THE LYMPHATIC SYSTEM
The lymphatic system consists of capillaries, vessels, ducts and nodes that
transport a fluid known as lymph. Lymph is formed from tissue fluid, which
surrounds all tissue cells and performs three important functions:
(i) transportation of lymphocytes, which defend the body against infection and foreign antigens
(ii) transportation of lipids
(iii) by its formation the drainage of excess fluid from tissues.
This system is one of the most important systems of the human body. Every 24 hours, the heart
receives approximately 3 litres of lymph that is rich in white blood cells (lymphocytes) which are
used to help fight cancer, viruses, bacteria, and infection. The most numerous immune system
cell is a lymphocyte .
Distinct patches of lymphatic tissue have been given specific names; these include tonsils,
adenoids, spleen and thymus.
Root
Combining form
Meaning
Lymph
Lymph/a/o
It is used to mean the fluid lymph or lymphatic tissue
Activity 1
Write the meaning of;
1.
Lymphocytosis _______________________________________________________
2.
Lymphorrhagia
_______________________________________________________
Build words which mean;
3.
Removal of a lymph gland
_____________________________________________
4.
_____________________________________________
Disease of a lymph gland
Phagocytes – ingest and destroy foreign cells or other harmful substances via phagocytosis
Types: neutrophils
monocytes
macrophages
Lymph nodes (glands) consist of lymphatic channels held in place by fibrous connective tissue
which forms a capsule. The nodes contain lymphocytes and special cells called macrophages,
which can engulf foreign substances and microorganisms (by phagocytosis). Lymph nodes
often trap malignant cells as well as microorganisms, some of which are also destroyed. During
infection lymphocytes and macrophages multiply rapidly, causing the lymph nodes to swell.
They may become inflamed and sore. Lymphocytes and macrophages can enter the lymph and
blood from nodes.
The macrophages, which line the lymph organs, are part of a large system of cells known as the
reticuloendothelial system or macrophage system. Cells that form this network have a common
ancestry and carry out phagocytosis in the liver, bone marrow, lymph nodes, spleen, nervous
system, blood and connective tissues.
Root
Combining form
Meaning
Lymphaden
lymphaden/o
A lymph node
Lymphangi
lymphangi/o
A lymph duct or vessel
Splen
splen/o
Spleen. This organ has four main functions: destruction
of old red blood cells, blood storage, blood filtration and
participation in the immune response.
Lymphatic System
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Activity 2
Build words which mean:
1.
Enlarged spleen ________________________________________________________
2.
Enlargement of the liver and spleen ________________________________________
(Port/o refers to the portal vein, which drains blood from the intestines, stomach, pancreas and
spleen into the liver.)
Root
Combining form
Tonsill
tonsill/o
Meaning
Tonsils form a ring of lymphoid tissue at the back of the mouth
and nasopharynx. They are thought to be important in the
formation of antibodies and lymphocytes.
Activity 3
Build words which mean:
1.
Inflammation of the tonsils _______________________________________________
2.
Removal of the tonsils ___________________________________________________
NOTE: An enlarged nasopharyngeal tonsil is known as an adenoid. Sometimes these obstruct
the passage of air or interfere with hearing. Removal of the adenoids is known as an
adenoidectomy.
Root
Combining form
Meaning
Thym
thym/o, thymic/o
Thymus gland which lies high in the chest above the aorta. It
controls the development of the immune system in early life.
IMMUNITY
This is the condition of being immune to infectious disease and antigenic substances, which
may harm the body. Immunity is brought about by the production of antibodies and cells, which
destroy invading pathogens. During our lifetime we acquire immunity to common diseaseproducing organisms, such as viruses, which cause colds and influenza. We can also acquire
immunity to more serious disease by vaccination.
Definitions:
Antibody – a substance, which circulates in the blood and can destroy or precipitate foreign
substances, which have entered the body.
Antigen – is any foreign substance that enters the body and stimulates antibody production.
Activity 4
Build words which mean:
1.
The study of immunity
Write the meaning of:
2.
Autoimmunity
_______________________________________________________
3.
Immunoglobulin _______________________________________________________
Root
Combining form
Meaning
Ser
ser/o
The clear portion of any liquid when separated. Blood
serum is the liquid formed when blood clots. This serum
can then be used as a source of antibodies.
Py
py/o
Pus.
Lymphatic System
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Serum investigations can lead to a patient being seronegative or seropositive for the presence
of a particular antibody.
Definitions:
Seronegative – means a lack of antibody.
Seropositive – means a high level of antibody
Pus is a yellow, protein-rich liquid, composed of tissue fluids containing bacteria and leucocytes.
When a wound is forming or discharging pus it is said to be suppurating. Pus is formed in
response to certain types of infection.
Activity 5
Write the meaning of;
1.
Pyogenic
___________________________________________________________
2.
Pyorrhoea
___________________________________________________________
The immune response of the lymphatic system not only resists invasion by infective organisms
but also functions to identify and destroy everything that is described as non-self, ie. foreign
antigens, which have entered the body, such as in, transplanted organs or body cells, which
have changed their form, such as malignant cells.
Patients infected with microorganisms, such as those present in tonsillitis, experience swollen
lymph glands and blood counts will indicate an increase in the number of circulating white blood
cells. Once the foreign cells have been destroyed, the lymph glands will return to their normal
size.
An important feature of some lymphocytes, which make the initial response to an infection, is
that they become memory cells. This means that they retain the ability to respond very rapidly to
the same organism should it enter the body again. This process is the basis of immunity.
Conditions of the Lymphatic System:
Tonsillitis
Inflammation of the tonsils due to bacterial or viral infection.
Glandular Fever
An infectious disease caused by a virus, it affects the lymph nodes in
the neck, armpits and groin.
Lymphangitis
Inflammation of the lymphatic vessels.
Elephantiasis
Lymphoedema
Lymphomas /
Lymphosarcomas
Lymphatic System
Gross enlargement of the skin and underlying connective tissues
caused by obstruction of the lymph vessels which prevents drainage of
lymph from the surrounding tissues.
An accumulation of lymph in the tissues, producing swelling. It can
result from a congenital abnormality or an obstruction of the lymphatic
vessels.
A malignant tumour of the lymph nodes.
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Abbreviations:
AIDS
Acquired immunodeficiency syndrome
ALL
Acute lymphocytic leukaemia
CLL
Chronic lymphocytic leukaemia
Ig
Immunoglobulin
T&A
Tonsils and adenoids
TLD
Thoracic lymph duct
Terms And Word Parts:
aden/o
gland
-cyte
cell
cyt/e/o
cell
hist/i/o
tissue
immun/o
immune
lymph/o
lymph (fluid, in lymphatic system)
leuc/o
leuk/o
white
(leucocyte – English leukocyte – American ) white
macro-
large
mono-
one/single
micro-
small
-megaly
enlargment
neutr/o
neutral
phag/o
eating, consuming
-phil
having affinity for/ cell type with affinity for
splen/o
spleen (mass of lymphoid tissue located in the left hypochondriac region)
tonsill/o
tonsil
thym/o
thymus
-tome
cutting instrument
Lymphatic System
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