1. Published by Hodder Education © 2010 Helen McGuinness
The lymphatic system
Published by Hodder Education © 2010 Helen McGuinness

2. Published by Hodder Education © 2010 Helen McGuinness
1 Objectives
By the end of this chapter you will be able to recall and understand the following knowledge:
the functions of the lymphatic system
the definition of lymph and how it is formed
the connection between blood and lymph
the circulatory pathway of lymph
Published by Hodder Education © 2010 Helen McGuinness

3. Published by Hodder Education © 2010 Helen McGuinness
2 Objectives
the names and positions and drainage of the main lymphatic nodes of the head, neck and the body
the immune response
the interrelationships between the lymphatic and other body systems
common pathologies of the lymphatic system.
Published by Hodder Education © 2010 Helen McGuinness

4. Published by Hodder Education © 2010 Helen McGuinness
3 Key words
parotid nodes
axillary nodes
supratrochlear nodes
thoracic nodes
abdominal nodes
pelvic nodes
inguinal nodes
popliteal nodes
thoracic duct
right lymphatic duct
subclavian veins
spleen
tonsils
thymus
immunity
specific immunity
non-specific immunity
antigen
antibody
humoral immunity
cell-mediated immunity
immunisation
allergic reaction
lymph
oedema
lacteals
lymphatic capillaries
tissue (interstitial) fluid
lymphatic vessels
lymphatic nodes
deep cervical nodes
superficial cervical nodes
submandibular nodes
occipital nodes
mastoid nodes
Published by Hodder Education © 2010 Helen McGuinness

5. Published by Hodder Education © 2010 Helen McGuinness
4 Functions
The lymphatic system is closely associated with the cardiovascular system.
The lymphatic system assists the blood by draining the tissues of excess fluid and returning the fluid from the tissues back to heart. This helps to maintain blood volume, blood pressure and prevent oedema (waterlogging of the tissues).
The lymphatic systems also plays an important role in the body’s immune system as the lymph nodes fight infection and generate antibodies.
The lymphatic system also absorbs the products of fat digestion through the intestinal lymph vessels called the lacteals.
Published by Hodder Education © 2010 Helen McGuinness

6. Published by Hodder Education © 2010 Helen McGuinness
5 Definition of lymph
Lymph is a clear, colourless, water fluid derived from tissue fluid and contained within lymph vessels.
Lymph is similar in composition to blood except that it has a lower concentration of plasma proteins.
Published by Hodder Education © 2010 Helen McGuinness

7. 6 Structures of the lymphatic system
Description
Function
Lymphatic capillaries
Minute blind-end tubes, similar in structure to blood capillaries
Drain away excess fluid and waste products from tissue spaces of body
Lymphatic vessels
Similar in structure to veins
Have one-way valves and thin, collapsible walls
Carry lymph towards heart
Lymphatic nodes
Oval or bean-shaped structures covered by a capsule of connective tissue
Made up of lymphatic tissue
Filter lymph of micro-organisms, cell debris or harmful substances
Lymphatic ducts
(thoracic and right lymphatic)
Thoracic duct is largest lymphatic vessel and extends from second lumbar vertebra up through thorax to root of neck
Right lymphatic duct is very short in length
Lies in root of neck
Collect lymph from whole body and return it to blood via subclavian veins
Published by Hodder Education © 2010 Helen McGuinness

8. 7 Circulatory pathway of lymph
The circulatory pathway of lymph begins with lymphatic capillaries which lie in the tissue spaces between the cells.
Tissue (interstitial) fluid drains into lymphatic capillaries and the excess fluid becomes lymph.
Lymphatic capillaries merge to form larger vessels called lymphatic vessels which convey lymph in and out of structures called lymph nodes.
Published by Hodder Education © 2010 Helen McGuinness

9. 8 Circulatory pathway of lymph
Lymph passes through at least one node where it is filtered of cell debris, micro-organisms and harmful substances.
Once filtered, the lymph is collected into two main ducts – the thoracic duct (the largest duct), which collects lymph from the left side of the head and neck, left arm, lower limbs and abdomen, and the right lymphatic duct, which collects lymph from the right side of the head and neck and the right arm.
The collected lymph is then drained into the venous system via the right and left subclavian veins.
Published by Hodder Education © 2010 Helen McGuinness

10. 9 Circulatory pathway of lymph
1. Plasma escapes blood capillary and bathes tissue cells
2. Excess fluid flows through a network of lymphatic capillaries
3. Tissue fluid enters lymph vessels where it becomes lymph
4. Larger lymphatic vessels lead to lymph nodes
5. Lymph passes through at least one lymphatic node where it is filtered
6. Filtered lymph is collected into lymphatic ducts
7. Collected lymph is drained into the venous system via the subclavian veins
Published by Hodder Education © 2010 Helen McGuinness

11. 10 Lymph nodes of head and neck
Name
Position
Areas where drained from
Cervical nodes
(deep)
Deep within neck, located along the path of larger blood vessels (carotid artery and internal jugular vein)
Drain lymph from larynx, oesophagus, posterior of scalp and neck, superficial part of chest and arm
(superficial)
Located at side of neck, over sternomastoid muscle
Drain lymph from lower part of ear and cheek region
Submandibular nodes
Beneath mandible
Drain chin, lips, nose, cheeks and tongue
Occipital nodes
At base of skull
Drain back of scalp and upper part of neck
Published by Hodder Education © 2010 Helen McGuinness

12. 11 Lymph nodes of head and neck
Name
Position
Areas where drained from
Mastoid nodes
(post auricular)
Behind ear in region of mastoid process
Drain skin of ear and temporal region of scalp
Parotid nodes
At angle of jaw
Drain nose, eyelids and ear
Published by Hodder Education © 2010 Helen McGuinness

13. 12 Lymph nodes of head and neck
Published by Hodder Education © 2010 Helen McGuinness

14. Areas from where drained
13 Lymph nodes of body
Name
Position
Areas from where drained
Cervical nodes
(deep)
Deep within the neck, located along the path of larger blood vessels
Drain lymph from larynx, oesophagus, posterior of scalp and neck, superficial part of chest and arm
(superficial)
Located at side of neck over sternomastoid muscle
Drain lymph from lower part of ear and cheek region
Axillary nodes
In underarm region
Drain upper limbs, wall of thorax, breasts, upper wall of abdomen
Supratrochlear/ cubital nodes
In elbow region (medial side)
Upper limbs which passes through the axillary nodes
Thoracic nodes
Within thoracic cavity and along trachea and bronchi
Organs of thoracic cavity and from internal wall of thorax
Published by Hodder Education © 2010 Helen McGuinness

15. Areas from where drained
14 Lymph nodes of body
Name
Position
Areas from where drained
Abdominal nodes
Within abdominal cavity, along branches of abdominal aorta
Organs within abdominal cavity
Pelvic nodes
Within pelvic cavity, along paths of iliac blood vessels
Organs within pelvic cavity
Inguinal
In groin
Lower limbs, external genitalia and lower abdominal wall
Popliteal
Behind knee
Lower limbs through deep and superficial nodes
Published by Hodder Education © 2010 Helen McGuinness

16. Published by Hodder Education © 2010 Helen McGuinness
15 Lymph nodes of body
Published by Hodder Education © 2010 Helen McGuinness

17. 16 Other lymphatic organs
Other lymphatic organs include the spleen, tonsils and thymus gland.
Published by Hodder Education © 2010 Helen McGuinness

18. Published by Hodder Education © 2010 Helen McGuinness
17 Types of immunity
Immunity is the ability of the body to resist infection and disease by the activation of specific defence mechanisms.
There are two types of immunity – specific and non-specific.
Non-specific immunity is programmed genetically from birth and includes mechanical barriers (skin and mucous membrane), chemicals, inflammation, phagocytosis and fever.
Specific immunity involves interaction between an antigen and an antibody.
An antigen is any substance that the body regards as foreign or potentially dangerous, and against which it produces an antibody.
Published by Hodder Education © 2010 Helen McGuinness

19. Published by Hodder Education © 2010 Helen McGuinness
18 Types of immunity
An antibody is a specific protein produced to destroy or suppress antigens.
There are two types of immune response produced by different types of lymphocytes – humoral immunity involving B-lymphocytes which produce free antibodies that circulate in the bloodstream and cell-mediated immunity effected by helper T-cells, suppressor T- cells and natural killer (NK) cells that recognise and respond to certain antigens to protect the body against their effects.
Immunisation is when the body is artificially stimulated into producing antibodies.
Published by Hodder Education © 2010 Helen McGuinness

20. Published by Hodder Education © 2010 Helen McGuinness
19 Types of immunity
An allergic reaction may occur when a foreign substance, or antigen, enters the body.
An allergic reaction can only occur if the person has already been exposed to the antigen at least once before and has developed some antibody to it.
Antibodies are located on the cells in the skin or mucous membranes of the respiratory and gastro- intestinal tracts. Typical antigens include pollen, dust, feathers, wool, fur, certain foods and drugs.
Published by Hodder Education © 2010 Helen McGuinness