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Thread: Regulation of Body Temperature

  1. #1

    Default Regulation of Body Temperature

    The temperature sensors are located in the skin (peripheral thermoreceptors) and the brain (central thermoreceptors), primarily in the hypothalamus.

    It is the central thermoreceptors that sense core temperature and provide input to control body temperature, whereas the peripheral thermoreceptors provide the brain with information about changes in environmental temperature.

    The main temperature control center is also located in the hypothalamus.

    The most important effectors are the sympathetic nerves to sweat glands, arterioles of the skin, and the adrenal medulla, as well as motor neurons to skeletal muscles.
    Clinical Pharmacy Specialist - Hematology

  2. #2

    Default Effector Mechanisms Regulating Temperature

    Increase the Body Temperature

    Body temperature can be increased when the body is cold by decreasing heat loss and/or by increasing heat production.

    Decreasing heat loss is accomplished primarily by vasoconstriction of the arterioles of the skin, minimizing heat transfer to the environment.

    Another mechanism of heat conservation is the reduction of body surface area by, for example, curling up, and behavioral responses such as putting on warm clothes or moving to a warmer environment.

    The short-term increase in heat production is accomplished primarily by an increase in voluntary movement and by shivering.

    Decrease the Body Temperature

    Body temperature can be decreased when the body is hot by increasing heat loss and/or by decreasing heat production. Increasing heat loss is accompanied primarily by vasodilation of arterioles in the skin, thereby increasing heat transfer from he blood to the skin and then to the environment, and by sweating to lose heat by increased evaporation.

    Sweat production is increased by increasing activity of autonomic nerves innervating sweat glands in the skin.

    The principal mechanism to decrease heat production is a decrease in voluntary movement.

    When first exposed to a cold environment, the thermal sensors in the skin signal the brain to decrease blood flow to and sweat production from the skin, thus minimizing heat loss. If the core temperature decreases, shivering and increases in adrenal medullary epinephrine can increase to increase heat production, although the latter is a minor pathway in humans.

    When one is exposed to a hot environment, thermal sensors in the skin can increase blood flow to the skin and sweating production, thus increasing heat loss. If core temperature increases, sweat production can increase profusely to greatly increase heat loss by evaporation. However, if evaporation cannot occur or is difficult because the air is already saturated or nearly saturated with water vapor, sweating is not a very effective means of heat loss.
    Last edited by CheneyHsiung; Sat 2nd January '16 at 2:22pm.
    Clinical Pharmacy Specialist - Hematology

  3. #3

    Default [Clinical Skill] Temperature

    Temperature regulatory mechanisms:
    1.Temperature set point - hypothalamus
    2.ANS, which control the blood flow (heat conducting) and sweat gland (evaporation)
    3.Shivering (muscle contraction)
    4.Behavioral adaptations

    Change in temperature are caused by:
    1.Change in set point (endogenous pyrogens; tissue necrosis, infection, inflammation, some tumors, and miscellaneous like habitual hyperthermia, subacute thyroiditis, Addison disease, drugs)
    2.Change in heat production
    3.Change in heat dissipation
    4.Change in regulatory system

    Normal temperature range:
    +- 0.6C
    37.5 (oral; without a baseline; it is reasonable to regard an oral temperature above 37.5C and a rectal temperature over 38.0C as fever)

    Temperature at different sites:
    4.Axilla (0.5C less than oral)

    Two types of elevated temperature
    1.Physiologic elevation - due to an elevation of temperature set point:
    • Noninfectious inflammatory diseases
    • Infections
    • Neoplasms
    • Miscellaneous (Habitual hyperthermia, subacute thyroiditis, Addison disease, drug fever)

    2.Pathologic elevation (hyperthermia) - due to unregulated heat generation and/or impairment of heat exchange with the environment (increased heat generation and/or impaired heat loss).

    Fever patterns:
    1.Continuous fever
    2.Remittent fever
    3.Intermittent fever
    4.Relapsing fever
    5.Episodic fever
    6.Pel-Epstein fever

    Fever of unknown origin:
    1.The illness has lasted >3 weeks
    2.The temperature is repeatedly >38.3C
    3. Three outpatient visits or >=3 days in the hospital have not yielded a diagnosis.

    Lowered body temperature:
    1.Decreased set point
    2.Insufficient heat generation
    3.Excessive heat loss

    • Endocrine: hypothyroidism
    • Idiopathic: advanced age
    • Infectious: sepsis
    • Mechanical/Traumatic: exposure and immersion, hypothalamic injury from trauma or hemorrhage, burns
    • Metabolic/Toxic: antipyretics, hypoglycemia, drug overdoses
    • Neoplastic: brain tumors
    • Neurologic: stroke
    • Psychosocial: poverty, homelessness, and psychosis all inhibit the ability to adapt to environmental challenges
    • Vascular: stroke

    Lower temperature (relative or absolute) in situations where fever would be expected is a poor prognostic sign.
    Last edited by Janis.Y.Chen; Sun 24th April '16 at 8:16pm.
    Clinical Pharmacy Specialist - Infectious Diseases

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