Chapter 24 (Part 1) Flashcards
infections
involve the invasion and multiplication of microorganisms in body tissues
Infections can become clinically significant and cause
disease if…
→ The infection persists
→ The organism gains access to the circulatory or lymphatic systems (infection becomes systemic)
Types of infectious organisms
→ Bacteria
→ Viruses
→ Fungi
→ Parasites:
→ Helminths (Worms)
→ Protozoa
there are more bacterial cells in your body than…
human cells
T/F - the majority of bacteria are harmful
false. the majority if bacteria are beneficial
an area of skin as small as 1 square inch may be home to…
more than half a million microorganisms
Beneficial roles of bacteria
- Produce nearly half the oxygen in the atmosphere.
- Used to purify water and to treat sewage.
- Used to make cheese, milk, yogurt, tea, sauerkraut, Kombucha, kefir, and sourdough bread
what is the function of normal flora?
- Regulate immune system to tolerate food molecules
- Prevent growth of harmful bacteria
- Help digest food, release some minerals from food
- Produce vitamin K and biotin
- Increase growth of intestinal mucosal cells
- Produce lactic acid during fermentation which lowers pH and inhibits growth of pathogenic species
- Ferment soluble fibre/undigested carbohydrates into short-chain fatty acids
The plasma membrane of most bacteria is encased within a cell wall of
peptidoglycan
Peptidoglycan walls stain purple in gram-staining therefore…
→ Gram-positive
→ Penicillin class of antibiotics act against gram-positive bacteria by inhibiting peptidoglycans
The peptidoglycan layer in some bacteria is thin and covered by an outer capsule therefore…
→ Gram-negative
→ Outer membrane may have lipopolysaccharide (LPS) molecules (an endotoxin in gram-negative capsule).
under harsh conditions some bacteria from…
think-walled endospores
endospores contain…
core of cytoplasm with DNA and ribosomes
bacterias that use endospores
Clostridium botulinum (botulism),
C. tetani (tetanus) and Anthrax
Why do some bacteria make us sick?
Usually through making a toxin, or directly killing cells