Anatomy and pattern recognition of the lymphatic system Flashcards
(18 cards)
What is the immune system?
It is the bodies first line of defence
Immunity and themlymphatic system
Microorganisms (viruses, bacteria, fungi and
parasites) are known as pathogens.
Each pathogen interacts with the body in a
characteristic way
• viruses exist within cells which they
eventually destroy
• Bacteria multiply in the interstitial fluids
• Parasites burrow through internal organs
The lymphatic system includes cells, tissues and
organs.
• The primary cells are lymphocytes.
types of immunity
immunity:
inate (at birth) = specific (against specific pathogen) and non specific
acquired = passive split into natural (from mother placental tcirculation to fetus) and artificial (administration of antitoxins)
active split into natural (infection recovery an actual disease) and artificial (immunisation and vaccination)
Blood cells
The 3 main types of blood cell are:
o red cells (erythrocytes)
o Platelets (thrombocytes)
o White cells (Leukocytes)
Leukocytes (White blood cells)
Our white blood cells are associated with defence and immunity
• They detect and destroy foreign / abnormal material through a range of processes
• They are the largest type of blood cells but only make up 1% of blood volume
There are 2 main types
o Granulocytes
o Agranulocytes
Phagocytosis
• Translates as cell eating
• This is the first line of defence for the
immune system
• The white blood cells are attracted to sites of
inflammation and infection by chemotaxis
• They engulf and destroy
• Microbes (e.g. bacteria)
• Foreign cells (e.g. tumour cells)
• Antigenic material (cause the production
of antibodies)
• Damaged cells and debris
• They can also release chemicals into the
lymph which are toxic to microbes
Lymphocytes
• Smaller than monocytes, and make up
approximately 30% of white blood cells
• They are found in the blood, but most
are in the lymphoid tissue
• They all originate from the same type of
stem cell in red bone marrow / lymphoid
tissue but they can develop into either
o Non specific
o Specific
B-lymphocytes
T-lymphocytes
B-Lymphocytes
o Produced and matured in red bone marrow, stored in lymphoid tissue
o They produce antigens (immunoglobins) - proteins that atta h to and destroy antigens
o They only respond to one type of antigen
o Provide antibody mediated immunity
T-Lymphocytes
o Mature in the thymus which programmes them to only respond to one antigen
o Found more in circulation
o They rely on other cells to present the antigen to be destroyed
o Cell mediated immunity
Interstitial fluid and lymph - overview
Interstitial fluid between the cells diffuses from the bloodstream
through the permeable capillary walls
• Most of this fluid diffuses back into the bloodstream through the venous capillaries
• The remaining fluid diffuses through the lymph capillaries – and is called lymph
• It passes through the lymphatic system and the lymph nodes before diffusing back into the blood
Functions of the lymphatic system
Immunity
• Production and maturation of white blood cells
• 90% of the body’s immune cells are within the lymphatic tissue
• All organs / tissue is supported by a network of lymph vessels and nodes
Tissue drainage (homeostasis)
• 21 litres of interstitial fluid diffuses from your bloodstream each day
• Most returns directly to the blood
• Excess fluid (3-4 litres) drains through the lymphatic system
Absorption of fat / fat soluble nutrients / fatty acids
• Absorbs into the central lymphatic vessels in the villi of the small bowel
lymph transportation
o Carries larger particles (bacteria and cell debris) to be filtered and destroyed in the lymph nodes
o It circulates lymphocytes throughout the lymphatic system
Lymph capillaries
They are designed to let fluid flow only one way
• Have a one way valve and are closed at the
proximal end
Lymphatic vessels
• Formed by a network of lymphatic capillaries
• Movement of lymph is similar to venous flow
and return via
• Rhythmic contraction of muscle layers
causes lymph movement
• Contraction of adjacent muscles
Lymphatic ducts
The lymphatic vessels drain into 2 large ducts
• Both drain back into the venous system through the respective subclavian veins
Lymph nodes
• Small oval shaped organs that are found along the lymph vessels, usually in groups
• Lymph normally passes through a number (8-10) nodes before re- entering the circulation
• They vary in size from 1mm to 20mm
• Their functions are
• Filtration and phagocytosis
• Multiplication of lymphocytes which, when activated release antibodies
Spleen
• Largest lymphatic organ
• Has a hilum containing
• Splenic artery
• Splenic vein
• Nerves and lymph vessels
Functions of the spleen
phagocytosis
blood storage
immune response
Erythropoiesis
