Transcript The Lymphatic System

The Lymphatic System
The Function of the Lymphatic
System
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The lymphatic system is
designed to fend off
pathogenic organisms. It
also removes excess
fluids in between cells
and brings it back to the
blood stream.
Lymph is also responsible
for the absorption of fats
in the small intestines.
Lymphatic pathways
 Patterns
of vessels that transport lymph.
This allows the transport and relocation of
various components like T-cells and
lymph.
Lymphatic capillaries

Microscopic tubes
that extend
interstitially (between
cells) and parallel to
the circulatory
system.
 The fluids inside
these vessels is
called lymph.
Lymphatic vessels
 Lymph
from the lymphatic capillaries is
carried into the lymphatic vessels. These
vessels have flaps on them just like in the
veins of the circulatory system to prevent
lymph from flowing backwards.
Lymph nodes and Lymphatic trunks
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The larger bundles of
lymphatic tissue are
referred to as lymph
nodes.
 Lymph nodes then
dump their lymph into
even larger bundles
called lymphatic
trunks.
Lymphatic trunks
 Lymphatic
trunks are aptly named for the
regions in which they serve. All trunks
dump into one of two specialized collecting
ducts.
 Collecting ducts
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Thoracic duct
Right lymphatic duct
Thoracic and right lymphatic duct
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Thoracic duct- Larger
and longer of the two
ducts. Gathers lymph
from the lower limbs,
abdominal region, left
side of the thorax,
head and neck.
Empties into the left
subclavian vein.
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Right lymphatic ductsmaller of the two,
gathers lymph from
the right side of the
head neck and
thorax. Empties into
the right subclavian
vein, near the right
jugular vein.
Lymphatic tissue fluid formation
 Tissue
fluid originates as blood plasma.
 That plasma contains water and dissolved
proteins in it. Parts of this fluid can be
removed by diffusion and filtration.
 Some of the smaller proteins free floating
in the plasma are not reabsorbed through
venular ends of the capillaries.
 This causes a change the level of osmotic
pressure in the fluid.
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The higher osmotic pressure in turn causes a
large increase in the hydrostatic pressure
(pressure that water has when at equilibrium)
forcing some liquid into the lymph capillaries
where it becomes lymph.
 The lymph returns most of the proteins lost back
when it enters the bloodstream.
 At the same time, lymph transports foreign
particles like bacteria and viruses to the lymph
nodes.
Lymph Nodes
 It
is in the lymph nodes that the most
lymphocytes and macrophages do battle
with the microorganisms that enter the
body everyday.
 There is an indented region in the lymph
node where blood vessels and nerves run
to the node. This region is called the
hilium.
Locations of major lymph nodes
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Thoracic cavity nodes- chest
Cervical nodes- throat
Axillary nodes- armpit
Supratrochlear nodes- distal end of the
humerous
Abdominal cavity nodes- abdomen
Pelvic cavity nodes- pelvic region
Inguinal nodes- upper thigh and groin region.
Major organs in the lymphatic
system
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Thymus- located
anterior to the heart
and posterior to the
sternum. Soft and
bilobed (two lobed).
Large in children,
small and reduced in
adults.
 Some T-cells can be
found here.
Spleen

Largest lymphatic
organ, located in the
upper left portion of
abdominal cavity.
Inferior to the
diaphragm. Posterior
and lateral to
stomach.
D
-
The body fighting against infection
 Pathogen-disease
causing agent
 Two types of defense:
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Nonspecific
Specific (immunity)
Nonspecific defenses
 Nonspecific
defenses are designed to deal
with a variety of different pathogens.
Different nonspecific defenses are:
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Species resistance
Skin and mucus membranes
Interferons- proteins secreted by immune
system to fight infection
Inflammation
Phagocytosis
Species defense
 When
a disease only affects one species
of organism, all other species are immune
to getting that disease.
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Oak blight kills oak trees. Humans are not
oak trees, thus cannot get oak blight.
Mechanical barriers
 Body’s
first line of defense. When not
damaged, they prevent most diseases
from entering the body.
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Skin
Mucus membranes
Chemical barriers
 Chemical
barriers are chemicals secreted
by the body that due to their very nature
can make it impossible for a bacteria to
survive.
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Pepsin and HCl in the stomach.
Interferons eliminating viral coats and tumor
cells.
Fever

The body begins to raise its overall temperature.
 Liver and spleen begin to hold on to extra iron
as a result.
 Bacteria need more iron as the temperature
rises, this causes a composition change in the
blood and kills the bacteria in the blood.
 (bad news) maintaining a high fever (105O F or
greater) over an extended period can cause
organ and brain damage if not brought down.
 Pus-
when lymphocytes and bacteria are
all collected in one place, pus may form.
Phagocytosis
 When
monocytes and neutrophils devour
foreign invaders, they attack
indiscriminately, regardless of the make up
of the bacteria or virus.
Specific Immunity
 Specific
immunity is designed to target
one specific problem. When you get a flu
shot each year, you receive a vaccine, you
receive immunity to a specific strand of the
flu virus. That strand has a unique protein
coat that only it has. When your body runs
into that protein coat again (after
vaccination) you will immediately produce
the antibodies to remove the threat without
getting sick again.
Antigens
 Cell
surface markers. Helps body
recognize other cells as “self” or “foreign.”
lymphocytes
 Provide
immunity by creating antibodies.
Can differentiate into B-cells and T-cells.
Upon reaching the thymus, lymphocytes
can be given the biochemical cocktail they
need to specialize into t-cells. B-cells will
specialize in the bone marrow.
T-cells and B-cells
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B-cell- 20-30% of lymphocytes in the blood. Bcells tend to settle in lymphatic organs. Produce
antibodies that destroy antigens and antigen
bearing agents. Using antibodies
(immunoglobulins) to destroy a pathogen is
called antibody-regulated immunity.
 T-cell- 70-80% of lymphocytes in the blood.
Interact directly with antigen source with agents
to destroy that source. Binding to the pathogen
directly is called cell-mediated immunity.
When to attack
 T-cell
activation- When a pathogen is
phagocytized by a monocyte, some of the
antigens from the pathogen stick out of the
monocyte near a major histocompatibility
complex (MHC). If the T-cell recognizes
the antigen as a foreign antigen, then the
T-cell will activate. This type of T-cell is
called a helper T-cell because it assists
another lymphocyte in non-self cell
removal.
 Another
way this occurs is when T-cells
subdifferentiate into cytotoxic T-cells.
They recognize a non-self antigen as
being cancerous or viral and binds to the
antigen and activates and releases a
protein that shreds the antigen bearing
agent.
B-cell activation
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B-cells will come in contact with an antigen
bearing source. As a result, the B-cell will bind
to it and begin to divide and create more copies
of itself. When an activated T-cell finds a B-cell
that is now bound to an antigen, the helper cell
will release cytokines that cause the B-cell to
grow and increase antibody producing cells.
 Later outbreaks of that pathogen will be easily
quelled due to some B-cells becoming memorycells and “remembering” that pathogen. When
that pathogen appears again, it will be quelled
near instantly.
Immune Response
 Primary
Immune Response- First
response to an antigen. Ends with
creation of memory cells.
 Secondary Immune Responsesubsequent response to encountering
antigen. Memory cells know what to do
and eliminate threat to the body.
Active Immunity
 Two
ways to acquire active immunity:
 First way- Get sick, produce memory cells
that now recognize antigen.
 Second way- Vaccination. Vaccinations
introduce a dead (inactivated) or
weakened (attenuated) virus into the body.
The body easily fights off this virus, gains
the memory cells it needs, and now is
ready to encounter the full strength virus.
Passive immunity
 When
immunity is given by receiving
antibodies from an outside source. Often
given when we fail to produce immunity
fast enough or if we are not able to at all.
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i.e. Rabies vaccine.
Allergies
 Hypersensitive
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response to a stimulus.
Eating tree nuts- not normally harmful but the
body perceives it as a threat and attacks the
threat in full force.