Transcript Lymphatic System

The Lymphatic System
The lymphatic system consists of :
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1.
Lymphatic Vessels that carry lymph (clear watery
liquid formed from tissue fluid)
2.
Lymph tissue called lymph nodes.
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Lymph nodes are often called glands.
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The spleen, tonsils (lymph nodes in the throat)
and thymus are also considered part of the
Lymphatic System.
 The
functions of the Lymphatic System are
 Drainage – returns extra cellular (leaked) fluid
to the blood
 Transport – lipid (fats and oils) are absorbed
from the small intestine and carried to the skin
or other organs for storage.
 Defence – filters blood. Germs that enter the
blood or tissue fluid will pass through the lymph
and lymph nodes, where WBC’s attack and
destroy them. Swollen glands are actively
fighting infection.
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When blood is pumped by the heart under high pressure,
some plasma leaks out of the capillaries and into the
space around the cells.
This extra-cellular fluid is collected by vessels
called lymphatics.
The lymph moves along through the lymphatics by the
action of our muscles.
Valves prevent the backflow of lymph in these
vessels.
The direction of flow is controlled by valves in the lymph
nodes (found in the groin, armpits etc).
These lymph nodes are also areas of lymphocyte
action and can swell when the body is infected with a
pathogen.
All lymph joins the blood stream in the Vena Cava just
before entering the heart.
 Immunity
is the ability of an organism to
resist infection.
 Pathogens
are micro-organisms that can
cause a disease.
 Your
have two types of defence system: General
and Specific.
 There
are a number of types of immunity.
 Natural,
Acquired, Artificial and Passive.
 Skin
provides a physical barrier
 Mucus
in our lungs trap germs
 Cilia
in our lungs remove the mucus
 Acid
in our stomach kill bacteria
 Enzymes
in our tears protect the eye
 Platelets
seal damaged blood vessels
 White
Blood Cells eat germs.
Acquired immunity arises when an organism makes
it own antibodies.
 Antibodies are Y shaped proteins, which attach onto
antigens (pathogens).
 Each antibody is specific to one type of
antigen.
 Should an infection occur, lymphocytes rush to the
area of infection and start producing antibodies.
 It usually takes a couple of days for the right
antibody to be produced that will match the invading
antigen.
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Once a match is found, that lymphocyte is triggered
to multiply.
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This marks the cell for destruction by other white
blood cells.
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Some of these lymphocytes remain in the blood and
act as memory cells.
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Should the same antigen invade again, the body can
react to the infection much more quickly. At this
point, one is said to be immune from the disease.
Some germs have the power to kill a human well
before the correct antibody can be found.
 For this reason, doctors have developed
vaccination.
 Vaccination involves injected “dead germs” which
causes a particular disease into the bloodstream.
 They cannot grow or cause major problems, but the
body still detects them and produces antibodies
against them.
 Should the “real germ” invade, the body had the
antibody ready to defend against it.
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 Passive
immunity involves the body using
antibodies which were not produced in the body.
 Examples
include an unborn child receiving
antibodies from the mother’s placenta and
during breast feeding.