense C.T., from which fibrous
strands called trabeculae extend inward to divide the node into
compartments.
flow of lymph
Afferent lymphatic vessels → lymph
sinuses → efferent lymphatic vessels
the lymph sinuses are spanned by a network of
f reticular fibers covered by
endothelial cells, which house many
macrophages that consume pathogens
and foreign particles in the lymph
Lymphatic collecting vessels
converge to form
larger lymph trunks
five major lymph trunks (inferior to superior)
lumbar trunks intestinal trunk bronchomediastinal trunk subclavian trunks jugular trunks
lumbar trunks
receives lymph
from lower limbs, pelvic organs, and
ant. abdominal wall (paired)
intestinal trunk
receives chyle from digestive organs (unpaired)
bronchomediastinal trunks
ascends
near trachea; collects lymph from
thoracic viscera (paired)
subclavian trunks
receive lymph
from upper limbs and superior thoracic
wall; near base of neck (paired)
jugular trunks
drain lymph from
the head and neck (paired)
lymphatic trunks drain into
lymphatic ducts that lead to neck
veins
thoracic duct
Ascends along vertebral bodies and empties into venous circulation at the junction of left internal jugular and left subclavian veins; drains three quarters of the body
cisterna chyli
most inferior
part of thoracic duct; located at
the union of lumbar and
intestinal trunks
right lymphatic duct
- Empties into right internal jugular and subclavian veins
- Present in ~ 20% of people
thoracic duct
Ascends along vertebral bodies and empties into venous circulation at the junction of left internal jugular and left subclavian veins; drains three quarters of the body -Found in all people
right lymphatic duct
Empties
into right internal jugular and
subclavian veins
-Present in ~ 20% of peopl
lymphatic vessels
1) Return excess tissue fluid to the bloodstream
2) Return leaked proteins to the blood
3) Carry absorbed fat from the intestine to the blood (though the
lacteals)
lymph nodes fight
disease in their roles as lymphoid
organs of the immune system
immune system
recognizes and
attacks specific foreign molecules, and
it destroys pathogens more and more
effectively with each new exposure.
immune system includes
a) Lymphocytes
b) Lymphoid tissue
c) Lymphoid organs: spleen, thymus,
lymph nodes, tonsils, and appendix
Infectious microorganism that
penetrate the epithelial barriers
encounter the underlying loose C.T.
where they are attacked by the
inflamatory response.
lymphocytes
are WBC’s that can
recognize and attack its own specific
type of foreign molecule (antigen).
two main classes of lymphocytes
T cells
B cells
T cells
(killer T-lymphocytes): attack
foreign eukaryotic cells directly; bind to
antigen-bearing cells and punch holes in its
membrane…which triggers apoptosis
B cells
multiply to become plasma cells that secrete antibodies (proteins that mark specific antigens for destruction by macrophages); mostly attack bacteria and bacterial toxins
lymphocytes originate in bone marrow from
lymphocyte stem cells
some lymphocytes travel to
to the thymus and become T
lymphocytes, while some stay in the bone
marrow and become B lymphocytes
Both T and B lymphocyte divide rapidly
; generate many
“families” where each recognize unique
antigens (immunocompetence).
yount T or B lymphocytes “seed”
lymphoid tissues
Antigenic challenge
lymphocytes meet and bind to its specific
antigen, where they become “fully activated” and proliferate rapidly
antigen presenting cells
(macrophages and dendritic cells) present
an antigen to a lymphocyte which elicits a specific response from the
“activated lymphocyte” to the antigen
both activating B and T cells produce clones of
effector lymphocytes
and memory
lymphocytes
effecgtor lymphocytes
short-lived cells that respond to the pathogen
immediately and then die
examplesof effector lymphocytes
plasma cells
Tcells
Memory lymphocytes
Plasma cells
which are formed by the
division of B cells, secrete antibodies that
bind to antigens marking them for
phagocytosis
T cells
wo types interact with antigens
differently
-Cytotoxic T cells
-Helper T cell
• Cytotoxic (CD8+) T cells
directly lyse the foreign cell (virus-infected
cell or cancer cell)
Helper (CD4+) T cells
stimulate other cells of the immune system by
secreting chemicals called cytokines; destroyed by HIV
Cytokines stimulate the
proliferation of activated B cells, cytotoxic T
cells, and macrophages
memory lymphocytes wait within the
lymphoid tissues until the body
encounters their antigen again…Days → Decades
-When a memory lymphocyte encounters their antigen again,
its
proliferative response and attack are vigorous and rapid.
The basis for acquired immunity
they guard against subsequent
infections and prevent people from getting many diseases more than
once.
lymphoid tissue
is a special type of C.T. in which vast quantities of
lymphocytes gather to fight microorganisms
two general locations of lymphoid tissue
1) Mucous membranes of digestive, urinary, respiratory, and
reproductive tracts, where it is called Mucosa-associated
lymphoid tissue (MALT)
2). In all lymphoid organs except the thymus
lymphoid tissue
main battleground and site where most
lymphocytes become activated
- A network of reticular fibers that houses T and B lymphocytes
lymphoid follicles
spherical clusters of densely packed
lymphocytes (Germinal centers: centers of dividing lymphocytes)
-Derives from the activation of a single B cell
lymphoid organs are designed to
gather and destroy infectious
microorganisms
primary lymphoid organs
bone
marrow (where B lymphocytes
mature), and thymus (where T
lymphocytes mature)
secondary lymphoid organs
lymph nodes, spleen, tonsils,
lymphoid nodules in small intestine,
and appendix
thymus located in
2 lobes located in the superior thorax and inferior neck,
just posterior to the sternum
thymus
- Where immature lymphocytes develop into T lymphocytes
- Secretes thymic hormones (cause immunocompetence)
- Most active in childhood and the functional tissue atrophies with
age and is replaced with fibrous and fatty tissue
thymus is composed of
a superficial cortex and a deep medulla
the cortex is packed with
rapidly dividing T lymphocytes
gaining immunocompetence.
medulla contains
thymic
(Hassall’s) corpuscles where Tlymphocytes
develop the ability to
recognize “self”
the thymus functions strictly in
lymphocyte
maturation and is the only
lymphoid organ that does not
directly fight antigens.
lymph nodes
the site where the lymphatic and immune systems
intersect
most antigenic challenges occur in
lymph nodes, where not only are
antigens destroyed but also
activate B and T lymphocytes
cortex
superficial part contains
the lymphoid follicles and most B
cells; deeper part contains T cells
medulla
contain both T and B
lymphocytes, plus plasma cells
spleen
unpaired organ; lies in the
left superior quadrant of abdominal
cavity, just posterior to stomach;
largest lymphoid organ
two main functions of spleen
1) Removal of blood-borne antigens
2) Removal and destruction of
old/defective blood cells by
macrophages
another function of spleen
site of hematopoiesis in the
fetus and stores platelets throughout
life
white pulp
: thick sleeves of lymphoid tissue; performs immune
functions
red pulp
surrounds white pulp and disposes of worn out blood cells
tonsils
swellings of mucosa lining the pharynx; simplest lymphoid
organs
four groups of tonsils
palatine
lingual
pharyngeal (adenoids)
tubal tonsils
palatine
directly posterior to mouth lateral to pharynx
lingual
on posterior surface of tongue
pharyngeal (adenoids)
on pharyngeal roof
tubal tonsils
: just behind openings of pharyngotympanic
tubes in pharynx
tonsils
The four groups of tonsils are
arranged in a ring around the entrance to the
pharynx to gather and remove pathogens
tonsils underlying CT (lamina propria) consists of
MALT packed with
lymphocytes and scattered lymphoid follicles
Mucosa-associated lymphoid tissue (MALT) is abundant in
walls of
intestines; consistently fights bacteria infection and generate a wide
variety of memory lymphocytes
a) Aggregated lymphoid nodules
(Peyer’s patches):
-Clusters of lymphoid follicles
- ~40 present the distal part of the
small intestine (ileum), each ~ 1 cm
wide and long
appendix
tubular offshoot of the cecum (1st part of the large
intestine)
-Dense MALT uniformly occupies over half the thickness of the
appendix wall
function of appendix
(of aggregated lymphoid nodules and appendix): destroys microoganisms that enter them; generate a wide variety of memory lymphocytes to protect the body
