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Study Guide for Third Partial Health Science
1. What are the physical and chemical barriers? Explain them.
* Physical: Skin and mucous membranes lining the respiratory, digestive and urinary tracts are mechanical or physical barriers to the entry of pathogens
* Chemical barriers: include the secretions of oil glands, the acid pH of the stomach and flora (bacteria that normally residein the intestines, vagina, skin, etc.)

2. What is the inflammatory reaction? Describe it mentioning the four characteristic signs.
Nonspecific response to foreign invasion, tissue damage, or both. Destroys invaders, removes debris, and prepares area for healing
* Redness
* Heat
* Swelling
* Pain

3. What are phagocytes and the natural killer cells?
Phagocytes: includeneutrophils and monocytes which convert into macrophages, and dendritic cells.
Natural Killer Cells: are lymphocyte like cells that kill some virus infected and cancer cells by cell to cell contact. These cells seek out and kill cells that lack a type of “self” molecule on their surface.

4. What are protective proteins? Describe them.
The complement systems are plasma proteins that areactivated by pathogens in the body. Complement can bind to the surface of pathogens ensuring phagocytosis or allowing fluids and salts to enter the cell and burst.
Interferons are proteins produced by virus infected cells that can bind to non infected cells causing them to prepare for possible attack by producing substances that interfere with viral replication.

5. Describe the cellmediated immunity: type of cells needed to occur and type of cells attacked.
Cell-mediated immunity against virus infected cells and cancer cells
Each T cell has a receptor that recognizes a specific antigen.
Activation of the T cell occurs when an antigen presenting cell (dendritic cell or macrophage) presents the antigen to the T cell.
Activation of T cells results in clonal expansion and manycopies of the same type of T cell are produced.

Helper T Cells: Regulate immunity by secreting cytokines which allow clonal expansion and activate both types of acquired immunity (cytotoxic T cells and B cells).
Cytotoxic T Cells: Destroy antigen-bearing cells, nonself protein-bearing cells. Bind to virus infected or cancer cells that present the foreign antigen and release perforinmolecules which form pores in the membrane and induce apoptosis.
Memory T cells: immediately recognize the antigen in the future.

6. What happens in the antibody mediated immunity? Mention the cells responsible for it, the type of cells or molecules attacked and the molecules that destroy them. Be sure to mention the different types of immunoglobulins that exist.
Immunoglobulins is anothername for the antibodies.
Common structure to them: Y shaped molecules
Antigen-antibody reaction produces complexes that mark antigens for destruction by neutrophils, macrophages or activate complement.

7. What is the difference between active and passive immunity? Mention the different ways to acquire them.

ActiveImmunity | PassiveImmunity |
the person produces an immune responseagainst an antigen | the person is given prepared antibodies or cells via an injection |
Antigen-containing material is injected | Purified antibody is injected |
Confers long lasting immunity | Protection is short lived |
Natural active immunity is acquired when a person gets over an illness, developing memory B and T cells . | Natural passive immunity occurs through the placenta and breastmilk. |
Acquired active immunity involves the use of vaccines, substances that contain an antigen to which the immune system responds. | Acquired passive immunity occurs when the person is given a gamma globulin injection to prevent disease in patients unexpectedly exposed to an infectious disease. |

8. Mention the functions of the urinary system.
Excretion of Metabolic Wastes
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