unit 3: infectious disease and stds Flashcards
(63 cards)
chain of infection
-pathogen
-reservoir
-portal of exit
-means of transmission
-portal of entry
-new host
pathogen
-microorganism that causes disease bc produces toxins that harm human tissue; or directly invading body cells
-HIV, SARS, tuberculosis
reservoir
-pathogen’s natural environment
-can be a person, animal, environmental component (soil, water) that spreads infection
-can be ill or asymptomatic carrier
portal of exit
-where the pathogen leaves the reservoir (saliva, mucous membranes, blood, feces, nose and throat discharges)
-mumps, sti’s, hiv/hepatitis, colds, influenza
means of transmission
directly or indirectly
-direct: passed from one to another w/o an intermediary –> close association that isnt always physical contact (sneezing, coughing particles in air and smo inhales)
-sexual contact or contact w/ blood
-indirect: vectors
-insects, animals, organisms that carry pathogen from one host to another
-contaminated soil, food, water or inanimate objects
-in air for long periods of time
portal of entry
-enter in 3 ways:
-direct contact w/ or penetration of the skin
-inhalation thru mouth or nose
-ingestion of contaminated food or water
systemic infection
An invasion by a microorganism that spreads though the blood or lymphatic system to large portions of the body.
the new host
-factors determine if a pathogen can establish itself and cause infection
–> how resistant a person is/immunity, # of pathogens that enter the new host and how able the body’s defenses are
if conditions are right, a new chain of infection starts in the new host.
how to break the chain
-quarantine, killing insects or animals that carry pathogens , public sanitation practices, handwashing, use of face masks, immunization
physical and chemical barriers
body’s first line of defense
- skin prevents many microorganisms from entering the body
-mouth lined w/ mucous membranes which has cells that prevent passage of unwanted organisms + particles
-tears, saliva, vaginal secretions
-enzymes
-cilia–> if cells dmged, coughing is the only way of ridding airways of foreign particles
white blood cells
neutrophils, macrophages, natural killer cells, dendritic cells, lymphocytes
neutrophils
-travel in bloodstream to areas of invasion, attacking and ingesting pathogens
macrophages
- take up stations in tissues and act as scavengers (big eaters)
-devouring pathogens and worn-out cells
natural killer cells
-directly destroy virus-infected cells and calls that have turned cancerous
dendritic cells
-reside in tissues, eat pathogens and activate lymphocytes
lymphocytes
-travel in both bloodstream + lymphatic system
lymph nodes
-lymphatic system
-where macrophages and dendritic and filter bacteria
lymphatic system
-a network of vessels and organs, that pick up excess fluid and proteins, lipids + other particles from body tissues
-pass through lymph nodes to be cleansed and then returned to the bloodstream
lymphocytes
T cells, b cells
T cells: helper t cells, killer t cells, suppressor t cells
b cells
lymphocytes that produce antibodies
memory t + b cells
Lymphocytes generated during an initial infection that circulate in the body for years, remembering the specific antigens that caused the infection and quickly destroying them if they appear again.
antigens
Markers on the surface of a foreign substance that immune system cells recognize as non-self and that trigger the immune response.
the inflammatory response
-special cells release histamine, causing blood vessels to dilate and fluid to flow out of capillaries into injured tissue. Produces increased heat, swelling, and redness in the affected area. WBC attack invaders. site of infection may be pus (collection of dead white blood cells + debris)
the immune response (response and phases)
- natural (innate) + acquired (adaptive) response
-phase 1: viruses invade the body through a break in skin or other portal of entry + take over body cells in order to replicate
-phase 2: helper t cells trigger the production of killer T cells and B cells
-phase 3: killer t cells and natural killer cells destroy infected body cells. b cells produce antibodies that bind to viruses + mark for destruction by macrophages
-phase 4: when danger ends, suppressor t cells halt immune response. memory t and b cells reserved to make a quick response in case of future invasions
