Chapter 22: Lymphatic System And Immunity Flashcards
Immunity
Is the ability to ward off damage or disease through our defenses.
2 types-
1. Innate: refers to defenses that are present at birth. Does not involve specific recognition of a microbe and acts against all microbes in the same way.
2. Adaptive : refers to defenses that involve specific recognition of a microbe once breached the innate immunity defenses. Based on a specific repose to a specific microbe.
Susceptibility
Vulnerability or lack of resistance.
Lymphatic System
Consists of:
-a fluid called lymph
-lymphatic vessels that transports the lymph
-A number of structures and organs containing lymphatic tissue and red bone marrow.
-Assists in circulating body fluid that helps defend the body against disease causing agents.
Lymph
Interstitial fluid that passes into lymphatic vessels.
Found in: lymphatic vessels and lymphatic tissue.
Is clear, pale yellow fluid.
Lymphatic Tissue
A specialized form of reticular connect tissue that contains large numbers of lymphocytes.
2 types of lymphocytes participate in adaptive immune responses:
B cells and T cells
Functions of Lymphatic System
- Drains excess interstitial fluid: drains excess fluid from tissue spaces and returns it to blood. This function links it with CVS
- Transport dietary lipids: lymphatic vessels transport lipids and lipid soluble vitamins A, D, E, K absorbed by the GI tract.
- Carries out immune responses: lymphatic tissue initiates highly specific responses directed against particular microbes or abnormal cells.
Lymphatic Capillaries
Lymphatic vessels begins as capillaries. Capillaries unite to form larger lymphatic vessels.
Capillaries are located in the spaces between cells and are closed at one end.
Have greater permeability than blood capillaries and can absorb large molecules such as proteins and lipids.
Lacteals
Specialized lymphatic capillaries in the small intestine.
Carry dietary lipids into lymphatic vessels and ultimately into the blood.
Chyle
A presence of dietary lipids causes the lymph draining from the small intestine to appear creamy white.
Lymph Trunks
Formed as lymphatic vessels that exit lymph nodes in a particular region of the body.
Principal trunks:
-lumbar: drains lymph for lower limbs, wall and viscera of pelvis, kidneys, adrenal glands and abd wall.
-intestinal: drains lymph from the stomach, intestines, pancreas, spleen and part of the liver.
-bronchomediastinal: drain lymph from thoracic wall, lung and heart.
-subclavian: drain the upper limbs
-jugular: drains head and neck
Formation of Lymph
Formed by excess of interstitial fluid about 3 L/day drains into lymphatic vessels to form lymph.
Proteins can move readily thought more permeable lymphatic capillaries into lymph.
Lymphatic Vessels
Formed by lymph capillaries.
Important function: to return the lost plasma proteins and plasma to the blood stream.
Contains: valves, ensures one way movement of lymph.
Flow of Lymph
Blood capillaries - interstitial spaces (fluid)- lymphatic capillaries (lymph) - lymph vessels (lymph) - lymphatic trunks or ducts (lymph) - junction of the internal jugular and subclavian veins (blood).
Pumps that Maintain Flow of Lymph
- Respiratory Pump: flow of lymph is maintained by pressure changes that occurs durning inhalation. Flows from abd region where pressure is higher towards the thoracic region where it is lower. During exhalation, the valves in lymphatic vessels prevent back flow of lymph.
- Skeletal Muscle Pump: the milking action of skeletal muscle contractions compresses lymphatic vessels and forces lymph towards the junction of the internal jugular subclavian veins.
Primary Lymphatic Organs
Sites where stem cells divide and become immunocompetent ( capable of mounting an immune response).
1. Red bone marrow: in flat bones and epiphyses of long bones of adults. Pluripotent stem cells in marrow give rise to mature immunocompetent B cells and to pre-t cells.
2. Thymus: pre-T cells migrate to thymus where they become immunocompetent T cells.
Secondary Lymphatic Organs
Sites where most immune response occur.
1. lymph nodes
2. spleen
3. lymphatic nodules (follicles)-non organ.
Lymph nodes, spleen as surrounded by CT capsule.
Lymphatic nodules as they lack a capsule.
Thymus
Largest functional capacity is a puberty.
Organ located in the mediastinum between the sternum and aorta.
Where T cells mature.
Extends from the top of sternum to the 4th costal cartilages, anterior to the top of the heart and its greats vessels.
Parts of the Thymus
Capsule: CT encloses each lobe separately
Trabeculae: extensions of the capsule
Lobules: trabeculae penetrate inward and divide each lobe
Cortex: composed of large numbers of T cells and scattered dendritic cells, epithelial cells and macrophages.
Medulla: consists of widely scattered, more mature T cells, epithelial cells, dendritic cells and macrophages.
Thymic Corpuscles: clusters of some epithelial cells become arranged into concentric layers of flat cells that degenerate, become killed with keratohyalin granules and keratin. Site of T cell death in the medulla.
Lymph Nodes
600 bean shape, located along lymphatic vessels.
Function: act as a type of filter.
Scattered throughout the body, both superficially and deep, usually occurs in groups.
Larges groups are present near mammary glands, axilla, and groin.
Parts of Lymph Nodes
Capsule: covering of dense CT, extends into node.
Trabeculae: capsular extension, divide the node into compartments, provide supports and route for blood vessels into the interior of node,
Cortex: consists of inner and outer.
Inner Cortex: do not contain lymphatic nodules. Consists of mainly T cells and dendritic cells that enter a lymph node other tissues.
Outer cortex: egg shaped aggregates of B cells called lymphatic nodules.
Primary Lymphatic Nodule
Smaller than lymph nodes
A lymphatic nodule consisting chiefly of B cells.
Secondary Lymphatic Nodules
Smaller than a lymph node
Most lymphatic nodules are in the outer cortex.
Form in response to an antigen and are sites of plasma cell and memory B cell formation.
Medulla of Lymph Node
Contains B cells. Antibody producing plasma cells that have migrated out of the cortex into the medulla and macrophages.
Afferent Lymphatic Vessels
Carry towards
Lymph flows though a node in one direction.
Enters several of these vessels which penetrate the convex surface of the node at several points.
Contains valves that open towards venter of the node directing the lymph inward.
Sinuses
A series of irregular channels that contain branching reticular fibers, lymphocytes and macrophages.
Efferent Lymphatic Vessels
To carry away.
Medullary sinuses drain into these vessels.
Are wider and fewer in number than afferent vessels.
Contain valves that open away from the center of the lymph node to convey lymph, antibodies and activated T c cells out of the node.
Hilum
Slight depression where efferent lymphatic vessels emerge from one side of the lymph node.
Where blood vessels enter and leave the node.
Spleen
Oval shaped.
Largest single mass of lymphatic tissue in the body.
Function: removes worn out blood cells.
Located: left hypochondrias region between stomach and diaphragm.
Parenchyma of Spleen
Consists of 2 different kinds of tissue.
1. White Pulp: lymphatic tissue, most of lymphocytes and macrophages arranged around branches of splenic artery known as ventral arteries
2. Red Pulp: consists of blood filled venous sinuses and cords of splenic tissue known as splenic cords.
Splenic cords consists of RBC, macrophages, lymphocytes, plasma cells and granulocytes.
Veins are closely associated with this pulp.
Mucosa Associated Lymphatic Tissue (MALT)
Lymphatic Nodules found in mucous membrane lining the GI, GU, Resp and resp airways.
Tonsils
Form a ring at the junction of the oral cavity and oropharynx and junction of nasal cavity and nasopharynx.
Positioned to participate in immune responses against inhaled or injected foreign substance.
Types of Tonsils
- Pharyngeal tonsil: (adenoid) single, embedded in the posterior walls of nasopharynx
- Palatine tonsils: paired, lie at posterior region of the oral cavity, one on each side. These are removed in tonsillectomy.
- Lingual tonsils: located at the base of the tongue. May also need removal during tonsillectomy.
Innate (nonspecific) Immunity
Depends against all types of invaders
A defense that you have since birth.
1.First line of defense: Includes the external physical and chemical barriers provided by the skin and mucous membrane.
-When a pathogen penetrate the fist line they met the second
2.Second line of defense: various deference as anti microbial substances: interferons, natural killer cells, phagocytes, inflammation and fever.
First Line of Defense for Immunity
Skin and mucous membranes.
Provide physical and chemical barriers to discourage pathogens and foreign substance from penetrating the body.
Consists of :
1. Hairs: traps and filter microbes.
2. Cilia: hairline projects that remove dust.
3.lacrimal apparatus: produce treats to remove irritants.
4. Saliva: washes mirrors from the surface of the teeth and mouth.
4. Flow of urine: removes microbes from Gu system
5. Vaginal secretions: moves micro out of the body
6. Defecation and vomiting; expel microbes.
7. Sebum: forms a protective acidic film/layer on the skin to prevent bacteria growth
Second Line of Defense: Internal
Occurs when pathogens penetrate the first line of defense of the skin and mucous membranes physical and chemical barrier.
Includes:
1. internal anti microbial substance: antibodies and interferons
2. phagocytes
3. natural killer cells
4. Cyctoxic cells
5. inflammation.
4 Main Types of Antimicrobial Sustances
- Interferons (IFNs): lymphocytes, macrophages and fibroblasts infected with viruses that produce proteins.
- Complements System: group of non active proteins in blood plasma and on plasma membranes. When activated complements or enchanted certain immune reactions.
- Iron Binding Proteins: inhibit growth of certain bacteria by producing the amount of available iron.
- Antimicrobial Proteins: short peptides that have a broad spectrum of Antimicrobial activity.
Natural Killer Cells
Bodies second line of defense after exposure to antigen.
Release perforin (protein) into the plasma membrane of the target cell and creates a channel in the membrane.
Lack the membrane that identify B and T cells
5-10% of lymphocytes in blood.
Also present in spleen, lymph nodes and red bone marrow.
Lack membrane molecules that identifies B and T cells.
Have ability to kill a wide variety of infected bloody cells and certain tumor cells.
Will release live pathogenic from infected cells called granzymes which are protein digesting enzymes
Perforin
Released by natural killer cells
Granules that contain proteins.
Does not contain chemicals so vasodilation and increased flow to infection does not occur.
Inserts into the plasma membrane of the target cell and creates channels in the membrane.
Causes extracellular fluid to flow into target cells and cell bursts.
Cytolysis
When cells bursts
Natural killer cells and cytosol cells can relapse performing rot cause this.
Granzymes
Relased by granules of Natural Killer cells.
Proteins digesting enzymes that induce the target cells to undergo apoptosis or self destruction.
Phagocytes
Specialized cells that perform phagocytosis.
2 major types:
1. Neutrophils
2. Macrophages
When infection occurs these 2 cell types migrate to infected area.
Wandering Macrophages
When monocytes enlarge during migration and develop into activity phagocytic macrophages.
Fixed Macrophages
Stand guard in specific tissues.
Phagocytosis Stages
- Chemotaxis: chemical stimulated movement of phagocytes to a site of damage,
- Adherence: attachment of phagocyte to the microbe or other foreign material.
- Ingestion: PM of phagocytes extends projections called pseudopods that engulf the microbe. When pseudopods meet, they fuse, surround microorganism with a space called phagosome.
- Digestion: phagosome enters cytoplasm, merges with lysosomes to form phagolysosome. Lysosome contributes lysozyme to break down microbial cell walls.
- Killing: chemical onslaught provided by lysozyme, digestive enzymes and oxidants with phagolysosome quickly kills many types of microbes.
Oxidative Burts
Process that occurs in digestion stage of phagocytosis.
Phagocytes forms lethal oxidant :superoxide, hypochlorite and hydrogen periods.
Residual Bodies
Structures that cannot be degraded further during the killing phase of phagocytosis.
Inflammation
Classified as acute or chronic
Nonspecific, defensive response of the body to tissue damage.
Condition that produces inflammation: pathogens, abrasions, chemical irritations, distortion or disturbances of cells and extreme temps.
Sign and Symptoms of Inflammation: PRISH
P: pain due to release of certain chemical
R: redness because more blood is rushed to the affected area
I: immobility that results from some loss of function in severe inflammations
S; swelling causes by accumulation of fluid
H: heat which is also due to more blood rushing to the affected area.
Inflammation: Vasodilation and Increased Blood Vessel Permeability
Two immediate changes occurs in the blood vessels in a region of tissue injury:
1. vasodilation-increase in diameter of arterioles. Allows more blood to flow through the damaged areas
2. Increased permeability of capillaries-substances normally retained in blood are permitted to pass from the blood vessel. Permits defensive proteins such as antibodies and clotting factors to enter area from blood.
Substances that Contribute to Vasodilation, Increased Permeability and Aspects of Immune Response
- Histamine: released by mast cells in CT and basophils and platelets in blood. Causes vasodilation and increased permeabiliy.
- Kinins: Inactive precursors form polypeptides in blood induce vasodilation and increased perm, serve as chemo tactic agents for phagocytes. Kinin= bradykinin.
- Prostaglandins: are released by damaged cells and intensify the effects of histamine and kinins.
- Leukotrienes: produced by basophils and mast cells
- Complement: different components of the complement system stimulate histamine.
3 Stages of Inflammation
- Vasodilation and increased permeability of blood vessel
- Phagocyte emigration
- Tissue repair
Emigration of Phagocytes during Inflammation
Depends of chemotaxis.
Phagocytes appear at site of inflammation within 1 hour.
Large amounts of blood accumulates.
Neutrophils begin to stick to the inner surface of the endothelium of blood vessels.
Neutrophils begin to squeeze through the walls of blood vessels to reach the site of damage.
Neutrophils attempt top destroy invading microbes by phagocytosis. Monocytes follow.
Neutrophils die out and monocytes transforms into wandering macrophages and engulf the damaged tissue and invading microbes.
Luekocytosis
An increase of WBC in the blood.
Pus
Collection of dead phagocytes and damaged tissue fluid that forms after the macrophages die out.
Occurs in most inflammatory responses and continues until the infection subsides.
Acute Inflammtion
Signs and symptoms develop rapidly and usually last for a few days or even weeks.
Mildly and self limiting.
Principle defensive cells: neutrophils
Chronic Inflammation
Signs and symptoms develop more slowly and can last for up to several months or years.
Often severe and progressive.
Principal deference cells: monocytes and maropahges
Fever
Is an abnormality high body temperature that occurs because the hypothalamic thermostat is reset.
Occurs during inflammation and infection.
Adaptive (Specific) Immunity
Specific recognition of a microbe
The ability of the body to defend itself against specific invading agents such as bacteria, toxins, viruses and foreign tissue.
1. Specificity: for particular foreign molecules (antigens) which also involves distinguishing self from non self molecules
2. Memory: for most previous encountered antigens so that a second encounter prompts an even more rapid response.
Antigens (Ags)
Substances that are recognized as foreign and provoke immune responses.
Produce a specific antibody.
B Cells
Mature in red bone marrow.
Involved in adaptive immunity.
Process that continues throughout life.
Will respond to antigens that have not been processed to help T cells
T Cells
Develop from pre-T cells that migrate from red bone marrow into the thymus where they mature.
Involved in adaptive immunity
In order to become activated T cells need to be bound to a foreign antigen and stimulations costimulation..
Most T cells arise before puberty but continue to mature and leave thymus throughout life.
Immunocompetene
The ability to carry out adaptive immune responses.
When T cells in thymus and B cells in red bone marrow are fully developed a leave their sites.
T and B cells make several distinctive proteins that are inserted into their plasma membrane.
Antigens Receptors
When some distinctive proteins molecules are capable of recognizing specific antigens.
2 Major Types of T Cells
- Helper T cells or CD4 T cells: in addition to antigen receptors their plasma membranes include a proteins called CD4.
- Cytotoxic T Cells or CD8 Cells: due to their plasma membrane contain only antigen receptors but also a preteen known as CD8.
2 Types of Adaptive Immunity
- Cell mediated immunity: cytotoxic T cells directly attack invading antigens.
Effective against: intercellular viruses, bacteria, fungi, some cancer cells and foreign tissue transplants. - Anti body mediated immunity: B cells transform into plasma cells which synthesize and secrete specific proteins called antibodies or immunoglobulin
Effective against: extracellular viruses, bacteria, fungi
Clonal Selection
Process by which a lymphocytes proliferates (divides) and differentiates (forms more highly specialized cells) in response to a specific antigen.
The result:
Memory Helper T cells
formation of a population of identical cells.
A clone can recognize the same septic antigen as the original lymphocyte.
2 Major Cells Type of Clonal Selection
Give rise to:
1. Effector cells: thousands of cells of a lymphocytes clone carry out immune responses that result in the destruction of inactivation of the antigen.
Include: active helper T cells, active cytotoxic T cells and plasma cells.
2. Memory cells: do not participate in initial immune responses. If same antigen enters body again the future, the thousand of cell lymphocyte clone are available. This response is far more fast and vigorous.
Include: memory helper T cells, memory cytotoxic T ells and memory B cells.
Immunogenicity
An important characteristic of antigens.
Ability to provoke an immune response by stimulating the production of specific antibodies.
Antigen
Derives from its function as an antibody generator.
Implies both immunogenicity and reactivity.
Includes: entire microbes or parts of microbes.
are large, complex molecules.
Usually proteins.
Nucleic acids, lipoproteins, glycoproteins and certain polysaccharides may act as antigens.
Epitopes
Introduces production of a specific antibody or activates a specific T cell
Or antigenic determinants.
Certain small parts of a large antigen molecule that act as a trigger from immune response.
.
Antigen Routes into Lymphatic Tissue
Antigens that get past the innate deference follow 1 of 3 routes:
1. Enter bloodstream, become trapped as they flow through the spleen.
2. Penetrate the skin enter lymphatic vessels and lodge in lymph nodes.
3. Penetrate mucous membranes are entrapped by mucosa-associated lymphatic tissue (MALT)
Hapten
A smaller substance that has reactivity but lacks immunogenicity.
Can stimulate immune response ONLY if it is attached to a larger carrier molecules.
Genetic Recomination
The diversity of an antigen receptor in both B and T cells is the result of shuffling and rearranging a few 100 versions of several gene segments.
The gene segment is put tighter in different combinations as the lymphocytes are developing from stem cells in red bone marrow and the thymus.
Major Histocompatibility Complex (MHC) Antigens
Self-antigens located in the plasma membrane of body cells.
Generates diversity in genetic recombination
Are transmembrane glycoproteins because they are first identified on WBC.
Your MHC is unique unless you are a twin.
Antigen Processing
Antigenic proteins are broken down into peptide fragments that then associate with MHC molecules.
Antigen Presentation
After processing, the antigen MHC complex is inserted into the plasma membrane of a body cells.
If a peptide fragment comes from a self protein, T cells ignore the antigen MHC complex.
Exogenous Antigens
Foreign antigens that are present in fluids outside body cells.
Include: bacteria, bacterial toxins, parasitic worms, inhaled pollen, dust and viruses that have not yet infected the body.
Antigen-Presenting Cells (APCs)
Special class of cells that process and present exogenous antigens.
Include: dendritic cells, macrophages, and B cells.
Strategically located in places where antigens are likely to penetrate the deferences of the body.
(Ie) epidermis, dermis, mucous membranes and lymph nodes.
Steps in Processing and Presenting of Exogenous Antigen by Antigen-Presenting Cell
- Ingestion of the antigen: ingest exogenous antigens by phagocytosis or Endocytosis.
- Digestion of antigen into peptide fragments: within the phagosome or endosome, proteins-digesting enzymes split large antigens into short peptide fragments.
- Synthesis of MHC-II molecules: the APC synthesizes MHC-II molecules at the endoplasmic reticulum.
- Packing of MHC-II molecules: once synthesized, the MHC-II molecules are packages into vesicles.
- Fusion of vesicles: vesicles merge and fuse.
- Binding of peptide fragments to MHC-II molecules: after fusion the 2 types of vesicles, antigen peptide fragments bind to MHC-II molecules.
- Insertion of antigen-MHC-II complexes into PM: the combined vesicles undergo exocytosis, as a result the antigen MHC-II complexes are inserted into the PM.
Endogenous Antigens
Foreign antigens that are present inside the body cells.
may be viral proteins produced after a virus infects the cell and takes over ells metabolic machinery.
Steps in the Processing and Presenting of an Endogenous Antigen by an Infected Cell
- Digestion of antigen into peptide fragments: within the infected cell, proteins digesting enzymes split the endogenous antigen into short peptide fragments.
- Synthesis of MHC-I molecules: at the same time, the infected cell synthesizes MHC-1 molecules at the ER.
- Binding of peptide fragments to MHC-I molecules: the antigen peptide fragments enter the ER and bind to MHC-I molecules.
- Packaging of antigen-MHC-1 molecules: from the ER, antigen MHC-I molecules are packaged into vesicles.
- Insertion of antigen-MHC-I complexes into the plasma membrane: the vesicle that contain antigen-MHC-I complex’s undergo exocytosis. As a result the complexes are inserted into the PM.
Cytokines
Small proteins hormones that stimulate or inhibit many normal cell functions like cell growth.
Secreted by: Lymphocytes, antigen-presenting cells, fibroblasts, endothelial cells, monocytes, hepatocytes and kidney cells.
Stimulate: proliferation of progenitor blood cells in red bone marrow.
Cell Mediated Immune Response
Begins with activation of a small number of T cells by a specific antigen.
Once T cells are activated they undergo Clonal selection.
T-Cell Receptors (TCRs)
Most T cells are inactive. To be active a T cell must bind to antigens receptors on surface of T cells recognize and bind to specific foreign antigen fragments that are presented in antigen MHC complexes.
Costimulation
A second signal a T cell receives when it becomes activated.
Examples:
cytokines: interleukin-2
T cells
Antigen presenting cells.
Anergy
A state of prolonged inactivity that occurs without costimulation in both T cells and B cells.
Helper T Cells
Also know as CD4 T cells. Most important cell in the immune system.
Most T cells that display CD4 develop into helper cells and interact with MHC Class II antigens.
Primary targets of the HIV virus.
These cells recognize exogenous antigen fragments associated with major histocompatibility complex class II molecules at the surface of an APC.
Aid from CD4 proteins, helper T cells and APC interact, costimulation occurs and helper T cells become activated.
Active Helper T cells
Once activated the helper T cells undergoes clonal selection hours after costimulation these cells start secreting a variety of cytokines.
Interleukin-2
Important cytokines produced by helper T cells.
Needed for virtually all immune responses and is the prime trigger of T cells proliferation.
Memory Helper T Cells
Memory of a helper T cell clone that is not an active cell.
If the same antigen enters the body in the future, these’d cells can quickly proliferate and differentiate into more active helper T cells and more memory helper T cells.
Active Cytotoxic T Cells
Attack other body cells that have been infected with antigens.
Memory Cytotoxic T Cells
Do not attack infected body cells.
Instead they can quickly proliferate and differentiate into more active cytotoxic T cells and more memory cytotoxic T cells if the same antigen enters the body at the future time,
Cytotoxic T Cells
apart of the adaptive immunity.
Most T cells that display CD8 develop into these ells.
There recognize foreign antigens combined with major histocompatibility complex class I with:
1. body cells infected by microbes
2. Some tumor cells
3. Cells of a tissue transplant
They leave secondary lymphatic organs and tissues and migrate to seek out and destroy infected target cells.
They release toxic substance granzymes that binds to a cells that lead to apoptosis.
They
Tumor Antigens
When normal cells transforms into a cancerous cells it will display novel cell surface components.
Immunological Surveillance
Immune responses carried out by cytotoxic T cells, macrophages and natural killer cells.
Recognizes a tumor antigen as nonself.
Most effect in eliminating tumor cells due to cancer causing viruses.
B Cell Receptors (BCRs)
Antigens binds to this cell during activation of a B cell.
These integral transmembrane proteins are chemically similar to the antibodies that eventually are secreted by plasma cells.
Antibody (Ab)
Can combine specifically with the epitope on the antigen that triggered its production.
Antibody’s structure matches its antigen.
Antibody belong to a group of glycoproteins called globulins.
Antibody Structure: Heavy H Chains
Two chains that are identical to each other.
Each consists of about 450 amino acids.
Short carbohydrates chains are attached to each heavy polypeptide chain.
Antibody Structure: Light (L) Chains
2 polypeptide chains that are identical to each other.
Each consists of about 220 amino acids.
A disulfide bond (s-s) holds each light chains to a heavy chain.
Antibody Structure: Hinge Region
2 disulfide bonds that link the mid region of the 2 heavy chains. This part of the antibody displays considerable flexibility.
Antibody Structure: Stem Hinge
Parts of the 2 heavy chains form this beyond the hinge region.
IgG
Most abundant class of immunoglobulin.
About 80% of all antibodies in blood.
Found in: blood, lymph and intestines.
Protects against bacteria and viruses by enhancing phagocytosis, neutralizing toxins and triggering complement systems.
Only class to cross placenta, gives immune protection in newborns.
IgA
Found mainly in sweat, tears, saliva, muscles, breast milk and GI secretions.
10-15 % in blood.
Smaller quantities are present in blood and lymph.
Levels decrease during stress, lowering resistance to infection.
Provides localized pretreat ion of mucous membranes against bacteria.
IgM
Class of antibody that indicates a recent invasion, first to be secreted after exposure.
About 5-10 % of all antibodies in blood. Also found in lymph.
Activates complement and causes agglutination and lysis of microbes.
IgD
Mainly found on surface of B cells as antigen receptors, where it occurs as monomers.
Involved in activation of B cells.
About 0.2 % of all antibodies in blood.
IgE
Less than 0.1 % of all antibodies in blood.
Located on mast cells and basophils.
Involved in allergic and hypersensitivity reactions
Provides protection against parasitic worms.
Naturally Acquired Active Immunity
Occurs following a natural exposure to a microbe or infectious agent.
Antigen recognition by B and T cells and costimulation lead to formation of antibody secreting plasma cells, cytotoxic T cells and B and T memory cells.
Naturally Acquired Passive Immunity
IgG antibodies are transferred from mother to fetus across placenta, or
IgA antibodies are transferred from mother to baby in milk during breast feeding.
Artificially Acquired Active Immunity
Antigens introduced during vaccination or IV injection of immunoglobulin stimulate cell mediated and antibody mediated immune responses leading to production of memory cells.
Antigens are pretreated to be immunogenicity but not pathogenic.
Artificially Acquired Passive Immunity
Intravenous injection of immunoglobulins (antibodies).
T Cell Traits
To function properly T cells must have 2 traits:
1. They must be able to recognize your own major histocompatibility complex (MHC) proteins and processes known as self recognition.
2. They must lack reactivity to peptide fragments from your own proteins, a condition known as self tolerance.
Positive Selection T cells
Some pre-T cells express T-cells receptors that interact with self proteins on epithelia’s cells in the thymic cortex.
Negative Selection T Cells
The developments of self tolerance occurs by a weeding out process.
T cells interact with dendritic cells at the junction of the cortex and medial in the thymus.
Deletion T Cells
Negative selection occurs this process.
Self reactive T cells undergo apoptosis and die.
Anergy T Cells
Negative selection also occurs by this process.
T cells remain alive but are inactive, self responsive cell to antigenic stimulation.
Major Difference between Lymph and Interstitial fluid
Is the location.
Lipids in Small Intestine
Causes lymph to appear white from the lacteals that transport it to blood from small intestine.
Thymic Corpuscles
Located in the thymus
Where T cells die.
Barriers in Innate Immunity
Epidermis
Mucus
Cilia
Hairs
Lacrimal apparatus
Saliva
Urine
Vaginal secretions
sebum
Perspiration
Gastric juice
Macrophages
Process and presentation of foreign antigens to T cells
Provides a non superficial cellular disease resistance mechanism
Do not provide a physical or chemical barrier.
Interferons
Anti microbial substance that reduces viral replication in uninflected cells.
A fever would intensify the effect of these and promotes the rate of repair.
Complement Proteins
Anti microbial substance that promotes cytolysis, phagocytosis and inflammation.
Antigen Presenting Cells
Class of cells that include macrophages, B cells and dendritic cells.
Lymphotoxin
T cell toxin that fragments DNA.
5 Actions of Antibodies
- Act as neutralizing agents
- Immobilize bacteria
- Agglutinate and precipitate the antigen
- Activate the complement
- Enhance phagocytosis
Opsonization
Action that makes microbes more susceptible to phagocytosis.
Immunodeficiency Diseases
Diseases that are caused due to the inability of the immune system to protect the body from a pathogen.
Lymphocyte
The most variable cell in the immune system
Primary Response in Exposure
Will peak at 10-17 days after exposure.
After an encounter with an antigen occurs, no antibody are present. Then as the antibody titer occurs they begin first with IgM then IgG. Once antibody titer declines, IgG antibodies remain.
This response is when you recover without taking antimicrobial medications
Reactivity
The ability of an antigen to react specifically with the antibodies or cells it has provoked.
Mast Cells
Cell that increase the permeability of blood vessels by releasing histamine.
Interleukin-1
Type of cytokine cell
Released by macrophages
Acts on the hypothalamus to raise the body temperature during fever.
Effects of Aging on Immune System
Increased susceptibility to infections
Increased susceptibility to malignancies
Decreases response to vaccines
Decreased production of antibodies
Stress Effects on Immune System
Decreased or inhibition response from the immune system
Organ System that are Aided by the MALT (mucosa associated lymphatic tissue)
Respiratory system
Digestive system
Urinary system
Reproductive system
Dendritic Cell
Process and presents antigens to T and B ells
Plasma Cells
Produces and secretes antibodies
Development of Self Tolerance
Development of this, cell undergo a process called negative selection that occurs via deletion and anergia. These occur in the thymus.
When T cells emerge they can become anergia due to an encounter with an unfamiliar self protein and lack of a costimulator.
Secondary Response in Exposure.
The accelerated and more intense response.
Antibodies produced have a higher affinity to the antigen than primary and are more successful in disposing of the antigen.
Newborn Immunity at Birth
Components of immunity:
1. Saliva: washes microbes and bacteria out of the mouth
2. Sebum: oily substance that protects the skin
3. Cilia: hairlike projections in resp tract that move dust and bacteria out of the throat.
