Unit 11 assignment 6
The lymphatic system
The lymphatic system is made up of lymph vessels, lymph and lymph glands. It is a
network of tissues and organs which helps rid the body of toxins, waste and other
unwanted materials. The function of the lymphatic system is to transport lymph, a fluid
containing infection-fighting white blood cells, throughout the body. The structure of the
lymph vessels consists of an inner lining of single layer epithelial cells, which are
composed of endothelium (a type of epithelial)
and can be also known as endothelial cells.
Following this, the next layer is the smooth
muscles which are organised in a circular
position around the endothelium. Smooth
muscles can adapt the diameter of the lumen
which can be done via contractions and
dilations. Then, the outer layer is called the
adventitia which is made of fibrous tissue. This
layer has the function of binding the lymph vessels to surrounding tissues.
Lymph contain water and there are no plasma proteins or red blood cells present( these
are the blood cells that carry oxygen.) However, white blood cells (which are part of the
body's immune response) are present. They help the body fight infection and other
diseases. Also, sometimes proteins may be present which can be derived from cells
which synthesise them. All that is contained will travel in the lymph vessels to join the
blood eventually in the subclavian vein, which vary in size and have no pumping
mechanism. Exercise is therefore important to squish the veins via muscle contraction.
Lymph vessels that carry lymph to a lymph node are called afferent lymph vessels, and
those that carry lymph from a lymph node are called efferent lymph vessels.
The thymus is a lymph gland which consists of two
lobes which merge in the middle. Surrounding these
are a capsule which extends out in to blood vessels
which further extend into the interior. The lobe is
made up of an inner medulla (which are less dense)
and an outer cortex, which is filled with cells.
Thymocytes make up the cortex and these are
immature T-cells which are supported by a network of
epithelial reticular cells. Epithelial reticular cells are
, Unit 11 assignment 6
the cells involved with making sure that no T cells can survive, which will attack the
body's own cells. In the medulla, networks of epithelial cells are coarser, unlike the
cortex, and there are less lymphoid cells available. Other cells which are also present in
the thymus are B-cells.
Tonsils are composed of tissues which are similar to lymph nodes and coated in pink
mucosa. Crypts (called pits) run through each tonsils’ mucosa. The structure of tonsils
consists of soft tissue located at the back of the throat called pharynx.
The spleen is a soft organ with a thin outer coating of tough connective tissue. This is a
material made up of fibres forming a framework and support structure for body tissues
and organs. The spleen contains two main regions of tissues which are the red pulp and
the white pulp. The red pulp contains cavities filled with splenic cords and blood, which
are connective tissue that contain red and white blood cells. White pulp is made of
mainly T-cells and B-cells which are immune cells.
The structure of a lymph node is a cortex and a capsule. The cortex is concealed in the
capsule and contains inactive B and T lymphocytes. The capsule is an outer layer of
connective tissue.
The lymph capillaries are the smallest, tiny vessels
which join up to create lymph trunks. The lymph
capillaries have no pump so walls are easily
squashed and very thin. Therefore, contractions of
muscles in limbs helps to push the lymph along.
Lymph trunks are bigger than the lymph capillaries
and join up to create lymph ducts. The lymph ducts
are even bigger and combine to create a thoracic duct - this is the largest vessel which
has valves in order to prevent the backflow of lymph. Tissue fluid enters through slits in
the walls of the vessels.
Lymphs need to flow into the blood to allow large proteins and white blood cells to join
the blood system, to maintain fluid content and prevent oedema or swelling. It allows
the absorbed fatty acids from the villi in the small intestine to join the blood system and
be used everywhere.
The main purpose of this system is protecting the body against infection. To help the
system do this, there are B lymphocytes divided to form plasma cells which will produce
specific antibodies against viruses and bacteria. Also, T lymphocytes move between the
The lymphatic system
The lymphatic system is made up of lymph vessels, lymph and lymph glands. It is a
network of tissues and organs which helps rid the body of toxins, waste and other
unwanted materials. The function of the lymphatic system is to transport lymph, a fluid
containing infection-fighting white blood cells, throughout the body. The structure of the
lymph vessels consists of an inner lining of single layer epithelial cells, which are
composed of endothelium (a type of epithelial)
and can be also known as endothelial cells.
Following this, the next layer is the smooth
muscles which are organised in a circular
position around the endothelium. Smooth
muscles can adapt the diameter of the lumen
which can be done via contractions and
dilations. Then, the outer layer is called the
adventitia which is made of fibrous tissue. This
layer has the function of binding the lymph vessels to surrounding tissues.
Lymph contain water and there are no plasma proteins or red blood cells present( these
are the blood cells that carry oxygen.) However, white blood cells (which are part of the
body's immune response) are present. They help the body fight infection and other
diseases. Also, sometimes proteins may be present which can be derived from cells
which synthesise them. All that is contained will travel in the lymph vessels to join the
blood eventually in the subclavian vein, which vary in size and have no pumping
mechanism. Exercise is therefore important to squish the veins via muscle contraction.
Lymph vessels that carry lymph to a lymph node are called afferent lymph vessels, and
those that carry lymph from a lymph node are called efferent lymph vessels.
The thymus is a lymph gland which consists of two
lobes which merge in the middle. Surrounding these
are a capsule which extends out in to blood vessels
which further extend into the interior. The lobe is
made up of an inner medulla (which are less dense)
and an outer cortex, which is filled with cells.
Thymocytes make up the cortex and these are
immature T-cells which are supported by a network of
epithelial reticular cells. Epithelial reticular cells are
, Unit 11 assignment 6
the cells involved with making sure that no T cells can survive, which will attack the
body's own cells. In the medulla, networks of epithelial cells are coarser, unlike the
cortex, and there are less lymphoid cells available. Other cells which are also present in
the thymus are B-cells.
Tonsils are composed of tissues which are similar to lymph nodes and coated in pink
mucosa. Crypts (called pits) run through each tonsils’ mucosa. The structure of tonsils
consists of soft tissue located at the back of the throat called pharynx.
The spleen is a soft organ with a thin outer coating of tough connective tissue. This is a
material made up of fibres forming a framework and support structure for body tissues
and organs. The spleen contains two main regions of tissues which are the red pulp and
the white pulp. The red pulp contains cavities filled with splenic cords and blood, which
are connective tissue that contain red and white blood cells. White pulp is made of
mainly T-cells and B-cells which are immune cells.
The structure of a lymph node is a cortex and a capsule. The cortex is concealed in the
capsule and contains inactive B and T lymphocytes. The capsule is an outer layer of
connective tissue.
The lymph capillaries are the smallest, tiny vessels
which join up to create lymph trunks. The lymph
capillaries have no pump so walls are easily
squashed and very thin. Therefore, contractions of
muscles in limbs helps to push the lymph along.
Lymph trunks are bigger than the lymph capillaries
and join up to create lymph ducts. The lymph ducts
are even bigger and combine to create a thoracic duct - this is the largest vessel which
has valves in order to prevent the backflow of lymph. Tissue fluid enters through slits in
the walls of the vessels.
Lymphs need to flow into the blood to allow large proteins and white blood cells to join
the blood system, to maintain fluid content and prevent oedema or swelling. It allows
the absorbed fatty acids from the villi in the small intestine to join the blood system and
be used everywhere.
The main purpose of this system is protecting the body against infection. To help the
system do this, there are B lymphocytes divided to form plasma cells which will produce
specific antibodies against viruses and bacteria. Also, T lymphocytes move between the
