Micro_Chap23 – Flashcards
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Unlock answers| Sterile Areas |
Internal organs Blood Cerebrospinal fluid |
| Where bacteria are normally found: |
Skin Oral Cavity Gastrointestinal Tract Respiratory Tract Urogenital Tract |
| Why is skin difficult to colonize? |
| BC skin is: dry, salty, acidic, protective oils, lysozyme |
| Skin is associated with: |
Sebaceous (oil) glands & Apocrine (sweat) glands--pH 4-6 |
| What are factors that affect types of normal flora? |
1. Weather 2. Age 3. Personal hygiene |
| Which microbes are most commonly associated with skin? |
Gram + bacteria: 1. Staphylococcus 2. Streptococcus 3. Propionibacterium 4. Bacillus 5. Candida - yeast found in mouth |
| Propionibacterium: what does it cause? |
Propionibacterium acnes can cause ACNE Gram + Anaerobic RODS |
| What is the eye most inhibited by? |
by lysozymes & Continual rinsing of conjunctiva (eye surface) |
| What temporarily resides in the eye without causing infection? |
Staphylococcus epidermidis Some Gram - rods |
| Pinkeye & Conjunctivitis can be caused by several types of bacteria and viruses. |
| What kind of bacteria are in the mouth prior to tooth formation? |
Aerotolerant anaerobes: 1. Streptococcus 2. Lactobacillus 3. some Yeast |
| What kind of bacteria are there after tooth formation? |
Anaerobes: 1. Prevotella 2. Fusobacterium |
| Teeth and Gingival crevices colonize about how many species of bacteria? |
| Over 500 species!! |
| What forms a layer on teeth providing a firm attachment site for...most commonly --Streptococcus species? |
| Acidic glycoproteins in saliva |
| Dental Plaque |
| When there is extensive growth of microbes resulting in thick bacterial layers. (EW. BRUSH YO TEETH.) |
| What can dental procedures cause? |
BACTEREMIA. --when organisms enter the bloodstream. --quickly cleared by immune system. (PHEW.) |
| Patients with Mitral Valve Prolapse (heart murmur) -- what can happen with teeth cleaning? |
Bacteria can be trapped in defective valve. -can form vegetations (bacterial cells, glycocalyx, fibrin) -(Subacute Bacterial Endocarditis) |
| Dental Caries |
When the microflora of dental plaques make acids that decalcify tooth enamel. -causing tooth decay & cavities. |
| Common sites of tooth decay? |
| Tooth surfaces in and near the gingival crevice where food particles remain. |
| Diets high in sucrose are: |
| Cariogenic - cavity causing |
| What does Lactic acid bacteria ferment to lactic acid? |
| Sucrose! |
| Which microbe produces DEXTRAN only when sucrose is present? |
| Streptococcus mutans. |
| Dextran? |
| Sticky polysaccharide used for attachment to the tooth surface. |
| What makes teeth more resistant to tooth decay and stronger? |
| Fluoride |
| Incorporation of fluoride into calcium phosphate crystal matrix increases resistance to decalcification. |
| What makes up the upper respiratory tract? |
Nasopharynx Oral cavity Throat |
| Most bacteria that are breathed in are trapped in WHAT? |
| Mucus |
| Where are many opportunistic pathogens located? |
| Nasopharynx |
| Which pathogens are found in nasopharynx? |
1. Staphylococcus aureus 2. Streptococcus pneumonia 3. Streptococcus pyogenes 4. Corynebacterium diphtheriae |
| In the nasopharynx, what does Staphylococcus aureus cause? |
Sinus & Ear infections |
In the nasopharynx, what does Streptococcus pneumonia cause? |
Sinus infections & Bronchitis |
In the nasopharynx, what does Streptococcus pyogenes cause? |
Sinus infections & Strep throat |
In the nasopharynx, what does Corynebacterium diphtheriae cause? |
| Diphtheria (life threatening) |
What makes up the Lower respiratory tract?
|
Trachea & Lungs |
| Bacteria are not normally found in lower respiratory tract |
| Mucociliary elevator |
| the Lower respiratory tract is lined with cilia which push bacteria & dust particles up where they are caught in mucus & saliva. |
| What is the pH of the stomach? |
| pH ~ 2 |
| What is the only type of bacteria that can colonize the stomach wall? |
Acid-tolerant bacteria such as: Helicobacter pylori (peptic ulcers) |
| Why does the # of bacteria increase down through small intestine? |
| The pH rises. |
| What makes up the small intestine? |
1. Duodenum 2. Jejunum 3. Ileum |
| What's in the Duodenum? |
Few bacteria due to stomach acids pancreatic secretions Bile Gram + cocci ; bacilli |
| What's in the Jejunum? |
Enterococcus & Lactobacillus |
| What's in the Ileum? |
Microbiota reflects large intestine Large # of Bacteroides ; facultative aerobes like E. coli |
Large intestine is a fermentation vessel. -;300 species of mostly anaerobic bacteria -10^11 bacterial cells/gram of intestinal contents. |
| E. coli consume oxygen, allowing obligate anaerobes to grow. |
Bacteria ferment ingested food into products we can absorb. About how much percentage is our caloric intake this way? |
| 15% |
| What are the common intestinal flora? |
1. E.coli 2. Bacteroides (bacteroidetes) 3. Clostridium (Firmicutes) 4. Enterococcus |
| What do many adults have that convert hydrogen ; carbon dioxide to methane gas? |
| Methanogens |
| Ex. of how diet affects intestinal flora? |
| More meat = more Bacteroides |
| What are some vitamins that are produced in the intestine by bacteria? |
1. Vitamin B-12 2. Riboflavin 3. Thiamine |
| Antibiotics can reduce # of normal flora, leading to digestive problems. |
What supplies bacteria?; Which bacteria? |
Probiotics supply: Lactobacillus ; Bifidobacterium |
What is the growth rate of bacteria in the lumen of the intestinal tract? ; |
| 1-2 doublings per day! |
What are the types of facultative anaerobes associated with Urethra? *Many of these are opportunistic pathogens that can cause UTI. |
1. Escherichia 2. Klebsiella 3. Proteus 4. Neisseria (Gram - cocci) |
| What is often found in the vagina of adult women? |
Lactobacillus acidophilus *acidic secretions prevent pathogens *probiotic treatment. |
| What are the benefits of commensal flora? |
makes vitamins digests food prevents colonization by pathogens |
| Ex. of surface breach allowing bacterial entry: |
Bacteroides: cause abscess or gangrene |
| Ex. of Immunocompromised hosts |
Clostridium difficile: causes Enterocolitis |
| Gnotobiotic animals? |
-either germ-free or all microbial species are known -poorly developed immune systems -low cardiac output -thin intestinal walls -very susceptible to infection by pathogens |
Innate/ nonadaptive immunity: .physical barriers to infection .nonspecific reaction destroy invading cells |
| Adaptive Immunity |
-reaction to specific antigens (foreign proteins, sugars, chemicals) -body reacts to antigens when exposed (retains memory of those antigens, faster response 2nd time) |
| White blood cells include: |
1. Neutrophils ; Monocytes 2. Basophils ; Eosinphils 3. Lymphocytes |
| Neutrophils ; Monocytes do what? |
Engulf ; destroy microbes Monocytes = macrophages ; dendritic cells (phagocytic) |
| Basophils ; Eosinphils do what? |
| Release toxins to poison microbes. |
| Lymphocytes include ; do what? |
1. ;T cells - regulate specific immune response 2. B cells - produce antibodies to bind antigens |
| What are the physical barriers to infection? |
1. Skin; 2. Mucous 3. Cilia 4. Toll-like receptor proteins on tissues |
Skin has keratin, oil, cells that are phagocytic. Dead skin cells, washing, removes attached cells. |
Mucous lines respiratory ; digestive tract. -trap and destroy pathogens -mucous layers slough off |
| Cilia removes microbes from lungs. |
What do Toll-like receptor proteins on tissues do? Give some examples. |
recognize pathogens and collect them and bring them to phagocytes. Ex. Gut - M cells Skin - Langerhans cells |
| What are the chemical barriers to infection? |
1. Acidic pH: stomach, skin, vagina 2. Lysozyme: tears, skin --Destroys peptidoglycan 3. Defensins - peptides that disrupt pathogens/ effective against Gram +, -, fungi, & enveloped viruses. |
| What are Defensins? --part of chemical barrier. |
Peptides (small proteins) that disrupt pathogens. Effective against Gram +, G -, fungi, and enveloped viruses. |
| Describe Inflammation |
-Redness, swelling, pain, heat - Fluids containing WBC's leak into wound -Clot forms to localize pathogen -Septic shock |
| Septic shock: |
| when infection & inflammation spread through out body. |
During Fever: - some products of pathogens (endotoxin) are pyrogenic (fever inducing) -cause Hypothalamus to reset body temp. -Endogenous pyrogens are produced by leukocytes |
| Higher temp. does what: |
-increases phagocytosis & antibody production -slows bacterial growth -high temp damages host tissue |
| What happens during Acute inflammatory response? (9 steps) |
1. infection releases microbes to tissue 2. resident macrophage engulf bacteria 3. macrophage release vasoactive factors & cytokines - causing capillaries to dilate 4. fluids containing WBC's leak into wound 5. macrophage squeeze between capillary cells (Extravasation) 6. damaged tissue secretes Bradykinin 7. Mast cells release histamine 8. histamine makes vessels open further 9. Prostaglandin stimulates nerve cells. |
| What does Bradykinin do? |
| Stimulate mast cells causing release of histamine. |
| What does histamine do? |
| open vessels further releasing blood plasma, platelets, Prostaglandin |
| Prostaglandin does what? |
| Signal itching, pain. |
| What is the enzyme involved in prostaglandin synthesis? |
| Cyclooxygenase (COX) |
| What are some inhibitors of COX? |
| Aspirin, Vioxx, Celebrex |
Chronic Inflammation: some pathogens (Mycobacterium) resist host defenses by? |
body walls of site in granuloma (fibrotic lesion around bacteria.)
|
Ex. of Autoimmune Response: (destruction of host tissue when immune sys. responds to body cells as if they were foreign) |
1. Lupus erythematosus 2. Rheumatoid arthritis 3. Crohn's disease |
| How do phagocytes kill & digest engulfed bacteria? |
- produce lysozyme & antimicrobial peptides to kill bacteria. - kill with "oxidative burst" (increase in oxygen consumption during phagocytosis results in production of reactive oxygen species such as superoxide ions.) |
Interferons : (2 types) Interfere with viral replication |
- produced by infected host cells -species specific (mouse interferon will not work with humans.) -virus nonspecific (human interferon helps protect against influenza & cold virus) |
Type 1 Interferon: what does it do? how? |
-antiviral -Bind to uninfected cells & make them resistant to viral infection (1 type cleaves viral RNA, another prevents translation of RNA) |
Type 2 Interferon: does what? |
Stimulates immune cells -nearby immune cells become for sensitive (act more rapidly) -activates macrophage, natural killer cells, T cells. |
| What do Natural killer cells do? |
| destroy infected & cancerous host cells. |
What do healthy cells make, but cancerous cells stop making called?
antibodies bind viral proteins on infected cell surface so NKC's can notice and kill the cell. |
| MHC 1 protein |
| How do NKC's kill antibody-bound or MHC1-less cells? |
-secretes perforin protein into target cells (perforin creates membrane pores to lyse cell) |
| What is the Role of Complement? |
-series of 20 proteins in blood serum -several are proteases which sequentially cleave each other -activation of complement cascade results in pores in target microbial membranes (membrane attach complex-MAC) -Cell content leak out, and dies. |
| A host's ability to resist infection depends on: |
Age Stress Diet General health and lifestyle Prior or concurrent disease Genetic conditions |
