Chapter 12 The Lymphatic System and Body Defenses

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Essentials of Human anatomy and Physiology 10th edition marieb

The Lymphatic System

Two semi-independent parts: 1) a meandering network of lymphatic vessels and 2) various lymphoid tissues and organs scattered throughout the body.

Edema

An abnormal accumulation of fluid in body parts or tissues -causing swelling

Lymph

the watery fluid in the lymph vessels collected from the tissue spaces. Flows only toward the heart.

lymph capillaries

weave between the tissue cells and blood capillaries in the loose connective tissues of the body and absorb the leaked fluid.

Lymphatic collecting vessels

The larger lymphatic vessels where lymph is transported through from the lymph capillaries.

Right lymphatic duct

drains lymph from the right arm and the right side of the body

Thoracic duct

receives lymph from the rest of the body. (not right arm or right side of body -that's the right lymphatic duct's job)

Lymph nodes

helps protect the body by removing foreign material such as bacteria and tumor cells from the lymphatic stream and by producing lymphocytes that function in the immune response.

Macrophages

Found within the lymph nodes these guys engulf and destroy bacteria, viruses and other foreign substances in the lymph before it is returned to the blood.

Lymphocytes

a type of white blood cell. Collections of these are strategically located in the lymph nodes and respond to foreign substances in the lymphatic stream.

Cortex

Outer part of a lymph node. Contains collections of lymphocytes called "follicles". many of which have dark-staining centers called "germinal centers"

Medulla

central part of a lymph node where macrophages are located.

Afferent Lymphatic vessels

where lymph enters the convex side of the lymph node through.

Sinuses

after lymph enters the afferent lymphatic vessels into the lymph node it flows through a number of sinuses that meander through the lymph nodes.

Hilum

where lymph leaves the lymph nodes via the efferent lymphatic vessels.

Lymphoid Organs

Lymph nodes, spleen, thymus, tonsils and Peyer's Patches (and the appendix of the intestine)

Spleen

A soft, blood-rich organ that filters blood. cleanses blood of bacteria, viruses and other debris. Site for lymphatic proliferation and immune surveillance. Stores platelets and acts as a blood reservoir. Produces lymphocytes.

Thymus

functions at peal levels as youth. produces a hormone called thymosin that program lymphocytes so they can carry out their protective roles of the body.

Tonsils

small masses of lymphoid tissue in the throat. Their job is to trap and remove bacteria or other foreign pathogens entering the throat.

Peyer's Patches

resemble tonsils -are in the wall of the distal small intestine. -also heavily concentrated in the wall of the appendix. The macrophages of these patches and the appendix are in an ideal position to capture and destroy bacteria.

MALT

Mucosa-associated lymphoid tissue
Peyer's patches, the appendix, and the tonsils
acts ar a sentinel to protect upper respiratory and digestive tracts fromt he never-ending attacks of foreign matter entering those cavities.

What two main mechanisms make up the immune system?

innate (nonspecific) defense mechanisms and the adaptive (specific) defense mechanisms

Innate Defense System

Respondes immediately to protect the body from all foreign substances, whatever they are.
This includes the first and second line of defense
First includes: skin, secretions of skin and mucous membranes.
Second includes: Phagocytic cells, Natural Killer cells, Antimicrobial proteins and the inflammatory response

Adaptive Defense System

Mounts the attack against particular foreign substances.
Includes: Lymphocytes, antibodies, macrophages and other antigen-presenting cells.
Creates our "immunity" against highly specific diseases.

Pathogens

harmful or disease causing microorganisms.

lysozyme

Saliva and lacrimal fluid contain this. It is an enzyme that destroys bacteria. (spit and tears)

Natural Killer Cells (NK cells)

Roam the body in blood and lymph. They can lyse and kill cancer cells, virus infected body cells and some other nonspecific targets well before the adaptive arm of the immune system is enlisted to fight. No phagocytic and are not picky when it comes to their targets. They can also release powerful inflammatory chemicals.

Inflammatory Response

a nonspecific response that is triggered whenever body tissues are injured.

What are histamine and kinins?

Inflammatory chemicals releases by cells that trigger an alarm for the inflammatory process to begin.
1) Cause blood vessels in the involved area to dilate and capillaries to become leaky.
2) Activated pain receptors
3) attract phagocytes and white blood cells to the area

Chemotaxis

When the inflammatory process begins histamine and kinins set the alarm.

This is the process when they attract phagocytes and white blood cells to the area it is down through the cells following a chemical gradient.

Pus

A mixture of dead and dying neutrophils, broken-down tissue cells and living and dead pathogens. If the inflammatory mechanism fails to fully clear the area of debris mixture gets walled off and becomes an abscess.

Phagocytes

Such as a macrophage or neutrophil engulfs a foreign particle. It is then broken down with the enzymatic contents of a lysosome.

Antimicrobial Proteins

enhance innate defenses either by attacking microorganisms directly or by hindering their ability to reproduce.
Include: complement proteins and interferons

Complement

refers to a group of at least 20 plasma proteins that circulate in the blood in an inactive state. When they become "fixed" to foreign cells they begin attacking the the invader.

Complement Fixation

Occurs when complement proteins bind to certain sugars or proteins (such as antibodies) on the foreign cells' surface.

Membrane attack complexes (MAC)

When complement fixation occurs the fixed proteins produce lesions, complete holes, on the foreign surface. These holes let water into the cell and cause it to burst.

Interferons

When virus infected cells help defend other cells that have not yet been infected by secreting these small proteins. These proteins binds to the membrane receptors of other cells interfering with the virus's ability to infect it.

Fever

abnormally high body temperature. Systematic response to invading microorganisms.

Pyrogens

Chemicals secreted by white blood cells and macrophages exposed to foreign cells or substances in the body

Humoral Immunity

antibody-mediated immunity

Cellular immunity

cell-mediated immunity

hapten

a small molecule that attaches to one of our own proteins and triggers our body to attack it because our body no longer recognizes that protein as ours.
Also called an "incomplete antigen"

Penicillin reaction

a hapten's provoking of an immune response. When penicillin links to blood proteins it causes our immune system to send an attack on our own proteins because it no longer recognizes it as our own.

B Lymphocytes

produces antibodies and oversee humoral immunity

T lymphocytes

non-antibody producing lymphocytes ghat constitute the cell-mediated arm of the adaptive defense system.

immunocompetent

capable of responding to a specific antigen by binding to it with antigen-specific receptors that appear on the lymphocytes surface.

T cells mature in the...

Thymus

B cell mature in the...

Bone Marrow

Antigen-presenting cells

play a major role in immunity. engulf antigens and then present the fragments of them, like signal flags, on their own surfaces where they can be recognized by T cells.
Major types: dendritic cells, macrophages and B lymphocytes.

Clonal Selection

The process during which a B cell or T cell becomes sensitized through binding contact with an antigen. Activates the lymphocyte.

Primary Humoral Response

The formation of and ARMY of identical lymphocytes to attack one certain antigen.

Plasma Cells

Most B-cell clones become these.

Memory Cells

B-cell clones that do not become short lived plasma cells become these and are capable of responding to the same antigen at later meetings with it.

Immunological Memory

Memory cells hold the key to this crucial piece of our immune system.

Secondary Humoral Responses

When the memory cells are called into action against the same foe (antigen) and create another army of clones to fight it off.

Active immunity

When B cells encounter antigens and produce antibodies against them.

Vaccines

Artificially acquired immunity
Insertion of dead or attenuated (extremely weakened) pathogens for the body to produce antibodies against.

Passive Immunity

Receiving antibodies from a donor for a short amount of time. Mainly a fetus receives antibodies from mom and her breast milk after the baby has been born.

Monoclonal Antibodies

descendants of a single cell and are pure antibody preparations that exhibit specifically for one and only one antigen. Used for research (especially in cancer research)

Antibodies (structure?)

Also referred to as immunoglobulins (or Igs)

4 polypeptide chains linked together by disulfide bonds. Tow are "heavy chains" two are "light chains" commonly a Y or T shape.

Variable (V) region and Constant (C) region

regions of four chains of an antibody

Antibody Function

Complete fixation, neutralization, agglutination and precipitation

Neutralization

Occurs when antibodies bind to specific sites on bacterial exotoxins (toxic chemicals secreted by bacteria) or on viruses that can cause cell injury. They block the harmful effect.

Agglutination

clumping of foreign cells, induced by cross-linking of antigen-antibody binding complexes (an antibody can bind to more than one antigen at a time)

Precipitation

immobilized lump of bacteria due to antibody work and agglutination

Antigen Presentation

When antigens are presented to T cells

Cytotoxic (Killer) T cells

cells that specialize in killing virus-infected, cancer, or other foreign graft cells.

Helper T cells

Managers of immune system
-interact directly with B cells.
release cytokine chemicals that act indirectly to rid the body of antigens.

Regulatory T cells

releases chemicals that suppress the activity of both T and B cells. Vital for winding down and stopping immune response.

Autografts

are tissue grafts transplanted from one site to another on the same person

Isografts

tissue grafts donated by a genetically identical person such as a twin

Allografts

tissue grafts taken from a different person

Xenografts

tissue grafts harvested from a different animal species -never works

Immunosuppressive therapy

includes one or more of the following: corticosteroids to suppress inflammation, anti-proliferative drugs, radiation (X-ray) therapy, and immunosuppressor drugs.

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