what is the purpose of the immune system?

to keep infectious microorganisms such as bacteria, viruses and fungi out of the body and destroy them if they invade the body

what is immunocompetence

is the ability of individual cells to recognize a specific antigen by binding to it

phagocytes are

cells that eat

what are immunocompetent cells

distinguish self from nonself

what are the parts of immune system

1 nonspecific (innate)
2 specific (adaptive)

what is non specific or innate

routine protection, regardless of pathogens, always present. (from birth)

what are specific or adaptive

protection against particular pathogen. (develops throughout life)

what are antigen

foreign substance that causes an immune response to produce antibodies

what are antiboies

Y shape protein that bind to antigen for destruction
they are glyoproteins also known as immunogobulins

where is the immune system located

origin is bone marrow (hemapoietic stem cells) and transported throughtout body by blood.
lymphatic system controls it

parts of nonspecific (innate)

1st line and second line defense

what are 1st line defense

physical and chemical barriers ex: skin, mucous membrane and secretions

what are 2nd line defense

it is reactive ex: inflammation and fever
Involves : phagocytosis, complement activation, interferons and NK cells

explain more about 1st line defense

physical barriers which is the skin that covers majority of surface. Also mucous membrane barriers that line digestive tract, respiratory tract and GI tract. Mucous protects these surfaces from infections

How do skin protect the body?

1. it has epiermal layer with waterproofing protein keratin.
2. shedding (takes off anything that adheres to it)
3. dry -slougged off with flakes of dead skin
4. acidic fatty acids in sebum(sebaceous/oil gland)
and lysozyme(sweat gland)

How does mucous membrane protect our body?

1. Barrier is epithelial layer with moist sticky flowing mucous covering
2. cleaning/washing action removes microbes ex: tears, urination
3. mucociliary escalator in lower respiratory tract
4. chemicals control microbes.

Skin and mucous membranes are protected by variety of antimicrobial substances. Name them

1 .lysosome
2. peroxide
3. lactoferin
4. defensins

Lysosome

enzyme that degrades peptidoglycan(destroys cell walls of bacteria)
found in tears, saliva, blood and phagocytes

Peroxidase enzyme

breaks downs hydrogen perioxide to produce reactive oxygen.
found in saliva, body tissue and phagocytes

Lactoferin

iron building protein that witholds iron preventing microbial growth
found in saliva and some phagocytes
transferin- found in blood and tissue fluid

Denfensins

antimicrobial peptides inserted into microbial membrane forming pores that damage cells
found in mucous membraes and phagocytes

Secretions

stomach ---- gastric juice
skin ------ sebum (fatty acid)

conditions that foster entry of pathogens

1. In skin -- wounds, excess moisture
2. In mucous membranes -- reduced movement of cilia that can be caused by smoking, narcotics, viral infection, allergies, chilling
3. In GI -- by reduced stomach acid, ingestion of antacid
4. distruction of normal flora with antibiotics, hormonal change

hemotopoietic stem cells

blood cells that give rise to all other blood cells that are located in bone marrow

Hematopoiesis

production, formation and development of blood cells

What process are involved in the 2nd line of defense of the body?

Phagocytosis, complement, interferon and inflammation

process of phagocytosis

chemotaxis, adherence, ingestion, digestion, killing

what are Granuloccytes? give examples of granules

category of WBC that contains cytoplasmic granules
ex: neutrophil, basophil and eosinophil

What are monocytes? give example

WBC that doesnt contain granules
they differentiate into either macrophages or dendritic cells when they migarte into tissue

Role of Monocytes

1. replenish resident microphages and dendritic cells under normal state
2. can move quickly to site of infection in the tissue and divide the macrophages to elicit an immune response

Role of Granulocytes

they are phagocytes that ingest foreign cells such as bacteria, viruses and other parasites

Role of Neutrophils

they are most common type
they phagocytize and digest engulfed materials

Role of Eosinophils

they are involved in allergic reactions and attack multicellular parasites like worms. Also participates in INFLAMMATORY reactions and immunity to some parasites

Role of Basophils

they mature in mast cells, they release histamine which helps trigger inflammation and heparin which prevents blood from clotting.

What are lymphocytes

they are small wbc that help regulate the bodys immune system (agranules)

what are mononuclear phagocytes

monnocytes, macrophages, dendritic cells
they are either stationary or wandering macrophages.

types of lymphocytes

B cells, T cells, NK cells

location of lymphocytes

in lymph organs, lymph nodes, spleen, thymus, appendix, tonsils

What do B cells do

they release antibodies Y-shaped that bind to infected microbes to mark them for attack by T cells

What are dendritic cells

they are initialy in tissues but migrate to secondary lymphoid organs such as lymph nodes, spleen, tonsils
Role- collect antigen from the tissues and then bring it to lymphocytes that gather in the lymph organs

Mononuclear phogcytic system

wandering and stationary macrophages

difference between monocyte and macrophage

monocyte--circulate in blood
macrophages-- when monocyte leaves bloodstream and migrate to tissues it becomes macrophages.

How do macrophages protect us against invasion of microbes?

they engulf microbes, then mark them as antigen so antibodies can be produced and also help stop inflammation process by removing dead cells from tissues and repairing wounds

Steps of phagocytosis

1. chemotaxis (movement)
2. Adherence (stick-macrophages stick to microbes)
3. Ingestion (surround by cell membrane/take in microbe)
4. Digestion (break down/kills-involves lysosomes/peroxide
5. Absorption

What is chemotaxis

movement towards chemical signals
ex; lymphokines and complements

what is adherence

attachment of macrophage to microbe

what is ingestion/endocytosis

surround microbe with cell membrane forming phagosome

what is digestion

by fusion w/ lysosome
digestion is carried out by lysosomal enzymes, killing from acids and toxic compounds such as hydrogen perioxide, nitric acid and hypocloride

which step of phagocytosis is affected by the presence of a capsule in bacteria

Aherence -- microbes adheres to capsule or else will escape

what are complement system

they are like "bombs" they aim in destroying pathogens

steps of inflammation

injury--mast cells release histamines---causes vasodialation and increase permeability---phagocyte migration/wall off---phaygocytosis--tissue repair

where is the complement system

they are proteins that circulate in blood and fluid that bathes the tissues

complement is composed of

1. family of proteins in blood
2. has enzymatic activity
3. activates in cascade fashion
4. kill foreign microbes
5. act as signal to the immune system

what triggers complement

antibodies and other carbohydrates

what are 3 pathways of complement for activation

alterative pathway, classical pathway and lectin pathway

alternative pathway of complement

- quickly and easily initiated
- is triggered when C3b binds to foreign cell surface
- initiates activation of other compliment proteins
- allows formation of complement complex
(c3b always circulates in blood)

Lectin pathway

- activation requires MBL (mannose binding lectin)
- pattern recognition molecules that detect mannose
- MBL attachs to surface
- activates complement proteins

Classical pathways

- activation requires antibodies
- antibodies interact complement C1
- activates protein
- leads to activation of all complex proteins

What is the job of complement

1. kills bacteria directly
2. Opsonization - enhance phagocytosis
3. Provide signals to recruit microphages to the area.

what is opsonization

a process where a pathogen coats with opsonins which enhances phagocytosis

what are NK cells

they are in blood and lymph cells that can lyse and kill cancer cells and viruses infected body cells before adaptive immune system is activated

What are the outcomes of Complement activation

1. Opsonization
2. Inflammation
3. Lysis of foreign cells

what is inflammation

complement components C3a and C5a induce changes to endothelial cells
it effect vascular permeabilty associated with inflammation
a localized physical condition in which part of the body becomes reddened, swollen, hot, and often painful, especially as a reaction to injury or infection.

how does opsonization work

C3b binds foreign material, allowing phagocytes to easily grab particles

Lysis of foreign cell through complement activation

- c5b combine with ,C6,C7,C8,C9 to form Mac
- spontaneously assemble
- forms donut shaped structure called MAC
- creates pores in membranes
- most effective on G-

What is alternative pathway (antibody independent)

-activated by bacteria and some fungi
- binding to certain proteins or carbohydrates on microbe by factors activate cascade sequences

How is the complement system activated?

The complement system can be activated in two main ways. The first means of activation is part of the innate (natural) immune response. (i.e.; neither antibodies nor T cell receptors are involved.) For example, certain polysaccharides found on the surface of bacteria can activate the system. This can occur immediately and does not require prior exposure to the molecules.

The second and most potent means occurs in a adaptive immune response when antibodies (IgG or IgM) binds to antigen at the surface of a cell. This exposes the Fc region of the antibody in a way that allows the first complement protein (C1) to bind.

What happens as a result of the activation

Name a molecule that activates the complement system as part of a specific immune response.

antibody

Name a component of the activated complement system that serves as a good opsonin.

C3b

how complement deals with inflammation

opsonization
chemotaxis
inflammation
lysis, apoptosis

Which type of immunity triggers the complement system via polysaccharides without any prior exposure

innate

which complement components is formed that results in killing of target cells

membrane attack complex (MAC) c56789

how are target cells killed by complement activation

by lysis

what is opsonization? what does it achieve?

it coats the outer surface of pathogen, achieves enhanced phagocytosis

function of compliment

1. cell lysis with MAC (kills tagged cells)
2. Opsonization of pathogesns (enhance phagocytosi)
3. recruitment of inflammatory cells (chemotaxis factor, activation of mast cells signaling phagocytes)

function of the inflammatory response?

- prevents the spread of the injurious agent to nearby tissue
- disposes of cellular debris and pathogens
- sets the stage for repair processes

7) The antibody molecule is held together by ________ bonds.

disulfide bond

what is the purpose of inflammation

1. destroy injurious agents
2. confine or wall off infectious agents and its by products
3. repair or replace damaged tissues

symptoms of inflammation

1. redness - increase blood flow to area
2. pain - tissue damage
3. heat- accumulation of blood
4 swelling - accumulation of fluid and mast cells

how is inflammation achieved

though vasodilation-- widening of blood vessels
When more blood comes to area, more pressure is build, that widens the blood vessels. When vessels vasodialate, pores get wider and bacteria leak out and are surrounded by phagocytes

what helps reduce inflammation

aspirin and epinepherine

sequence of events in inflammation

1. damage/tissue injury
2. mast cells signal-- release histamins
3. vasodialation
4 phagocyte migration and wall off (neutrophils /monocyte migrate to tissues)
5. phagocyte migration and phagocytosis (microbes englulfed and destroyed by wbc)
6 tissue repair

what is a pus

abscess from collection of dead tissues/cells , fluids, microbes in a cavity

why should you remove pus

to heel quicker and improve circulation

In clonal selection of B cells, which substance is responsible for determining which cells will eventually become cloned?

antigen

the redness and heat of an inflamed area are due to a local hyperemia caused by ________.

vasodialation

why does your skin turn red and swell when it becomes infammed

red-blood flow on surface
swell - more mast cells

can inflammation be harmful

yes if there is swelling of airways, swelling of tissues, internal swelling because it can cut off circulation

what types of inflammation are harmful

over inflammation and systemic inflammation (anaphalyxsis)

how is inflammation beneficial

1 prevents the spread of damaging agents to nearby tissues
2. disposes of cell debris and pathogens
3. alerts the adaptive immune system
4. set the stage for repair

what is systemic inflammation/anaphylaxis

1. bronchioles constrict
2. vasodialation
3. fluid loss
4. BP drops
5. death

how is fever triggered

---in response to foreign invasion such as endotoxin production of interleuking by macrogphages (systemic response to invading microphages)
-- stimulation of hypothalamus
--- higher metabolic activity

can fever be beneficial

if it is within limits, can enhance reaction
increase rate of chemical reactions , more rapid repair
-inhibits growth of some microbes

what are interferons

(natural substance produced by all)
1. calls of antiviral protein
2. produced by different viral infected animal cells
3. binds to uninfected cells to make them resistant to infection by virus "anti-viral state"
4. stimulation of other cells of immune system
Interferons are named for their ability to "interfere" with viral replication by protecting cells from virus infection.
IFNs also have other functions: they activate immune cells, such as natural killer cells and macrophages; they increase host defenses by up-regulating antigen presentation by virtue of increasing the expression of major histocompatibility complex (MHC) antigens.

what are te main types of interferon

1. alpha interferon - produced by microphages and monocytes
2. Beta interferon - produced by fibroblasts and other cells
3. gamma interferon- macrophage activation, promotes certain adatptive immune response like inflamatory response.

Alpha Interferon does what

induces fever , contributes to inflammation

what is the role of NK cells

1 kills cell with reduction or absense of selfmarker (MHC)
2. kills infected/tumor cells triggered wit antibodies (ADCC)
They directly attach cancer or virus cells without having to activate by attaching to antibodies and secreting perforin that causes apoptosis. Also produce cytokines that regulate n direct immune responses.

how does compliment and antibodies work together

compliment bind wit antibodies to kill microorganism
antibody when bind to antigen changes shape

membrane attack complex MAC

the complex of terminal complement components that forms a pore in the membrane of the target cell, damaging the membrane and leading to cell lysis

how does complement system ddestroy cells

lysis

types of antimicrobial proteins

interferon and complement

what do antimicrobial proteins do

they attack microbes directly or limit their ability to reproduce

form of complement protein

group of plasma protein that circulate through blood in an inactive state and are activated by immune system signal of presence of microbes

why is high fever dangerous

becoz it denatures enzymes

types of specific immune responses

humoral and cellular

humoral repsonse is

cells derived from B cells secrete antibodies that bind to microbes to target them for distruction

cellular reponse

cytotoxic lymphocytes directly destroy infected body cells, cancer cells, and foreign tissues

advantage and disadvantage of specific immune repsonse

adv: more vigorous and effectivve against particular foreign invader
disadv: takes time

what is adv of nonspecific response

always present and defesne is immediate

hallmark of specific response

recognition, memory and regulation

what is recognnitized by specific response

speicific shapes and antibody generator

what are antibodies

glycoproteins known as immunoglobulins

what is antigen

substance that can trigger an immune response and sepcifically directed against it

what are antigens made of

proteins n carbohydrates , molecules weigh less then 10,000 molecular weight

what are haptens

small molecule that become antigenic only when combining wiht larger molecule
antibody once generated will bind hapten

what is recognized by antibody

specific part of antigen called antigenic determinant epitopes

what produces antibodies

plasma cells (b cells)

structure of antibody

2 identical heavy chains and 2 light chains
heavy chains identify antibody class (GAMED)
Each chain has a constant region (C) and a variable region (V)

variable region

can change in response to antigen
antigens react to variable regio
marcropages introduce antigens to variable region

which antibodies are always on B cell receptors

IgD and IgM

IgM

primary antibody response. first to appear ater exposure to antigen
short lived

IgG

secondary response
main class/most common

IgA

found in body secretions like saliva, milk, tear
monomer in serum

IgD

part of antigen receptor on Bcells
unknown functio

IgE

bind to receptors on mast cells n basophils in allergic response and parasitic infection

outcomes of antibody

opsonization, complement activation (antibody binding triggers classical pathway)
, antibody dependet cellular cytotoxicity

opsonization

caoating of bacteria with antibody to enhance phagocytosis

do we have enough Dna to encode all the antigen receptors

antigen receptor genes
and mutations

are all B cells genetically identical?

No
after DNA rearangement each B cell is different
B cells cloned after antigen exposure is identical

what is MHC

major histocompatibility complex
on the surface of all cells

how does antibody kills microbes

attaching to complement, enhanced phagocytosis, killer cells

parts of cellular response

T cells
virus infected cells
tumor cells

antigen presentation by APC by macrophage

1 macrophage digest microbes
2. associates with MHC
3 .antigens present on surface of APC
4. bind wit t cell
5. bind releases cytokines turn on t effector cells to activate t helper cell

how are helperT cells activated

when they are presented with antigens by MHC class II molecules, which are expressed on the surface of antigen-presenting cells (APCs). Once activated, they divide rapidly and secrete small proteins called cytokines that regulate or assist in the active immune response

how do cytotoxic (killer t) cell kill microbes

once they bind with the specific antigen, killer cells release cytokines and perforin .Perforin first makes a pore, or hole, in membrane of the infected cell. Cytotoxins go directly inside the cell through this pore, destroying it and any viruses inside.

difference between NK cells and killer cells (cytotoxic)

NK are part of innate that kills viurs and tumor cells
cytotoxic cells are released by t cells to directly kill the microbes

which type of T cell lyses cells that have been infected with viruses?

cytotoxic t cells

Your body has millions of different antibodies for detecting millions of different antigens because

antibody genes undergo somatic rearrangement and somatic mutation

Which type of surface marker is present on every nucleated cell in your body?

MHC1

Activated helper T cells release regulatory molecules called

lymphokines

what do memory B cells do

provide an accelerated immune response upon second exposure to a particular antigen

Complement and antibody are similar in that both

may make bacteria more attractive to phagocytes

How do macrophages kill bacteria cells

by engulfing the one presenting appropriate antigen

how does the complement system work

the complement system is composed of a series of about 20 freely-circulating proteins in the blood. When they encounter an infected cell, they assemble an "attack complex" that creates a pore in the membrane of the infected cell. Water can then enter the cell, ultimately causing it to burst

MHC1 MHC2

MHC I proteins are found on all nucleated cells in the body, identifying it to the body as "self," so that when an immunological attack is in progress, the body does not destroy its own cells along with the pathological invaders. MHC II proteins are found only on macrophages, B-cells, and CD4+ T cells; they function in identifying each other.

How do macrophages activate helper T cells?

Macrophages activate helper T cells by engulfing the invading pathogen and presenting the pathogen's antigens on its surface for the helper T cells to recognize. Macrophages also secrete interleukin-1 that stimulates the helper T cells. Once activated, helper T cells secrete lymphokines that mobilize cytotoxic T cells to fight off the pathogen

how do B cells mature?

When a B lymphocyte responds to an antigen, it is stimulated to replicate, producing a clone of cells that provides an initial, weak immune response. Some of the cells become memory B cells. The next time the body is invaded by the same pathogen, it is ready to provide a rapid, strong secondary immune response.

complement protein works by

forming pores in the membrane of the target cells

how is complement triggered

1 classical pathway - involves antibodies
2. alternate pathway - involves bacterial chemicals

what is antegenic determinant

3D shape of a region of an antigen that is recognized by the immune system.