2. cells and tissues of the immune system

Describe the different cells of the innate immune response and how they respond to infection. Identify the primary and secondary lymphoid organs and their functions. Describe how innate and adaptive immune cells are generated in the bone marrow and briefly outline their main functions.

What is the primary function of the immune system

to eliminate pathogens and minimise the damage they cause

LABEL

1. adenoid

2. tonsil

3. (right subclavian vein)

4. lymph node

5. appendix

6. lymphatics

7. bone marrow

8. Peyer’s patches

9. spleen

10. thoracic duct

11. thymus

What do primary lymphoid organs do

develop and mature adaptive immune cells (lymphocytes)

what are the primary lymphoid organs, and for what cells

Bone marrow for B cells, Thymus gland for T cells

what do secondary lymphoid organs do

let the mature lymphocytes meet pathogens to practice being cool

what are the secondary lymphoid organs?

spleen, adenoids, tonsils, appendix, lymph nodes, Peyer’s patches, mucosa-associated lymphoid tissue (MALT)

Where are lymph nodes

all over the place. strategically

what do they act as

a ‘meeting place’ for immune cells like T and B lymphocytes, which enter the node and congregate at specific regions

what do T and B lymphocytes do there?

they encounter a matching dendritic cell showing off an antigen, and activate and multiply to find and destroy the source of invasion.

what’s the shape and size of the node

it changes in response to lymphocytes being activated.

how’s the shape and size of the node change

the dendritic cells crawl across the meshwork of fibroblast cells (that keep the shape intact) to warn them that the node’s gonna fill up.

fibroblasts relax, allowing the node to expand. meanwhile, the meshwork expands too.

when the lymphocytes leave, the node less full, the fibroblasts regain tension and the node gets smaller.

what’s the spleen do

It does a similar thing to lymph node, though not as organised as lymph nodes. it’s also the biggest secondary lymphoid organ

What the MALT do?

• takes all the food w bacteria in it

• translocates some of it throught the gut epithelium

• innate immune cells pick them up and present them to lymph nodes

• etc~

where is MALT?

lining intestinal epithelium in big lymphoid follicles lining it.

what’s haematopoiesis?

the making of blood in the bone marrow.

LABEL (good luck)

1. multipotent stem cell

2. myeloid progenitor

3. megakaryocyte

4. platelets

5. erythroblast

6. reticulocyte

7. red blood cells

8. myeloblast

9. monocyte

10. macrophage

11. dendritic cell

12. neutrophil

13. basophil

14. eosinophil

15. lymphoid progenitor

16. B-lymphocyte

17. Plasma cell

18. T-lymphocyte

19. NK cell

abundance distribution of leukeocytes

50-70% neutrophils

20-40% lymphocytes

1-6% monocytes

1-3% eosinophils

<1% basophils

what are innate immune systems like

non-specific

fast response (minutes)

no memory

what is an adaptive immune system like

highly specfic (discriminates among other molecular entities)

slow response (days)

memory ( recalls previous contact w an antigen & shows a stronger response the 2nd time)

diversity (has capacity to respond to almost any antigen that may be encountered)

what happens w monocytes → macrophages

Monocytes circulating in the blood migrate to tissues where they either differentiate to macrophages.

macrophages can then either become activated, or differentiate again into smth specific

macrophages for the lung

alveolar macrophages

macrophages for connective tissue

histocytes

macrophages for kidneys

mesangial cells

macrophages for brain

microglial cells

macrophages for liver

kupffer cells

macrophages for bone

osteoclast

What is phagocytosis

the ingestion and destruction of particles/microbes by macrophages

steps of phagocytosis

1. bacterium becomes attached to membrane evaginations called pseudopodia

2. bacterium is ingested, forming phagosome

3. phagosome fused with lysosome

4. lysosomal enzymes digest captured material

5. digestion products are released from the cell.

why are granulocytes called that

they have lots of different granules, that stain differently depending on the cell type

3 types & the granule stain colour

eosinophil- pink

basophil- blue

neutrophil- purple

neutrophil abundance percentage in granulocytes, live length, notable component, roles

95%

short-lived

major component of pus

do phagocytosis and release antimicrobial factors

eosinophil, basophil and mast cell roles

killing parasites using target recognition.

Associates w allergies too

how do the three kill parasites

they use IgE to grab a parasite and release the granule contents onto the helminth, killing it <3

How are they associated with allergies

they release cytokine, which triggers inflammation

difference between the phils and mast cells here?

mast cells reside in tissues while eosinophils and basophils circulate in the blood.

natural killer cells use

they recognise and destroy “abnormal cells” such as cells that’re virus-infected and cancer cells, cuz those are small. they do so with cytotoxic granules containing perforins and granzymes

how do natural killer cells detect the cells

problem cells don’t have MHC class I molecules peeking out of the cell.

how are T and B cells similar

morphologically when not activated

how’s activation happen

antigen-presenting cells displaying them and blah blah blah.

three steps of B-cell activation

Selection

Multiplication

Differentiation

selection

a B cell is for a specific receptor for the antigen is selected among millions

multiplication

the B cell multiplies and gives a clone on B cells after binding of the antigen

differentiation

multiplied B cells differentiate into plasma cells and memory cells

what do plasma cells do

they produce antibodies specific for the antigen

what do memory cells do

they’re kept to be ready for the second entry of the same antigen.

diffentiation of T cells

T helper 1 cells

T helper 2 cells

Cytotoxic T cells

what do T helper 1 cells do

they help macrophages digest pathogens

what do T helper 2 cells do

they help B cells produce antibodies

what to cytotoxic T cells do

they kill virus-infected cells