Monday, February 21, 2011

Body breakdown II

For my little brother Michael and sister Grace.

The immune system works on it's ability to distinguish the differences between the foreign organisms trying to attack or enter the body. It first identifies
               "what are characteristic proteins or protein-linked components of this invading substance?"
Proteins matter to the immune system.
Once it identifies this important fact, two kinds of lymphocytes are provoked to respond.
One set of lymphocytes produce antibodies that directly attack those invading substances (this is called antibody-mediated immunity).
The other set of lymphocytes start making antibodies that they will direct to attack the invading substances (this is called cell-mediated immunity).

Where do these lymphocytes come from? Stem cells in the center of bones called "bone marrow." Stem cells in bone marrow are basically the factories that pump out hundreds and thousands and millions of the cells that make up your bodies defenses every day. They're the industrial part of your inside cities, where it's all work and no cool stores.

There are two types of lymphocytes: B-cells and T-cells. They can either be called B- or T- cells or B- or T- lymphocytes but lymphocyte and cell mean the same thing.
When a disease enters the body and one of the cells is attacked and devoured by a phagocyte, the information about what that devoured cell was is displayed on the phagocyte as an antigenic determinant, which is how the B- and T- cells know what to do next. The antigenic determinant provokes the appropriate immune response and says "this is how you should get those bad guys."

Cell-mediated immunity.
Say hello to an impressive, scary little defender cell called a cytotoxic T-lymphocyte.
Hello cytotoxic T-lymphocytes!
These muscular tough guys circulate through the blood vessels, then gather at the infection site. Acting fast, they interact directly with diseases or problem cells such as fungi, protozoa, cancer cells, bacteria-infected and virus infected cells. These little T-cells exert a "lethal hit" on cells and secrete substances into them that lead to cellular destruction.

They also have substances inside them called "lymphokines."
Say "hello lymphokines!"
Lymphokines attract phagocytes to the area and encourage them to perform phagocytosis (envelop and destroy) on fungi, protozoa, diseased and infected cells. Why are lymphokines important?
They help to rapidly relieve infection. They're your Supervisors of your body's defenses, getting the right microorganisms to go to the right places and making people are showing up for work on time.

With all of this activity going on, there are also your boring, lame and buzz-killing lymphocytes called "suppressor T-cells" that regulate and suppress the activity of the immune system so that it's not excessive. They come into the room and say "guys, guys, everyone calm down. The neighbors are complaining that the noise level is too high, so can we get things a little bit under control? Why is he on top of the bookcase? Sir, sir, please come down."

Now it gets interesting.

Antibody-mediated immunity.
When a B-cell sees (or is exposed to) an antigenic determinant (sign telling the immunity system WAKE UP! ALARM! ALARM! on the back of a phagocyte) the B-cell says "hey, okay! Alright! Move move move!" and starts producing plasma cells.
Plasma cells are antibodies (good guys) that are specific for antigens (bad guys). If the bad guys are good at pistol skills, the plasma cells create super talented pistol-shooting bad guys. If the bad guys (antigens) are good with swords, the plasma cells create good guys (antibodies) that are good with swords to beat the bad guys.
Other B-cells take notice of what's going on and think "hm. The bad guys are good with swords, so we need to remember that. Next time they try and come back we'll already be coded and ready to make way more sword-men to conquer them quicker."
That is how a vaccine works. Your body is introduced to the bad guys of chicken pox when you're young so that when you're old you're already stocked with plenty of good guys to handle any bad guy chicken poxes that come around.
Or if you go and get an MMR (measles, mumps and rubella) vaccine, in the needle is only a little bit of each of those diseases. Your body says "hey! Those measles need us to fight them with these, those mumps need us to fight them with these, and those rubella virus cells need us to fight them with those." It's only a little bit of each virus that your body gets used to fighting, so if the virus ever comes back for real to your body, you can fight them off easily because you already have before.
That is what B-cells called "memory cells" do best.

So we're back to plasma cells. Your B-cells read the signs and go "heck yes" and start creating plasma cells. Those plasma cells specialize in antibodies. What do antibodies do? They're the good guys. They're the specific defenses against each and every single disease that comes to your body. They're protein-based and do all the dirty work that isn't done by other cells to make sure the disease-infected cells are completely destroyed. Sometimes antibodies are called immunoglobulins.

This is an immunoglobulin. Never mind all the confusing titles and terms for each section, what creature does it remind you of?
Look at it and try to imagine it's lying flat on the ground. The ground around it is all the white space, what kind of animal is it like?
A lobster or a crab. Where it says "antigen binding-site" up in the yellow area at the top, those could be the pincers, and the blue area could be the body and arms. These immunoglobulins shoot out of plasma and then go attack the antigens (infected cells that could hurt the body) and then attach to them at the end of their "arms" area. This is the place on the cell that knows exactly how to react to the bad cells because it has been told by the phagocyte's alarm system (or antigenic determinant).
When the antibody (immunoglobulin) reacts with the antigen (infected or bad cell) the two surfaces fit together like a jigsaw puzzle. This ability is exquisitely accurate and accounts for the extreme specificity of antibody molecules.
The immunoglobulin cells in your body that protect you are told EXACTLY how to respond in a way that fits perfectly against the bad cells that are invading your body. It wouldn't work for them to just go out and fight; they have to be shown exactly how and what to do with the ends of their "arms", and then it works perfectly.

Psalms 139:1
1 You have searched me, LORD, 
   and you know me.
7 Where can I go from your Spirit?
   Where can I flee from your presence?
8 If I go up to the heavens, you are there;
   if I make my bed in the depths, you are there.
9 If I rise on the wings of the dawn,
   if I settle on the far side of the sea,
10 even there your hand will guide me,
   your right hand will hold me fast. 
13 For you created my inmost being;
   you knit me together in my mother’s womb.
14 I praise you because I am fearfully and wonderfully made;
   your works are wonderful,
   I know that full well. 
15 My frame was not hidden from you
   when I was made in the secret place,
   when I was woven together in the depths of the earth.
16 Your eyes saw my unformed body;
   all the days ordained for me were written in your book
   before one of them came to be. 

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