Review: Normal Flora and Disease Processes ---- Host-Microbe Relationship Flashcards
What are the three symbiotic relationships between microbes and the human body?
Commensalism
Microbe benefits while host is neither harmed nor benefits
Most Normal flora fit this category
EX. Staphylococci on the skin
Mutualism
Both microbe and host benefit
Normal flora in this category
Gut flora: provided a warm, moist protected environment; make it difficult for pathogens to establish
EX. E.coli in intestine synthesize vitamins K (blood clotting)
Parasitism Microbe benefits, host is harmed All pathogens Ectoparasite: external infestation Endoparasite: internal infection Normal flora can become opportunistic pathogens
Define Normal flora.
Microorganisms that grow on external or internal surfaces of the human body without producing harmful effects
How and when is normal flora acquired on/in the human body?
How are Normal Flora first established on/in newborn?
Breath – microbes from the air
Skin – microbes from the air/touch
Intestinal tract – microbes in milk/food
Where in the human body can normal flora be found? What are the nonspecific inhibitors at each of these locations?
Skin: Nasal Cavities: Conjunctiva of Eye: Mouth: Stomach: Small Intestine: Large Intestine: Urogenital tract:
Where is the highest microbial population in the human body?
Colon is highest
colonized area of human body with normal flora.
Where is normal flora not found in the human body?
Blood/Body fluid Brain/Spinal fluid Eye Lungs (below larynx) Kidneys Bladder (urine) Pancreas Liver/Gall bladder Heart Spleen
What is an opportunistic pathogen?
Organisms that cause disease when introduced into an irregular location
Organism introduced into individuals with weakened immunity
Normal flora or environmental microbes can become an opportunistic pathogen if given the chance
What are some possible reasons that normal flora become pathogenic?
Impaired immune system Recovery from surgery Wound Trauma Chemotherapy Alcohol/Drug Abuse Normal flora in wrong location
Where in the human body can normal flora be found? What are the nonspecific inhibitors at each of these locations? Skin
pH = 4 – 6.8 Too dry Too salty Desquamation of skin cells Lysozyme enzyme
Where in the human body can normal flora be found? What are the nonspecific inhibitors at each of these locations? Nasal Cavities
Mucous secretions trap bacteria
Lysozyme enzyme
Nasal hairs trap dust/bacteria
Where in the human body can normal flora be found? What are the nonspecific inhibitors at each of these locations? Conjunctiva of Eye
Flow of tears
Lysozyme enzyme
Few or no normal flora
Where in the human body can normal flora be found? What are the nonspecific inhibitors at each of these locations? Mouth
Desquamation of mucous cells
Lysozyme enzyme
Flow of saliva (pH= 6.2 – 7.4)
Dental Plaque: 100 billion bacteria/gram (many streptococcus species)
Where in the human body can normal flora be found? What are the nonspecific inhibitors at each of these locations? Stomach
Low pH ( 2)
Stomach acids
Peristalsis – physical movement of food through digestive tract by muscular contractions
Where in the human body can normal flora be found? What are the nonspecific inhibitors at each of these locations? Small Intestine
pH: 6 – 7.5 Few bacteria in duodenum due to digestive enzymes flushing this area Desquamation Peristalsis Lysozyme enzyme, bile, salts
Where in the human body can normal flora be found? What are the nonspecific inhibitors at each of these locations? Large Intestine
pH: 6.8 – 7.3 High microbe population: 25-33% feces (billions microbes/gram of feces) Desquamation Peristalsis Lysozyme enzyme
