Protein - Shona

[Guest guest]

I did a search for protein compliment + immune system. Here is a chapter on the immune system and when you scroll down through it you will find information on proteins.

Barb

London, Ontario, Canada

Immune System

Chapter 22

Objectives: 1. Understand the how each of the body's three lines of defense function.

2. Know how the inflammatory response and temperature response are carried out.

3. Know how the immune response is carried out . 4. Know what it means to be immune to a pathogen.

5. Be familiar with autoimmune disease, allergies, HIV infection and transmission .

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ One aspect of an animal's fitness is its ability to defend against invading pathogenic bacteria and viruses that are present in its environment.

OVERVIEW OF THE BODY'S DEFENSES: 1) nonspecific defense mechanisms: First line: skin and mucous membranes & their secretions Second line: phagocytic white blood cells, complement system & interferon, inflammatory & temperature response

2) specific defense mechanisms - your immune system: Third line of defense: lymphocytes and antibodies First line: SKIN and MUCOUS MEMBRANES

The skin and mucous membranes present physical barriers against potentially invading microbes, but also combat them with chemical defenses.

SKIN Outermost layer of the body - first defense against invasion of microbe Three distinct layers: epidermis dermis subcutaneous layer epidermis: 10-30 cell layers thick outer layer is stratum corneum; cells in this layer shed continuously innermost layer is basal layer - cells here are actively dividing; new cells migrate upward into stratum corneum as migrate upward they make keratin protein which makes them tough psoriasis - persistent dandruff; cells are replaced every 3-4 days (8X faster than normal rate)

dermis -- layer just beneath epidermis, provides structural support for epidermis, wrinkling occurs in this layer. subcutaneous layer - fat-rich cells, cushion and insulation

When not injured or irritated the skin presents an impermeable barrier Oil and sweat with epidermis make skin surface acidic - not conducive to bacteria Sweat, tears and mucous secretions also contain lysozyme - enzyme that can digest bacterial cell wall

MUCOUS MEMBRANES

Mucous membranes lining respiratory, digestive, and genitourinary tracts first line of defense against invasion of microbe across these cell tissue layers. mucous - sticky viscous fluid secreted by cells of mucous membranes; this fluid traps particles and organisms

Mucous membrane lining trachea (upper respiratory tract) also consists of specialized epithelial cells with cilia;

cilia beat, sweeping mucous and any stuck particle up away from dead-ended lungs.

Second line of defense: lymphocytes, complement system & interferon, inflammatory & temperature response Skin and mucous membranes are highly effective barriers, but can be overcome at times.

Then bacteria and viruses enter the body, invading deeper tissues.

THREE TYPES OF WHITE BLOOD CELLS Most important defense against invading microbes is conducted by your white blood cells. They remove and/or kill foreign organisms by phagocytosis. 1) Macrophages: patrol for invaders mobile cells, circulating in blood and lymph;

some are specialized/localized to specific organs (liver, spleen, kidney; lungs) amoeboid-type cells that engulf one microbe (bacteria) at a time digest it and live

2) Neutrophils: conduct suicide missions also mobile cells, circulating in blood and lymph; have capacity to phagocytic capacity however, primary means of attack is release chemicals that neutralize infected area killing invaders and themselves neutrophils are attracted to infected area by chemical signal - example of chemotaxis

3) Natural Killer Cells: kill off the weak Figure 22.5

don't kill invaders, but kill infected cells Body's most effective means of detecting and killing off cells infected by a virus. These cells also kill cancerous cells early on before proliferate into defined tumor.

ANTIMICROBIAL PROTEINS -- COMPLEMENT SYSTEM and INTERFERONS

A chemical defense system; functions as a non-specific defense;

attacks micro-organisms directly or by impeding their reproduction.

compliment system - group of about 20 special proteins; figure 22.6

named so because they cooperate with (or complement) other immune defense mechanisms.

free-floating and circulating in blood in inactive state; activity is triggered when encounter bacterial or fungal cell wall

when activated, complement proteins form membrane attack complex (MAC) that inserts into pathogen wall. forms a hole - fluid floods into pathogen - it bursts Some components of complement system may function as chemoattractants & recruit phagocytes to infection site.

interferons - 3 types, alpha-, beta-, gamma-

substances produced by viral-infected cells that help other uninfected cells resist infection by virus

these substances are not virus-specific; help especially in controlling short-term viral infections (flu and colds) interferon-gamma activates phagocytes, enhancing their ability to ingest and kill microbe.

THE INFLAMMATORY RESPONSE

localized response to an invading microbe, usually at site of tissue damage by physical injury

1) INJURY in area of injury injured cells and white blood cells release chemicals white blood cells release histamines; white cells and damaged cells release prostaglandins 2) REDNESS & SWELLING localized vasodilation & increased permeability blood vessels in response to chemicals 3) PHAGOCYTE INFILTRATION macrophages & neutrophils migrate out of blood stream and enter injured area neutrophils arrive first and chemically kill invading organism and dead or dying cells and themselves macrophages consume pathogens and cell debris - healing begins pus - mixture of dead or dying neutrophils, injured tissue, dead cells and dead pathogens

THE TEMPERATURE RESPONSE Figure 22.7

Recall heat will also kill bacteria. Fever is another non -specific mechanism to combat infection. At site of infection macrophages release interleukin-1 ("between white blood cells")

interleukin-1 stimulates hypothalamus to increase setting of body temperature brain sends nervous stimulation to muscle causing contraction - shivering producing heat - fever other nervous stimulation causes vasoconstriction at skin surface (paling) minimizes heat loss as heat kills off bacteria, macrophages in area decrease and reduce interleukin production - "fever breaks"

fever higher than 37C or 98.6F; 103F or 39.4C considered dangerous; 105F or 40.6C can be fatal.

THIRD LINE OF DEFENSE: IMMUNE SYSTEM : Figures 22.8, 22.9, 22.11

Fortunately immune system not localized to one place in body and not controlled by one organ. Immune system consists of several types of white blood cells or lymphocytes

made in bone marrow and circulate in blood and lymph In the event that a virus or bacteria evades the first and second lines of immune defense;

three other types of white cells in addition to macrophages, neutrophils and natural killer cells have key roles in mediation of immune response: T cells; B cells; helper T cells

THE IMMUNE RESPONSE: Macrophages initiate the immune response.

Ô each cell in your body carries surface protein, major histocompatibility (MHC) proteins

MHCs "mark" your cells as yours

A pathogen or foreign particle not carrying or presenting your MHC is identified by the macrophages as "foreign" Macrophages will also identify a viral infected cell because viral proteins are attached to its surface - foreign proteins

Ô after they identify the foreign particles or foreign surface proteins, macrophages release interleukin-1

Ô interleukin-1 activates helper T cells;

helper T cells simultaneously initiate the cytotoxic response by T cells and antibody response by B cells

T cells attack infected body cells - the cytotoxic response

Ô helper T cells release interleukin-2 ; interleukin-2 will recruit killer T cells;

Ô killer T cells will identify infected viral cells by the viral proteins attached to the infected cell's surface

by puncturing holes in membrane of infected cell

Ô and ANY T cell that detects a foreign protein on a cell surface will rapidly replicate, forming large numbers of T cells;

each of the over million types of T cells as a unique surface receptor protein; figure 22.10

each receptor (and therefore type of T cell) binds to a surface protein on a particular virus or bacteria

B cells tag invading microbes - the antibody response

Ô B cells also have surface receptors - every type of B cells as a unique receptor;

B cells will identify infected cells by specific viral or bacterial proteins on surface of infected cell

Ô B cells will then "tag" or place markers on surfaces of infected cells;

this marker will recruit complement proteins to attack infected cells

Ô B cells will also replicate a million-fold when they encounter the infected cells

Most of these new B cells will produce & secrete into blood receptor proteins that recognize the pathogen. these released specific receptor proteins are called antibodies.

the antibodies will bind to any free viruses or infected cells with the attached virus. the virus and infected cells are now "tagged" for destruction by macrophages and natural killer cells. Ô Some new B cells produced during pathogen-stimulated B cell proliferation do not produce antibodies;

They become a line of memory B cells that are capable of recognizing that specific pathogen. They circulate in your blood and lymph "patrolling" for that specific pathogen.

Ô Should that specific pathogen enter the body again, these memory B cells will identify it

and replicate producing a new antibody-producing B cells directed specifically against that pathogen.

The pathogen will be destroyed by macrophages before you become ill. Now, you are said to be immune to that particular pathogen.

Ô vaccinations - deliberate introduction of dead or disable pathogen into your body; piggyback vaccines this triggers the immune response against the pathogen without infection ever occurring. However, memory B cells directed specifically against the pathogen are circulating in your body Vaccinated people are "immunized" against a disease.

Because genes for a virus' surface proteins, including the flu, can mutate,

a vaccine from one type of flu virus may not keep you immune to every flu strain.

IMMUNE SYSTEM FAILURE

AUTOIMMUNE DISEASES

Killer T cells and B cells loose the ability to distinguish between your body's own cells from cells of foreign. They will begin to attack your own cells.

Examples: Multiple sclerosis; type I Diabetes

ALLERGIES

Major immune defense against a harmless substance; such an immune response is called an allergy. Antibodies against the allergen are formed and will attach to mast cells.

In response, mast cells release histamines and other chemicals that cause capillaries to swell. Histamines also increase mucous productions by cells in mucous membranes - hay fever symptoms. Antihistamines block actions of histamines. Asthma is a form of allergic response; histamines cause restrictions of airways in lungs.

AIDS

HIV attacks the immune system; the body is overwhelmed with pathogens.

Everyone infect with HIV will eventually develop AIDS. There is no cure for AIDS.

During the latency period no AIDS symptoms are present, but the infected person can still spread the disease.

Most HIV viruses are present in macrophages rather than being free particles.

HIV is contracted only taking into your body HIV infected blood cells or body fluids form infected

Understand the ways HIV is transmitted and not transmitted.

Remember: You cannot contract HIV from donating blood if all needles & syringes are sterile as at the Red Cross.