Chapter 16 PPT: Immunity Flashcards
Definition for Pathogens
Disease causing agents
Examples of pathogens?
Bacteria, viruses, complex microorganism like protozoa
What are innate defenses?
Nonspecific
General defenses.
Protect against many types of pathogens
What is Adaptive Defense?
Specific , known as immunity
More specific and precise. Carried out by lymphocytes that recognize certain foreign molecules
Types of Innate Defenses?
Species Resistance Mechanical Barriers Inflammation Chemical Barriers Natural Killer Cells Phagocytosis Fever
What is Species Resistance?
Refers to the fact that certain species are resistant to diseases that affect other species
Species Resistance: Certain species do not have
the appropriate temperature or chemical environment for a particular pathogen to survive and proliferate
Mechanical Barrier considered to be the first
line of defense
Examples of Mechanical Barriers?
Epidermis Sloughs of, removes superiffical bacteri
Ciliated epithelium in respiratory tract traps and dsweeps away pathogens
Hair traps pathogens
Examples of Chemical Barriers?
Enzymes Interferons Defensins Collectins Complement
Chemical Barriers: Enzymes…
in body fluids provide a chemical barrier to pathogens
Chemical Barriers: Example of Enzymes
Pepsin in gastric juuice and lysozyme in tears destroy microorganisms
Chemical Barriers: Interferons block
viral replication, act against growth of tumors, stimulate phagocytosis
Chemical Barriers: Defensins are
peptides produced by neutrophils and other granulocytes; they cripple microbes by making openings in cell membranes or walls
Chemical Barriers: Collectins are
proteins that protect against many bacteria, yeast, and some viruses
Chemical Barriers: Complement is a group of
proteins in plasma and other body fluids that stimulates inflammation, attracts phagocytes and enhances phagocytes
NK cells are a small population of
lymphocytes
NK cells are very different from
B CElls and T cells that provide adaptive defenses
NK Cells defend against
viruses and cancer cells by secreting cytolytic substances called perforins, that lyse celll membrane
NK cells also enhance
inflammation
Blood vessels dilate, cpaillary permeability increases and fluid leaks into tissue spaces results in
tissue become red, swollen, wamr and painful
White blood cells invade the region resulting in
Pus forming as white blood cells, bacterial cells, and cellular debris accumulate
Tissue fluids containing cloting factors seep into the area resulting in
a clot containing threads of fibrin may form
Fibroblasts arrive results in
connective tissue sac may form around the injured tisseus
Phagocytes are active resulting in
bacteria, dead cells, adn other debris are removed
Cells divide resulting in
newly formed cells replacing injured one
Phagocytosis: Removes
foreign particles from the lymph
Phagocytosis: In the blood vessels and the tissues of the spleen, liver ,or bone marrow remove
particles from blood
Phagocytosis: Most aactive phagocytic cells are
neutrophils and monocytes
Phagocytosis: Chemicals from damaged tissues attract
these phagocytic cells to the injury, this is called chemotaxis
Phagocytosis: Monocytes that leave the blood become
macrophages, which can be free or fixed in tissues
Mononuclear Phagocytic System consists of
monocytes and macrophages of the body
Fever begins when
viral or bacterial infection stiulates lymphocytes to proliferate, producing cells that secrete a substance called interleukin 1 (IL-1) which raises thermoregulatory set point
IL-1 is also called
endogenous pyrogen
Fever : Elevated body temperature indirectly inhibits
microbial growth
causes liver and spleel to take up iron, making it unavilable for bacteria and fungi to use in their nromal metabolism
Third line of defense is resistance to
particular pathogens or to their toxins or metabolic by products
Adaptive DEfense response based on
ability to distinguish molecules that are part of the body from “non-self”
Antigens are
non-self molecules that can elicit an immune response
Adaptive responses are carried out by
lymphocytes and macrophages that can recognize specific antigens
Two types of adaptive defenses?
CEllular Immune Response (Perofrmed by Immune Cells)
Humoral Immune REsponse (Performed by Antibodies)
Receptors on the surface of lymphocytes enable
the cells to recognize non-self antigens
Antigens may be
proteins
polysaccharides
Glycoproteins
Glycolipids
The most effective antigens are
large and complex molecules
Haptens are
small molecules that are not antigenic by themselves, but when they combine with large molecule in the body, they can evoke an immune repsonse
Red bone marrow releases
unspecialized lymphocytte precursors into blood
T Cells specialize in
thymus
After T Cells released from Thymus, make up
70-80% of circulating lymphocytes
Some T cells settle in
lymphatic organs, such as lymph nodes, thoracic duct, white pulp on spleen
After B cells released from bone marrow, make up
20-30% of lymphoctes in blood
B cells abundant in
lymph nodes, spleen, bone marrow, intestinal lining
Step one in lymphocyte origin
Stem cells in red bone marrow give rise to lymphocyte precursors
Step 2 in lymphocyte origin
Some lymphocyte precursors are processed in the thymus to become T cells
Step 3 in lymphocyte origin
Some lymphocyte precursors are processed within the bone marrow to become b cells
Step four in lymphocyte origin
Both T cells and B cells are transported though the blood to lymphatic organs such as lymph nodes and spleen
Origin of T Cells
Red bone marrow
Origin of B Cells
Red Bone Marrow
Site of differentiation of T Cells
Thymus
Site of differentiation of B Cells
Red bone marrow
Primary Locations of T Cells
Lymphatic tisssues
70-80% of the circulating lymphocytes in blood
Primary Locations of B Cells
Lymphatic Tissues
20-30% of the circulating lymphocytes in blood
Primary function of T Cells
Provide cellular immune response in which T Cells interact directly with the antigens or antigen bearing agents, to destroy them
Primary function of B Cells
Provide humoral immune response in which B cells interact indirectly, producing antibodies that destroy the antigens or antigen-bearing agents
A lymphocyte must be activated before
it can respond to an antien
T Cell activation requires that
antigenic fagments be attached to anti-gen presenting cell (APC) such as macrophages, b cells, and several other types
T Cells can secrete polypeptides called
cytokines, which enhance some cellular responses to antigens
What are Helper T Cells
Activate other cells; help B cells produce antibodies
What are Cytotoxic T Cells
Attack virally-infected or cancerous cells
What are Memory T Cells
Provide future immune protection
What are four different cytokines
Colony-Stimulating Factors
Interferons
Interleukins
Tumor Necrosis Factor
Function of Colony-Stimulating Factors
Stimulate bone marrow to produce lymphocytes
Function of Interferons
Bloc viral replication, stimulate macrophages to engulf viruses, stimulate B cells to produce antibodies, attack cancer cells
Function of Interleukins
Conrol lymphocyte differentiation and proliferation
Function of Tumor Neecrosis Factor
Stops tumor growth, releases growth factors, causes fever that accompanies bacterial infection, stimulation lymphocyte differentiation
B cells can be activated when
an antigen fits the shape of their receptors, and binds to them
Further B Cell activation requires
cytokines from T Cells
Once proper cytokines are released from Helper T Cells, B Cells respond by
proliferating, enlarging clone of identical cells
Some new B cells become
memory B cells, which provide future immunity
Other new B cells differentiate into
plasma cells, which produce and secree large globular proteins called antibodies or immunoglobulins
B cell prolifertion both
dormant memory B cells and antibody-secreting plasma cells
B Cell Activities: Step 1
Antigen-bearing agents enter tisseus
B Cell Activities: Step 2
B cell encounters an antigen that fits its antigen receptors
B Cell Activities: Step 3
Either alone or more often in conjuction with helper T cells, the B cell is activated. The B cell proliferates, enlaring its clone
B Cell Activities: Step 4
Some of the newly formed B cells differentiate further to become plasma cells
B Cell Activities: Step 5
Plasma cells synthesize and secrete antibodies whose molecular structure is similar to the activated B Cells antigen receptors
T Cell Activites: Step 1
Antigen-bearing agents enter tisseus
T Cell Activites: Step 2
An accessory cell, such as a macrophage, phagocytizes the antigen-bearing agent, and the macrophages lysosomes digest the agent
T Cell Activites: Step 3
Antigens from the digested antigen-bearing agents are displayed on the membrane of the accessory cell
T Cell Activites: Step 4
Helper T cell becomes activated when it encounters a displayed antigen that fits its antigen receptors
T Cell Activites: Step 5
Activated helper T cell releases cytokines when it encounters a B cell that has previously combined with an identical antigen-bearing agent
T Cell Activites: Step 6
Cytokines stimulate the B cell to proliferate , enlarging its clone
T Cell Activites: Step 7
Some of the newly forme dB cells give rise ot cells that differentiate into antibody-secreting plasma cells
Antibodies are what type of protein
globular
Antibodies make up the
gamma globulin fraction of plasma proteins
Antibodies also called
immunoglobulins
Y shaped proteins composed of
4 amino acid chains : 2 heavy and 2 light chains
Each type of antibodies has a
unique amino acid sequence and conformation, making it specific for its antigen
What are the five major types of antibodies
IgG (80%) IgA (13%) IgM (6%) IgD (<1%) IgE (<1%)
IgG occurence
Plasma and tissue fluid
IgG major function
Defends against bacteria, viruses and toxins
Activates complement
IgA occurence
Exocrine gland secretions
IgA major functions
defends against bacteria and viruses
IgM occurrence
plasma
IgM major functions
Reacts with antigens on some red blood cell membranes floowing mismatched blood transfusions ; activated complement
IgD occurence
Surface of most B lymphocytes
IgD major functions
B Cell activation
IgE occurrence
Exocrine gland secretions
IgE major functions
promotes inflammation and allergic responses
Antibodies react to antigens in what 3 ways
Direct attack on antigens
Activation of complement
Stimulation of local change, inflammation, to help prevent spread of infection
Immunotherapy makes use of
immune system components to fight disease (both the humoral immune response by antibodides and the cellular immune response by cytokines)
What are Monoclonal Antibodies?
A specific B Cell which produces a single type of antibody that can be fused with a cancerous cell to produce a cell that produces 1 type of antibody and keep dividing
What are Cytokines used for in Immunotherapy
Can now be produced in large quantities due to recombinant DNA and monoclonal antibody techniques
What is the Primary Immune REsponse?
Produced by first encounter with antigen.
First antibodies apper in 5-10 days and remain for several weeks. Memory B cells are also produced
What is the SEcondayr Immune Response
Subsequent exposure to antigen produces high concentraction of antibodies in 1-2 days. Antibodies remain for m onths or years.
Memory b can live for many years
What is a Type 1 reaction?
Overproduction of IgE antibodies (Hay Fever)
What is a Type II Reaction?
Phagocytosis and complement mediated lysis of antigen
Mismatched blood transfusion
What is a Type III Reaction
Phagocytosis and lysis cannot clear antigen-antibody complexes
Autoimmunity
What is a Type IV reaction
T cells and macrophages release chemical factors into the skin
Dermatitis
What is eleased in a Type I reaction?
Histamine
Symptoms of Type I reaction?
Hives, Hay Fever, Asthma, Eczema, Gastric Disturbances
In a Transplant, it is important to match what?
MHC antigens between donor and recipient; the greater the antigenic difference, the stronger and faster the rejection will be
What are the four types of transplant
Isograft
Autograft
Allograft
Xenograft
What is a Isograft donor
Identical twin
Isograft example
Bone marrow transplant from a healthy twin to a twin who has leukemia
What is a autograft donor
self
what is a autograft example
skin graft from one part o fthe body to replace burnt skin
what is a allograft donor
same species
what is a allograft example
kidney transplant from a relative or closely matched donor
what is a xenograft donor
different speices
what is a xenograft example
heart valves from a pig
what would not cause rejection reaction
isograft or autograft
what would tend to cause a rejection reaction
allografts and xenografts
What antibodies are produced in autoimmunity?
Autoantibodies. Its an attack by the immune system against own tissues
What immune part shrinks as you grow older
thymus gland
T cell and B cells as you get older?
T cells decrease slightly and b cells do not change
IgA and IgG as you get older?
antibodies increase
IgM and IgE as you get older?
Antibodies decrease
What is HIV?
Virus that breaks down immune system function
HIV may stay silent for years and then progress to
AIDS (Acquired immune deficiency syndrome)
HIV attacks
macophages and helpter T cells
When Helpter T Cell number decline, B cells cannot
produce antibodies, due to lack of cytokine activation
