hepatitis B

4 genes

associated liver disease

stopped growing up

most adult cells are no longer replicateing.

3 kinds of defenses

physical barriers

 innate immune system

adaptive immune system

dead cells

maturing cells

new (basal) cells

basal membrane

because of all the anti viral compounds in saliva.

that's why most viruses don't infect the mouth

squamous

squamous cells cover the epithelial cells in the vagina

that's squamous cells, basal cells, and then the basal membrane

because of the squamous, non proliferating (dividing) cells, mucous coating, and the pH 5 acid environment

(cells that aren't multiplying are of no use to a virus. Most STIs actually take root in tears in vaginal tissue)

second line of defense (after physical barriers such as the skin)

it's called "innate" because all animals seem to have it.

"eating cell"

(white blood cells)

young macrophages

reinforcement to macrophages

they consume all

most of the time this is good, but some viruses are want  to be ingested so that they can hijack the macrophage

circulating white blood cells (not sentinal like macrophages)

70% of all white blood cells are neutrophils

when a virus is covered in C3b

macrophages that gobble up opsonized viruses are stimulated to search for more viruses (to eat more)

this is the universal alarm amoung cells.

Cells under attack launch this alarms, (interferon alpha and beta) which bind to the surfaces of other cells. The alerted cells then know that a virus is lurking around, and if they come in contact with it, they must commit suicide.

sometimes when a virus comes in contact with a cell membrane. Other times because of the presence of large quantities of double stranded RNA (that most viruses have)

cells that have been warned with interferon are more sensitive to linking double stranded RNA to attack

MHC is the signal that says "don't kill me" on the surfaces of most cells.

Some viruses turn off the production of MHC, and this can be a signal to killer cells that alerts "I have been hijacked"

proteins cells use to communicate amoungst themselves

cytokines can be used to activate killer cells and make macrophages "big eaters". These activated cells give off cytokines themselves, and the result is a positive feed back cycle

viruses that destroy the infected cell once they're done with it.

this triggers the inflammatory response which causes fever, malaise, and fatigue. Temp raising makes the body inhospitable to a virus, and malaise and fatigue encourage a person to rest and take it easy.

B cells are the factories that pump out anitbodies on demand.

Produced in bone marrow

Found on the surface of every B  cell, B cell receptors come in two flavors: heavy chains and light chains. The chains are created by stringing together V, D, J, and C segments. You can create millions of different segments using these four letter combinations, and more combinations arise from combineing and deleting segments.

This mix and match scheme allows B cells to pick up almost any organic molecule.

a molecule that can bind to a cell's receptors

(like virus coats binding to B cell receptors)

Antibodies are not anchored to the surface of the B cell.

Five classes of antiodies are....

IgM

IgG

IgA

IgD

IgE

IgM

(these are the first antibodies that are produced when B cells are stimulated to proliferate)

IgM antibodies have ten "hands" that can bind to antigens.

Igm can sometimes also prevent viruses from entering host cells or impeding viral reproduction after hijacking.

Oh, and in the case that the oh-so-clever virus has found a way to bypass getting peppered with complementary system fragments, the IgM make short work of them.

IgG

(produced later on in the infection)

phagocytes have receptors for IgG (not IgM)

as a result the complementary system is quickly activated

as a result all those phagocytes in the blood get around the infection quickly

What is a superpower IgG has the IgM doesn't?

IgG can create a direct bridge in between virus infected cells and natural killer cells

(the infected cells have to be sending their baby's protein coats to the surface though)

IgG and babies

IgG is the only immunoglobin that can pass from mother to child via the placenta

(until baby can produce its own)

baby gets the added perk of gaining immunity to all the past infections Mama's had.

IgA is really two IgG clipped together at the tail (bridge). IgA therefore has four antigenic hands and can get large clumps of virus that can then be swept away in a cough or swallow or sneeze.

The clipped tail also allows them to transmit across intestinal walls and withstanding the acids and enzymes of the digestive tract.

Mothers have IgA in their milk and it helps defend babies from infection.

it cannot activate the complement system.

phagocytes are less likely to kick in and help.

B cells that have chosen to specialize in one virus and be ready for future attacks.

what would cause an autoimmune disease

(B and T cells)

the production of "battle cytokines" such as interferon gamma and tumor necrosis factor.

(and the innate immune system can tell they're in trouble if there a lot of cells dieing and a lot of interferon floating around)

The food taster.

It's phagocytic. It slurps up lots of fluid and most of it will pass as sound and spit back out. However, if it tastes tumor necrosis factor or other battle cytokines it will flee to the nearest lymph node.

Dendritic cells that have tasted battle cytokines flee to the lymph nodes where they alert the adaptive immune system that a battle is a foot.

The gentle butler makes sure the adaptive immune system is only turned on in times of infection.

the dendritic cells.

The butlers are a wise and worldly lot. Not only can they tell when it is time to go to the police station (lymph nodes) but they are intelligent enough to gather information (virus or bacteria), and can map out a plan for the police. However sometime the noble butler gets infected along the way, but even then he can stumble into the lymph node and provide the stationed police with an autopsy.

CSI :)

These cells take the message from the destraught dendritic cell and then communicate it to the killer T cells and antibodies.

(the exact means of communication are still foggy. It could involve cell contact or cytokines or both)

It's slow. It takes time for the innate immune system to signal for help, and then more time for the custom made antigens and T cells to hit the scene. And if the virus is clever enough to keep its host alive and preventing the production of interferon, the innate system is clueless so the cytokines aren't produced so the dendritic cells taste nothing, so there is no reason to travel to the lymph nodes and call on the adaptive immune system.

And the adaptive immune system is not efficient for  tots and snr.citz. It peaks efficiency at puberty.