Lymphatic System
- Falls under as part of the circulatory system
- Is a network of nodes and vessels that cover almost all aspects
of the body
- All lymph empties into the venous circulation in the upper
thorax and neck
- Starts in the region of the capillary beds
- Principle function: to pick up or collect an excess extracellular
fluid and return it to the circulatory system
Body Defences
- is also involved in the body’s defence mechanisms
- The body’s resistance to pathogens is determined by innate or acquired/adaptive immunity
- Innate immunity – genetically determined, no prior exposure or antibody production
involved
- Responsible for this: cellular components, proteins and peptides
- Adaptive immunity: produced by prior exposure or antibody production
- Responsible for this: lymphocytes
- Adaptive is further divided into passive immunity and active immunity (look at image for
further guidance)
Components of the lymphatic system
- Lymph - connective tissue dominated by lymphocytes
- Interstitial fluid entering the lymphatic vessels – similar to plasma
- Lymphatic vessels – drainage system. Are smaller at the peripheries, increase in size as they
travel towards centre of body
, - Lymphoid tissues – in mucosa of organs (MALT)
- Lymphoid organs
- Primary – bone marrow and thymus
(generate lymphocytes from immature
progenitor cells)
- Secondary – spleen and lymph nodes
- In the limbs there are very few lymph
nodes
- When looking at people for possible
infections would need to look in the
inguinal region- superficial inguinal nodes
(groin) and in the axilla (armpits)
- These areas would need to increase white
blood cell count when body is infected
- The major lymphatic vessel in the thorax or
abdomen commence at the cisterna chyli
- Cisterna chyli – vessel where lymph begins
to collect. It runs up into the thoracic duct
and empties back into the venous system at the point where the left subclavian vein meets
the left internal jugular vein
- The thoracic duct receives lymph from the peach section (3/4 of the body)– upper left, lower
right and lower left quadrants
- The lymphatic duct receives lymph from the light blue section (1/4 of the body) – upper right
quadrant
How the lymph is collected from the capillary bed
- In the image there is an artery flowing in and a venule flowing out.
- The capillaries at this level are leaky and so fluid as well as other plasma components can
leak out
- The lymphatic vessels commence as capillaries to form afferent lymphatic vessels
- An afferent lymphatic vessel will flow into a lymph node, from that lymph node there will be
an efferent vessel flowing to another lymph node or into the thoracic duct
- Whether the vessel is afferent or efferent depends on the node and vessel. Afferent means
flow in and efferent means flow out.
Lymphatic system functions
- Transport fluids back to the blood (CVS)
- Provides defence and resistance to disease
Properties of lymphatic vessels
- One way system toward the heart
- Falls under as part of the circulatory system
- Is a network of nodes and vessels that cover almost all aspects
of the body
- All lymph empties into the venous circulation in the upper
thorax and neck
- Starts in the region of the capillary beds
- Principle function: to pick up or collect an excess extracellular
fluid and return it to the circulatory system
Body Defences
- is also involved in the body’s defence mechanisms
- The body’s resistance to pathogens is determined by innate or acquired/adaptive immunity
- Innate immunity – genetically determined, no prior exposure or antibody production
involved
- Responsible for this: cellular components, proteins and peptides
- Adaptive immunity: produced by prior exposure or antibody production
- Responsible for this: lymphocytes
- Adaptive is further divided into passive immunity and active immunity (look at image for
further guidance)
Components of the lymphatic system
- Lymph - connective tissue dominated by lymphocytes
- Interstitial fluid entering the lymphatic vessels – similar to plasma
- Lymphatic vessels – drainage system. Are smaller at the peripheries, increase in size as they
travel towards centre of body
, - Lymphoid tissues – in mucosa of organs (MALT)
- Lymphoid organs
- Primary – bone marrow and thymus
(generate lymphocytes from immature
progenitor cells)
- Secondary – spleen and lymph nodes
- In the limbs there are very few lymph
nodes
- When looking at people for possible
infections would need to look in the
inguinal region- superficial inguinal nodes
(groin) and in the axilla (armpits)
- These areas would need to increase white
blood cell count when body is infected
- The major lymphatic vessel in the thorax or
abdomen commence at the cisterna chyli
- Cisterna chyli – vessel where lymph begins
to collect. It runs up into the thoracic duct
and empties back into the venous system at the point where the left subclavian vein meets
the left internal jugular vein
- The thoracic duct receives lymph from the peach section (3/4 of the body)– upper left, lower
right and lower left quadrants
- The lymphatic duct receives lymph from the light blue section (1/4 of the body) – upper right
quadrant
How the lymph is collected from the capillary bed
- In the image there is an artery flowing in and a venule flowing out.
- The capillaries at this level are leaky and so fluid as well as other plasma components can
leak out
- The lymphatic vessels commence as capillaries to form afferent lymphatic vessels
- An afferent lymphatic vessel will flow into a lymph node, from that lymph node there will be
an efferent vessel flowing to another lymph node or into the thoracic duct
- Whether the vessel is afferent or efferent depends on the node and vessel. Afferent means
flow in and efferent means flow out.
Lymphatic system functions
- Transport fluids back to the blood (CVS)
- Provides defence and resistance to disease
Properties of lymphatic vessels
- One way system toward the heart
