Lecture 7 part 2

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Author:
mlhayes
ID:
17646
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Lecture 7 part 2
Updated:
2010-05-04 14:16:45
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BU forensic pathology
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Hyperthermia/hypothermia blast injuries
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  1. The normal human body temperature is ____
    • 98.6 F or 37 C
    • (infants and elderly average 1c degree higher)
  2. Exercise can increase body temperature by several degrees. (T/F)
    True
  3. Heat load:
    Heat generated by oxidation of metabolic products and heat acquired from the environment
  4. Daily cyclic variation
    Lowest early in the morning, highest in the afternoon
  5. Heat flows from _____ to _____ areas
    Hotter to cooler
  6. What are the four mechanisms of heat transfer?
    Conduction, convection, radiation and evaporation (insensible and sweat loss)
  7. Conduction is:
    The direct transfer of heat from one object to another

    Conduction to water is 25X that of air
  8. Radiation is:
    Heat transfer by emission of infrared rays (sun, radiator/heaters)
  9. Evaporation is:
    Loss of heat when water vaporizes into the atmosphere
  10. The primary means by which an overheated body cools itself is through_______
    Evaporation
  11. Two modes of body water loss is ______ and _______
    • Sweat loss-water lost from skin due to sweat glan activity
    • (up to 700ml/hr)

    Insensible loss-water lost by skin and lungs (600 ml perday)
  12. Convection is:
    Movement of air currents around an object with resultant transfer if heat by conduction and evaporation
  13. Increased heat loss is due to…
    Decreased environmental temperature

    Increasedconvection

    Wet skin

    Increased blood flow to skin

    Riskof hypothernia
  14. Decreased heat loss is due to….
    Increased environmental temperature

    Increased insulation (body fat, clothing)

    High humidity

    Risk of hyperthermia
  15. When environmental temperature exceeds body temperature:
    • Body gains heat by radiation and conduction
    • Body looses heat only by evaporation
  16. ______interferes with evaporation even though sweating continues
    High humidity
  17. What happens during hyperthermia?
    Core temperature greater that 105F

    Occurs when heat load exceeds heat loss

    Mild forms of heat illness (body temperature normal or minimally elevated)
  18. Vigorous exercise in hot environment can cause______
    • Heat cramps
    • (may be due to salt depletion)
  19. Heat exhaustion is due to….
    • Exercise in hot environment
    • Due to loss of salt and water
    • Headache, n & v, dizziness, weak
  20. Acclimatization causes
    • Changes in sweat production
    • Aldosterone increases salt reabsorbtion from sweat
  21. In hot weather the normal max rate of sweat is 700ml per hour (T/F)
    True- rate can be increased to 1500ml per hour
  22. Unacclimatized person may lose ___g salt per day at high temperatures
    30
  23. What happens when someone suffers from heatstroke?
    • Normal heat dissipating mechanisms of the body become incapable of compensating for increased environmental heat
    • A life threatening condition-required immediate treatment
    • Increased body temp-causes direct themal injury to the cells and tissues
    • Temp 105F or greater
  24. Mortality up to ___% when body temperature greater that 106F
    75
  25. Environmental causes of Hyperthermia
    High temperature

    High humidity
  26. Non-environmental causes of hyperthermia
    • Brainhemorrhage
    • Salicylate(asprin) overdose
    • Reaction to anesthetics or antipsychotic drugs
    • Cocaine/amphetimines
  27. Signs and symptoms of hyperthermia
    • Hot dry skin with absence of sweating
    • n/v, musclecramps, shortness of breath
    • central nervous system dysfunction-hallucinations
    • vasodilatation-decrease in blood volume, circulatory collapse and heart failure
  28. Autopsy findings of deaths due to hyperthermia
    • Autopsy findings are non specific
    • Diagnosis of heat stroke can be made if : post mortem core body temp indicates hyperthermia (and environmental temp is lower) and autopsy does not reveal anyother cause of death
  29. Factors that cause Increased risk of hyperthermia:
    • Alcoholism-dilates skin capillaries
    • Extremes of age
    • Obesity
    • Heartdisease
    • Physical exertion
  30. Hypothermia is:
    • Defined as core body temp of less than 95F (35C)
    • Can occur when heat loss exceeds heat production
  31. What are the body defenses against cold?
    • Vasoconstructionof skin and muscle blood vessels
    • Increased heat production
    • Shivering –increased muscle metabolism
    • Chemical thermogenesis- brown fat, especially important in infants, production of heat instead of atp
  32. Increased risk of hypothermia
    • extremes of age- infants have a high surface to volume ratio
    • immersin in water
    • wet clothing
    • alcohol intoxication
    • preexisting disease-hypothyroid
    • inadequate nutrition
  33. physioloic effects of hypothermia
    • decreased repiration and heart rate
    • menal confusion and deterioration-ending in euphoria
    • unstable blood sugar
    • cardiac arrhythmias-atrial and ventricular fibrillation
  34. Scene investigation in hypothermia
    • Environmental temperature does not always have to be extremely low
    • Hide and die syndrome
    • Paradoxical undressing
  35. Hide and die syndrome
    • Terminal behavior in 20% of hypothermia
    • Primitive brainstem reflex to hide (body found behind furniture, under bed)
  36. Paradoxical undressing
    Terminal behavior in 50% of hypothermia deaths due to hallucinations and “paradoxical” feeling of warmth
  37. External examination autopsy findings in hypothermia deaths:
    • Pink (cherry red) livor mortis
    • Brownish-pink discoloration to skin of joint surfaces and perhaps face
    • Possible frostbite
  38. Internal examination autopsy findings in hypothermia deaths:
    • Changes are present with a period of survival before death
    • Acute gastric erosions- wischnewsky ulcers
    • Acute hemorrhagic pancreatitis
    • Pulmonary edema
  39. Air blast cases what type of injuries?
    Ear and lung injuries
  40. Water blast injuries cause what type of injuries?
    Abdominal injuries
  41. What are some of the effects of blast injuries to consider?
    • Local heat effects
    • Blast wave striking the body
    • Flying debris striking the body
    • Human body in motion striking other objects
    • Other structures collapsing on the body
  42. High order explosives
    • Supersonic pressure wave producing all 5 injury types (heat, blast
    • wave, flying debris, human body in motion, structural collapse
    • Dynamite
    • Plastic explosives- C4
  43. Lower order explosives
    Subsonic pressure waves-usually no blast wave damage to body

    Gunpowder
  44. Goals of death investigation of bombing:
    • Reconstruct the explosive device-compound, type ofdetonation mechanism
    • Determine role of the deceased: intended victim, innocent bystander, bomb manufacturer
  45. Name the three bomb types.
    • Straight bomb
    • Disguised bomb
    • Hidden bomb
  46. straight bomb
    eplosive device that can be easily recognized as a bomb- ex pipe bomb
  47. disuised bomb
    • explosive device housed in a non-suspicios container
    • trigger device- pull, application of pressure, release of pressure, time delay
  48. hidden bomb
    explosive device placed in a vehicle or other large complex housing

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