immunity & infection Flashcards
1
Q
infection & toxins
A
- infection = invasion of the body by microorganisms
- toxins = poisonous substances
- systemic infection invasion by microorganism that spreads through blood or lymphatic system to large portions of body
2
Q
chain of infection - pathogen
A
- a microorganism that causes disease
3
Q
chain of infection - reservoir
A
- person, animal, or environmental component (ex; soil or water) where pathogen lives
4
Q
chain of infection - portal of exit
A
- to transmit infection, pathogen must leave reservoir (ex; saliva, mucous membranes, blood, faces, nose & throat discharges
5
Q
chain of infection - means of transmission
A
- in direct transmission, pathogen is passed to another without an intermediary
- usually requires fairly close association with infected host but not necessarily physical contact (ex; sneezing, coughing)
- most common respiratory/intestinal infections are passed directly
- transmission can also occur indirectly (animals & insects can serve as vectors = organisms that carry & transmit pathogen from one host to another)
- can also be transmitted via contaminated soil, food, water, inanimate objects
- some float in air for long periods & can travel long distances before they are inhaled
6
Q
chain of infection - portal of entry
A
- pathogens can enter one of three ways;
- direct contact or penetration of skin
- inhalation through mouth or nose
- ingestion of contaminated food or water
- agents that cause STIs enter through mucous membranes lining urethra (males) or cervix (females)
7
Q
chain of infection - new host
A
- variety of factors determine whether pathogen will be able to establish itself & cause infection (number of pathogens is also important)
8
Q
immune system
A
- body’s collective physical & chemical defences against foreign organisms & pathogens
- physical & chemical barriers = skin (body’s largest organ) prevents many microorganisms from entering body, few organisms can penetrate through skin without cut or break
9
Q
examples of physical & chemical barriers
A
- mouth is lined with mucous membranes which contain cells to prevent passage of unwanted organisms & particles
- body openings & fluids that cover them (tears, saliva, vaginal secretions) are rich in antibodies & enzymes which break down & destroy microorganism
- respiratory tract is lined with mucous membranes & cells with hair-like protrusions called cilia (sweep foreign matter up & out of respiratory tract)
- particles not caught by cilia are expelled by cough (this is why smokers have chronic cough usually)
10
Q
white blood cells
A
- neutrophils = engulfs foreign organisms & infected, damaged, or aged cells (particularly prevalent during inflammatory response)
- macrophages = large phagocytic (cell-eating) cells that devour foreign particles
- natural killer cells = directly destroys virus-infected cells & cancer cells
- dendritic cells = specialized to active T & B cells
- lymphocytes = works in both bloodstream & lymphatic system
11
Q
two main lymphocyte cells
A
- T cells = arises in bone marrow & matures in thymus
- B cells = matures in bone marrow & produced antibodies
- helper T cells = help activate other T cells & may help B cells produce antibodies
- killer T cells = kill body cells that have been invaded by foreign organisms; also kill cells that have turned cancerous
- suppressor/regulatory T cells = inhibit growth of other lymphocytes
- memory T & B cells = generated during initial infection that circulate body for years, remembering specific antigens that caused infection & quickly destroy them if they appear again
12
Q
antibodies
A
- specialized proteins produced by white blood cells that recognize & neutralize specific microbes
13
Q
antigens
A
- markers on surface of foreign substance that immune system cells recognize as non-self & that trigger immune response
14
Q
inflammatory response
A
- special cells in area of invasion or injury release histamine & other substances that cause blood vessels to dilate & fluid to flow out of capillaries into injured tissue
- this produces heat, swelling, & redness in affected area
- histamine = chemical responsible for dilation & increased permeability of blood vessels in allergic reactions
- white blood cells drawn to area & attack invaders
- pus = collection of dead white blood cells & debris resulting from encounter
15
Q
immune response
A
- two responses to invading pathogens; natural (innate) & acquired (adaptive)
- neutrophils, macrophages, dendritic cells, & natural killer cells part of natural response
- recognize pathogen as ‘foreign’ but have no memory of past infections → respond same way no matter how many times pathogen invades
- essentially eat invaders & destroy them internally, also destroy infected body cells
- T & B cells part of acquired response
- change after one contact with pathogen, developing memory for antigen
16
Q
immune response phase 1
A
- dendritic cells drawn to site of injury, consume foreign cells, & provide info about pathogen by displaying its antigens on their surface
- helper T cells read this info & rush to respond
17
Q
immune response phase 2
A
- helper T cells multiple rapidly & trigger production of killer T cells & B cells in spleen & lymph nodes
18
Q
immune response phase 3
A
- killer T cells & natural killer cells destroy infected body cells + B cells produce antibodies that bind to viruses & mark them for destruction by macrophages
