1. What you should master in this topic:
Describe the formation of interstitial fluid
State the composition of interstitial fluid
State the importance of interstitial fluid
Describe the fate of interstitial fluid
Describe the structure of the lymphatic system
Explain how the lymphatic system complements the
circulatory system
Compare the contents of blood, interstitial fluid &
lymph
Predict what will happen if the interstitial fluid fails to
return to the circulatory system
Unit review

2. Blood flows from arteries into
capillaries – higher hydrostatic
pressure
Forces
some
plasma
pass
through capillary walls into
intercellular
spaces
between
cells.
Another 15% of interstitial fluid
goes into lymph capillaries.
Now, known as Lymph
Now, the fluid known as
Interstitial fluid @ tissue fluid
It fills the spaces between cells &
constantly bathes the cells.
85% of interstitial fluid re-enter
the blood capillary

3. Importance
Forms the internal environment of
body
Bathes the cells & supplies them
with O2 & nutrients which diffuse
from blood through the interstitial
fluid into cells
Excretory waste products diffuse
out of the cells into interstitial
fluid
Composition
About similar to blood plasma
content
but
minus
erythrocytes, platelets, plasma
protein
molecules
(albumin, globulin, fibrinogen)
Leucocytes esp. phagocytes can
pass through capillary wall & be
present in interstitial fluid
Interstiti
al Fluid
FACT
85% of interstitial fluid flows back into venous end of the capillary system
where the hydrostatic pressure low
Remaining 15% enters lymphatic capillaries and known as LYMPH
Lymphatic capillaries unite to form lymphatic vessel
Excess interstitial fluid unable to return to blood circulatory system will
accumulate & cause tissue swelling known as OEDEMA

4. Structure of the Lymphatic System
Lymphatic system is a one-way system consisting of a network of lymph
capillaries, lymphatic vessels & lymph nodes

5. How the lymphatic system complements the circulatory system

6. Relationship between the
Lymphatic System & Circulatory
System
Heart
Blood capillaries
Left subclavian
vein
Right
subclavian vein
Interstitial fluid
Thoracic duct
Right lymphatic
duct
Lymph capillary
Lymph vessels

7. Role of the Lymphatic System in Transport
Collects the interstitial fluid and returns it to the
circulatory system
Fats & fat-soluble vitamins are absorb through
lacteals & transported to the blood circulatory
system
The lymph nodes filter out bacteria & other
foreign particles. Phagocytes present in the
nodes engulf & destroy foreign particles.
Lymphocytes produce antibodies which aid in
the destruction of pathogens & the neutralisation
of toxins

8. The lymphatic system returns excess interstitial fluid to the blood,
absorbs fats and fat-soluble vitamins, and provides defense against
disease.
Lymph is the fluid in the lymphatic vessels. It is picked up from the
interstitial fluid and returned to the blood plasma.
Lymphatic vessels carry fluid away from the tissues.
The right lymphatic duct drains lymph from the upper right quadrant
of the body and the thoracic duct drains all the rest.
Pressure gradients that move fluid through the lymphatic vessels
come from the skeletal muscle action, respiratory movements, and
contraction of smooth muscle in vessel walls.
Tonsils are clusters of lymphatic tissue associated with openings
into the pharynx and provide protection against pathogens that may
enter through the nose and mouth.
The spleen is a lymph organ that filters blood and also acts as a
reservoir for blood.
The thymus is large in the infant and atrophies after puberty.