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Assignment 2 Unit 8 - Physiology of Human Body Systems
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Aimee Baish FSC Group AAssignment B
What is the Lymphatic System?
The lymphatic system (Figure 1) is the organ system in the body which uses a type of white blood
cells, known as lymphocytes, to help fight pathogens and infections that they detect in lymph and it
also helps to transport and form lymph and lymphocytes. The lymphatic system also removes the
extracellular fluid from tissues, it maintains hydrostatic and osmotic pressure, and finally, it absorbs
fats from the digestive system. The structure of the lymphatic system is as follows. The lymphatic
capillaries, which run alongside the veins and arteries of the cardiovascular system, and they join to
lymphatic vessels, which include lymphatic valves, these vessels then connect to and run through the
lymphatic organs. Lymphatic vessels also run through and connect to the lymph nodes. It contains
vessels, primary lymphatic organs, secondary lymphatic organs and tissues. The lymphatic system is
formed of lymph, lymphatic vessels, lymphoid tissues and lymphatic organs, which is split into
primary and secondary categories. The lymphatic system also contains a lymphatic pathway which
forms and transports lymph. The primary lymphatic organs include: your red bone marrow and the
thymus. The secondary lymphatic organs include: the lymph nodes, tonsils, spleen, and the Peyer’s
patch. The Lymph nodes have 5 main regions. They are the supratrochlear region, the axillary region,
the popliteal region, the abdominal region, and the inguinal region.
Functions of the Lymphatic System
The lymphatic system contains and transports white blood cells (WBCs), macrophages and Dendritic
cells. Those white blood cells are called lymphocytes, and there are three different types which are:
B-cells, T-cells and Natural Killer cells. Macrophages are a type of WBC cell which digests foreign
materials, for example, dead pathogens or bacterial cells. Dendritic cells are cells which find the
correct antigen to fight a specific pathogen and then they present as that antigen to the T-cells. Then
these T-cells go to the site of infection and attack and/or kill infected or cancerous cells. B-cells make
the antibodies to help fight against antigens or infections. Finally, Natural Killer cells (NK cells) have
granules which contain enzymes, which help them to kill infected body cells, for example, NK cells
would kill an infected macrophage cell by using their enzyme granules. This is important because if
this fails then the body wouldn’t be able to fight off infections which means that the immune system
and body would be so much weaker, meaning that the body would then be overwhelmed with
infections. This means that your body would be extremely unwell and would need a lot of antibiotics
and medicines to help fight off these infections.
The lymphatic system transports and forms lymph. Formation of lymph will be explained later in this
assignment. The transportation of lymph works as follows. Step 1: Lymph is passed through
lymphatic vessels and lymphatic valves. Step 2: Lymph is passed through a lymphatic duct and then it
is transported into your subclavian veins which will lead to the lymph being added to general
circulation. If lymph isn’t transported around the body properly, then a build up of lymph would
occur. This would cause a serious condition called lymphoedema.
The lymphatic system removes interstitial fluid (extracellular fluid). Extracellular fluid is found among
cells inside of tissues. The lymphatic system drains out the excess extracellular fluid that builds up in
the lymphatic vessel. Which then forms lymph. The lymph then travels through the network of
capillaries, multiple lymph nodes and then larger vessels with valves. After that, the lymph is then
drained and filtered into the veins via thoracic ducts. Which then the lymph travels through venous
circulation. This removal of extracellular fluid is important because it helps to remove pathogens
, from venous circulation and the bloodstream. It also prevents abnormalities from occurring. For
example, swelling or muscle swelling, which can also lead to tears in the muscle.
The lymphatic system maintains hydrostatic and osmotic pressure. Hydrostatic pressure is the type
of pressure which pushes fluid out and away from the blood vessels or blood capillaries into the
lymphatic capillaries. Osmotic pressure is centred around osmosis. It’s a type of hydrostatic pressure
which is caused by water flowing across a membrane to higher concentration of solute particles.
Both osmotic and hydrostatic pressure work together to send fluid out of your blood stream and
make it return. This hydrostatic and osmotic pressure is responsible for moving fluid away from the
blood stream, if this process is not completed properly then it can lead to filtration and re-entry of
the fluid into capillaries going wrong, and there will be too much extracellular fluid in your blood
which can cause welling, high blood pressure, headaches and many other symptoms.
The lymphatic system absorbs fats from the digestive system. The digestion products are soaked up
through the ileum wall. The ileum is the part of your small intestine at the end which connects to
your rectum. The lacteals in the ileum then absorb the fat and the fat-soluble vitamins to form chyle.
Lacteals are the vessels which transport chyle from the ileum to the thoracic duct. Fat-soluble
vitamins are vitamins are dissolved in fat/fatty acids instead of water. These are vitamins A, D, E and
K. Chyle consists of lymph, emulsified fats and fatty acids. The chyle will then pass through the
lymphatic vessels to the thoracic ducts, then the chyle is transported through these thoracic ducts
and drained into the blood vessels. This process is super important because if fats aren’t absorbed,
then fat-soluble vitamins can’t be absorbed and made into chyle. This leads to a fat-soluble vitamin
deficiency which can cause serious conditions. For example, a vitamin A deficiency can lead to skin
conditions and a vitamin D deficiency can cause osteomalacia which is a condition which is very
similar to osteoporosis. However, Osteomalacia is reversible and you can reverse it just by increasing
your vitamin D intake, but osteoporosis is irreversible.
What is lymph?
Lymph is extracellular fluid (interstitial fluid), which is colourless (clear), it travels to the lymphatic
system from the cardiovascular system, so it travels to the lymphatic vessels through the lymphatic
pathway from the blood capillaries. Lymph is made up of lymphocytes, water and chyle (when the
extracellular fluid has been through the digestive system too). Chyle is a milky fluid which consists of
lymph, emulsified fats and fatty acids. However, when lymph has not reached the lymphatic vessels
or it has already passed through, it isn’t known as lymph. It is known as extracellular fluid instead.
Lymph is used to move nutrients to the required cells, it is important this role is performed because
if not, the body wouldn’t be able to absorb the correct nutrients into the correct organs and/or
vessels which could lead to deficiencies in different nutrients, for example, iron, calcium, vitamin A,
etc. Lymph also allows for communication between cells, this role means that the cells in the blood
capillaries or arteries can communicate with the cells of the lymphatic vessels, this means that if
there is an infection and the white blood cells in your blood vessels aren’t enough to completely
fight the infection, then lymph will tell the lymphatic cells in your lymphatic vessels to release
lymphocytes and then the lymphocytes will travel through the lymphatic vessels and into the
bloodstream to the site of infection. Lymph has one last function, it gets rid of the metabolic waste
from the cells in your blood capillaries or your lymphatic vessels, this helps to filter the metabolic
waste out of cells and into the right vessels to get rid of it. This will lower the chances of the
pathogens (infectious cells) getting into your cells and multiplying, which then decreases the risk of
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