The Lymphatic
System
By Emily Lopez, Alejandro Campos, and
Jennifer Leon
What Is the Lymphatic System?
 It
is the network of vessels in which lymph
drains from the tissue into the blood
 It
is composed of lymph vessels, lymph
nodes, the spleen, the thymus, tonsils, and
bone marrow.
Functions of the Lymphatic
System

The functions of this system include:
 the
absorption of excess fluid and its return to the
blood stream
 Absorption
 Its
of fat (In the villi and small intestine)
Immune System Response
Lymph Vessels

Thin walled, valve structures that carry lymph

Complementary to the cardiovascular system

Lined by endothelial cells, a thin layer of smooth muscles,
and adventitia(binds lymph vessels to surrounding tissue)

Types of vessels: Afferent vessels, Efferent vessels, and
Lymph Trunks
Different types of Lymph Vessels

Afferent lymph vessels: Carries unfiltered lymph into
the node
 Found

Efferent lymph vessels: Carries filtered lymph out of
the node
 Found

only in the lymph nodes
in the thymus and spleen
Lymph Trunk: Carries lymph and is formed by
confluence of many efferent lymph vessels
Different types of Lymph Vessels(Cont…)

Lymph Trunks carry lymph and then drain
them into either the right lymph duct, or the
thoracic duct.

There are four pairs and one unpaired lymph
trunk:
 Jugular
Lymph Trunk
 Subclavian
Lymph Trunk
 Bronchomediastinal
 Lumbar
Lymph Trunk
Lymph Trunk
 Intestinal
Trunk(unpaired)
Lymph Nodes

Lymph nodes are areas of concentrated lymphocytes and
macrophages along the lymphatic veins.

Located in the neck, armpit, groin, center of chest and
abdomen

Act as filters for foreign particles and cancer cells


Do NOT deal with toxicity
They become inflamed or enlarged in various infections
and diseases
The Spleen

It is a reservoir for blood

It filters the blood and lymph fluid that flows through

It sits under the rib cage in the upper left part of the
abdomen towards the back
The Thymus

secretes hormone, thymosin, that causes pre-T-cells to
mature into the T-cells
The Bone Marrow

contains tissue that produces lymphocytes
 All
lymphocytes derive from stem cells in the bone
marrow
Absorption(and return) of Fluid

The Lymphatic System returns excess interstitial
fluid(A.K.A tissue fluid) to the blood

Lymph capillaries pick up the excess interstitial fluid and
proteins and return them to the venous blood
 When
lymph
the fluid enters the lymph capillaries it is called
Fluid Formation
Lymph starts as Interstitial fluid
 The interstitial fluid forms at the end of the
arterial end of capillaries, through which
hydrostatic pressure pushes outward,
creating a fluid similar to plasma in terms of
function. Interstitial fluid maintains
equilibrium by osmotic pressure, which
pushes water into the capillaries due to
solubility.
 90% returns to the venules. The other 10%
enters the lymph capillaries making it now
lymph

Absorption of Fat

The Lymphatic system’s second function is the absorption
of fats and fat-soluble vitamins from the digestive system,
and the transport of these to the venous circulation

There are lymph capillaries called lacteals in the villi of
the small intestine that absorb fats and fat solubles
Immune System Function

Lymph nodes and other lymphatic organs filter the lymph
to remove microorganisms and other foreign particles

The nonspecific responses are the first line of defense

Highly specific responses are the second line of defense
and are tailored to an individual threat
Non-specific vs. Specific
Non-specific vs. Specific

The immune response includes both specific and
nonspecific components

Nonspecific responses block the entry and spread of
disease-causing agents.
examples: Physical Barriers(skin), Inflammation, the
Complement system, and Immune Response
Non-specific vs. Specific(cont…)

Specific responses generate to specific invaders.

The immune system is more effective than the nonspecific
methods, and has a memory component that improves
response time when an invader of the same type (or
species) is again encountered(antibodies)
Specific Cells
T-Cells

A.K.A “T lymphocytes”

Act as helpers to other immune cells or attack pathogens
directly

After an infection, memory T cells persist in the body to
provide faster reaction to the same antigen
B-Cells

A.K.A “B lymphocytes”

Form plasma cells to produce antibodies

These antibodies neutralize the pathogen until other
immune cells destroy it
NK-Cells

A.K.A Natural Killer Cells

Lymphocytes that respond to a wide range of pathogens
and cancerous cells
Non-Specific Cells
Macrophages

A phagocyte that consumes pathogens, destroys cells, and
debris by phagocytestosis
Dendritic Cells

They detect pathogenic antigens which activate T and B
cells to help body fight off parasites
Eosinophils

granular leukocytes that reduce allergic inflammation and
help body fight off parasites
Basophils

granular leukocytes that trigger inflammation by releasing
heparin and histamine
Neutrophils

granular leukocytes that act as the first responder to the
site of infection

Neutrophils use chemotaxis to detect chemicals produced
by the infection agents
Inflammatory Response
1.
Damaged cells release histamine, a chemical messenger, that increases blood
flow to the infection site
2.
Inflammation produces heat; unfavorable to microbes; promotes healing;
raises mobility of W. blood cells; increases metabolic rate of cells
3.
Capillaries pass fluid into interstitial areas, which causes swelling
4.
Clotting factors trigger blood clots
5.
Monocytes clean up dead microbes, cells, and debris
Allergen Response

Allergies result from immune system hypersensitivity to weak antigens that do
not cause an immune response in most people

Some allergens include dust, molds, pollen, certain foods and some medicines
1.
After an exposure to an allergen, some people make IgE antibodies as well as
B and T memory cells
2.
Subsequent exposure to the same allergen releases IgE antibodies
3.
IgE antibodies bind to mast cells, which then releases histamine
1.
In some individuals, histamine causes life-threatening anaphylaxis
The Cardiovascular
System vs. The
Lymphatic System
The Cardiovascular System
I.
Carries oxygen throughout the body
II.
Flows in a continues loop
III.
Uses a pumping action
IV.
Blood is filtered by kidneys
The Lymphatic System
I.
collects and removes waste left behind in tissue
II.
Flows in an open circuit and only one direction
III.
Flows passively into the lymph capillaries by
movement such as breathing, muscle movement
and blood pumping
IV.
Invisible and difficult to detect damage
V.
Filtered by lymph nodes throughout the body
Bibliography
Boundless. Cardiovascular and Lymphatic System Defenses. 1 January 2015. Webpage. 23
March 2015.
Farabee, M.J. Lymphatic System and Immunity. 2001. Webpage. 23 March 2015.
Knowedgebase. Lymphatic versus Cardiovascular Systems. 11 December 2013. Article. 23
March 2015.