Flashcards in Lecture 2 - Immunology Deck (29):
What is the function of the lymphatic system?
– Maintain fluid balance in the
• Filters & returns some interstitial fluid to blood.
• Absorbs fats & fat-soluble vitamins from the intestine & delivers them to blood.
– Active role in immunity – houses & supports immune cells
What is the direction of flow of lymph?
One direction: from periphery back to central circulation (heart).
(START) Initial lymphatic capillary – collecting lymphatic capillary- lymphatic veins – right and left thoracic duct – return to bloodstream (END).
Initial lymphatic capillary: begin blindly in the intercellular spaces of the soft tissues, they do not form a closed circuit – an open or one-way system (CVS is a closed network).
What is the structure of the lymphatic system?
• The conducting system (lymphatic capillaries (conduits), lymph vessels (veins) and right lymphatic duct and left thoracic duct).
• Lymphoid tissue (lymph nodes, spleen, thymus, mucosa associated lymphoid tissue, gut MALT).
What is the function of the lymphatic vessels?
• Act as ‘drains’ to collect excess tissue fluid and return it to the venous blood just before it returns to the heart.
• Also transport proteins, fats, antigens and other substances to the general circulation.
• Lymphatic vessels begin blindly in the intercellular spaces of the soft tissues, they do not form a closed circuit – an open or one- way system (CVS is a closed network).
• Fluid flow through the lymphatic system relies on the skeletal muscle pump, respiratory pump
& one-way valve.
What is lymph?
A clear, watery fluid found in lymphatic vessels.
Closely resembles plasma, containing electrolytes, lower percentage of dissolved proteins (mostly albumin).
On its journey to join blood picks up other constituents = WBC as it passes through lymph nodes; migrating cancer cells.
Higher protein in thoracic duct lymph due to protein rich lymph from the liver and small intestine.
What are the function of lymph nodes?
• Filtration, both mechanical & biological:
– Trap pathogens, cancer cells (removal or radiation prevents further spread) - breast cancer cells first spread to axillary nodes.
– Phagocytosis - of microorganisms and other injurious particles.
• Haematopoiesis (training camps):
- Final stages of maturation of some lymphocytes & monocytes.
What are the tonsils?
Masses of lymphoid tissue form a broken ring around the opening of the throat at the back of the mouth.
Protect against pathogens that may invade tissues around the openings between nasal and oral cavities.
Palatine, pharyngal, lingual
Often subject to chronic infection.
What is the thymus?
Central organ of the lymphatic system located in the mediastinum.
70g in infants, 30g at puberty, shrinks with aging (3g).
Vital role in immunity.
Enables immature lymphocytes to develop into T cells before migrating to other lymphoid organs (thymosin and thymopoeitin).
Source of lymphocytes before birth.
What is the function of the spleen?
Defence - macrophages in spleen remove microorgansisms from blood and phagocytose them.
Haematopoiesis - production of new cells and destruction of old RBC and capturing iron.
Site of RBC production in foetus & severely anaemic adult.
Primary immune response to bacteria, viruses, parasites, antigens.
What is MALT?
Mucosal associated lymphoid tissue.
Located on mucous membranes.
What is lymphodema?
Chronic swelling of a region of the body where the lymphatic system has failed to function properly.
What is primary lymphodema?
Inborn error in the lymphatic endothelial cell arising from genetic mutation (familial or spontaneous).
What is secondary lymphodema?
Cancer treatment or parasite infection means lymph nodes have been removed and lymph has nowhere to go.
What is lipidema?
Due to lymphatic abnormalities there is an increased accumulation of adipose tissue, mechanism unknown, drainage required.
What is a lymphatic malformation?
Due to somatic mutation - accident/spontaneous.
Grows with child (developed after).
No effective treatment
What is a lymphatic tumour?
Characterised by uncontrolled growth.
Generalised lymphatic anomaly (GLA).
No effective treatment.
Unique molecules present on surface of cells, viruses, bacteria etc that our body uses to identify foreign particles/organisms.
Define antibody (immunoglobulin)?
Y-shaped proteins made by our bodies to neutralise foreign particles/invading pathogens.
Chemicals released from cells to regulate or induce adaptive and innate immune responses.
Our ability to effectively respond to an antigen.
Our ability to effectively respond to an antigen is impaired/suppressed.
Belongs to our body.
Foreign to our body.
Define innate immunity?
Already present naturally at birth eg skin.
Requires no education or programming (fast response).
general defence against variety of non-self threats.
Define adaptive immunity?
Recognise foreign particle then adapt immune system to respond and destroy foreign particle.
Ability to attack abnormal or foreign cells but spare our own normal cells.
Free of or protected against.
What is the first line of defence?