By:M. Thiru murugan Unit – 5: Structure and function of lymph vessels Lymph nodes and lymph circulation lymphatic tissue - spleen and thymus Lymphatic system: The lymphatic system, or lymphoid system, is part of the circulatory system and the immune system. It is made up of a large network of lymph, lymphatic vessels, lymph nodes, lymphatic organs, and lymphoid tissues. It also maintains fluid balance and plays a role in absorbing fats and fat-soluble nutrients. Functions: Return tissue fluid to the bloodstream. It absorbs and transports fat and fat soluble vitamins from the intestine. Kill the micro-organism. LYMPH VESSELS: A thin tube that carries lymph (lymphatic fluid) and white blood cells through the lymphatic system. Also called lymphatic vessel. Similar to blood vessels The lymphatic vessels transport lymph fluid around the body. There are two main systems of lymph vessels: Superficial vessels: found superficially and accompany venous flow. They supply into deep vessels. Deep vessels: collect from the deeper structures of the body, such as the internal organs. They tend to accompany deep arteries. Structure of lymph vessels: The endothelium the inner layer, middle is smooth muscles and adventitia is the outermost layer One of the main structure of lymph vessels is their valves, which are semilunar structures, valves is to prevent backflow of fluid Function: Carry the lymph fluid in one direction toward the heart. Providing sites for certain immune system Facilitating plasma circulation in the CVS Lymph node: It is a part of the body’s immune system. Lymph nodes filter substances that travel through the lymphatic fluid, and they contain lymphocytes (WBC) that help the body fight infection and disease. There are hundreds of lymph nodes found throughout the body. They are connected to lymph vessels. Lymph nodes are found in the neck, axilla, chest, abdomen, and groin. Structure: Lymph nodes are small, bean-shaped glands Lymph nodes are classified as "secondary" lymphoid organs, with the primary lymph organs being the thymus gland, tonsils, spleen, and bone marrow. The lymphatic vessels are the highways the immune police cells travel to survey the body, and the lymph nodes are like police stations Lymph nodes are divided into lobules, each of which contains an outer cortex, para cortex, inner medulla. B lymphocytes (b cells) are found in the cortex, with T lymphocytes (t cells) and para cortex. Plasma cells and macrophages are present in the medulla. The entire lymph node is enclosed by a tough fibrous capsule. Lymph circulation: Lymph. After blood travels through capillary and is moved to the venous system, some of fluid is left behind in the tissues it called lymph. Lymph is a clear, colorless liquid, it contains oxygen, proteins, glucose and WBC. Fluid that is forced out of the bloodstream during normal circulation is filtered through lymph nodes to remove bacteria, abnormal cells and other matter. This fluid is then t

1. By:
M. Thiru murugan
The Lymphatic system

2. Unit – 5:
a)Structure and function of lymph vessels
b)Lymph nodes and lymph circulation
c)lymphatic tissue - spleen and thymus

3. Lymphatic system:
• The lymphatic system, or lymphoid system, is part of the circulatory
system and the immune system.
• It is made up of a large network of lymph, lymphatic vessels, lymph
nodes, lymphatic organs, and lymphoid tissues.
• It also maintains fluid balance and plays a role in absorbing fats and
fat-soluble nutrients.
Functions:
• Return tissue fluid to the bloodstream.
• It absorbs and transports fat and fat soluble vitamins
from the intestine.
• Kill the micro-organism.

4. LYMPH VESSELS:
• A thin tube that carries lymph (lymphatic fluid) and white blood cells
through the lymphatic system. Also called lymphatic vessel.
• Similar to blood vessels
• The lymphatic vessels transport lymph fluid around the body.
• There are two main systems of lymph vessels:
1. Superficial vessels: found superficially and accompany venous
flow. They supply into deep vessels.
2. Deep vessels: collect from the deeper structures of the body, such
as the internal organs. They tend to accompany deep arteries.

5. Structure of lymph vessels:
• The endothelium the inner layer, middle
is smooth muscles and adventitia is the
outermost layer
• One of the main structure of lymph vessels
is their valves, which are semilunar
structures, valves is to prevent backflow of
fluid
Function:
• Carry the lymph fluid in one direction toward
the heart.
• Providing sites for certain immune system
• Facilitating plasma circulation in the CVS

6. Lymph node:
• It is a part of the body’s immune system.
• Lymph nodes filter substances that travel through the
lymphatic fluid, and they contain lymphocytes (WBC) that
help the body fight infection and disease.
• There are hundreds of lymph nodes found throughout the
body.
• They are connected to lymph vessels.
• Lymph nodes are found in the neck, axilla, chest, abdomen,
and groin.

7. Structure:
• Lymph nodes are small, bean-shaped glands
• Lymph nodes are classified as "secondary" lymphoid organs, with the
primary lymph organs being the thymus gland, tonsils, spleen, and bone
marrow.
• The lymphatic vessels are the highways the immune police cells travel to
survey the body, and the lymph nodes are like police stations
• Lymph nodes are divided into lobules, each of which contains an outer
cortex, para cortex, inner medulla.
• B lymphocytes (b cells) are found in the cortex, with T lymphocytes (t
cells) and para cortex. Plasma cells and macrophages are present in the
medulla.
• The entire lymph node is enclosed by a tough fibrous capsule.

8. Types & location of lymph nodes
Function of lymph node:
• Lymph nodes work like filters, or security
guards to filter bacteria, viruses, parasites,
other foreign material.
• Lymph nodes play important roles in
immunity. (T cells & B cells)
• Produce lymphocytes

9. Lymph circulation:
• Lymph.
• After blood travels through capillary and is moved to the venous system,
some of fluid is left behind in the tissues it called lymph.
• Lymph is a clear, colorless liquid, it contains oxygen, proteins, glucose and
WBC.
• Fluid that is forced out of the bloodstream during normal circulation is
filtered through lymph nodes to remove bacteria, abnormal cells and other
matter.
• This fluid is then transported back into bloodstream via the lymph vessels.
• Lymph only moves in one direction, toward the heart.
• Lymph circulation occurs despite low pressure due to peristalsis, valves, and
compression during contraction of skeletal muscle and arterial pulsation

11. Lymphatic Tissues:
• Lymphoid tissue is found in many organs including the
lymph nodes, as well as in the lymphoid follicles in the
pharynx such as the tonsils.
• Lymphoid tissues contain lymphocytes, but they also
contain dendritic cells, which play a key role in the
immune system.

12. • Several other organs contribute to
lymphatic function
• Spleen
• Thymus
• Tonsils
• Peyer's patches
Lymphoid Organs

13. The Spleen
• Filters blood
• Destroys worn out blood cells
• Forms blood cells in the fetus
• Acts as a blood reservoir

14. The thymus
• Functions at peak levels only
during childhood
• Produces hormones (like thymosin)
to program lymphocytes

15. Tonsils:
• Cluster of lymphatic tissue just under
the mucous membranes that line the
nose, mouth, and pharynx (throat)
called tonsils.
Function:
• Provide protection against harmful
substances and pathogens that may
enter the body through the nose or
mouth.

16. Peyer’s Patches
• Found in the wall of the small
intestine
• Capture and destroy bacteria
in the intestine

17. Mucosa-Associated Lymphatic Tissue (MALT)
• Includes:
• Peyer’s patches
• Tonsils
• Other small accumulations of lymphoid tissue
• Acts as a sentinal to protect respiratory and digestive
tracts