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BIO 040 Flashcards

(47 cards)

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1
Q

Definition of Disease

A

An impairment of health.

A condition that impairs the bodily function of a particular organ/system.

A pathological condition of an organism caused by infection, genetic defect, or environmental stress.

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2
Q

Types of Disease

A

Genetic: Hemophilia, Cystic Fibrosis

Infectious: Smallpox, Bubonic Plague, Malaria, Influenza

Lifestyle/Environmental: Heart Disease, Diabetes, Lung Cancer, Hypertension

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3
Q

Impact on Disease History

A

Large population declines

Advancements in medicine and public health

Changes in social, economic, and political environments (including art)

Lifestyle modifications

Altered outcomes of war and conquests

Cultural and psychological impacts (belief systems, behaviors)

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4
Q

Properties of Living Organisms

A

Growth
Reproduction
Obtain and use energy
Respond to environment
Adaptation

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5
Q

Cell Theory

A

All living organisms are made of cells.

Cells are the smallest structures with properties of life.

All cells come from preexisting cells.

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6
Q

Key Scientists

A

Schwann – animal cells

Schleiden – plant cells

Virchow – cells from preexisting cells

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7
Q

Basic Components of a Cell

A

Plasma membrane

Genetic material

Protein machinery

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8
Q

Prokaryotic Cell

A

No nucleus, usually unicellular (Bacteria, Archaea)

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9
Q

Eukaryotic Cell

A

Nucleus, membrane-bound compartments, unicellular or multicellular (Protists, Plants, Fungi, Animals)

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10
Q

Cells – Appearance and Observation

A

Cells vary in appearance.

Frog eggs: visible to naked eye
Mouse fibroblasts: require microscope

Concept: Cells are the basic unit of life.

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11
Q

Sedentary Lifestyle

A

Evolutionary mismatch due to inactivity

Leads to chronic diseases, impaired metabolism, inflammation

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12
Q

Hunter-Gatherers

A

Semi-nomadic, small
groups, lower reproductive rate

Diet: whole foods, high physical activity, low stress

Fewer metabolic and cardiovascular diseases

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13
Q

Agricultural Revolution (~12,000–10,000 yrs ago)

A

Humans transition from hunter-gatherers to farmers

Domestication of plants and animals

Larger population, higher density → more infectious diseases

Waste disposal challenges and more human-animal contact

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14
Q

Animal Traits for Domestication

A

Herbivore, tameable, social, breeds in captivity, fast growth

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15
Q

Animal-Human Disease Links

A

Dogs → Distemper → human measles

Cattle/Camels → Smallpox, Measles

Sheep/Goats → Q fever

Poultry/Pigs → Influenza A

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16
Q

Infectious Diseases

A

Causative Agents (Smallest → Largest):

Prions: Proteinaceous infectious particles (Mad Cow, Creutzfeldt-Jakob, Kuru)

Viruses
Bacteria
Protozoans
Multicellular parasites

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17
Q

Historical Ideas of Disease

A

Aristotle: Spontaneous generation (flies from meat)

Girolamo Fracastoro: Diseases from transferable agents

Anton van Leeuwenhoek: Microscope; opposed spontaneous generation

Francesco Redi: Flies from flies, not meat (1668)

John Needham: Vegetative force theory

Lazzaro Spallanzani: Disproved Needham
Louis Pasteur: Swan-neck flask experiment (1859), ended spontaneous generation idea

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18
Q

Robert Koch and Microbiology/ Major Contributions

A

Isolated pathogens (Anthrax, Tuberculosis, Vibrio cholerae)

Used model organisms

Proved microorganisms cause infectious diseases

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19
Q

Koch’s Postulates

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A

Microbe present in diseased hosts

Microbe can be grown in pure culture

Inoculation into healthy host → same disease

Re-isolate same microbe from new host

20
Q

Disease Terminology

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A

Disease: Pathogenic condition of a host, including signs and symptoms.

Parasites & Pathogens: Agents causing disease; parasites may harm but don’t always cause disease.

Infectious diseases: Disorders caused by micro/macro parasites transmitted between organisms.

Zoonotic pathogens: Pathogens transmitted from animals to humans.

21
Q

Epidemiological Triad

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A

Outbreaks occur when the ecology of host, pathogen, or environment changes.

3 elements of triad:
Susceptible host populations

Infectious pathogens

Favorable environmental conditions

22
Q

Emerging Infectious Diseases (EIDs)

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A

Definition: Diseases appearing or increasing due to ecological changes.

Types:
Wildlife EIDs: first appearance in wild populations
Domestic Animal EIDs: spillover from wildlife, often RNA viruses
Human EIDs: recently appeared infections or rapidly spreading

Drivers: Climate change, human encroachment, wildlife movement, land use change, global travel

23
Q

Origins & Evolution of Infectious Disease

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A

Many human-only diseases originated in animals.

24
Q

Stages of disease evolution:

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A

Animal-only pathogens

Primary infection: animal → human (e.g., Anthrax)

Limited outbreaks (Ebola, Monkeypox)

Long outbreaks (Yellow Fever)

Exclusive human pathogens (Smallpox, HIV-1 M)

Stage 5 development:
Pathogen co-speciation: ancestral pathogen evolves with humans
Pathogen adaptation: recent animal pathogen evolves to human-specific

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Reservoir/Maintenance host
Maintains pathogen without symptoms (e.g., white-footed mouse for Lyme).
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Bridge host:
Transmits pathogen from reservoir to target (e.g., pigs, horses for Nipah virus).
27
Target host
Host of concern (humans, domestic animals, threatened wildlife).
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Zoonotic Hazard & Risk
Risk formula: Risk = Hazard × (Vulnerability × Exposure) Definitions: Hazard: potential microbial harm Exposure: likelihood of contact with hazard Vulnerability: likelihood of harm after exposure
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Post-Infection Stages
Incubation period: Exposure → first symptoms Latent period: Exposure → infectiousness Infectious period: Host can transmit disease Latent < Incubation: Person infectious before symptoms Latent = Incubation: Easier control
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Transmission Rate (R0)
R0: Average number a single infected person infects in a fully susceptible population Factors: Population density, contacts, immunity, duration of infectiousness Example: Influenza: Incubation 1–4d, Latent 2d, Infectious 3d, R0 = 1.5
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Endemic, Epidemic, Pandemic
Endemic: Constant, low-level, region-specific Epidemic: Sudden increase in cases, local or regional Pandemic: Epidemic across multiple countries or continents
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Parasites
Definition: Live on/in host; benefit at host’s expense Macroparasites: Large, produce eggs/larvae (arthropods, worms) Microparasites: Microscopic, multiply in host (bacteria) Ectoparasites: Live on host surface Endoparasites: Live inside host cells, tissues, or gut
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Modes of Transmission
Direct Transmission: Immediate transfer (skin-to-skin, droplets, sexual contact) Indirect Transmission: Via air, objects, vectors, or vehicles (food, water, blood) Transmission examples: Droplet: Direct Direct contact: Direct Vector-borne: Indirect Mechanical: Indirect Airborne: Indirect Vehicle-borne: Indirect
34
Dengue Virus Chain of Infection
Reservoirs: Humans (primary), monkeys (Asia, Africa) Portal of exit: Skin via Aedes mosquito bite Mode of transmission: Indirect, mosquito vector Portal of entry: Skin via infected mosquito bite Host susceptibility: Universal, depends on location and immunity (serotype-specific)
35
Dengue Prevention & Control
Avoid mosquito bites (protective clothing, repellents) Reduce mosquito breeding sites (eliminate standing water) Educate communities on symptoms and early medical consultation Monitor cases and lab confirmations to contain outbreaks early
36
Father of Epidemiology
John Snow (1813–1858) Conducted pioneering work during the 1854 cholera outbreak in London Used mapping and surveys to trace cholera cases to a contaminated water source (Broad Street pump) Founded modern epidemiology: study of disease patterns in populations
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Epidemiology Overview
Definition: Study of the distribution and determinants of disease in populations; applied to control health problems Historical Roots: Hippocrates (~400 B.C.) suggested environmental and host factors influence disease
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Cholera – Disease Overview
Pathogen: Vibrio cholerae, Gram-negative, comma-shaped bacterium Symptoms: Profuse, painless watery diarrhea ("rice-water stool"), vomiting, rapid dehydration Transmission: Indirect, via contaminated food/water Incubation: 12 hours – 5 days Infectious Period: 1–2 weeks Fatality Rate: 25–60% if untreated
39
Cholera Pandemics
1. 1817-1823: India, SE Asia - stopped by severe winter 2. 1826-1837: Europe & Americas - spread via trade 3. 1846-1862: India, Europe, US, Africa - >150,000 deaths 4. 1864-1875: Europe & Africa - massive loss of life 5. 1883-1896: Asia, Europe - Vibrio cholerae isolated by Robert Koch (1884) 6. 1899-1923: Africa & Asia - heavily affected India, Russia, Middle East 7. 1961-present: Africa, Asia, Indonesia, Central & South America
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Cholera Origins
Origin: Ganges River Delta, Bengal, India Became endemic due to contaminated water Spread globally via trade routes 19th-century Industrial Revolution worsened spread: urban crowding, poor sanitation, contaminated water
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Vibrio cholerae Life Cycle
1. Environmental Survival: Lives in brackish water, forms biofilms, enters VBNC state 2. Ingestion: Survives stomach acid, enters small intestine 3. Colonization: Adheres to intestinal cells using pili 4. Virulence & Infection: Produces cholera toxin → massive diarrhea 5. Shedding & Transmission: Bacteria excreted, hyperinfectious in new hosts
42
Cholera Virulence Factors
Cholera Toxin: A subunit → enters cell, activates cAMP → secretory diarrhea B subunit → binds intestinal epithelium Toxin-Coregulated Pilus (TCP): Adhesin proteins for colonization of gut lining Only strains with all 3 genes (2 for toxin, 1 for pilus) cause cholera
43
Drug Resistance
O1 and O139 strains: multidrug resistance observed globally (India, Angola, Brazil, Kerala) Resistant to ampicillin, chloramphenicol, tetracycline, ciprofloxacin, polymyxin B, and others Constant development of new treatments required
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John Snow & the 1854 London Outbreak
Surveyed affected residents with Reverend Henry Whitehead Mapped cholera cases → linked to Broad Street pump Removal of pump handle stopped outbreak Supported germ theory over miasma theory (diseases not from "bad air")
45
Historical Cholera Theories
Miasma: Disease caused by "bad air" from rotting matter/sewage Germ theory: Microscopic organism causes cholera (proven by Koch)
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Societal & Urban Impacts
Scientific Advancement: Germ theory validated, epidemiology established Urban Infrastructure: Sewage separation (Bazalgette’s London sewers) Water filtration & chlorination Global Public Health: Centralized health boards, international cooperation → led to WHO Social & Political: Cholera riots (1831–32): poor neighborhoods protested, distrusted authorities Graverobbing: bodies sold to medical schools → distrust of elites Led to mausoleums, stricter burial protections
47
Vibrio cholerae Modern Strains
O1: Original 1817 strain, all subsequent epidemics O139: Appeared 1992, India & Asia Hyperinfectivity: Recently shed bacteria more infectious than lab-grown strains
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