Model 3 Flashcards
Lymphatic vessels
Transport fluids that have escaped from blood vascular system back into the blood.
Lymphoid organs
House phagocytize cells and lymphocytes (body defense and resistance to disease)
Edema
Fluid accumulation in the tissues which impairs the ability of tissue cells to make exchanges with the interstitial fluid and blood.
What is the function of the lymphatic vessels
Pick up excess tissue fluid (lymph)and return it to the bloodstream.
One way system (lymph only flows toward the heart) - massage in the right direction.
Adventitia
Outermost connective tissue covering of an organ, vessel, or other structure.
Also called tunica adventitia or tunica externa.
What does the lymphatic system consist of?
2 semi-independent parts:
1) a meandering network of lymphatic vessels
2) various lymphoid tissues and organs scattered throughout the body
Afferent
Going in
Efferent
Going away
Hills
Entrance
Thymus
- primary lymphatic organ
- provides environment for stem cells to convert into T-lymphocyte
- reaches max size at puberty
- never disappears completely
- very sensitive to radiation and infection
Thymus structure
Comprised of lobes surrounded by a capsule
1) Capsule
2) Cortex (no lymphatic nodules but more lymphocytes than medulla)
3) Medulla (Hassall’s corpuscle and form thymus corpuscles)
Spleen
1) blood rich organ that filters blood
2) doesn’t filter lymph, but cleanses blood of bacteria viruses and other debris
3) destroy worn-out RBCs and return some of their breakdown products to liver
4) stores platelets and acts as blood reservoir (like the liver does)
Peyer’s Patches
- lymphoid tissues found in wall is small intestine
- AKA aggregated nodules
- part of mucosal-associated lymphoid tissue (MALT) and gut associated lymphoid tissue (GALT).
- macrophages of peyers patches are in ideal position to capture and destroy bacteria (always present in tremendous amounts in the intestine)
Bone marrow
Network of connective tissue fibers, fat cells, blood vessels, and blood producing cells.
Produces both red and white blood cells including lymphocytes and T-lymphocytes and B-lymphocytes.
Young T-cells move into Thymus for development, but B-cells stay in bone marrow until mature and then go out into circulation.
B-cells
Produced in bone marrow
Are white blood cells that are sensitive to antigens and produce antibodies against them.
When antigen is present, Bcells activate and produce antibodies against that antigen.
Once a Bcell makes antibodies against an antigen it keeps a memory of that antigen preventing a second infection of same antigen.
Antigen
Any chemicals that produce an immune response in the body (toxins, foreign proteins, particulate matter, bacterial cells)
Antibodies
Special proteins that bind to antigens and mark them for destruction
2 systems that defend our bodies
1) Non specific defense systems
2) specific defense systems
Non specific defense system
Responds immediately to protect body from all foreign substances.
Provided by intact skin and mucous membranes, inflammatory response, a number of proteins produced by body cells.
Reduces workload of second protective arm, the specific dense system, by preventing entry and spread of microorganisms throughout the body
Specific defense system
Aka immune system
Mounts the attack against particular foreign substances
Natural killer cells
NK cells, K cells, WBCs “police” the blood and lymph (defensive cells)
Can kill cancer cells and virus infected body cells well before immune system is enlisted to the fight.
Act spontaneously by recognizing certain sugars on the surface.
NOT phagocytic
Inflammatory response
Second line of defense
Non specific response triggered when body tissue is injured.
- redness
- heat
- swelling
- pain
Begins with an chemical alarm when cells are injured.
1) blood vessels in area dilate and capillaries become leaky
2) activate pain receptors
3) attract phagocytes and WBC to area
- clotting proteins are activated and begin to walk off the damaged area with fibrin
Inflammatory response
- prevents the spread of damaging wants to nearby tissue
- disposes of cell debris and pathogens
- sets the stage for repair
Stages of inflammatory response
1) inflammatory chemicals are released
2) blood vessels dilate and capillaries become leaky
3) pain receptors activated
4) WBCs and phagocytes enter area
What does the inflammatory response do?
1) prevents the spread of damaging agents to nearby tissues
2) disposes of cell debris and pathogens
3) sets the stage for repair
How does inflammation prevent the spread of pathogens or harmful agents to neighboring tissues?
Clotting proteins leaked into the area from the blood are activated and wall off the damaged area with fibrin and the forms a scaffolding for permanent repair by increasing local heat and metabolic rate of tissue cells.
If area has pathogens that have previously invaded the body, the third line of defense (immune response) enters the scene.
What is pus?
Infection
Mixture of dead or dying neutrophils, broken down tissue cells, and living/dead pathogens
Complement
A group of at least 20 plasma proteins that circulate in the blood in an inactive state and becomes activated when attached to a foreign cell (bacteria, fungi, mismatched RBCs)
The body’s third line of defense is?
Immune response
Antimicrobial chemicals
Body’s most important antimicrobial chemicals are complement proteins and interferon
Complement
A group of at least 20 plasma proteins that circulate the blood in an inactive state. When it becomes attaches to foreign cells (bacteria) it is activated and becomes a major factor I. The fight against the foreign cells. Occurs when complement proteins bind to sugars or proteins (antibodies) on foreign cells surface and lesions form. This allows water to rush into the cell causing it to burst.
Nonspecific defense mechanism that “complements” or enhances the effectiveness of both nonspecific and specific defenses
Complement also amplifies inflammatory response.
Interferon
Small proteins secreted by virus infected cells.
Interferon molecules diffuse to nearby cells and bind to their membrane receptors disabling viruses from multiplying within these cells.
Viruses that lack cellular machinery to produce ATP or make proteins get Interferon to do their dirty work by entering tissue cells and taking over cellular machinery needed to reproduce themselves.
Fever
Abnormally high body temperature
Systematic response to invading microorganism
Limits bacteria growth
Speeds up repair process by increasing metabolic rate of tissue cells.
2 antimicrobial chemicals
Complement proteins
Interferon
Three important aspects to the immune response
1) Antigen specific (acts against particular pathogens)
2) Systematic (not limited to initial infection site)
3) Has memory (recognizes and attacks stronger against previously encountered pathogens)
2 types of immunity
1) Humoral (Antibody-mediated)
- provided by antibodies present in body’s humors or fluids
2) Cellular (cell-mediated)
- lymphocytes defend the body
- protective factor is living cells
Allergies
Our own cells have antigens mounted on them that the body recognizes as ‘self’. These are antigenic to other people (body will attack skin graphs from other people etc).
Small molecules are not antigenic but if linked up to our own proteins the immune system may attack them as it recognizes them as foreign. These incomplete antigens are called hapten and are found in things like pet dander or poison ivy.
Crucial cells of immune system
Lymphocytes - T and B cells
Macrophages - do not respond to specific antigens but help the lymphocytes that do.
Clonal selection
Binding of antigen to surface of B cell to stimulate the completion of its development and activates the B cell to “switch on” where it grows and clones itself multiple times.
Difference between active and passive humoral immunity
Active immunity is when B cells encounter antigens and produce antibodies against them.
Passive immunity is when antibodies are obtained from a serum of an immune human or animal donor and provide temporary protection.
Monoclonal antibodies
Antibodies produced by descendants of a single cell and are pure antibody preparations that exhibit specificity for one antigen.
Used for diagnosis of pregnancy, hepatitis, cancers, and rabies.
Antibodies
Aka immunoglobulin or lg
Are soluble proteins secreted by activated B cells or by their plasma cell offsprings in response to an antigen and are capable of binding with that antigen.
Every antibody contains four amino acid chains.
Antibody classes
5 major immunoglobulin classes 1) igM 2) igA 3) igD 4) igG 5) igE MADGE
IgD, igG, igE antibodies have same basic Y shape and are monomers.
IgA antibodies occur in both monomer and dimer (2 linked monomers) forms. Found mainly in mucus and helps prevent pathogens from entering body.
IgM antibodies are huge (5 linked monomers) and called pentamers.
IgG is most abundant in body and only type that can cross placenta barrier.
IgE antibodies are troublemaker antibodies involved in allergies.
How do antibodies inactivate antigens?
1) complement fixation
2) neutralization
3) agglutination
4) precipitation
What does antibody neutralization do?
Masks dangerous parts of bacterial exotoxins/viruses that can cause cell injury.
Antibody agglutination
Cell bound antigens cross linking causing clumping of foreign cells
Antibodies have multiple binding sites and can bind to more than one antigen at a time which means antigen-antibody complexes can be cross linked into large lattices.
Antibody precipitation
When cross linking involves Soluble antigenic molecules that the antibody complexes are so large they become insoluble and settle out of solution.
Explain how macrophages are important (Cellular immune response)
Macrophages are important as antigen presenters and phagocytes. After they eat an antigen they display parts of it on their surface membranes where Helper T cells bearing receptors of the same antigen can recognize it. The T cell binds to the antigen and the macrophage receptor which leads to T cell activation and cloning. Macrophages release monokines which enhance T cell activation. Activated Helper T cells release lymphocytes which stimulate proliferation and activity of helper T cells and help activate cytotoxic T cells and B cells.
Cytotoxic (killer) T Cells
Cells that specialize in killing virus infected, cancer, or foreign graft cells by binding to them and inserting a toxic chemical called perforin into the foreign cell’s plasma membrane.
Helper T cells
T cells that act as the directors or managers of the immune system. They circulate through the body once activated recruiting other cells to fight the invaders. The release chemicals called lymphokines that act indirectly to rid body of antigens
