ch 15 physio
What are the 3 types of phagocytic cells? How do they go about phagocytosis?
-Neutrophils- first to arrive at an infection -Mononuclear phagocytic cells- arrive later, they are monocytes in the blood and macrophages and dendritic cells in the tissue. -organ specific phagocytes- located in lymphoid organs like the spleen, liver, lymph nodes, lungs, and brain which include fixed phagocytes that are immobile and are in the walls of these organs and just there to protect the organs.
B lymphocytes
-made in bone marrow - is humeral and secretes antibodies -have memory cells and plasma cells -have presence of IgM or IgD
T lymphocytes
-made in thymus -cell mediated and kill by contact -have receptor cells or killer T cells or suppressor cells -non-detectable -good at killing parasitic infections
Innate immunity?
Inherited immunity, it's the first line of defense against pathogens. Uses internal( phagocytic cells, interferons, complement protein, endogenous pyrogens, natural killer cells, mast cells) and external defenses (epithelia, acid in stomach,acidic urine, secretion of mucus, etc)
How do antibodies bind to antigens on bacteria?
It's Y shaped, the Fc region is on the bottom which is a polypeptide that doesn't chance. We have two short arms which are the Fab regions and they change specificity for different antigens. Short arms of the Y attach to an antigen on the surface of bacteria.
adaptive immunity?
Its mediated by antigens and antibodies, it's more specific
How do neutrophils react in this situation?
Kill microorganism through phagocytosis and they release NET(neutrophil extracellular traps). They undergo apoptosis and spill protein digest enzymes cause pus, the release granule proteins that draw monocytes to that area to eat up debris or bacteria that is still there.
How do WBC leave blood cells and go to the site?
Neutrophils leave blood cells through extravasation (coming out of vessel) where they squeeze and leave the tissue to find bacteria and engulf it and lysosomes will become active. They're attracted to cytokines when they're excreted on the tissue making them leave the blood vessel and go to the site.
How does phagocytosis work?
Neutrophils/ macrophages can make a vacuole and engulf bacterium and break it down with lysosomes and digestive enzymes.
What are dendritic cells?
Originate in bone marrow but are in most tissues of of the body. they break apart the antigens and place them out onto the specific receptors which are associated with histocompactibility antigens and attract T lymphocytes and activate. We also creat memory T cells for that specific antibody
What's the complement system?
Part of the nonspecific defense system where activity is triggered by binding of antibodies and antigen(classic) and by poly saccharides on bacterial membranes (alternative). This labels the target for attack by phagocytic cells and stimulates opsonization and doesn't kill it.
Agglutination?
when antigen encounters specific anybody so it forms a clumping mechanism and we use it in ELIZA
Symptoms of inflammation?
Redness and warmth because of the histamines stimulating vasodilation. Increase in swelling due to bulid up of interstitial fluid. Pain due to release of PGE2, and pus due to phagocytosis
complement system?
Series of protein that are inactivated in plasma and become activated when specific or adaptive immune responses create antibodies. Integrates innate and adaptive immune responses. Compliment proteins promote phagocytosis, lysis of target cells, and inflammation.
How do B cells become plasma cells and memory cells?
Starts with B cell activated by antigen which attaches a specific antibody receipt then proliferation (mitosis) causes formation f a clone. then plasma cells and memory cells are formed
Describe regulatory T lymphocytes, T(reg)
Surface molecule are CD4 and CD25 and they inhibit b lymphocytes and Killer T lymphocytes. Activates Fox P3 gene which transcribing Treg lymphocytes
What is cell mediated destruction ?
T cells must touch the target victim they secrete performs to create large pore in the cell and secrete granzymes to trigger apoptosis with caspace enzymes
killer t cell recognizes antigens by
The MHC1 receptor and Killer T cells will recognize it by the CD8 coreceptor.
What else occurs after complement activation?
We have chemotaxis which is attracting phagocytic cells. Opsonization also occurs and phagocytic receptors for C3b and form a bridge between the phagocyte and victim cell to facilitate phagocytsis. C3a and C5a stimulate mast cells to release histamine to increase blood flow to the area.
How does local inflammation occur?
When bacteria enters the skin it's intitates inflammation by nonspecific mechanism of phagocytisis by toll like receptors. Neutrophils will get to the location fast, Macrophages and mast cells release cytkines and chemokines to attract more neutrophils to the area. Complement proteins are then activated which attract phagocytic cells. The more phagocytic cells arrive via extravasation from nearby venules and lastly the T lymphocytes arrive. Mast cell will degranulate and secrete heparin,histamines, prostaglandin, leukotrienes, cytokines, TNF-alpha which produce warmth and swelling and pain and recruit more lymphocytes.
How do they both work together
a macrophage that is an antigen presenting cell will engulf foreign particle and break it apart and protrude it with MHC 2, once MHC has present antigen the Helper T cell will be activated and drawn to it and attaches through the CD4 receptor and give the message to B cells with MHC1 and create antibodies and become a plasma cell and memory B cells. With and infected cell it cal present little fragment of the virus into an MHC1 molecule so killer T cell can attach it through the CD8 receptor and viral cell is destroyed
Describe the interaction between antigen presenting cells and T cells?
all cell have MHC1 except red blood cells. They can activate citotoxic cells class2 is made by antigen presenting cells and B cells . Class 2 MHC molecules and foreign antigens are presented together to helper T lymphocytes.
What are antibodies?
also known as immunoglobulins and have 5 classes IgG, IgA, IgM, IgD, IgE
What do secondary lymphoid organs do?
capture and present pathogens to macrophages and house lymphocytes. Lymphocytes migrate between lymphoid organs to sample blood and lymph. The spleen filters blood from pathogens and other organ filter the lymph for pathogens.
What are the coreceptors for Helper T cells
have CD4 for MHC-2
What are the two types of immunity we have?
innate(nonspecific immunity) and adaptive(specific immunity)
adaptive immunity?
learned form exposure to specific pathogens and is the function of lymphocytes
List the secondary lymphoid organs
lymph nodes, spleen, tonsils, and peyer's patches in the mucosa of the intestine.
IgG
main form of antibody in circulation
IgA
main type of antibody in external secretions like saliva or mothers milk
What are the different locations for the types of macrophages in our body: neutrophils, monocytes, histiocytes( tissue macrophages), Kupffer cells, alveolar macrophages, and microglia?
neutrophils- blood and tissue monocytes- blood histocytes-all tissue( including spleen,lymph nodes, bone marrow) kupffer cells- liver alveolar macrophages-lungs microglia- CNS
What is complement fixation?
one complement protein start to attach one on top of the others. So a bacteria embrace(made of phospholipid bilayer) so specific antibodies attaches aka opsonization, the complete gets added so C4 enters and we get C4a then C4b the others start to come in. When all C5-C9 occur we get a membrane attachment complex of MAC and thats when we create an opening or pores into the cell membrane which causes fluid to rush inland causes lysing of the cell.
What lymphokines are produced by helper T cells?
produced by T helper cells to call other cells TH1-produces IL-2 and gamma interferon activates killer T cells and stimulates NO ( its a vasodilator) production in macrophages TH2- produces IL-4, IL-5, IL-13 and others- stimulates B cells and blood immunity, recruits eosinophils and induces IgE production TH17- secretes IL17, fight infection in skin,lungs, and mucus membrane; stimulates neutrophils
IgE
responsible for allergic symptoms in immediate hypersensitivity reactions
How do T lymphocytes and macrophages interact?
A killer T cell can be activated by helper T cell through CD4 and MHC2. Helper cell secretes interleukin 2, the killer T cell recognizes virus and it'll proliferate and attach to the cell and destroy it.
What is a fever?
An increase in body temp and is controlled by the hypothalamus. It occurs because leukocytes secrete a cytokine chemical know as endogenous pyrogen which sets the body temperature higher. Endotoxins from some bacteria will stimulate leukocytes and produce these cytokines. It induces fever and sleepiness and a fall in plasma iron concentration which limits bacterial activity
how do Helper T cells recognize the antigen
Antigen presenting cell will present antigen so Helper T cell can immediately recognize it and attach through CD4 coreceptor and has Class 2 MHC molecule
IgD
Antigen receptor on lymph surface prior to immunization
What are T cell receptor protein?
Antigen recognition proteins on the membranes of T cells and can bind directly to antigens. Antigens presenting cells such as dendritic cells and macrophages, help T cells bind to antigens
What are interluekin called? IL
stimulate T cells, neutrophils, and B cells
What are interferons and what are the three types?
Antiviral polypeptides made by the infected cells, immune system doesn't produce a huge amount. First cell attacked my virus will produce interferon but the interferon will leave and attach to other cells to stop the viral take over of the next cell. Three types are alpha/beta (which inhibit viral replication and assembly) and gamma (which helps fight infections and cancer).
antigens?
Anything your body recognizes as a non self molecule. then our adaptive immunity will create antibodies and create the antibody-antigen complex (very specific). Surface molecules which stimulate the production of specific antibodies and combine with those antibodies. If foreign antigens are present it illicites an immune response (self vs. non-self). Antibodies bind to their specific antigen . large molecules can have several sites or epitopes that stimulate the production and binding to antibodies.
What do the monocytes do?
Become macrophages and eat up the dead neutrophils and release growth factor and other things that end inflammation and promote repair. Then B lymphocytes produce antibodies against bacteria antigens. This amplifies phagocytosis by neutrophils,monocytes, and macrophages called opsonization(making bacteria very visible).
Helper T cells?
CD4 is surface molecule it improves ability of B lymphocytes to become plasma cells and enhance ability of cytotoxic T cells to kill target. The secrete lymphokines.
What are the corecceptors for killer T cells
CD8 for MHC1
How are the labeled by the complement system?
Complements are plasma proteins activated by binding of antibodies and cantingness. C1-C9. C1 recognition protein, C2/C3/C4 serves as activators. C5-C9= attack cells by attaching to a cell membrane and destroying it.
What happens if you have a deficiency?
Defiency in regulatory T lymphocytes results in autoimmune diseases and allergies
Describe histocompactability antigens
they're on all surface of all body cells called human leukocyte antigen (HLAs). Coded by 6 genes (A,B,C,D) the different combination of it called MHC (major histocompatibilty complex) needs to be match with a donor transplant
describe local inflammation?
First response of the immune system, stimulation of innate immune response. When the immune system is exposed to DAMPs or danger associated molecular patterns. It can cause tissue damage or necrosis
IgM
Function as antigen receptor on lymphocytes surface prior to immunization
Describe the killer cytotoxic T lymphocytes?
Have surface molecule call CD8 and destroy body cells that harbor foreign antigens (pathogens,virus,cancer). they kill cells by lysing them. They also recognize transplant cells.
