lymphatic system-converted.pdf

•The lymphatic system is part of the circulatory
system and the immune system, comprising a
network of lymphatic vessels that carry a clear
fluid called lymph unidirectionally towards the
heart.

 Removal of interstitial fluid from tissues
 Absorption of Fat: Lymph
vessels called lacteals are present in the lining
of the small intestine. Which absorb fat.
 Transportation of WBC
 Immune function: Cells in the lymphatic
system react to antigens presented or found
by the cells.

The four components of lymphatic system are:
1. LYMPH
2. LYMPH VESSEL
3. LYMPHOID TISSUE/ LYMPHOID ORGAN
4. LYMPHOCYTES and PHAGOCYTES

A clear fluid composed mainly of water,
electrolytes and some plasma proteins
Transported in lymphatic pathway from
lymphatic vessels to collecting ducts and end
disposed into venous blood
When blood circulates in high pressure, the
fluid (plasma) portion seeps through thin
capillary walls into surrounding tissue.

This interstitial fluid is returned to blood through
walls of venules.
The remainder enters a network of thin walled
tubes called lymphatic vessels and now is called
lymph.

 The flow of lymph in the thoracic duct in an
average resting person usually
approximates 100 ml per hour.
 Accompanied by another 25ml per hour in
other lymph vessels.
 The total lymph flow in the body is about 2
to 3 litres per day.

Lymphatic capillary run parallel to blood capillaries
in all body tissues and allow diffusion of fluid from
interstitial spaces into lymphatic pathway.
Structurally identical to veins- vessel wall composed
of 3 thin layers of tissue, and contain valves to
prevent backflow.
They form specialized lymphatic organs called
lymph nodes which store macrophages and
lymphocytes to eliminate foreign substance in the
lymph.

Thoracic duct returns lymph from left side of the
body to left subclavian vein, and Right lymphatic
duct returns lymph from right part of the body to
right subclavian vein.

Transport lymph away from tissues
Collect and filter lymph (at the nodes) as
it continues to move toward larger vessels
called collecting ducts.

Lymphatic organs are divided as primary lymphatic
organs and secondary lymphatic organs:
1. Primary Lymphatic Organs are red bone marrow
and thymus gland. The red bone marrow produce T-
cells in response to an antigen and they get matured
in thymus gland.
2. Secondary Lymphatic Organs are lymph nodes,
spleen, lymphatic nodules. These are the sites of
immune responses.

 Bone marrow is a semi-solid tissue found
within the spongy portions of bones
 It is the primary site of haematopoiesis.
 It is composed of hematopoietic cells,
marrow adipose tissue, and
supportive stromal cells

 The thymus is an organ with two lobes that
is located anterior to the ascending aorta and
posterior to the sternum.

 Each lobe surrounded by a capsule and
divided into lobules, which are separated
from each other by strans of connective
tissue called trabeculae.

Each lobule organized into 2 compartments: the
outer compartment cortex, and the inner
compartment medulla.
The maturation of T cells and monocytes takes
place in the medulla which is supported by
epithelial cells and macrophages present in the
thymus.
In addition it also secrete hormone such as
thymosin which stimulate the development of
antibodies.

 Around 600 bean shaped lymph nodes are
located throughout the body.
 Lymph nodes filter substances that travel
through the lymphatic fluid, and contain
lymphocytes (white blood cells) that help the
body fight infection and disease

Lymph node can be divided into 3 centric
regions: the Cortex, the Paracortex and the
Medulla.
 The outer most cortex contains B lymphocytes,
macrophages and follicular dendritic cells.
 Beneath cortex, paracortex contains T
lymphocytes.
 Medulla contains lymphoid cells, and plasma cells
which actively secrets antibodies.

 Filteration of lymph- lymph node filter and
purify the lymph (remove cell debris, virus,
fungi etc) before return to the venous
circulation
 Trapping the antigen- traps the antigen and
presents infront of lymphocytes
 Production of lymphocytes (maturation)
 Phagocytosis

 The spleen is a fist-sized
organ in the upper left side of
abdomen, next to the stomach
and behind left ribs.
 It is surrounded by a capsule
from which a number of
projections (trabeculae)
extend into interior to form
compartments.

 Compartments are of two types: the RED pulp
and the WHITE pulp, separated by a diffuse
marginal zone.
 The white pulp surrounds the branches of
splenic artery, forming Periarterial Lymphatc
Sheath (PALS) which containsT lymphocytes.
 Within the red pulp the following functions such
as removal of defective blood cells and platelets,
storage of platelets for emergency use, and
production of blood cells during fetal life etc.

 Phagocytosis (destruction of RBC and
Platelets)
 Storage of blood (approx 350 ml of blood is
stored which can be used in critical conditions)
 Erythropoiesis (in fetus)
 Immune response (spleenomegaly in case of any
infection due to activatedT and B lymphocytes)

 They are egg shaped masses of lymphatic tissues
different from lymph nodes since they do not have
capsules.
 They are located at the mucosal lining of GI, urinary,
respiratory and reproductive tracts and also referred
as MALT (mucosa-associated lymphatic tissue)
 The tonsils (in the throat), the Peyer patches (within
the small intestine), and the vermiform appendix are
examples of MALT.

The nomenclature incorporates
location; therefore, MALT is understood to
include
 Gut-associated lymphoid tissue (GALT),
 Bronchial associated lymphoid tissue
(BALT)
 Nose-associated lymphoid tissue (NALT)
 Vulvovaginal-associated lymphoid tissue
(VALT).

 T CELLS
 B CELLS
 MONOCYTES AND
MACROPHAGES/PHAGOCYTES
 MAST CELLS
 DENDRITIC CELLS: derived from monocytes and have
long branched projections similar to neurons.
 GRANULOCYTIC CELLS: Neutrophil. Eosinophil,
Basophil

 Water and solutes continually filter out from
capillary into interstitial space. To balance this
outflow, fluid continually reenters blood through
lymphatic system.
 Fluid (lymph) is filtered through lymph nodes to
remove bacteria, abnormal cells and other foreign
materials.
 This fluid is then transported back into the
bloodstream via the lymph vessels.
 Lymph only moves in one direction, toward the
heart.

Lymphedema: It is a condition of
localized fluid retention and tissue swelling caused
by blocked/ improper lymphatic system.
The main symptom is swelling in an arm or leg
that may be accompanied by pain or discomfort.

The condition can be inherited or can be caused
by an injury to lymph vessel or nodes as a result
of treatment of cancer such as radiation, surgery
or a parasitic infection called filariasis.
Lymphedema Filariasis

 There's no cure for lymphedema.
Therapies for lymphadema:
 Exercises. Gentle contraction of the muscles in the
arm or leg can help move the excess fluid out of
the swollen limb.
 Manual lymph drainage
 Compression bandages
 Compression garments

lymphatic system-converted.pdf

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lymphatic system-converted.pdf