Lecture 18 - Lymphatic System Flashcards
What are the constituents of the lymphatic system?
what are the tissue and organs ? Cells ?
- Fluid -Lymph
- Vessels -Lymphatics
- Cells:
- Lymphocytes –B cells, T cells, NK cells
- Supporting cells –Dendritic cells, macrophages
- Tissues:
- Diffuse –Mucosal-Associated Lymphoid Tissue (MALT) • Lymphoid nodules -E.g. Tonsils, Peyer’s patches, vermiform appendix
- Organs:
- Lymph nodes
- Thymus
- Spleen
what are the functions of the lypmhatics system ?
adaptive immunity
fluid drainage
fat absorption
structure and function of lymphatic vessels ?
what factors aide lymph flow
- Lymph flows from superficial to deep
- Tend to run adjacent to arteries and veins
- Larger lymphatics (e.g. thoracic duct) have smooth muscle
• No lymphatics in CNS –Danger of oedema
- Factors aiding lymph flow: • Skeletal muscle contractions
- Negative thoracic pressure during breathing
- Pulsations of adjacent arteries
has a valve to prevent back flow - like the veins
deep muscular contraction will aide lymph movement
some larger lymph have smooth muscle to help movement
drains through tissue fluid into lymph cappiliaries and vessels then it will flow though lymph nodes to lymph trunks before reentering into circulation
what are lymphoid nodules ?
structure ?
Structure
Nodule capsule structure - like a bean -has feeding artery and vein for blood flow - lymphoctyes enter through feeding artery
afferent lymph enter via convex surface and efferent lymphatics leaves via hillium
Lymphocytes enter via feeding artery and leave via the efferent lymphatic
• Germinal centres – Macrophages and dendritic cells present antigens to lymphocytes
filters the lymph - traps and presents antigens to T cells
marophages, T and B cells work toghether to produce and inflammitory response and immune response
in the nodes B cells will present antigens to the T cells
Locations
tonsils - prevents pathogen entry through mouth and nose
peyers patch - stops pathogen entry via digestion
in appendix
Lymphadenopathy
Lymphadenopathy
an increasing number of lymphocytes in the nodes causing swelling and pain
- Causes:
- Infection
- Malignancy / cancer
- Sentinel lymph nodes –The lymph nodes that a cancer will tend to spread to first
- Sentinel lymph node biopsy can determine whether a cancer has metastasised
what is lymphodema
primamry is a congenital lack of lymphatics - from birth
secondary - due to removal of lymph nodes eg cancer patients
is non-pitting
massive odema of the limbs - due to the body not being able to drain via the lymph system
what is the thymus ?
Site of T cell maturation
useless fat by adulthood
spleen ?
what is its function ?
if you can , not vital, what are some issues?
spleen filers blood like lymph nodes filer lymph, both immune and heamopoeitic functions
• White pulp –Immunological function, similar to lymphoid follicles - APC antigen presenting
proliferation of T and B lymphoctyes, production of antibodies
• Red pulp –Removal and destruction of old/damaged/abnormalRBCs
- Can enlarge (splenomegaly) –Prone to rupture
- Overworking of white pulp –I.e. Infection(particularly glandular fever, malaria and sepsis)
- Overworking of red pulp –I.e. Haemolytic anaemias • Portal hypertension
- Splenectomyis common –If spleen ruptures it can lead to death by exsanguination
- Increases risk of infection by encapsulated bacteria(e.g. meningococcus)
summarise the functions of the lymphatic system
- Fluid balance
• Most of the interstitial fluid is returned to the circulation by this route - Transport of fats and fat-soluble vitamins
• Quickest way to send lipid soluble materials from the digestive system to the venous circulation - Defence against invading pathogens and disease
• Lymph nodes and other lymphatic organs filter the lymph to remove microorganisms, parasites,
foreign particles and [cancer cells]
• ‘Visiting’ T and B lymphocytes and macrophages – motel system - Storage of and destruction of aged erythrocytes
• The spleen is responsible for this role – liver can take over after splenectomy
