Week 6 Review Flashcards
What are the predisposing factors for disease?
Gender
Genotype (genetic makeup of an organism)
Nutritional status
Age
Therapy-radiation, anti-inflammatory
Emotional state
What are the stages of infectious disease? Describe each and be able to identify it on a graph.
Incubation period: the period between infection and the appearance of the first signs and symptoms
Prodromal period: mild symptoms may appear, but may not be specific to a particular infection
Period of illness: acute signs and symptoms occur
Period of decline: The body’s defense begins to contain infection
Period of convalescence: body clears infection and returns to resistance (exception: latent or persistent infection)
What are the reservoirs for infection? Name some examples
Animal reservoirs
- Infections transmitted to humans from nonhuman animals are zoonotic (rabies, toxoplasma, possibly ebola)
Human reservoirs
- Most viral infections require human reservoirs
Human reservoirs may be carriers with inapparent infections
Passive carrier= contaminated with pathogen and can mechanically transmit to another host (ex: health care worker who doesn’t wash hands)
Active carrier= infected individual who can transmit disease to others
Non-living reservoirs
- Soil and water
- Contaminated water reservoir for transmission of gastrointestinal tract infections
- Ex: C. tetani causes tetanus; V cholerae causes cholera
Name and describe the ways diseases are transmitted.
Contact transmission (Between human hosts)
- Direct contact transmission = person to person, two types:
- Vertical contact transmission = pathogen transmitted from mother to child during pregnancy, birth, or breastfeeding
- Horizontal contact transmission = contact between mucous membranes may be site-specific
- Droplet transmission: droplet nuclei; common transmission of respiratory tract infections
- Indirect contact transmission: disease agent transmitted from a nonliving object to the host
Vehicle Transmission (through water, food, air)
- Waterborn transmission
- Foodborne transmission
- Airborne transmission
Vector Transmission (through animals)
- Mechanical transmission: transport on insects’ feet or body
- Biological transmission: complex cycle where arthropod bites infected organism, pathogen reproduces in vector, then that vector bites host, infecting the host
What are nosocomial infections and what factors influence them?
Nosocomial infections = infections occurring in a hospitalized patient that were not present on admission (healthcare-associated infections)
Factors:
Microorganisms in hospital:
- The hospital is a reservoir of pathogens
- Normal microbiota on the human body are opportunistic
- Antibiotic-resistant strains are of concern
Compromised host:
- Resistance is impaired by disease, therapy, or burns
- Two principal conditions: broken skin and suppressed immune system (drugs)
Chain of transmission:
- Direct contact from staff to patient or patient to patient
- Indirect contact through fomites (infected objects) and hospital ventilation system
What are the contributing factors for emerging infectious diseases?
Previously undetected or unknown infectious agens
Known agens spread to new geographic locations/new populations
Previously known agents whose role is specific diseases have previously gone unrecognized
Re-emergence of incidence that significantly declined in the past, but has reappeared
What is the difference between morbidity and mortality?
Morbidity = being in a state of illness
Mortality = death from illness
What is Epidemiology? Who were the founders of epidemiology and what did they contribute?
Epidemiology= the study of where and when diseases occur
John Snow: mapped occurrence of cholera in London
Florence Nightingale: showed that improved sanitation decreased the incidence of epidemic typhus
What are the different types of epidemiology?
Descriptive = collecting all data that describe the occurrence of a disease
- Ex: Snow’s investigation of cholera
Analytical = analyzes a particular disease to determine probable cause
- Case-control method: factors that preceded disease
- Cohort method: studies two populations (one that has contact with disease, other has not)
Experimental = begins with a hypothesis about a disease, experiments on a group of people
Case reporting = procedure that requires health care workers to report specific diseases to local, state, and national health officials
How do genomes differ in eukaryotes and prokaryotes?
Eukaryotes: multiple linear chromosomes
Prokaryotes: single circular chromosomes
What is the typical size of a prokaryotic chromosome? Be able to calculate the number of genes given a genome size.
Ex: how many genes if the genome is 6 Mb?
Megabase: 1 x10^6 bases
1 gene per 10^3 bases
Ex: how many genes if the genome is 6 Mb?
(6Mb/1) x (10^6/1Mb) x (1 gene/10^3 bases) = 6000000/1000=6000 genes or 6 x 10^3 genes
How are chromosomes and genes related?
Chromosomes are composed of DNA, and DNA is composed of genes
How is DNA organized in prokaryotes vs. eukaryotes?
Eukaryotes:
- Chromatin: DNA + proteins
- Heterochromatin: tightly packed
- Euchromatin: loosely packed
- Occurs during DNA replication or transcription
Prokaryotes:
- DNA is supercoiled, DNA coils into a tight, small form
- Circular chromosome
Percentage of DNA made into protein in prokaryotes, yeast, and humans.
90% in prokaryotes
70% in yeast
30% in humans
What are the steps in DNA replication? What are the enzymes involved?
- DNA is duplicated before the cell divides
- Information is expressed as products (ex: proteins)
Transcription: DNA to RNA
Translation: RNA to protein
