NURS115 Thermoregulation

Thermoregulatory response

Getting back to set body temp to maintain homeostasis by undergoing different processes.

Vasoconstriction

Increase body temp (shivering).

Vasodilation

Decrease body temp (sweating).

Core body temperature

A reflection of the balance between heat gain and heat loss by the body to maintain normal core body temp. 97-99.5 degrees. Core body temp is slightly higher than oral, axillary and tympanic.

Hypothalamus

The thermal control center. Receives information from peripheral and central thermoreceptors and compares it with its temperature set point.

Heat loss

Transfer of body core heat to the surface through the circulation. Most body heat is produced by deep core tissues and is lost at the surface of the skin. Metabolism is the main way the body produces heat.

Methods of heat loss

Radiation, conduction, convection, evaporation.

Radiation

Losing heat because the environmental air around us is cooler than our temp.

Conduction

Coming in contact with an item that is cooler.

Convection

Movement of air currents.

Evaporation

Water on skin that gets converted to a water vapor to get rid of heat.

Factors effecting an alteration in core temperature

Conservation of heat (vasoconstriction, shivering, position), heat loss (vasodilation, sweating), metabolism (hormonal increases or decreases).

Methods of obtaining a core temperature

From a rectal thermometer, from the esophagus using a flexible thermometer, from a pulmonary artery catheter that is used for thermodilution measurement of cardiac output, from a urinary catheter with a thermosensor that measures the temperature of urine in the bladder.

Pyrogen

“Fire makers.” Exogenous or endogenous substances that produce fever.

Exogenous pyrogens

Derived from outside the body (bacterial products, bacterial toxins, or whole microorganisms). Induce host cells to produce fever-producing mediators (endogenous pyrogens).

Endogenous pyrogens

Bacteria/products get into blood or tissue, WBC from immune system engulf by-product of bacteria. This releases pyrogenic cytokine, which induces a prostaglandin, which makes hypothalamus move set point, causing fever. Interleukin-1, Interleukin-6, tumor necrosis factor.

Intermittent fever

Temperature returns to normal at least once every 24 hours (spike in temp).

Remittent fever

Temperature does not return to normal and varies in either direction (varies, but not back to normal).

Sustained or continuous fever

Temperature remains above normal with minimal variations.

Recurrent or relapsing fever

There is one or more episodes of fever as long as several days with one or more days of normal temperature between episodes.

Prodrome

Mild headache, fatigue, malaise, fleeting pains.

Chill

Uncomfortable sensation of being chilled, shaking.

Flush

Cutaneous vasodilation, skin warm and flushed.

Defervescence

The initiation of sweating