IM 5 Flashcards
what can lead to reduced resistance?
- protein calorie malnutrition (greatest contributor worldwide)
- pre-existing disease (infectious or non-infectious)
- sleep deprivation
- basic resistance mechanisms being deficient (either genetic deficiency or medication to suppress like medication for organ transplants
what are variable factors for immunity?
- stress or state of mind
- exercise
- physical conditioning
what is critical to immunity?
- eat well
- exercise regularly
- adequate sleep
- relaxation
- positive outlook
- good interpersonal relationships
*all can suffer under stress
does immunity being affected mean we shouldn’t do exhaustive exercise?
no, just means sufficient rest and recovery should be done
what are the 4 types of tissue grafts?
- autografts
- isografts
- allografts
- xenografts
what are autografts?
grafts from you to you
what are isografts?
identical twin to identical twin
what are allografts
most common, individual to individual of same species
what are xenografts?
grafts transplanted from another species
what’s a critical consideration for recipient and donor?
histocompatibility (MHC protein match)
why is histocompatibility so important?
class 1 MHC on cells of graft and class 2 MHC on macrophages in graft differ from recipients
these MHC proteins are foreign to T cells and so cells that hold these proteins destroyed by cytotoxic T cells and helper T cells
what’s the most ideal donor?
autograft or isograft because same MHC proteins
what’s needed for an allograft to be okay?
enough immunosuppresion to prevent rejection while not being toxic as well as antibiotics to keep infections under control
what is the problem with the allergic response?
not antigen, rather immune response because it should not be happening
what’s the first step of the allergic response?
sensitization, first exposure to allergen that produces lgE antibodies that bind to mast cells or basophils
what is the immediate hypersensitivity?
-occurs within a few minutes (under 20 minutes) after person is re-exposed to allergen after being already sensitized
what’s the results of immediate hypersensitivity?
- vasodilation of blood vessels
- increased blood capillary permeability
- airway smooth muscle contraction
- mucus secretion
- nerve endings stimulated (pain and itch)
what are signs/symptoms of immediate hypersensitivity?
nasal congestion, sneezing, runny nose, itching, watery eyes, difficulty breathing
what can also occur hours or days later after immediate hypersensitivity?
late phase reaction
what’s the late phase reaction?
eosinophils migrate to area to secrete mediators that prolong inflammation and sensitize area (this means less allergen needed to trigger in future)
not guaranteed
what is anaphylaxis?
when very large amounts of allergen/chemicals released by mast cells or basophils enter blood circulation and cause systemic symptoms that may lead to severe hypotension or bronchoconstriction
how is anaphylaxis treated?
injection of epinephrine to bronchodilate airways and strengthen heart rate
what is self-recognition?
able to recognize own MHC proteins
what is self tolerance?
lack reactivity to own proteins
what leads to development of autoimmune diseases?
loss of self tolerance
what’s the process of autoimmune diseases?
-body’s own proteins act as antigens and trigger an inappropriate immune attack
-the immune attack is mediated by autoantibodies and self-reactive T cells and directed against body’s own cells that contain the proteins
how is self-recognition developed?
through positive selection
- immature T cells have receptors that interact with self MHC proteins on epithelial cells in thymus
- ones that interact survive/ones that do interact undergo apoptosis
how is self-tolerance developed?
through negative selection
- immature T cells interact with self-antigens on dendritic cell surface in thymus
- ones that do not interact survive/ones that interact undergo apoptosis or anergy (alive but unresponsive)
how many immature T cells survive to develop?
1-5% in thymus receive proper signals and survive both positive and negative selection
what causes autoimmune diseases?
- failure of positive and negative selection in thymus or apoptosis and anergy later in body
- normal body proteins altered by drugs or environment chemicals to become “foreign” proteins
- immune attacks on virus-infected body cells = too many cells destroyed and disease results
- genetic mutations in body cells may yield new proteins that serve as antigens (ex. cancer)
- pathogens whose antigens are so close in structure to body’s own proteins that attacks occur
