2 - APP - Unit 4.3 - Immunity Flashcards
Immunity
Body’s ability to resist pathogens and foreign materials penetrating a person’s first line of defense (the unbroken skin) and the diseases they cause
Individual differ in their ability to resist infection
An individual resistance varies at different times
Immunity - Types of immunity
- Natural
- Acquired
Immunity - Natural immunity
Immunity with which we are born
Inherited & permanent
Consists of:
- Anatomical barriers - as unbroken skin
- Cellular secretion - as mucus & tears
- Blood phagocytes & local inflammation - body trying to kill invaders by creating substance to combat it.
Body tries to become permanently resistant to intruders.
Immunity - Acquired immunity
Reaction occurring as a result to invaders exposure
Immunity developed during an individual’s lifetime
May be passive or active
Immunity - Acquired immunity - Passive
Borrowed immunity
Acquired artificially by injecting antibodies from other individuals or animals blood.
Immunity produced: immediate but temporary (only 3-5 weeks - then individual’s macrophages inactivate the antibodies)
Used when one exposed to virulent disease (as measles, tetanus, infectious hepatitis) & not acquired active immunity to it.
Expl:
- Baby has temporary immunity from Mother’s antibodies passing through placenta to enter baby’s blood.
- Mother’s milk offers some passive immunity
- Measles & mumps immunity may last for nearly a year - then child must develop his/her own active immunity.
Immunity - Acquired immunity - Active
Preferable to passive as it lasts longer
2 types:
- Natural actively acquired immunity
- Artificial actively acquired immunity
Immunity - Acquired immunity - Natural actively acquired immunity
Result of having had & recovered from disease
> Expl: Child got measles and recovered will not ordinarily get it again. Body manufactured antibodies.
Also acquired by series of unnoticed or mild infections
> Expl: person had mild form of disease one or more times, has fought it off, sometimes unnoticed, is later immune.
Immunity - Acquired immunity - Artificial actively acquired immunity
Inoculated with suitable vaccine, antigen or toxoid
> Expl: Child vaccinated for measles has been given very mild form of disease. Body stimulated to manufacture own antibodies
Immunity - Immunization
Process of increasing individual’s resistance to particular infection by artificial means
Antigen may be injected to stimulate production of antibodies
> Expl of antigens: toxins produced by bacteria, dead or weakened bacteria, viruses & foreign proteins. This weakened toxins stimulate body to produce antibodies.
AIDS/HIV - AIDS
= Acquired Immunodeficiency Syndrome
Disease that suppresses the body natural immune defense system
A - Acquired - Disease is not inherited
I - Immune - Body’s natural defenses against cancers, disease & infections
D - Deficiency - Lack of cellular immunity
S - Syndrome - Situation that involves a set of diseases or conditions present to signal a specific diagnosis
Individual with AIDS: susceptible to life-threatening diseases = opportunistic infection
AIDS/HIV - HIV
= Human immunodeficiency virus
- Causes AIDS
- Progressively destroys the body’s T4-lymphocytes cells (=immune system’s key infection fighters)
- Initially disables or destroys these cells without causing symptoms
AIDS/HIV - T4-lymphocytes cells
Immune system’s key infection fighters
AIDS/HIV - AIDS - Transmission
1 - Sexual contact with infected partner.
Virus enters body through: lining of vagina, vulva, penis, rectum or mouth
2 - Sharing hypodermic needles (IV drug users)
Infected blood injected into the body
3 - In utero or at birth from infected mother
4 - Blood transfusion
Almost eliminated as blood banks test all blood donors to determine if they have been exposed to HIV
AIDS/HIV - Detection
HIV infection often no symptoms: primarily detected by testing blood for presence of antibodies to HIV
HIV antibodies don’t reach detectable levels until 1 to 3 months after infection
Positive results:
- Person fought off infection or now immune to AIDS - Person carrying the infection but not sick
Or
- Person developing or already has AIDS
AIDS/HIV - 2 types of antibody tests
- Enzyme-linked immunosorbent assay (ELISA)
> An AIDS antibody indicator.
> Detects antibodies for AIDS but not virus itself - Western blot
> Follow-up to confirm ELISA results
