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Gabriela Samson P:1 Immune System - Coggle Diagram
Gabriela Samson P:1 Immune System
Major functions of the Lymphatic & Immune systems (include BOTH)
Lymph Movement
Factors that help in the movement of lymph: Hydrostatic pressure of tissue fluid drives entry of fluid into
lymphatic capillaries, where it is now called lymph
Lymph formation depends on tissue fluid formation
Muscular activity moves lymph through lymphatic vessels
Lymph: Tissue fluid that has entered a lymphatic capillary
Edema: accumulation of lymph in the interstitial spaces, due to interference with the flow in lymph
Tissue Fluid and Lymph
Example: during surgery, such as removing cancerous breast, lymphatic vessels or tissues may be removed or disturbed; obstruction results in edema
Have flaplike valves on the inside, like veins
Lymphocyte Origins: Red bone marrow releases undifferentiated lymphocyte precursors into circulation, starting in fetal development, and continuing throughout entire lifespan
Lymphatic Vessels-Walls of lymphatic vessels are thinner than those of veins, but are constructed with the same 3 layers
About half go to thymus, and specialize into T lymphocytes or T cells; make up 70 to 80% of circulating lymphocytes; some settle in the lymph nodes, spleen, and thoracic duct
Lymphatic pathways start as lymphatic capillaries, that merge to form larger vessels, and then lymphatic trunks, that empty into veins in the thoracic cavity
Other lymphocytes differentiate in red bone marrow to become B lymphocytes or B cells; these represent 20 to 30% of circulating lymphocytes; also settle in lymphatic organs (lymph nodes, spleen)
and lining of intestines
Lymphatic Pathways
Immune Responses
Lymph nodes, which are situated along lymphatic vessels,
contain lymphocytes, which help defend body against disease
Primary immune response: Activation of B or T cells during the first encounter with an antigen
Lymphatic vessels collect and carry away excess tissue fluid
from interstitial spaces, eventually returning it to the blood
Antibodies (IgM, then IgG) are released into blood; help destroy antigens for several weeks
Lymphatic System: A second circulatory system
Some B cells remain as memory B cells, remaining dormant at the time, but remembering the antigen
Lymphatic System & Immunity
Secondary immune response: Rapid, long-lasting, response to a subsequent encounter with the same antigen; accomplished by memory B cells and memory cytotoxic T cells
Memory B cells proliferate, antibodies appear in 1-2 days, and remain for months to years
Memory B cells can live for many years, providing long-term
immunity
Humoral response and cellular response
When a helper T cell encounters a B cell that has already encountered and bound to an antigen, the helper T cell releases cytokines that activate the B cell, stimulating it to proliferate (divide and form a clone).
Some of the B cells differentiate into plasma cells, which produce and secrete antibodies (immunoglobulins)
But most B cells need helper T cells for activation
Antibodies travel through the body fluids to attack and destroy antigens; this is called the humoral immune response
A B cell may become activated and produce a clone of cells when it encounters an antigen that matches its receptors, and binds to it
Other B cells become memory B cells; these remain dormant at the time, but respond to future encounters with the antigen
B Cells and the Humoral Immune Response
Passive vs. Active immunity
Immunity can be active or passive:
Active immunity is obtained through antigen exposure; an
immune response occurs in the person, in which antibodies and memory B cells are produced; this is long-lasting immunity
Immunity can be acquired by natural events, such as getting a disease, or induced artificially, by an injection
Passive immunity is obtained by receiving antibodies; since
there is no antigen contact and no immune response occurs, no memory B cells are produced; this is short-term immunity
Practical Classification of Adaptive Immunity
Purpose and examples of First, Second and Third line of defense
The function of inflammation is to stop the spread of pathogens and infection.
Innate defenses: Chemical Barriers are chemicals that kill many pathogens.
Innate Defenses: Inflammation is a tissue response to injury or infection.
Acidic environment provided by HCI is gastric Juice is led to some pathogens.
The rest of the Innate defenses are part of the second life of defense.
Innate Defenses:Natural Killer (NK) cells is a small group of lymphocytes, other than T cells and B cells.
Mechanical barriers represent the body's first line of defense
Defend the body against viruses and cancer cells by secreting cytolytic substances called perforins which lyse break apart cell membranes of pathogens.
Includes hair, mucus, and sweat.
Innate Defenses: Phagocytosis is an engulfment and digestion of pathogens, foreign particles, and debris.
Example: Unbroken skin and mucous membranes of the body.
Most active phogocytes are neutophils and monocytes, which leave the blood stream in areas of injury.
Mechanical Barriers: Prevent the entry of certain pathogens by providing a physical separation of pathogens and internal tissues.
Fever occurs when body temperature is re-set to a higher set point.
Results in elevated body temperature.
Immunity (adaptive immune defenses): Response by the body against specific pathogens, their toxins or metabolic products.
Third line of defense against pathogens.
Performed by lymphocytes and macrophages that recognize and remember specific foreign molecules on particular pathogens.
Include cellular immune response and numoral immune response.
Cells involved in the immune system and their functions
When T cells recognize and bind to antigenic fragments that match their receptors, they become activated
T Cells and the Cellular Immune Response 2
MHC proteins help T cells recognize displayed antigens
Cellular immune response or cell-mediated immunity: response through cell-to-cell contact, as activated T cells interact directly with antigen-bearing cells
Macrophages acting as APCs digest the pathogen, and display the antigenic fragments on their own cell membrane, complexed with special proteins called major histocompatibility complex (MHC) proteins
T cells also synthesize and secrete cytokines (such as interleukins and colony stimulating factors) that enhance cellular responses to antigens
T cell activation requires an encounter with an antigen-presenting cell (accessory cell, APC), such as a B cell or macrophage, that has already encountered and phagocytized the antigen
Some T cells secrete toxins, growth-inhibiting factors, or interferon
Lymphocytes require activation before they can respond to
antigens
T Cells and the Cellular Immune Response
T Cells and the Cellular Immune Response
Types of T cells:Helper T cells stimulate B cells to produce antibodies against the displayed antigen
Other lymphocytes differentiate in red bone marrow to become B lymphocytes or B cells; these represent 20 to 30% of circulating lymphocytes; also settle in lymphatic organs (lymph nodes, spleen) and lining of intestines
Cytotoxic T cells monitor the body's cells, recognizing and
eliminating cancer cells and virus-infected cells
About half go to thymus, and specialize into T lymphocytes or T cells; make up 70 to 80% of circulating lymphocytes; some settle in the lymph nodes, spleen, and thoracic duct
Cytokines from helper T cells activate cytotoxic T cells, which then increase number of identical cells in their clone
Red bone marrow releases undifferentiated lymphocyte
precursors into circulation, starting in fetal development, and continuing throughout entire lifespan
Cytotoxic T cells then bind to antigen-bearing cells, and release perforin, which cuts pores in the cell membrane, destroying the cells
Lymphocyte Origins
Memory T cells provide a quick response to any future
exposure to the same antigen, by dividing to produce a large number of cytotoxic T cells
Location of Lymphatic organs and their functions
Locations of Lymph Nodes-The lymph nodes generally occur in chains along the parts of the larger lymphatic vessels
Lymph nodes are not found in the central nervous system
Filtered lymph leaves lymph node through efferent lymphatic vessels removing many pathogens
Major areas of concentrations of lymph nodes: cervical, thoracic, axillary, supratrochlear, abdominal, pelvic, and inguinal regions
Afferent lymphatic vessels enter on the convex surface
Functions of Lymph Nodes-
Lymph nodes are bean-shaped
Main functions of lymph nodes:Filter lymph and remove bacteria and cellular debris before lymph is returned to the blood
Structure of a Lymph node:
Immune surveillance: Monitor body fluids; performed by
lymphocytes and macrophages
Lymph Nodes:Lymph nodes are located in groups or chains along lymphatic vessels
Encapsulated lymphatic organs:Lymph nodes, Thymus, Spleen
Lymph nodes are also centers of lymphocyte production
Lymphocytes attack viruses, bacteria and parasitic cells that
enter a lymph node
Tonsils, appendix, and Peyer’s patches are compact masses of lymphatic nodules
Macrophages engulf and destroy foreign particles, debris, and damaged cells
Unencapsulated lymphatic tissue associated with the digestive,respiratory, urinary, and reproductive systems is called mucosa-associated lymphoid tissue (MALT)
Lymphatic tissue contains lymphocytes, macrophages, and other cells
Lymphatic Tissues and Organs
Thymus: Shrinks in size during the lifetime; large in children, small in adults, replaced by adipose & connective tissue in the elderly
Lobules contain lymphocytes, some of which mature into T cells or T lymphocytes, that leave the thymus to provide immunity
Spleen: Lies in the upper left abdominal cavity
Largest lymphatic organ in body
Similar to a large lymph node, except it contains blood instead of lymph
Filters the blood and removes damaged blood cells and bacteria
Artificial vs. Naturally acquired immunity
Artificially acquired passive immunity involves the injection of gamma globulins containing antibodies or antiserum; this is short-term, because there was no antigen exposure, no immune response, and no memory B cells produced
Naturally acquired active immunity- Exposure to live pathogens - Stimulation of an immune response with symptoms of a disease
Naturally acquired passive immunity occurs as antibodies are passed from mother to fetus; this is short-term immunity, due to lack of an immune response and lack of memory B cell formation
Artificially acquired active immunity- Exposure to a vaccine containing weakened or dead pathogens or their components- Stimulation of an immune response without the severe symptoms of a disease
Artificially acquired active immunity occurs through the use of vaccines, without the person becoming ill from the disease; since vaccines contain weakened or dead pathogens, person develops long-term immunity, due
to an immune response that includes memory B cell formation
Naturally acquired passive immunity- Antibodies passed to fetus from pregnant woman with active immunity or to newborn through colostrum or breast milk from a woman with active immunity - Short-term immunity for a newborn without stimulating an immune response
Naturally acquired active immunity occurs after exposure to the antigen; long-term resistance results, due to the events of a primary immune response (memory B cells are produced)
Artificially acquired passive immunity- Injection of antiserum or gamma globulins- Short-term immunity without stimulating an immune response
Practical Classification of Adaptive Immunity
Innate(natural) immune defenses and Adaptive(acquired) immune defenses
Respond against only a specific of pathogen; respond more slowly.
Accomplished by specialized lymphocytes, which serete cytokines or antibodies.
Adaptive (Specific) defenses or immunity
Innate (Nonspecific) Defenses:
Including species resistance, mechanical barriers, chemical barriers, natural killer cells, inflammation, phagocytosis, and fever.
A species is resistant to diseases that affected other species.
Innate (nonspecific) defense: Guard against many types of pathogens; respond quickly.
Based on the following factors:
Two basic mechanisms of defense against pathogens.
Different chemical environments
Can be bacteria,virus,fungi or protozoans.
A body temperature that does not provide the conditions required by the pathogen
Presence and multiplication can produce an infection.
Presence or absence of receptors for a particular type of pathogen.
Pathogens: Disease-causing agents.
Antigens and antibodies
Steps in Antibody Production
T Cell Activities- Antigen-bearing agents enter tissues.
Plasma cells synthesize and secrete antibodies whose molecular structure is similar to the activated B cell’s antigen receptors.
An accessory cell, such as a macrophage, phagocytizes the antigen-bearing agent, and the macrophage’s lysosomes digest the agent.
Some of the newly formed B cells differentiate further to become plasma cells.
Antigens from the digested antigen-bearing agents are displayed on the membrane of the accessory cell.
Either alone or more often in conjunction with helper T cells, the B cell is activated. The B cell proliferates, enlarging its clone.
Helper T cell becomes activated when it encounters a displayed antigen that fits its antigen receptors
B cell encounters an antigen that fits its antigen receptors.
Activated helper T cell releases cytokines when it encounters a B cell that has previously combined with an identical antigen-bearing agent.
B Cell Activities- Antigen-bearing agents enter tissues.
Cytokines stimulate the B cell to proliferate, enlarging its clone.
Steps in Antibody Production -
Some of the newly formed B cells give rise to cells that differentiate into antibody-secreting plasma cells.
Immune response is directed against “nonself” molecules,
which are usually large and complex foreign molecules
Types of Antibodies
Before birth, the body makes an inventory of “self” antigens
5 major types of antibodies (immunoglobulins) constitute the gamma globulin fraction of the plasma (IgG, IgA, IgM, IgE, IgD)
Antigens: Can be any large molecules that that can trigger an immune response (ex: proteins, food, chemicals, etc...)
Antibody Actions
3 methods by which antibodies react to antigens: Direct attack by agglutination, precipitation, or neutralization of
antigens; these methods make antigens more susceptible to phagocytosis
Activation of complement results in opsonization, chemotaxis, inflammation, agglutination, neutralization, alteration, or lysis of antigens or antigen-bearing cells
Inflammation: Stimulation of local inflammatory changes in the area, that helps prevent the spread of the pathogens
Disorders associated with the Immune system
Pertussis (Whooping Cough)- A respiratory infection that is caused by bacteria.
Meningitis- Meningitis is an inflammation of the protective membranes covering the brain and spinal cord.
Measles- A childhood infection caused by a virus.
Rubella- Rubella is a contagious disease caused by a virus.
Malaria- Malaria is a mosquito-bone disease caused by a parasite.
Pinworm Infection- Parasitic worms that live in anal cavity of an infected person.
Small Pox- Serious infection caused by the variola virus.
Poliomyelitis (Polio)- Poliomyelitis is a highly infectious viral disease that largely affects children under 5.
Hepatitis B- Contagious liver infection caused by the Hepatitis B virus (HBV).
Toxoplasmosis- An infection caused by a single called parasite called Toxoplasma gondii.
Hand-Foot And Mouth Disease (HFMD)- A mild contagious viral infection common in young children.
Tetanus- A serious bacterial infection that causes painful muscle spasms and can lead to death.
Cholera- Cholera is an infection caused by eating food or drinking water contaminated with a bacterium called Vibrio.
Varicella (Chicken Pox)- A highly contagious disease caused by the varicella-zoster virus (VZV).
Haemophilus Influenzae Type B-Severe bacterial infection, particularly among infants.
Tuberculosis (TB)- Bacterial infection that usually affects the lungs caused by mycobacterium tuberculosis.