Transcript Chapter 12 The Lymphatic System

Chapter 12 The Lymphatic
System
Biology 110
Tri-County Technical College
Pendleton, SC
Lymphatic Components
• Lymphatic vessels, lymph nodes, & various
lymphatic organs and tissues
• Has two semi-independent parts
– Meandering network of lymphatic vessels
– Various scattered lymphoid tissues and organs
• Vessels transport fluids that escaped from blood
vascular system back to blood
• Organs house phagocytic cells/lymphocytes
essential in body defense & resistance to disease
Lymph System Visual
Vessels and “Ebb and Flow”
• Vessels pick up excess tissue fluid (lymph) and
return it to bloodstream
• Lymphatics form one-way system and lymph
flows ONLY toward heart
• Lymph capillaries spiderweb between tissue cells
and blood capillaries in loose CT
• Absorb leaked fluid (mostly water & small
dissolved proteins
• Lymph capillaries remarkably permeable
Lymph Flow Visual
Vessels, cont.
• All lymph vessels drain into 2 large vessels
– RIGHT lymphatic duct drains right arm and right side
of head and thorax
– THORACIC duct drains rest of body
• BOTH empty into Subclavian vein on their side
of body
• Vessels are thin-walled and larger ones have
“valves
• Is low pressure but pumpless system
Lymph System Visual
Vessels, cont.
• Lymph transported by same mechanisms
that aid return of venous blood
– Milking action of skeletal muscles and pressure
changes in thorax during breathing
– Smooth muscle in walls of larger lymphatic
vessels contracts rhythmically which helps
“pump” lymph
– Valves in larger vessels prevent backflow
Lymph Nodes
• Nodes are located along lymphatic vessels
• Lymph filtered as passes through 1000s of
nodes
• Large clusters found in inguinal, axillary,
and cervical regions of body
• Nodes may enlarge (become swollen)
during active infection
• Nodes composed of soft reticular
connective tissue
We still talking about nodes…?
• Macrophages located within nodes
– Engulf and destroy bacteria/viruses/foreign
substances in lymph before its returned to
blood
• Plasma cells for antibody production also
located in nodes
• Collections of lymphocytes (WBC type)
also in nodes and respond to foreign
substances in lymph stream
Nodes, nodes, and nodes
• Nodes composed of outer cortex containing
collections of lymphocytes called follicles
– Follicles have germinal centers = generate plasma
cells that release antibodies
– Rest of cortical cells = lymphocytes in transit
• Inner medulla area contains phagocytic
macrophages
• Enters cortex of node via afferent lymphatic
vesselssinusesexits node at HILUS via
efferent lymphatic vessels
Node Structure Visual
Lymphatic Organs
• Spleen, thymus, tonsils, & Peyer’s patches
• Spleen located in left hypochondriac region
• Filters/cleanses blood of bacteria, viruses,
and other debris
• Most important function=destroy worn-out
RBCs and recycle iron to make hemoglobin
– Some iron secreted in bile
Organs, cont.
• Spleen also stores platelets and acts as blood
reservoir (so does liver)
• Produces blood in the fetus
• In adults, spleen produces only lymphocytes
• Meanwhile, back at the ranch, and not wanting to
waste space, I am practicing my typing skills, and
if I may say so, not doing too badly for a over the
hill ex-long haired bearded hippy….
Thymus Gland
• Functions at peak levels during youth
• Is lymphatic mass found in throat overlying
heart
• Produces the hormone THYMOSIN that
functions in programming lymphocytes so
they can perform protective roles in body
• NOT active during adulthood
Say ahh……!!!!
• Tonsils are small masses of lymphatic tissue
that ring pharynx where they are found in
the mucosa
• Trap and remove bacteria/other foreign
pathogens entering throat
• May become swollen and red = tonsillitis
• My mom treated with warm salt water
gargle, but I have switched to aspirin
Peyer’s Patches
• Found in walls of small intestines
• In ideal location to capture/destroy bacteria that
could cause enteritis
• Tonsils & Peyer’s patches part of “mucosaassociated lymphatic tissue” (MALT)
• Acts as sentinel to protect upper respiratory and
the digestive tract from never-ending attacks of
foreign matter entering those cavities
Lymph Organs Visual
Antibodies and more…
• B lymphocytes (B cells) produce antibodies
and oversee humoral immunity
• T lymphocytes (T cells) constitute cellmediated arm of immunity
• Antibodies called Immunoglobulins (Igs)
• GMADE
• Heavy and light chains; Variable and
Constant regions
Antibody Visual
Antibodies, cont.
• IgG is most abundant is ONLY type that can
cross placenta
• Only IgM and IgG fix complement
• IgA found only in mucus (major role in
preventing pathogens from gaining entry
into body
• IgE “troublemaker” involved in allergies
What it are…?
Antibody Action
• Inactive antigens by complement fixation,
neutralization, agglutination, and
precipitation
• Complement fixation and neutralization
most important to body function
• Complement is chief weapon against
cellular antigens (bacteria/mismatched
blood cells)
Complement Action Visual
I know what it is, but how does it
work?
Acquired Immunity Visual
Autoimmune Disorders
• Body produces antibodies (autoantibodies)
and sensitized T cells that attack and
damage its own tissues
• Graves disease-thyroid gland produces
excess thyroxine
• Multiple sclerosis, Myasthenia gravis,
Juvenile (I) diabetes mellitus, Systemic
lupus erythematosus, Glomerulonephritis,
and Rheumatoid arthritis (p. 396)
Same Coin but Two Sides