The Lymphatic system and Immunity Flashcards
The lymphatic system transports excess fluid out of the interstitial spaces and returns it to the…
Blood stream
Lymphatic vessels are found in bone? T or F
False
What are the two primary lymphoid organs?
Bone marrow and Thymus
Where are the lymphocytes produced?
Bone marrow, Lymph nodes
Name types of our first line of physical barriers or ‘innate (non-specific) defence’ of the body
skin, mucous membranes, hair, sweat, mucus
What do the lymphatic vessels have which prevent backflow of lymph?
Valves
Which direction do the lymphatic vessels move in?
One direction to the heart
Lymph from lymphatic vessels drains into one of two collecting ducts. Which are the two collecting ducts?
Right lymphatic duct and Thoracic (left) duct
What is it called when tissue fluid accumulates in the interstitial space?
Oedema
Name two types of lymphocytes
T cells, B cells
Name two types of Innate, internal defences
Antimicrobial proteins, Natural killer cells
Components of the Lymphatic system
Lymph, lymphatic vessels, lymphatic tissue, red bone marrow
Functions of lymphatic system
- Drains excess interstitial fluid from the tissue space back into the blood
- Immune responses
What are lymph trunks?
They are formed as lymph vessels converge after leaving lymph nodes
What are the 5 lymph trunks?
-Lumbar
-Interstitial
-Bronchomediastinal
-Jugular
-Subclavian
Lumbar trunks
Drain the lower limb, pelvic organs, kidneys, adrenal glands and abdominal wall
Interstitial trunks
Responsible for the stomach, intestines, pancreas, spleen and parts of liver
Bronchmediastinal trunks
Responsible for the thoracic wall, heart and lungs
Subclavian trunks
Responsible for upper limbs
Jugular trunks
Responsible for head and neck
Formation of lymph
- More fluid filters out of the blood into the interstitial fluid than returns so excess fluid drains into lymphatic vessels to become lymph
- Proteins are too large to leave blood vessels so interstitial fluid only contains a small amount of protein
Flow of lymph
-Lymph drains into venous blood through the right lymphatic duct and the thoracic duct at the junction of the internal jugular and subclavian veins
1. Blood capillaries
2. Interstitial spaces
3. Lymphatic capillaries
4. Lymphatic vessels
5. Lymphatic trunks or ducts
6. Junction of the internal jugular and subclavian veins
Primary lymphatic organs
Where stem cells divide and become immunocompetent e.g red bone marrow, thymus
Secondary lymphatic organs
Sites where most immune responses occur e.g lymph nodes, spleen
Innate immunity
External physical and chemical barriers provided by skin and muscous membranes.
As well as internal defences e.g antimicrobial substances, natural killer cells, inflammation
First line of defence- Skin and mucus membranes
-The epidermis provides a physical barrier to the entrance of microbes
-The periodic shedding of epidermal cells helps remove microbes at the skin surface
-Mucous membranes and cilia, saliva and urine etc act to remove any pathogens that have infiltrated the broken skin
Second line of defence- Internal defences
- Antimicrobial substances
- Natural killer cells
- Phagocytes
- Inflammation
T cells
-Develop from primary lymphatic organs
-Mature in the Thymus
-Mature T cells exit the Thymus as helper T cells
B cells
-Develop from primary lymphatic organs
-B cells complete their development in red bone marrow throughout life
Types of adaptive immunity
Cell-mediated
Antibody mediated immunity
Cell-mediated (adaptive immunity)
- Begins with activation of a small number of T cells by a specific antigen
- It undergoes clonal selection forming clones of cells that can recognise the same antigen as the original lymphocyte
- Some of the T cells become effector cells and some become memory cells. Forming clones of both
- Effector cells can carry out immune responses that result on elimination of the intruder
Antibody-mediated immunity
- B cells in lymph nodes, spleen or lymphatic tissue become activated
- Undergoing clonal selection forming a clone of plasma cells and memory cells
- The plasma cells secrete antibodies which circulate in the lymph of blood to reach that site of invasion
- Memory cells don’t secrete antibodies but instead they proliferate and differentiate into plasma and memory B cells
- Plasma cells do secrete antibodies- our antibody action sends this five classes of antibodies and their actions
The 4 types of antibody actions
Neutralising antigens
Immobilising bacteria
Activating complements
Enhancing phagocytosis
Neutralising antigens
Blocks of neutralises toxins and prevents attachment of viruses to body cells
Immobilising bacteria
Antigens reactions are on cilia e.g the bacteria lose their mobility
Activating complements
An antigen antibody reaction which activates the complement system.
These complement proteins cause a cascade reaction which means that one reaction triggers another and brings about phagocytosis, cytolysis and inflammation (effector functions)
What enhances the action of phagocytosis
Antibodies
Types of adaptive immunity
Naturally acquired active immunity- antibodies developed in response to an infection
Naturally acquired passive immunity- which is transferred from mother to foetus across the placenta or milk
Artificially acquired active immunity- vaccination stimulates production of antibodies
Artificially acquired passive immunity- where you have intravenous injection of immunoglobulins or antibodies
Ageing and the immune system (5 things)
- Increased susceptibility to infection and malignancies
- Response to vaccine decreased- less responsive to antigens as we age
- Lower levels of immune system function
- T and B cells become less responsive to antigens
- Antibodies do not increase as rapidly in response to antigens
