Chapter 6 Specific Host Defense Mechanism Flashcards
scientific study of the immune system and immune response
immunology
a condition of being immune or resistant to a particular infectious disease
immunity
Categories of Host Defense Mechanisms
always involves the production of antibodies
humoral immunity
Categories of Host Defense Mechanisms
involves many different cell types, including macrophages, T helper cells, cytotoxic T cells, natural killer cells, killer cells and granulocytes
cell-mediated immunity
immunity results from the active production or receipt of antibodies during one’s lifetime
acquired immunity
the process of exposing the body to an antigen to generate an adaptive immune response; the response takes days/weeks to develop but may be long lasting/ life time
active acquired immunity
the process of providing IgG antibodies to protect against infection; it gives immediate but short-lived protection - several weeks 3 to 5 months at most
passive acquired immunity
immunity that is acquired in response to the entry of a live pathogen into the body (in response to an actual infection)
natural active acquired immunity
immunity that is acquired in response to vaccines
artificial active acquired immunity
the immunity that is acquired by a fetus when it receives maternal antibodies
natural passive acquired immunity
immunity that is acquired when a person receives antibodies contained in antisera or gamma globulin
artificial passive acquired immunity
the material that can artificially induce immunity to an infectious disease, usually after injection or, in some cases, ingestion of the material
vaccines
An ideal Vaccine is on that:
- contains antigenic determinants to stimulate the immune system to _ (antibodies that will protect individuals from infection by the pathogen)
- contains antigenic determinants from ____ that cause disease, such as vaccines are referred to as multivalent or polyvalent
- has few (preferably, no) side effects
- does not cause disease in the person
produced protective antibodies
all the strains of the pathogens
How does vaccine works?
Vaccines stimulate the recipient’s immune system to produce _____
The protective antibodies or memory cells produced in response to the vaccine then remain in the recipient’s body to do battle with a particular pathogen, should that pathogen enter the recipient’s body at some time in the future, body becomes ready
protective antibodies
Humoral Immunity
_ are foreign organic substances that are large enough to stimulate the production of antibodies; antibody – generating substance
antigens
Substances that are capable of stimulating the production of antibodies
antigenic
Antibodies are proteins produced by ____ in response to the presence of an antigen.
Usually, an antibody is ____ in that it will recognize and bind to only to the antigenic determinants that stimulated its production.
The term antibodies refer to ____ with particular specificity for an antigen
lymphocytes
specific
immunoglobulins
Where do Immune Response Occur?
Antigens in the:
* Blood -
* Tissues -
* Mucosal surfaces -
- spleen
- lymph nodes
- mucosa-associated lymphoid tissues
What do antibodies do to fight pathogens?
- ____ via blocking or antibody-dependent cellular toxicity
- ____ compliment dependent cytotoxicity
- ____ opsonization and phagocytosis
- neutralization of infectious agents
- activation of the complement system
- binding of foreign substances to be destroyed
Cell-mediated Immunity
T cells rely on antigen-presenting cell that contain membrane-bound MHC (major histocompatibility complex) class I proteins in order to ____
the binding specificity between MHC proteins and foreign antigens in essential for the ____ of naïve T cells into helper or killer T cells
With the assistance of MHC class I proteins, T cells can also recognize ____ cells
recognize intracellular target antigens
maturation and differentiation
cancerous
Cell-mediated Immunity
What lymphocytes are involved in cell-mediated immunity?
helper T cells, killer T cells, and macrophages
- when a “helper” T cells finds an antigen-presenting cell in the body, it releases a set of signaling proteins called cytokines
- these cytokines activated “killer” T cells and macrophages to move to the site of interest in order to destroy the antigen-presenting cell/s
results when as person’s immune system no longer recognizes certain body tissues as self and attempts to destroy those tissues as if they were non-self or foreign
-this may occurs with certain tissues that are not exposed to the immune system during fatal development
Autoimmune Diseases
-if a person’s immune system is functioning properly, that person is said to be ___
immunocompetent person
- Ways in which the body protects itself from pathogens
- Can be thought of as an army consisting of three lines of defense
HOST DEFENSE MECHANISMS
Non-specific Defences
Innate Immunity
Adaptive Immunity
Specific Defences
Non-specific Defences (Innate Immunity)
First line of Defense
- Skin
- Mucous membranes
- Secretions of skin and mucous membranes
Non-specific Defences (Innate Immunity)
Second line of Defence
- Phagocytic leukocytes
- Antimicrobial proteins
- Inflammatory response
- Fever
Specific Defences (Adaptive Immunity)
Third line of Defence
- Lymphocytes
- Antibody
- Memory cells
Host Defense Mechanisms
In the third line of defense, special proteins called ____ are usually produced in the body in response to the presence of foreign substances called antigens.
antibodies
General and serve to protect the body against many harmful substances
innate or inherited resistance (natural resistance) makes some people and animals more resistant to some diseases
Nonspecific Host Defense Mechanisms
serves as a nonspecific host defense mechanism by flushing organisms from the pores and the surface of the skin
- also contains the enzyme, lysozyme, which degrades peptidoglycan in the bacterial cells (especially Gram-positive bacteria)
Perspiration
is a protein that binds iron, a mineral that are required by all pathogens
Lactoferrin
is an enzyme that produces superoxide radicals, highly reactive forms of oxygen, which are toxic to bacteria
Lactoperoxidase
Factors protect the digestive system from bacterial colonization
-Digestive Enzymes
-Acidity of the stomach (approximately pH 1.5)
-Alkalinity of the intestines
is an interaction where resident microbes of the indigenous microflora prevent the colonization of new arrivals to a particular anatomical site.
Microbial Antagonism
Factors that attributes to the inhibitory capability of indigenous microflora:
-Competition for colonization sites
-Competition for nutrients
-Production of substances that kill other bacteria
Cell involves in the Second Line of Defence
- Neutrophils
- T helper cells
- Cytotoxic (killer) T cells
- Macrophages
- Dendritic cells
- B cells
- Suppressor T cells
- -General purpose phagocytes
- -These cells primarily attack bacteria. They are dispensable rather like pawns on a chessboard.
- -They rush to the site of incoming bacteria to fight them, but are easily killed.
Neutrophils
- only last a few days in the body (before they self-destruct), but our bone marrow produced more everyday. Some bacteria avoid neutrophils by hiding inside cells
- These cells are like the bosses.
- Each T helper cell only looks out for one type
- Many T helper cells are needed to watch for many different diseases or invaders
T helper cells
- They give instructions to other cells by producing signals.
- These are killer cells
- They punch holes in the walls of the pathogen cell so that the contents ooze out.
Cytotoxic (killer) T cells
- means ‘big eater’
- These cells “eat” (ingest) or clean up the mess of dead cells
Macrophages
-These cells are like the spies.
-They notice if there is an invader and then present evidence of the invader to T cells in the ____
Dendritic cells
lymph nodes
- These produce antibodies, which lock onto the antigen of invading bacteria and immobilize them until the macrophage consumes them
- some of them become memory cells after being activated by the presence of antigen
- These cells are able to live for a long time and can respond quickly following a second exposure to the same antigen
B cells
- When the infection is gone, the immune system needs to be calmed down (or the killer cells may keep killing)
-These cells slow down or turn off the immune system to prevent damage to good cells
Suppressor T cells
- The lymphatic system is a system of thin tubes that runs throughout the body. These tubes are called lymph vessels. They contain lymph.
- Lymph is fluid in which ____ cells are found.
white blood (immune)
- Lymph nodes are small, round masses of tissue that are found in certain areas (such as the neck, groin and armpits). They ____ bacteria and other foreign materials out of lymph and expose them to B and T cells and macrophages that can engulf them.
- These cells multiply in response to accumulation of such materials, which is why lymph nodes ____ during infections.
filter
swell
.
-A glycoprotein synthesized in the liver, has a high affinity for iron
-It functions to store and delivered iron to the host cells
Transferrin
Substances that stimulate the production of fever is called ____ which may originate either outside or inside the body.
pyrogens or pyrogenic substance
is an example of pyrogen that is produced within the body (endogenous pyrogen)
Interleukin I (IL – 1)
Fever augment is Host defense:
- -By stimulating WBC to deploy and destroy invaders
- -By reducing the plasma iron
- -By inducing the production of IL – 1 (causes the proliferation, maturation, and activation of lymphocytes in the immunologic response)
Benefits Fever
-Inhibits the multiplication of temperature-sensitive microorganisms
-Impedes the nutrition of bacteria by reducing the availability of iron
-Increases metabolism and stimulates immune reaction and naturally protective physiological process
Small, antiviral proteins produced by virus infected cells.
-Three known types alpha (α), beta (β), and gamma(γ) ____, are induce by different stimuli and produced by different cells.
interferon/s
localized physical condition in which part of the body becomes reddened, swollen, hot, and often painful, especially as a reaction to injury or infection
Inflammation
Major Events
- Vasodilation
- increased permeability of the capillaries (allowing the escape of plasma and plasm proteins)
- Egress of leukocytes from the capillaries and their accumulation at the site
Purpose of inflammation
-localized an infection
-prevent the spread of the microbial infection
-neutralized any toxins
-aid in the repair of damaged tissue
Phagocytosis begin when phagocytes move to the site where they are needed. This directed migration is called chemotaxis results of chemical attractants called ____ .
hemotactic agent
How does it work?
1/
-When a pathogen (disease-causing organism) invades the body, the neutrophils ____ and try to engulf it and destroy it.
-Should the invaders get past the neutrophils, several things may happen.
gather at the entry site
How does it work?
2/
The macrophages (big eaters) will be attracted by the ____ those of the neutrophils. These cells attempt to engulf the invader, but they also send signals to other cells for help.
death
How does it work?
3/
The dendritic cells, which are constantly scouting around (they can communicate with up to 200 other cells at once) may find the pathogen and ____ to T helper cells that congregate in the lymph nodes in the body.
take a piece to present
How does it work?
4/
- A T helper cell will recognize only one pathogen. If the T helper cell recognizes the invader, it will immediately ____ to increase numbers.
- The T helper cell then activates the appropriate immune cells for the attack.
- if the invading organism is a ____, the T helper cell will signal the cytotoxic (killer) T cells to come to the rescue. These cells punch holes in the walls of invading virus-infected host cells, killing the cells and destroying the virus.
clone
virus
How does it work?
5/
- B cells can also be activated to produce antibodies that will stick to free invaders, ____
- If the invader is ____, B cells are usually drawn to the task. They squirt an antibody (IgG) onto the bacteria (a bit like squirting tomato sauce onto chips)
* This sticks everything together and makes it attractive to macrophages, which clear up the mess.
- If the bacteria enters the system through the gut, the antibodies released by the B cells are usually IgA antibodies.
- These antibodies acts by blocking the bacteria adhering to the gut cells, preventing infection
marking them out for macrophages to clean up.
bacterial
How does it work?
6/
After a few days of fighting off the pathogen, you will recover from your infection. At this stage, the immune system activates T suppressor cells. These cells send out ‘calm down’ signals, which ____ the immune system.
quieten down
