chapter 2 pt 2

Chapter 2: Altered Cellular and Tissue Biology: Environmental Agents

Carbon Monoxide (CO) Poisoning

  • Symptoms: Headache, giddiness, tinnitus (ringing in the ears), chest pain, confusion, nausea, weakness, vomiting.

    • Notable skin coloration: Cherry red coloration of the skin and mucous membranes in victims.

  • Sources: Environmental air pollutant found in combustion fumes from:

    • Cars and trucks

    • Small gasoline engines

    • Stoves

    • Gas ranges

    • Gas refrigerators

    • Heating systems

    • Lanterns

    • Burning charcoal or wood

    • Cigarette smoke

  • Chronic Exposure Risks: Particularly hazardous for those in confined spaces like underground garages and tunnels. Fumes accumulate in enclosed or semi-enclosed spaces.

  • Susceptible Populations: Fetuses, infants, individuals with chronic heart disease, respiratory issues, and anemia.

Cyanide Poisoning

  • Overview: Cyanide is a highly toxic salt that acts as an asphyxiant.

  • Mechanism:

    • Combines with ferric (iron) ions in hemoglobin, impeding oxygen transport to tissues.

    • Inhibits cytochrome oxidase by disrupting the electron transport chain in mitochondria.

    • Result: Inability to produce ATP aerobically, leading to oxygen deprivation despite the presence of oxygen.

  • Symptoms: Similar skin coloration to CO poisoning, may detect a bitter almond odor (noted by 20-40% of the population).

Hydrogen Sulfide Poisoning

  • Description: A chemical asphyxiant and neurotoxin interfering with oxygen transport in the body; characterized by a "rotten egg" odor detectable at low levels.

  • Symptoms: Brown-tinged blood may also be observed, along with general signs of asphyxiation.

Methane Asphyxiation

  • Nature: Nontoxic but can displace oxygen leading to asphyxiation, particularly in environments like septic tanks, cesspools, and manure pits.

Cerebral Hypoxia

  • Overview: Leads to unconsciousness within minutes; outcomes depend on factors like age, health, water temperature, and exposure duration.

  • Key Factor: Irreversible injury occurs more rapidly in warm water versus cold water.

  • Drowning Considerations: Requires suspicion of underlying incapacitation condition.

Drowning

  • Definition: Death caused by water inhalation and suffocation; fifth leading cause of unintentional injury death in the U.S., third worldwide.

  • Statistics: 236,000 drowning deaths worldwide; 2nd leading cause of unintentional death in children (1-14 years) in the U.S.; males are twice as likely to drown as females.

  • Mechanism of Injury: Primarily due to hypoxemia.

    • Evidence suggests drowning does not result in fluid and electrolyte disturbances in many cases; airway obstruction is critical.

  • Dry-Lung Drowning: Involves vagal-mediated laryngospasm closing the airway, even with minimal water inhalation.

Infectious Injury

  • Pathogenicity: Microorganisms' ability to survive within the host, producing diseases through:

    1. Cell invasion and destruction

    2. Toxin production

    3. Hypersensitivity reactions.

Immunologic and Inflammatory Injury

  • Cause: Injury from immune/inflammatory responses - phagocytes (lymphocytes, monocytes) and resultant biochemical agents.

  • Injurious Agents: Histamine, antibodies, lymphokines, etc.

    • Mechanisms:

    • Complement system leading to potassium leakage and water influx.

    • Antibody interference with receptor function or cellular junction integrity.

Climate Change Impact on Human Health

  • Drivers: Increasing greenhouse gases due to human activities (combustion of fossil fuels, agriculture).

  • Health Effects:

    • Clean air, safe drinking water, food security, secure shelter affected.

  • Health Impacts Summary (Table 2.10):

    • Increased heat-related mortality and respiratory disease exacerbations.

    • Changes in microbial and vector habitats leading to new patterns in human disease (e.g., cholera, schistosomiasis).

Mechanisms of Cellular Injury (Table 2.9)

  • Categories:

    • Genetic factors (e.g., sickle cell anemia)

    • Epigenetic factors (e.g., gene silencing in cancer)

    • Nutritional imbalances (protein deficiencies, hyperlipidemia).

Effects of Physical Agents

  • Various forms of physical stress, including temperature extremes, noise, and mechanical forces on cellular injury.

Ionizing Radiation (IR)

  • Definition: Radiation capable of removing electrons from atoms, leading to ionization.

  • Sources: X-rays, gamma rays, alpha and beta particles.

  • Effects:

    1. Cellular Attributes: Fast-proliferating cells (gonads, bone marrow) are more sensitive to damage.

    2. Radiation Damage Mechanism: ROS generation due to radiolysis of water affects DNA.

    3. Classification: Early tissue reactions vs. stochastic effects (e.g., carcinogenesis).

High-Altitude Illness (HAI)

  • Types: HAPE (High-Altitude Pulmonary Edema) and HACE (High-Altitude Cerebral Edema), as well as Acute Mountain Sickness (AMS).

    • Symptoms include headache, dizziness, nausea; both HAPE and HACE can be fatal.

Manifestations of Cellular Injury

  • Accumulates: Water, lipids, carbohydrates, proteins, pigments, and urates reflecting various metabolic disturbances.

  • Mechanisms: Inadequate substance removal or degradation leading to organ enlargement (hepatomegaly/splenomegaly).

Aging and Cellular Biology

  • Definition: Aging as a time-dependent decline in function.

  • Hallmarks (Table 2.13): Genomic instability, mitochondrial dysfunction, cellular senescence, etc.

Mortality and Aging**

  • Normal Life Span: ~80 to 100 years, with life expectancy affected by socioeconomic factors.

  • Frailty: Syndrome characterized by weakness and functional decline due to interrelated physiological system alterations associated with aging.