Multiple Sclerosis
Elimination of Invaders
Antibody Structure
T Cells
Spleen
Thymus Gland
Lymphatic System
Prions
Virus
Pathogens
Microbes
I. Microbes, Pathogens, and You
II. Lymphatic System
III. Nonspecific Defenses
IV. Specific Defenses
V. Acquired Immunity
VI. Hypersensitivity Reactions
I. Microbes, Pathogens, and You
A. Microbes: microscopic organisms, like bacteria) are all over the environment.
B. Many microbes are useful to humans: some bacteria produce food, and some drugs are produced by bacteria. They also break down materials.
(Insert microbes picture / www.sdnhm.org / http://www.sdnhm.org/exhibits/epidemic/teachers/museum-microbe.html)
C. However, human infectious diseases are typically caused by bacteria and viruses, called pathogens.
(Insert pathogens picture / ehp.niehs.nih.gov / http://ehp.niehs.nih.gov/members/2004/112-1/focus.html)
D. Body has three lines of defense against pathogens:
1. Barriers to entry (skin / mucous membranes of body cavities)block entry to body.
2. First Responders: ie. phagocytic white blood cells, prevent infection after an invasion.
3. Specific defenses overcome an infection by killing the particular disease-causing agent that has entered the body. (Also protect us against cancer.) (Mader 122)
E. Bacteria:
1e. Prokaryotic cells. (Frolich PowerPoint Slide 19)Single-celled, no nucleus. Independent cells, metabolically competent.
2e. 3 Common Shapes: bacillus (rod), coccus (spherical), and spirillum (curved).
3e. Capsule: A thick, gummy substance that surrounds the cell wall of some bacteria, which allows the bacteria to stick to surfaces. Also prevents phagocytic white blood cells from destroying them.
4e. Flagellum: Long, very thin appendages on motile bacteria.
5e. Fimbriae: Stiff fibers that allow bacteria to adhere to surfaces such as host cells. Allows bacteria to cling to and gain access to the body.
6e. Pilus: Elongated hollow appendage used to transfer DNA from one cell to another.
7e. Plasmids: Accessory rings of DNA in bacteria. Oftentimes, this is where the genes that allow bacteria to be resistant to antibiotics are often located.
8e. Binary Fission: Method of reproduction for bacteria.
9e. Toxins: Inhibit cellular metabolism. (Mader 122-123)
F. Viruses: Viruses are escaped parts of genome or DNA of different organisms. They cannot live independent of the cells they escape from. (Frolich PowerPoint Slide 19)
1f. Acellular: Not composed of cells. Much smaller than bacterium.
2f. Causes disease: cold, flu, measles, chicken pox, AIDS, polio, rabies, genital warts, and genital herpes.
3f. Always has two parts:
- Outer Cuspid: Composed of protein units.
- Inner Core: Nucleic acid.
4f. Carries the genetic information needed to reproduce itself. Relies on the host's enzymes and ribosomes for its own reproduction. (Mader 123)
(Insert virus picture / Frolich PowerPoint Slide 19)
5f. Emerging Viruses: A virus can emerge by being transported from one location to another where it has not been before.
- Others are transmitted by vectors (usually insects) that carry diseases from an infected individual to a healthy individual. Disease can also emerge when a mutation allows a virus to use a new and different insect vector.
- Viruses can also come about because of the immune system is unable to recognize a change in the virus. (ie. HIV) (Mader 124)
G. Prions: Proteinacious infectious particles that causes a group of degenerative diseases of the nervous system (AKA wasting diseases). (ie. mad cow disease)
- Transmitted by ingestion of brain and nerve tissues from infected animals. (Mader 124)
(Insert prions picture / www.news.utoronto.ca / http://www.news.utoronto.ca/bin5/030602a.asp)
II. Lymphatic System: Consists of Lymphatic vessels and organs.
A. Closely associated w/ the cardiovascular system.
B. 4 main functions that contribute to homeostasis:
1. Lymphatic capillaries absorb extra fluid from tissues and return it to the bloodstream.
2. In the small intestines, lymphatic capillaries called lacteals absorb fats and transport them to bloodstream.
3. Lymphatic system is responsible for the production, maintenance, and distribution of lymphocytes.
4. Helps defend the body against pathogens. (Mader 126)
(Insert lymphatic system picture / www.aikidofaq.com / http://www.aikidofaq.com/bilder/anatomy/Lymphatic.jpg.html)
C. Lymphatic Vessels: Form a one-way system of first, capillaries (side streets), then, vessels (streets), and then ducts (highways)that transport lymph to cardiovascular veins in the shoulder.
D. Lymph: Fluid inside lymphatic vessels.
E. Two ducts: Thoracic and Right Lymphatic.
- Thoracic: Returns lymph from the body below the thorax, the left arm, and left side of head and neck into the left subclavian vein.
- Right Lymphatic: Returns lymph from right arm and right side of head and neck into right subclavian vein.
F. Lymphatic Organs:
- Primary: Red bone marrow and thymus gland. Matures white blood cells.
- Secondary: Lymph nodes and spleen. Purify and protect the lymph and blood.
1f. Red Bone Marrow: Produces all types of blood cells, including neutrophils, eosinophils, basophils, lymphocytes, and monocytes.
2f. Thymus gland: Located in thoracic cavity between the trachea and sternum, superior to heart.
- Two functions:
1. Produces thymic hormones that aid in the maturation of T lymphocytes.
2. Immature T lymphocytes move from bone marrow though bloodstream to thymus, where they mature. Critical to immunity. No T cells, no response to pathogens. (Mader 126-127)
(Insert thymus gland picture / www.pitt.edu / http://www.pitt.edu/~anat/Head/Thymus/Thymus.htm)
G. Secondary Lymphatic Organs: spleen, lymph nodes, and others.
1g. Spleen: Filters blood. Largest lymphatic organ. Located in upper left region of abdominal cavity posterior to the stomach. Connective tissue divides it into white pulp and red pulp:
- White pulp: ?
- Red pulp: Involved in blood filtering.
(Insert spleen picture / www.umm.edu / http://www.umm.edu/imagepages/9943.htmfiltering.)
H. Lymph Nodes: Occur along lymphatic vessels. Filter lymph.
1h. Divided into compartments, with each one containing a sinus that increases in size toward center of node.
2h. Lymphatic Nodules: Concentrations of lymphatic tissue not surrounded by a capsule. (ie tonsils) (Mader 128)
III. Nonspecific Defenses: Immunity: Ability to combat diseases and cancer with lines of defense:
A. Barriers to entry (skin and mucous membranes), and phagocytic white blood cells.
B. Chemical Barriers: Secretions of sebaceous glands of skin. Lysozymes: Contain bacterial enzymes. Resident bacteria: Flora- microbes that usually reside in mouth, intestine, and other areas. Prevents potential pathogens from taking up residence.
C. Inflammatory Response: 2nd line of defense.
1c. Inflammation sends neutrophils and macrophages to surround and kill pathogens.
2c. 4 signs of inflammation: redness, heat, swelling, and pain.
3c. Histamine: Released by damaged tissue cells and mast cells. Makes capillaries dilate and become mor permeable.
4c. Cytokines: Attract more white blood cells to area.
5c. Macrophages: More powerful phagocytes than neutrophils. (Mader 128-129)
D. Protective Proteins: Complement system: Blood plasma proteins that "complement" certain immune responses.
1d. Membrane Attack Complex: Produces holes in surface of bacteria and some viruses.
2d. Interferons: Proteins made by virus-infected cells as a warning to noninfected cells nearby. (Mader 130)
IV. Specific Defenses
A. Come into play if nonspecific defenses do not work.
B. Specific Defenses: Overcome an infection by getting rid of particular disease-causing agents. Also helps protect against cancer.
C. Antigens: Molecules the immune system recognizes as foreign to body.
D. Depend primarily oj the action of lymphocytes. (T Cells or B Cells) (Mader 130)
(Insert T Cell picture /www.mcg.edu / http://www.mcg.edu/news/mcgtomorrow/i1.htm)
E. Clonal Selection: How do immune cells recognize invaders?
- Invaders are viruses, bacteria and any other substance that is not part of our body. Remember symbiotic bacteria and other organisms that normally in and on our body are part of it (we are more bacterial cells than human cells!)
- During fetal/childhood/adolescent development, immune cells are exposed to body’s own cells and the proteins that they have on their surface. This happens mostly in the thymus and bone marrow. Those immune cell precursors that attack our own cells are eliminated. Those that recognize other cells continue to develop as T-cells and B-cells.
- This process is called clonal selection.
-The T-cells and B-cells recognize the foreign proteins that are on invaders but have been selected so that they don’t recognize (and try to kill) the body’s own cells.
(Frolich PowerPoint Slide 20)
F. Antibody editing by clonal selection or deletion: Variety of B-cells produced by random recombination of genes for variable regions of antibody.
- During B-cell development, certain clonal lines are eliminated because their antibodies glom onto the bodys own antigens. B-cell production and clonal selection occurs in bone marrow during early years of life. BCRs (B-Cell Receptors or antibodies recognize.) (Frolich PowerPoint Slide 21)
- Most of cloned B cells become plasma cells: Circulate in blood and lymph. (Mader 131)
G. Structure of an Antibody: Antibodies are the highly variable proteins that are produced by B-cells in order to recognize the foreign proteins on the invaders (called antigens). Antibodies are free in the blood stream. When they are on the surface of B-cells, they are called BCRs or B-Cell Receptors. T-cells also make variable proteins that can recognize antigens called TCRs or T-Cell receptors. Don’t forget that these proteins are made by transcription and translation of certain regions of the DNA. (Frolich PowerPoint Slide 22)
(Insert structure of antibody picture / Frolich PowerPoint Slide 22)
H. Each cell has its own different antibody, even though they all have the same DNA.
1h. DNA is processed and can change as new cells are formed.
- Recombining regions of DNA that make the antibody recognition site produces all the billions of different combinations of antibodies (and BCRs, TCRs) that recognize any possible invader by the proteins it has on its surface.(Susumau Tonegawa)
(Frolich PowerPoint Slide 23)
2h. Immune cells "get rid" of invaders by Phagocytes moving through blood and lymph and into connective tissues (part of inflammation response as cells and fluid move out of capillaries into surround aleolar tissues--diapedesis.) Then, these macrophages actually engulf and dissolve the invading microbes. There are several different sources or kinds of macrophages:
- Langerhans cells in skin
- Phagocytes in blood
- Microglial cells in Central Nervous System
This is called “non-specific immunity". It does not depend on the antibodies or B-cells and T-cells. It does not work very well once an infection spreads. Then we need “specific” immunity based on those specific antibodies that recognize the invader.
(Frolich PowerPoint Slide 24)
(Insert elimination of invaders picture / Frolich PowerPoint Slide 24)
I. T Cells and Cell-Mediated Immunity: Named for T cells directly attacking diseased cells and cancer cells.
1. T Cells Recognize an Antigen: Antigens are displayed to T cells by antigen -presenting cells, such as macrophages.
-APC cells break apart pathogens in a lysosome, APCs travel to a lymph node or spleen, where T cells group together.
- A piece of the broken down pathogen is visible in the groove af an MHC (major histocompatibility complex) protein on the cell's surface.
2. HLA: Human leukocyte antigens: Human MHC proteins. Found on all body cells.
- Comparison studies of HLA antigens must occur before a transplant to compare and match as many proteins as possible.
3. T cells and all of the daughter cells formed by them can recognize "foreign" from "self" and destroy only cells carrying the foreing invaders. When the illness diappears, activated T cells becomes susceptible to apoptosis.
J. Cytotoxic T Cells: After a cytotoxic T cell attaches to a virus-infected cell or tumor cell, it releases perforin molecules, which punch holes into the plasma membrane, forming a pore. They then deliver granzymes into the pore, causes the cell to undeergo apoptosis and die. These are responsible for "cell-mediated immunity".
K. Helper T Cells: Regulate immunity by secreting cytokines, the chemicals that enhance the response of all types of immune cells. B cells cannot be activited without T cell help.
L. Memory T Cells: Remain in the body and can jump-start an immune reaction to an antigen previously present in the body. (Mader 134-135)
V. Acquired Immunity
A. Immunity occurs in two ways:
1. Naturally, by infection,or
2. Artificially, by medical intervention.
B. Two types of acquired immumnity:
1. Active Immunity: Individual alone produces antibodies against an antigen. Active immunity is dependent on the presence of memory B cells and memory T cells. (Vaccines: substances that contain an antigen to which the immune system responds.) Usually, vaccines are the pathogens themselves, that have been treated so theyare no longer violent- can't cause disease.
2. Passive Immunity: Individual is given prepared antibodies via an injection. (Gamma gloculin: injection of serum containing antibodies.) Temporary, since antibodies are not produced by the individual's plasma cells. ie. newborns are passively immune due to mother's antibodies crossing the placenta.
- Monoclona antibodies: Antibodies that are the same type and are produced by plasma cells derived from the same B cell.
1b. Antibody Titer: Determining the amount of antibody present in a sample of plasma. (Mader 136-137)
C. Cytokines: Signaling molecules produced by T lymphocyte, macrophages, and other cells. Regulate white blood cell formation; possible therapy for AIDS.
1c. Interferon and Interleukins: immunotherapeutic drugs to enhance the aability of an individuals' own T cells to fight cancer. (Mader 138)
D. Summarized: "Immunity is acquired by making more copies of pre-existing cells not by creating something new. Therefore a huge number of cells are necessary to combat the wide range of potential antigens." (ARIS Mader Text Website)
VII. Hypersensitivity Reactions
A. Allergies: Hypersensitivities to substances such as pollen, foor, animal hair, etc. Allergens: response to the antigens, usually include some degree of tissue damage.
1a. Immediate Allergic Response: After contact with antigen.
2a. Anaphylactic Shock: An immediate allergic response that occurs because the alleren has entered the bloodstream. (ie beestings)
3a. Delayed Allergic Response: Initiated by memory T cells at site of allergen contact in body. (ie skin test for tuberculosis)
D. Tissue Rejection: Results because the recipient's immune system recognizes that the tranplanted tissue is not "self". Cytotoxic T cells then attck the cells of the transplanted tissue.
1d. Immunosuppresive drugs: Can control organ rejection. These inhibit the production of T-cell cytokines.
2d. Xenotransplantation: use of animal organs instead of hman organs in tranplant patients.
E. Disorders of Immune System: When a person has an autoimmune diseaes, cytotoxic T cells or antibodies mistakenly attack the body's own cells as if they were foreign invaders.
1e. Myasthenia gravis: Antibodies attach to and interfere with the functioning of nueromuclular juntions, and reulsts in weak muscles.
2e. Multiple Sclerosis: T cells attack the myelin sheath of nerve fibers, which causes neuromuscular symptoms.
(Insert multiple sclerosis picture / www.bodyofwealth.com / http://www.bodyofwealth.com/entry/research-for-ms-cause-is-on-the-way-to-start)
3e. Systemic Lupus Erythematosus: Various symptoms preio to death due to kidney damage from the deposition of excessive antigen-antibody complexes.
4e. Rheumatoid Arthritis: Jounts are affected.
F. When a person has an immune deficiency, the immune system is unable to protect the body against disease. (ie AIDS)
1f. Severe Combined Immunodeficiency Disease: Both antibody and cell-mediated immunity are lacking or inadequate.
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