Med Micro - Review Questions 1 Flashcards
How does HIV infect and cause disease?
Attachment and internalization. Integration. Reverse transcriptase. Protease.
Why do we care, what can we do with info about infection?
Need to produce treatments etc.
Mutualism, Commensalism, Parasitism
M: both benefit (bac in colon); C: one benefits but offers no pros or cons (bac get nutrients on skin); P: one benefits and other harms (TB in lungs)
Normal Flora
No disease (bind but do not invade). Resident flora: usually mutualistic. Transient flora, don’t stay very long.
How do we acquire normal microbiota?
At birth, food (yogurt), all over
Why might normal microbiota become opportunistic pathogens?
When we are immunocompromised or parenteral route
What do opportunistic pathogens lack?
Virulence factors, no toxins and no entry.
What are the normal routes of entry?
Mouth, conjunctivae, nose, genitals, urethra, placenta, anus, skin, injury, bite
What are the main defense mechanisms by skin?
Sebum: change pH, lubricate (less cracking); salt secretion; antimicrobial peptides; sloughing off of dead cells.
What are the main defense mechanisms by mucous membranes?
Enzymes (lysosymes); pH (ie stomach); traps then swept by cilia; sloughing;
Why can bacteria survive through stomach?
Very resistant to enzymatic degradation.
What are the main defense mechanisms by the placenta?
Must be able to cross placental membrane. It is a selectively permeable membrane.
How does a microorganism gain entry across the skin?
Must be able to enter (enzymes and burrowing). Eg. Hookworm in feces
How does a microorganism gain entry across the mucous membranes?
adhere, then they can secrete enzymes to break down mucous and get to epithelial cells, then extracellular enzymes to gain entry; or they can induce endocytosis and cross the cells
How does a microorganism gain entry across the placenta?
Method to cross placental barrier (lysteria can cause abortion), few can do this
