Emergency Medicine Book


Temperature Regulation

Aka: Temperature Regulation, Thermoregulation, Heat Conduction, Heat Convection, Heat Radiation, Thermal Maximum
  1. See Also
    1. Heat Illness
    2. Hypothermia
  2. Physiology: Nervous system
    1. Hypothalamus controls Thermoregulation
    2. Parasympathetic Nervous System controls sweating
    3. Sympathetic Nervous System controls skin Blood Flow
      1. Vasodilation results in heat dissipation
  3. Physiology: Temperature variation
    1. Ideal Body Temperature for physiologic function: 98.6 (37 C)
    2. Heat
      1. Core Temperature rises 1 C per 30 C Ambient Temperature
      2. Core temp. rise 0.6 C, raises basal metabolic rate 10%
      3. Cellular damage occurs at core Body Temperature above 104 F (40 C)
      4. Cellular death occurs at core Body Temperature above 107.6 F (42 C)
        1. Known as Thermal Maximum
        2. Cell death occurs at variable duration of exposure: 42 C (107.6 F) for 45 minutes to 8 hours
    3. Cold
      1. Mild Hypothermia at 95 to 90 F (35 to 32.2 C) presents with shivering, vasconstriction, Tachycardia, cold diuresis
      2. Moderate Hypothermia 90 to 82.4 F (32 to 28 C) presents with confusion to stupor, Bradycardia, Mydriasis
      3. Severe Hypothermia 82.4 to 75 degrees F (28 to 24 C) presents with coma, apnea, VT/VF, DIC
      4. Very Severe Hypothermia < 75 degrees F (24 C) absent Brainstem reflexes, Vital Signs absent and Asystole
  4. Physiology: Heat Dissipation Mechanisms
    1. Sweat evaporation (primary mechanism at >68F or 20C)
      1. Optimally dissipates 600 kcal/hour
      2. Sweat loss maximum 3 Liters/hour
        1. Endurance athletes lose up to 1.5 Liters/hour
      3. Rate of perspiration in hot environments is almost exclusively responsible for heat loss
      4. Perspiration becomes less effective in humid environments
    2. Heat Conduction
      1. Cold packs applied to skin
      2. Cold water emersion is the most expedient way to dissipate heat
      3. Conductive heat loss is typically minor, but increases 5 fold with wet clothing, and 25 fold with cold water immersion
    3. Heat Convection (Air or wind flows over skin)
      1. Body can dissipate heat with greater air circulation
      2. Cooler air also dissipates heat by providing a larger gradient between Body Temperature and air Temperature
      3. Permeable clothing allows for greater heat dissipation
    4. Heat Radiation (Infrared dissipation)
      1. Radiant energy is resorbed or reflected
      2. Light-colored clothing reflects away heat
      3. Half of heat loss is radiative (of which 60% is via the head)
  5. Physiology: Heat Adaptation
    1. Athletes may require 10-14 days to acclimitize to Exercise in hot environments
    2. Mechanisms
      1. Improved Sodium retention
      2. Increased Glomerular Filtration Rate
      3. Increased cardiovascular performance
      4. Heat shock Proteins
  6. Physiology: Children and increased propensity for Heat Illness
    1. Greater surface area to body mass
    2. Slower sweat rates
    3. Sweating initiated at a higher Temperature set point
    4. Sweat is more dilute
    5. Slower accilimitization to hot environments than adults
    6. Decreased thirst response
  7. References
    1. Becker (2011) Am Fam Physician 83(11): 1325-30 [PubMed]
    2. Glazer (2005) Am Fam Physician 71(11):2133-42 [PubMed]
    3. Howe (2007) Am J Sports Med 35(8): 1384-95 [PubMed]

Physiologic Thermoregulation (C0005905)

Definition (GO) A homeostatic process in which an organism modulates its internal body temperature. [GOC:jl]
Definition (MSHCZE) Procesy ohřívání a ochlazování, které organismus využívá k řízení svojí teploty.
Definition (NAN) The physiologic process of regulating heat and energy within the body for purposes of protecting the organism
Definition (MSH) The processes of heating and cooling that an organism uses to control its temperature.
Definition (PSY) Homeostatic behavioral or physiological responses that maintain body temperature within a viable range. Compare THERMAL ACCLIMATIZATION.
Definition (CSP) processes of heating and cooling that an organism uses to control its temperature.
Definition (NOC) Balance among heat production, heat gain, and heat loss
Concepts Organism Function (T040)
MSH D001833
SnomedCT 276535009, 386726008, 1942004
English Body Temperature Regulation, Body Temperature Regulations, Regulation, Body Temperature, Regulations, Body Temperature, Temperature Regulation, Body, Temperature Regulations, Body, Thermoregulation, Thermoregulations, Body Thermoregulation, body temperature regulation, Physiologic Thermoregulation, Thermo regulation, THERMOREG, BODY TEMPERATURE REG, REG BODY TEMPERATURE, TEMPERATURE REG BODY, temperature homeostasis, thermoregulation, regulation of body temperature, regulations body temperature, Body temperature--Regulation, Body temperature regulation, Thermoregulation, function (observable entity), Thermoregulation, function, Thermoregulation (Body)
Swedish Kroppstemperaturreglering
Czech termoregulace
Finnish Kehon lämpötilan säätely
French Régulation de la température corporelle, Thermorégulation, Thermorégulation du corps, Régulation de la température du corps, Thermorégulation corporelle
Italian Termoregolazione, Regolazione della temperatura corporea
Japanese 熱損失, 体温調節
Polish Regulacja ciepłoty ciała, Termoregulacja
Norwegian Not Translated[Body Temperature Regulation]
Spanish termorregulación (entidad observable), termorregulación, Regulación de la Temperatura Corporal, Termorregulación
German Thermoregulation, Körpertemperaturregelung, Temperaturregelung, Körper-
Dutch Lichaamstemperatuur, regulatie van de, Regulatie van de lichaamstemperatuur, Thermoregulatie
Portuguese Regulação da Temperatura Corporal, Termorregulação
Derived from the NIH UMLS (Unified Medical Language System)

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