The lymphatic system acts as a filter for the body's tissues by collecting excess fluid, proteins, debris, and cells from tissues and returning them to the bloodstream. It is made up of lymph vessels, lymph nodes, the spleen, thymus, tonsils, adenoids and bone marrow. The lymphatic system helps maintain fluid balance in the body, absorbs and transports fats and fat-soluble vitamins, and plays an important role in the immune system by filtering pathogens and producing immune cells.

1. Lymphatic System
V.Mythily,JCE
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Lymphatic System _V.Mythily,JCE

2. Lymphatic System
• The lymphatic system- Middle man between blood
and the body tissues.
• All interchanges of nourishment and waste products
between the blood and the body tissues take place
through the medium of tissue fluid.
• Colloid material from the tissue fluid cannot re-enter
the blood capillaries.
• Lymph capillaries receive collids, electrolytesb, water
and other substances and return them to the blood
stream.
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3. Lymphatic System
• The lymphatic system is, therefore , a
subsidiary or second circulatory system, which
drains the tissue fluids.
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4. Functions of lymphatic system
• Returns proteins from tissue spaces to blood
• Act as transport mechanism to remove RBC that have lost into
the tissues as a result of haemorrhage.
• Supplies nutrients and oxygen to those parts where blood
cannot reach.
• Role in defence mechanism as lymph nodes associated with
lymphatic system act as efficient filters and involved in
phagocytosis.
• The main role of the lymphatic system is to act as a filter
against microbes, organic wastes, toxins and other debris.
• It carries lymphocytes throughout the body that fight against
infections.
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5. Functions of lymphatic system
• As a vital part of immune system, lymphatic
system protects a person from infection and
destroys old or abnormal cells a body doesn’t
need.
• Lymphatic system functions also include
maintaining normal fluid levels in your body
and absorbing fats and fat-soluble vitamins so
they can make their way into bloodstream.
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6. Lymphatic system -Lymph
• Lymphatic system is a network of organs, vessels
and tissues that work together to move a
colorless, watery fluid (lymph) back into
your circulatory system .
• Lymph
• Lymph is essentially the name given to the
tissue fluid when it has entered the lymphatics.
• Lymph is a colourless fluid that circulates
throughout the lymphatic system.
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7. Introduction
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8. Lymph Flow
• Lymph enters the lymphatic capillaries under the influence of
osmotic pressure of tissue fluid.
• The lymph flow is controlled largely by the outside forces
which include:
• Contraction of smooth muscles in the walls of large lymph
vessels,
• Contraction of skeletal muscles,
• Movement of different body parts
• Arterial pulsations
• Compression of tissue by object outside the body
• Negative intra thoracic pressure and action of respiratory
muscles. 8
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9. Lymphatics
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11. Organization of Lymphatic System
Lymphatic System
• Lymphatic system is a closed system of lymph channels or lymph
vessels, through which lymph flows.
• It is a one-way system and allows the lymph flow from tissue
• spaces toward the blood.
Organization of Lymphatic System
• Lymphatic system arises from tissue spaces as a meshwork of
delicate vessels. These vessels are called lymph capillaries.
• Lymph capillaries start from tissue spaces as enlarged blindended
terminals called capillary bulbs.
• These bulbs contain valves, which allow flow of lymph in only one
direction.
• There are some muscle fibers around these bulbs.
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12. Organization of Lymphatic System
These muscle fibers cause contraction of bulbs so that, lymph
is pushed through the vessels.
• Lymph capillaries are lined by endothelial cells.
• Capillaries unite to form large lymphatic vessels.
• Lymphatic vessels become larger and larger because of the
joining of many tributaries along their course.
• The structure of lymph capillaries is slightly different from
that of the blood capillaries.
• Lymph capillaries are more porous and the cells lie
overlapping on one another.
• This allows the fluid to move into the lymph capillaries and
not in the opposite direction.
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14. Lymph capillaries
• The lymph capillaries originate as
closed endothelial tubes that are
permeable to fluid and HMW
compounds.
• Structure is basically similar to that
of blood capillaries.
• Differences:
• The basal lamina around the
endothelial cells is absent / poorly
developed.
• Pericytes / connective tissue are not
present around the lymph caillaries.
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15. Lymphatic vessels
• The lymphatic system constitutes an accessory
route for the removal of interstitial fluid.
• The small lymph vessels are called lymph
capilllaries and large lymph vessels are called
lymphatic trunks and the largest lymph vessel
is thoracic duct.
• The lymphatic capillaries are present in most
tissues of the body except brain, cartillage,
bone marrow and avascular structures (e.g.
cornea, crystalline lens, nails and hairs). 15
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16. Lymphatic Vessels to Lymph Node
• Lymph node receives lymph by one or two
lymphatic vessels called afferent vessels.
• Afferent vessels divide into small channels.
Lymph passes through afferent vessels and
small channels and reaches the cortex.
• It circulates through cortex, paracortex and
medulla of the lymph node.
• From medulla, the lymph leaves the node via
one or two efferent vessels.
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17. Lymphatic Ducts
Larger lymph vessels ultimately form
the right lymphatic duct and thoracic
duct.
• Right lymphatic duct opens into right
subclavian vein.
• The thoracic duct opens into left
subclavian vein.
• Thoracic duct drains the lymph from
more than two third of the tissue
spaces in the body.
• Blue area = Drained by right
lymphatic duct
• Pink area = Drained by thoracic duct.
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18. Lymph Tissues
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19. Lymphatic trunks and collecting
ducts
Examples:
Lumbar trunk: It drains lymph
from the lower limbs, lower
abdominal wall, and the pelvic
organs.
Intestinal trunk : It drains lymph
from the various viscera of
abdomen.
Intercoastal trunk: It drains from
portions of thorax.
Bronchomediastinal trunk: It also
receives lymph from the portion
of thorax
Subclavian trunk: It drains lymph
from the upper limb.
Jugular trunk: It drains lymph
from portions of the neck and
head. 19
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20. Collecting Ducts
• Two Main Ducts
• Thoracic Duct- collects lymph
drained from the lower limbs,
the abdomen, the left upper
limb, and the left side of the
thorax, head, and neck
• Right Lymphatic Duct- collects
lymph drained from the right
upper limb and the right side of
the thorax, neck, and head.
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21. Lymphatic organs and tissues
• The lymphatic organs and tissues in the body
include:
– Lymph nodes
– Spleen
– Thymus , and
– Mucosa- associated lymphoid tissue (MALT)
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22. Lymph Nodes
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25. Lymph nodes
Distribution of Lymph Nodes
• Lymph nodes are present along the course of lymphatic vessels
in elbow, axilla, knee and groin. Lymph nodes are also present
in certain points in abdomen, thorax and neck, where many
lymph vessels join.
Functions of lymph nodes :
• Lymph nodes serve as filters which filter bacteria and toxic
substances from the lymph.
1. When lymph passes through the lymph nodes, it is filtered, i.e.
the water and electrolytes are removed. But, the proteins and
lipids are retained in the lymph.
2. Bacteria and other toxic substances are destroyed by macrophages of lymph
nodes. Because of this, lymph nodes are called defense barriers. 25
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27. Spleen
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28. Thymus
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29. Function
• What does the lymphatic system do?
• Your lymphatic system has many functions. Its key functions include:
• Collecting excess fluid from your body’s tissues and returning it to your
bloodstream. This supports healthy fluid levels in your body. Your
lymphatic system also filters out waste products and abnormal cells from
this fluid.
• Helping your body absorb fats. Most nutrients can travel through tiny
openings (pores) in the walls of your capillaries, and your body can then
absorb and use them. But certain fats and other molecules are too large to
travel in this way. Your lymphatic system collects fluid from your intestines
that contains these molecules and transports it back to your bloodstream.
• Protecting your body against invaders. Your lymphatic system is part of
your immune system. It produces and releases lymphocytes (a type of
white blood cell) and other immune cells. These cells look for and destroy
invaders — such as bacteria, viruses, parasites and fungi — that may enter
your body.
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31. Anatomy – Lymphatic System organ
• Bone marrow. This is the soft, spongy tissue in
the center of certain bones, like your hip
bone, backbones and breastbone. Your bone
marrow has the vital job of making white
blood cells, red blood cells and platelets.
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