Lymphatic and Immune System

Question 1

4 Functions of the Lymphatic system

Answer 1

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

Question 2

4 basic components of Lymphatic system

Answer 2

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

Question 3

What do Lymphatic vessels do?

Answer 3

-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

Question 4

Components of lymph (5)

-colour if healthy

Answer 4

Comprised of;

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

*Is clear if healthy

Question 5

Lymphatic capillaries - what they do & where they are

-how they’re structured

Answer 5

• 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

Question 6

How does Lymph move?

-negative implications

Answer 6

• 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

Question 7

Lymph Nodes - what they do, what they are

Answer 7

• 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

Question 8

Lymph Nodes -> structure

-size

Answer 8

• 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

Question 9

Extra role of lymphatic vessels in lower GI tract

-chyle

Answer 9

• 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)

Question 10

What lymphatic vessels collect into (2)

Answer 10

• 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

Question 11

What lymphatic ducts do

Answer 11

• joins lymphatic and cardiovascular systems together

- Ducts run right alongside blood, allows lymph to fall back into blood withOUT pressure

Question 12

When things go wrong in lymphatic system

Answer 12

• 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

Question 13

Antigens - what is it

-what triggers immune reaction

Answer 13

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

Question 14

Role of lymph nodes and antigens

• 2 ways antigens get to lymph node
• dendritic cells (what do they do)

Answer 14

-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

Question 15

Lymphocytes

Answer 15

• 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)

Question 16

Lymph organs

-2 types

Answer 16

-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)

Question 17

2 main types of lymphocytes in body

-where found in lymph nodes

Answer 17

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

Question 18

Spleen

Answer 18

• 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

Question 19

Cardiovascular system vs Lymphatic system

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

Answer 19

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

Question 20

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

Answer 20

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

Question 21

3 components of immune system

Answer 21

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

Question 22

Level of protection and lines of defense

Answer 22

• 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

Question 23

Innate vs Adaptive

Answer 23

Innate:
-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)
Adaptive:
-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)

Question 24

What happens to lymphocytes once made

Naive T & B cells

Answer 24

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

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

Question 25

B Cells - what they do -antibody binging

Answer 25

- 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

Question 26

T Cells - what they do

Answer 26

- 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

Question 27

2 main types of T cells

Answer 27

1. Helpers 2. Killers - either help or ill infected cells in tissue * overall they provide cell-mediated immunity

Question 28

Interaction between T cells and Dendritic cells

Answer 28

- 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

Question 29

T cell response to receiving a peptide of an antigen

Answer 29

- 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

Question 30

Adaptive immune response - memory

Answer 30

- 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