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BIO 111 > Chapter 20 & 21 > Flashcards

Chapter 20 & 21 Flashcards

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1
Q

Alcohols

A

An exception to the concentration as these are more effective when some water is used (should be diluted to 75%); proteins dissolve in water which allows these to damage proteins:

  • Effectiveness: low-intermediate
  • Toxicity: varies
  • Actions: disrupt cell membranes and denature cellular proteins; evaporates quickly
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2
Q

Types of Alcohols

A
  • Ethyl (ethanol, grain): non-toxic; more expensive than isopropyl
  • Isopropyl (rubbing): more effective microbial agent, but more toxic to animals (vapors can damage CNS of humans)
  • Neither kills endospores
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3
Q

Hydrogen Peroxide

A
  • Effectiveness: low
  • Toxicity to humans: none
  • Actions: large amounts quickly overwhelm any catalase and peroxidase found within the cell; acts as a free radical which is highly toxic to living oranisms
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4
Q

Surface-Action Agents

A
  • Effectiveness: Anionic (soaps)- essentially none; used in removing microorganisms but does not kill them; Cationic (quaternary ammonium compounds)- low effectiveness; ineffective against gram- bacteria
  • Toxicity to humans: none-low
  • Action: no action; disrupts cell membranes
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5
Q

Heavy Metals

A
  • Effectiveness: low
  • Toxicity to humans: little on skin, but toxic if placed on wounds; topical only (used on burns)
  • Action: denatures proteins
  • e.g., mercury containing compounds including metaphen, silver containing compounds including silver nitrate; in the past used to prevent gonorrheal infections in the eyes of newborns, but ineffective and was irritating
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6
Q

Phenol (corbolic acid) and its Derivatives

A
  • Effectiveness: intermediate; often ineffective against non-enveloped viruses
  • Toxicity to humans: very toxic to tissues; used as a topical antiseptic only (surgeon hand creams)
  • Action: damage cell membranes and denature proteins
  • Examples: Lysol (phenol derivative & 79% alcohol)- very effective; Chlorhexidine (hand cleanser)
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7
Q

Ethylene Oxide

A
  • Effectiveness: high
  • Toxicity to humans: high; carcinogenic
  • Action: denatures proteins and mutates DNA strands
  • Usually in vapor form; does not require water to function well; slow acting; explosive; used extensively in hospitals when items may be damaged by heat or water
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8
Q

Chlorine and Iodine

A
  • Effectiveness: intermediate
  • Toxicity to humans: slightly toxic; irritating to tissues and a potential carcinogen
  • Action: denatures proteins, DNA
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9
Q

Dry Heat

A

Hot dry ovens or direct exposure to flame are used for this process; quickly incinerates microbes; used to sterilize glassware, powders, oils; flame of a Bunsen burner reaches 1870 degrees C

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10
Q

Incineration

A
  • Used to completely destroy most hospital items
  • Using dry heat ovens, steriliztion of all living cells and endospores would require (at minimum): 150-180 degree C heat; 2-4 hours of contact time
  • Disadvantages: time, many items cannot tolerate such heat extremes
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11
Q

Moist Heat

A
  • This process would be considered boiling or steaming items
  • Kills most vegetative forms of bacteria in minutes, but will not destroy endospores
  • Boiling of water brings the temperature up to 100 degrees C
  • Pasteurization: Flash Method- heats the fluid to 72 degrees C for 15 seconds, usually conducted as the fluid flows through pipes (very common); Holding Method- liquid heated in bulk to 63 degrees C for 30 minutes
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12
Q

Disadvantages to Moist Heat

A
  • Some viruses and bacteria can tolerate short boiling times
  • Endospores can survive several hours
  • Does not usually sterilize the items, but greatly reduces the number of bacteria found on or within a substance
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13
Q

Moist Heat Under Pressure (the autoclave)

A
  • Most medical and laboratory products are sterilized in this manner
  • When water is present, all macromolecules are denatured at relatively low temperatures
  • Complete sterilization possible (including endospores)
  • Typical Criteria: 15psi (no direct role in destruction of bacteria, 121 degrees C, 15 minutes
  • Disadvantages: expensive, cannot be used on something that will be ruined when it comes into contact with water at high heat
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14
Q

Harvey Chemiclave

A
  • When an alcohol/formaldehyde vapor is pressurized and heated
  • Very quick turnaround time
  • Used often with dental instruments
  • Disadvantages: expensive, cannot be useed if articles will be damaged by chemicals, heat, or pressure
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15
Q

Non-Ionizing Radiation (UV light)

A
  • In general, will alter the structure of DNA molecules by creating thymine dimers
  • Many of these mutations can be repaired by the bacterial cell, but in high doses the DNA molecule is rendered non-functional (unable to repair all damage)
  • Used as disinfection tool most often
  • Often placed near air ducts in sterile areas like operating rooms
  • Very good at reducing the number of living organisms (99%+)
  • Very good against actively reproducing cells, but less so against endospores
  • Disadvantages: readily passes through air, sightly through liquids, and much less so through solids; damaging to human tissues
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16
Q

Ionizing Radiation (X-rays and Gamma Rays)

A
  • Very high energy wavelengths
  • Action: breaks linkages between adjacent nucleic acids and in the process produces free radicals
  • Used in food preparation and becoming ever more popular in the hospital community
  • Can penetrate fabrics, plastics, liquids, and foods
  • Very good potential, just not in wide used as of yet
17
Q

Filtration

A
  • Contain pores that range from 0.02 micrometers to 8 micrometers; the larger sized pores will catch the bacteria as it travels through, and smaller will even catch viruses but not very small toxins or viruses
  • Effective in removing microorganisms from liquids and gases that are heat sensitive, but does not destroy microbes; used extensively in food processing market to being placed in air handlers in sterile environments (operating rooms)
18
Q

Modes of Action

A
  • Cell Wall: disrupt synthesis of or digest, causing lysis
  • Cell Membrane: cause leakage
  • Protein and Nucleic Acid Synthesis: bind to ribosomes preventing protein synthesis; bind to DNA preventing transcription and translation; change base pair pattern of DNA
  • Altering Protein Function: alter shape (denature)
19
Q

Epidemiology

A

The study of the cause, frequency and distribution of disease

20
Q

Epidemiology Questions

A
  • What pathogen is responsible for the disease?
  • What is the source (reservoir) of the disease?
  • Who in the population is at risk?
  • How is the disease spread?
  • How many people have the disease?
  • Geographically, where is the disease located?
21
Q

Communicable Disease

A

An infectious disease caused by a pathogen that can be transmitted from person to person

22
Q

Rate of Disease

A

Describes the proportion (percentage) of a population who have the disease; e.g., if 100 people of 1000 were infected were sick, this population would be 100/1000 or 10%; looks at the entire population, not just those exposed

23
Q

Attack Rate of Disease

A

Describes the proportion (percentage) of a population that develop the disease after they have been directly exposed to the pathogen; out of 1000 people, 100 drank contaminated water and 10 developed chronic diarrhea: 10/100 or 10%

24
Q

Morbidity

A

Describes the rate of disease along with time of the month or year; describes your chance of developing a disease at a certain time of year or a certain season

25
Q

Mortality

A

The proportion (percentage) of people who have contracted the pathogen and died from the disease

26
Q

Epidemic

A

A disease found in unusually high frequencies within a population

27
Q

Pandemic (Pan = all)

A

An epidemic spread across the world

28
Q

Endemic

A

Disease is constantly present within a given population; flu, colds never leave our population

29
Q

Chain of Infection

A
  • Reservoir: pathogen is found in a source in which it is capable of living, growing, and spreading to other hosts (another person, other animals, the environment)
  • Portal of Exit: if the pathogen is found in another human, then it must escape their reservoir through some orifice
  • Mode of Transmission: a person must come in contact with the exposed material from the portal of exit
  • Portal of Entry: how the organism enters the body
30
Q

Portal of Exit/Entry

A
  • Digestive System: anus or mouth (feces, vomit)
  • Urinary System: urethra (urine)
  • Respiratory System: mouth, nose (mucus)
  • Reproductive System: vagina, urethra (vaginal fluid, semen)
  • Breaks in the skin
  • Eye
31
Q

Droplet of Transmission

A

Inhalation of large vaporized respiratory droplets (sneeze, cough)

32
Q

Incubation Period

A

The length of time between exposure to the pathogen and onset of disease symptoms

33
Q

Symptomatic

A

Hosts that are showing symptoms of a disease; easy to identify and therefore easy to isolate to slow the transmission of the pathogen through a population

34
Q

Asymptomatic

A

Hosts that are not showing symptoms, but can potentially still transmit the pathogen to another host; difficult to identify hosts so easy for disease to spread through the population

35
Q

Dose

A

The number of pathogens a person (host) is initially exposed to; large are more likely to cause disease and will shorten the incubation time while small are less likely to cause disease and will lengthen the incubation time

36
Q

Herd Immunity

A

A disease has a difficult time spreading to susceptible hosts because only a few reservoirs exist

37
Q

Population Characteristics That Can Increase Susceptibility to a Disease

A
  • Malnutrition
  • Crowding
  • Fatigue
  • Stress
  • Age
  • Gender
  • Genetics: blood types AB, A, B, O (from most to least) resistant to many intestinal bacteria

BIO 111 (15 decks)

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