presentation Body temperature regulation

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Body Temperature Regulation : 

Body Temperature Regulation

Introduction: Heat Production : 

Introduction: Heat Production The rate of metabolism in skeletal muscle differs before, during and after exercise Chemical reactions occur within cells released some energy in form of heat When the rate of chemical reaction increased in muscle fibers during contraction, the rate of heat production also increase causing an increase in body temp. Vasolidation of blood vessel in the skin and sweating speed heat loss and keep body temp. in range.

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Body temperature is a balance between heat gain and heat loss. Heat is produced through metabolism Heat is exchanged through radiation, conduction, convection and evaporation The greater the temperature difference between the body and environment, the greater the rate of heat exchange. Body temp. is regulated by a set point in the hypothalamus.

Hypothalamus : 

Hypothalamus Promotes heat loss when hypothalamic temp increases ( anterior nucleus) Promotes heat production when hypothalamic temp. decreases (posterior nucleus) During fever the intake of aspirin effects the preoptic area to reduce fever

Thermoregulation : 

Thermoregulation Def : an ability of an organism to keep the body temperature within certain boundaries One aspect of homeostasis process Most enzymes are very sensitive Human average normal body temp. usually 37°C ( 98.6°F)

Determine core temp. : 

Determine core temp. Most usually temp is taken in the mouth, axilla, ear, groin Occasionally temp of the urine may be use The most accurate place is in rectal

Heat Exchange – 4 ways (R,C,C,E) : 

Heat Exchange – 4 ways (R,C,C,E)


FIGURE OF HEAT EXCHANGE Radiation from sun and water Convection from cool breeze Evaporation Radiation from sand Conduction from hot sand

How Temp. Regulation Work? : 

How Temp. Regulation Work?

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Increased heat loss decreases body temp. : Increased sweating increases evaporating heat loss Dilation of skin blood vessels increases loss Behavioral modifications, such as taking off a jacket Decreased heat loss and increased heat generation increases body temp. : constriction of skin blood vessels heat loss Shivering increases heat production Behavioral modifications, such as putting on a jacket

Cold condition mechanism : 

Cold condition mechanism Sweats stops being produced Arrector pili lifting the hair follicle upright Arterioles rerouting blood away from the skin towards the warmer core of the body ( vasoconstriction) Muscle received message to cause shivering either low intensity or high intensity of shivering Low intensity tends to use fats High intensity uses glucose as a fuel source

Vasoconstriction : 


Hot Condition mechanism : 

Hot Condition mechanism Sweats glands secrete sweat The hair on the skin lie flat to increasing heat loss by convection Arrector pili muscles relaxing Blood flow through the artery increasing heat loss by radiation and conduction

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° C

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° c

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FEVER A fever is defined as a temperature 1° or more above the normal 98.6 degrees Fahrenheit (F) or 37 degrees Celsius (C). Fever is not a disease. Fever helps the body fight infections by making the body's defense systems work more efficiently. Bacteria and viruses cannot live at higher temperatures and are killed by fever.

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CAUSES OF FEVER Infections caused by bacteria,ricketsia,chlamydia,viruses and parasites. Immune reactions including the defects in collagen, immunological abnormalities and acquired immunodeficiency. Destruction of tissues and inflammatory reaction in tissues and vessel. Specific inflammation( sarcoidosis, granulomatous hepatitis ) Infection of intestine and inabdominal inflammatory process. Acute metabolic failure such as arthritis uric. Administration of some drugs. Dehydration of salts. Administration of foreign proteins.

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PROGRESS OF FEVER AND ACCOMPANYING SYMPTOMS First phase: - it is called prodromal phase or pre report phase that occurs about 15-90 minutes. - the release of endogenic pyrogen occurs on the basis of exogenic pyrogen effects. -affects the thermosensitive neurons of thermoregulatory center in hypothalamus. -at this stage , the resetting of thermoregulatory center for a different tempsture take place.

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Second phase: - it is called phase of increase. -at this stage, the thermoregulatory center is reset. - the thermoregulatory center has probably two compartments. In cutaneous and subcutaneous vessels,they cause vasoconstriction,thus they decrease the heat outcome. -on the other hand, muscle, liver and heart under influence of sympathetic compartment increase production of heat that forms,together with decreased outcome of heat, the optimal situation for heat accumulation in an organism. - Body temperature increase, but the sick person has a feeling of cold.

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Third phase - It is called the climax phase. Climax means that body temperature culminates. -At culmination of fever, such a temperature is achieved to which the thermoregulatory center is reset. - The center is washed by blood that has temperature originally adjusted. -This cause the activation of sympathetic compartments to stop. - These changes are the reason of decreased of blood pressure and increase pressure in the pulmonary artery. -The patient has warm and red skin, sweats, and looses heat by conduction, radiation and evaporation.

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Fourth stage -It is called the descent stage. -This stage start from the peak of fever and is characterized by the decrease of body temperature. -With the decrease of fever, the frquency of puls and respiration also decreased. - Sudden decrease especially of longlasting fever may cause temperature crisis.

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Several types of fever characterized by temperature changes. Temperature changes less than 1^ c - febris continua fever temperature shanges 3 to 5 ^c - febris septica-heptica fever Several hour lasting apyretic periods - febris intermittens temperature is higher in morning than evening - fever inversa ( patients suffering from tuberculosis )