Specific Defense mechanisms of the host

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Specific: Defense mechanisms

Antigens, Antibody, autoimmune diseases, cellular immunity, Humoral immunity, types of immunity

antigens

any agent/substance that, when introduced into the body, causes the body to produce specific antibodies

antigen consistency

most are protein based, like microbes, but almost anything can be an antigen

antigen examples

bacteria, virus, pollen, egg white, incompatible blood cells, or transplanted organs.

Antibody

a protein produced by the body in response to the presence of an antigen. it is capable of combining specifically with the antigen, also called an immunoglobin.

antibody reactions with antigens

antibodies do not form against the entire antigen but react and combine with specific receptor sites on the antigen (lock and Key)

antibodies produce by

activated B lymphocytes (plasma cells) or B cells

Autoimmune Diseases examples

rheumatoid arthritis, systemic lupus erythematosis, rheumatic fever, hemolytic anemia, myasthenia gravis, multiple sclerosis, crohn't disease, etc.

autoimmune diseases caused by

when something happens to the body that causes it not to be able to recognize a part of itself, than that part of the body is considered to be an antigen and results in a type of autoimmune disease.

Autoimmune diseases function

since the bodyhas the ability to recognize each one of its cells as self any other invading cell or substance would be considered an antigen or non-self.

cellular immunity

occurs through the mechanisms of the t-lymphocytes or t cells.

T lymphocytes or t-cells

includes 70 to 80 % of all circulating lymphocytes, t-cells directly deal with the antigens, referred to as "cell-mediated immunity"

T lymphocytes formation

in the bone marrow and are eventually released into the blood stream and make their way into the thymus gland. Will mature in the thymus as t lymphocytes with the influence of thymosin. then leave the housed in other types of lymphatic tissue or circulate in the bloodstream.

thymosin

programer to tell t lymphocytes to leave to circulate or be housed elsewhere.

T lymphocytes information

all types of t-cells that will ever be formed by the body are produced shortly before birth and for a few months after birth (100s of millions. Each different ype of t-cell is capable of responding to a different or specific antigen.

actions of t lymphocytes

1.active macrophages will "tear" the specific antigen into many pieces and display pieces of that antigen into their cell membranes
2. they will then search the body for that one specific t-cell that has receptors that are complimentary to the antigen.
3.A macrophage will then present a piece of the antigen to the T cell, and the T cell will then attach the antigen to its cell membrane.
4. this activates or sensitizes the t-cell causing it to divide repeatedly to form a clone of identical t cells.

results of actions of t-lymphocytes

with these actions, a complex process involving, four different types (subtypes) of T cells begin carrying out their different functions:

four different functions

1..secreting substances that may activate or further activate macrophages.
2.neutralizing toxic substances
3. secreting growth inhibiting substances
4. producing interferon.

t-lymphocytes effectiveness

This type of immunity is most effective against fungi, parasites, intercellular viral infections, cancer cells, and foreign tissue transplants.

Humoral immunity

Occurs through the mechanisms of the b-lymphocytes or B-cells. includes 20 to 30% of all circulating lymphocytes, more indirectly deals with the antigens. also, referred to as antibody-mediated immunity

B lymphocytes are formed /humoral immunity

in the bone marrow and then processed into mature lymphocytes in certain bone marrow sites with stromal cells, which provide chemical signals that initiate b-cell development (hundreds of millions of these will form too.)

B stand for /hum. imm./

bursa of Fabricius,

bursa of fabricius /hum. immunity/

which is a small pouch of lymphatic tissue attached to the intestines of birds where B lymphocytes are known to mature in these animals.

Mature B-cells migrate to /hum. immunity/

various lymphatic tissues, but usually not in the same tissue as t-cells

actions of the B lymphocytes

most B lymphocytes require stimulation from t-helper cells, activated t-helper cells release lymphokines (type of cytokine) which is a chemical specific B lymphocyte that was formed against that specific antigen.
when activated, b cells enlarge, divide and differentiate into a clone of plasma cells. With each division, one newly formed cell will become a plasma cell and the other will become a memory cell.
the plasma cells become active at this time and scretes about 2000 antibodies per second/per cell, for up to about 4-5 days, until the plasma cell dies.
antibodies that are produced then react to antigens by attaching to them directly which completely disables them from multiplying, producing toxins, or doing any further damage to the body.

memory cells

remain dormant during this time, but may be activated during a subsequent infection from the same kind of antigen. Could respond more rapidly and forcefully if the antigen appears again.

Primary response ( Hum, imm.)

The primary response to a specific antigen occurs when one recovers from an infection beginning with the initial entry of the antigeninto the body, passing by the first and second line of defenses, activating the specific immune response (meanwhile exhibiting the symptoms) as long as no antibiotics are taken if it is a bacterial infection.
* if antibiotics are taken, memory cells may not form and the possible encounter with the same antigen would be as if i t were the first.

secondary response

odies for that specific "change" into plasma cells and immediately begin producing antibodies for that specific antigen.
*** The time involved with the secondary response ( in producing antibodies) is almost immediate, unlike the time it takes to produce antibodies in the primary response.

Types of immunity

Natural, active acquired, passive acquired, adoptive

genetic Natural

blood type a person has when born.

innate natural

in the physiology of a person

inate ex. 1st and 2nd line of defense

intact skin resistance, able to carry out processes like phagocytosis, protective digestive enzymes in the stomach.

active acquired immunity

do it yourself, by acquiring an antigen and then producing antibodies

two forms of active acquired immunity

a)natural active acquired, contract an infection , go through the symptoms, the body will heal itself over a period of time. Antibodies will then be in the blood against infection.
b) artificially active acquired, obtain immunity by getting a deactivated form of the antigen (vaccine)

Passive acquired

Get protection or antibodies from someone or somewhere else. Natural passive acquired, artificially passive acquired.

artificially passive acquired

someone produces antibodies against anantigen while going through the primary response, and then gives the antibodies to another by serum injection.

natural passive acquired

mothers antibodies pass through placenta to the fetus and then later through breast milk.

adoptive

transfer of cells (ex. stem cells) in a bone marrow trasplant

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