Transcript the lymphatic system

The lymphatic system
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
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
3 Key words
lymph
oedema
lacteals
lymphatic capillaries
tissue (interstitial) fluid
lymphatic vessels
lymphatic nodes
deep cervical nodes
superficial cervical
nodes
submandibular nodes
occipital nodes
mastoid nodes
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
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
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
6 Structures of the
lymphatic system
Structure
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 microorganisms, 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
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
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
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
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
Cervical nodes
(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
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
12 Lymph nodes of
head and neck
Published by Hodder Education © 2010 Helen McGuinness
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
Cervical nodes
(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
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
15 Lymph nodes
of body
Published by Hodder Education © 2010 Helen McGuinness
16 Other lymphatic organs
 Other lymphatic organs include the
spleen, tonsils and thymus gland.
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
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 Tcells 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
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 gastrointestinal tracts. Typical antigens include pollen, dust,
feathers, wool, fur, certain foods and drugs.
Published by Hodder Education © 2010 Helen McGuinness