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Flashcards in Lymphatic and Immune System Deck (30):

4 Functions of the Lymphatic system

1. Maintenance of blood volume in cardiovascular system
2. Filtration of foreign material to defend against infection
3. Development/maturation of lymphocytes
4. Initiation of specific immune responses


4 basic components of Lymphatic system

1. lymph (fluid)
2. Lymphatic vessels
3. Lymphatic cells
4. Lymphatic organs


What do Lymphatic vessels do?

-transport interstitial fluid (Lymph) from the tissues back into the blood

*Due to nature of blood and the blood system, we lose approx 3-4 L fluid per day (if not returned we'll die)
-liquid leaks into tissue between capillaries (needs to as that's how O2 and nutrients get to cells)
-lymphatic system is involved in returning this fluid - and lymphatic vessels important


Components of lymph (5)

-colour if healthy

Comprised of;
-interstitial fluid
-solutes (i.e. salt, sugar -> anything not dissolved by cells)
-foreign material
-immune cells

*Is clear if healthy


Lymphatic capillaries - what they do & where they are
-how they're structured

-Allow interstitial fluid to drain back into circulation
*surround capillary beds (capillaries allow fluids, nutrients, proteins and even cells to pass into tissues)
-are soft, have openings so that fluid can flow through passively (is NO pump)
-structured so that liquid will flow into capillaries in one direction
-have little valves


How does Lymph move?

-negative implications

-muscles, movement, gravity etc stimulates the valves to open and close, thus moving the lymph.

*if in coma & can't move, start getting lymphatic & blood volume problems because of this


Lymph Nodes - what they do, what they are

-Is where lymphatic vessels drain into
-are filtration systems -> are packed full of lymphocytes

*critical as body needs to ensure it isn't allowing anything that shouldnt be in the body back into the blood stream


Lymph Nodes -> structure


-Has blood flow coming in and out (artery and vein) as well as afferent lymphatic vessels and a single lymph vessel (that leaves)
-more than one entry but only one exit
-lymph vessel that exits is going to thoracic duct
-usually greater than 1 cm in size


Extra role of lymphatic vessels in lower GI tract


-Allows for transport of lipids
-Lipids are large and insoluble
-are a classic source of energy, but hard to get into bloodstream -> lymphatic system helps get them in
*Lymph containing lipids = chyle (is yellow)


What lymphatic vessels collect into (2)

-lymphatic vessels collect into lymphatic trunks
-trunks eventually merge to form 2 ducts;
1. Right lymphatic duct
2. Thoracic duct (drains 3/4 of lymph in body


What lymphatic ducts do

-joins lymphatic and cardiovascular systems together
-Ducts run right alongside blood, allows lymph to fall back into blood withOUT pressure


When things go wrong in lymphatic system

-Blockage or disruption of lymphatic vessels or flow leads to fluid build up = lymphoedema
-Damage to thoracic duct or trunks can lead to build up of chyle in lungs = chylothorax


Antigens - what is it

-what triggers immune reaction

-Antigens = antibody generating substances (activates immune system)
-foreign substances (aka antigens) that enter the body trigger an immune reaction


Role of lymph nodes and antigens

-2 ways antigens get to lymph node

-dendritic cells (what do they do)

-Lymph nodes trap antigens coming from tissues

-dendritic cells (are in every tissue in the body) are special immune cells in the tissue that also CAPTURE antigens to take to lymph nodes
-long process capture antigens, internalise it and transport it to lymph node



-are immune cells that live in lymph nodes
-are the key to adaptive immunity
-enter lymph nodes from the blood
-antigens enter from the tissue

-Lymph nodes therefore bring antigens and lymphocytes together (to accelerate immune response)


Lymph organs

-2 types

-Contain large number of lymphocytes in a framework of non-lymphoid cells
2 types;
1. Primary lymphoid organs: bone marrow and thymus (is where lymphocytes develop -> bone marrow = B cells; thymus = T cells)
2. Secondary Lymphoid organs: lymph nodes and spleen (lymphocyte responses)


2 main types of lymphocytes in body

-where found in lymph nodes

1. T Cells: cell mediated immunity: help other cells
2. B cells: antibody mediated immunity: make antibodies

*within lymph node, T cells are on the inside and B cells are on the outside



-filters antigens from blood
*if something invades bloodstream, there are no lymph nodes there to filter
-spleen is like a giant lymph node that filters blood (same structure as lymph node but no vessels

*if spleen ruptures/lost become more prone to blood infections


Cardiovascular system vs Lymphatic system

-Fluids transported
-major vessel types
-mode of transport
-sites of filtration
-major point of intersection (vessels)

Cardio - Lymph

Blood; Lymph
Capillaries, veins, arteries; lymph vessels & lymph trunks
Pressure from heart; passive - gravity and muscle movement
spleen; lymph node
Thoracic duct; vein in chest


Immune system of all vertebrates made up of (2 systems)

1. Innate Immune system (inborn defense mechanism) - found in all classes of animals
2. Adaptive immune system (Acquired immune defenses) - are unique to vertebrates and generated during lifetime of an individual


3 components of immune system

-Specialised immune cells (that do things)
-Specialized receptors and defense molecules
-Specialised immune organs/tissues


Level of protection and lines of defense

-First line = barriers and defense molecules (offers lowest level)
-Second line = phagocytosis and inflammation
-3rd line = activation of T cells and B cell responses (this is adaptive immunity that offers highest level of protection and memory)

*innate immunity works first, then adaptive


Innate vs Adaptive

-Include phagocytes and granulocytes
-many types of recognition receptors on each cell
-inherit genes from mother and father
-present from birth
-mainly recognise microbial molecules (non-self)
-comprise of lymphocytes
-one type or recognition receptor on each cell
-receptors assemble from multiple gene fragments
-formed after birth
-Recognise ALL antigens (self and non-self)


What happens to lymphocytes once made

Naive T & B cells

-Released and circulate in bloodstream
-For majority of cells - nothing happens

Naive T & B cells = lymphocytes that never seen an antigen


B Cells - what they do

-antibody binging

-B Cell receptor promiscuous ->sticks to things directly
-once it sticks, it activates then divides, pumping out same cells
-It will start secreting its B-cell antigen receptor (BCR) as an antibody once it is activated by an antigen

*B cells are the antigen making factories

-antibody binding: just bind and tag antigens. If binds to a toxin, it sticks to it and neutralises it


T Cells - what they do

-Not as promiscuous as B cells -> need another cell to show it where antigen is
-T cell antigen receptor (TCR) is related to immunoglobulin but evolved separately
-TCR can only recognise an antigen when it is presented as a peptide in a special molecule found on antigen-presenting cells
-antigen presenting cells = dendrite

*only right T cell will respond once dendritic cell shows it a peptide


2 main types of T cells

1. Helpers
2. Killers

-either help or ill infected cells in tissue
*overall they provide cell-mediated immunity


Interaction between T cells and Dendritic cells

-Dendritic cells constantly moving around through body
-once it has acquired an antigen, it takes it to the lymph node and shows T cell
-T cells are constantly sending out signals to dendritic cells as to where lymph node is -> dendritic cells only recognise signal once it has an antigen


T cell response to receiving a peptide of an antigen

-When the right T cell fits with the antigen, it proliferates (which is the response)
-swollen lymph node can sometimes occur as lymphocyte division cause the lymph node to swell.

-Unlike B cells, T cells can't secrete receptor - they therefore go to the tissue to help fight and kill infected cells


Adaptive immune response - memory

-Specificity, diversity and memory are all properties of adaptive immune response
-first time immune system exposed to antigen, primary response takes a while to build up
-after infection, most of T cells and B cells die off, but slightly more than what began with is left
-these are the memory B & T cells
-second infection with same antigen = much faster and quicker immune response because there are more cells that have right receptors to that antigen