Body_Temp_2021

Homeostasis

• Homeostasis refers to the body's ability to maintain a stable internal environment despite changes in external conditions.

Body Temperature

• The regulation of internal body temperature is crucial for optimum conditions for enzyme-catalysed reactions.

Normal Internal Body Temperature

• Normal Body Temperature: 37°C.

• Consequences of Temperature Changes:

  • Above 37°C:

    • Enzymes denature (lose structure and function).

    • Metabolic pathways are blocked.

  • Below 37°C:

    • Metabolism slows.

    • Can affect brain function.

Methods of Heat Loss and Gain

Radiation

• Heat transfer through infrared electromagnetic rays.

• Body radiates heat; loses heat if the surrounding temperature is lower than body temperature.

• About 60% of total heat loss in a nude person occurs via radiation.

Conduction

• Heat exchange between objects in direct contact.

• Minimal heat loss from contact with solid objects (3%).

• Larger heat loss occurs through conduction to air.

Convection

• Heat removal through air currents.

• Heat must be conducted to air first, increasing removal ceiling.

• 12% of body heat is lost via this method; wind increases heat loss significantly.

Evaporation

• Water evaporates from skin/lungs, even without sweating (approx. 600 ml/day).

• Sweating is a key regulated heat loss method.

• Heat loss occurs primarily through evaporation when other methods are ineffective.

• Humidity decreases evaporation efficiency.

Other Losses

• Small heat loss through urine and faeces.

Body Temperature Control

• Hypothalamus: Contains Thermoregulatory Centre that monitors blood temperature.

  • Acts as a thermostat set to 37°C.

  • Receives input from skin thermoreceptors.

Feedback Systems

• Feedback System: Cycle of monitoring and evaluation affecting body conditions.

Basic Components

1. Receptor: Sensors that respond to changes (stimuli).

2. Control Centre: Sets range of values, evaluates inputs, and sends outputs.

3. Effector: Receives output from control centre and produces response.

Response to High Body Temperature

• Detection: Thermoreceptors in hypothalamus respond to high body temperature.

• Responses:

  • Vasodilation: Blood vessels widen, increasing blood flow toward skin surface.

  • Sweating: Heat energy converts sweat into vapor, cooling the body.

Response to Low Body Temperature

• Detected by thermoreceptors in the hypothalamus.

• Responses:

  • Vasoconstriction: Blood vessels constrict, reducing blood flow to skin.

  • Decreased sweating.

  • Shivering: Muscle contractions generate heat.

Keeping Warm

• Piloerection: Hair muscles contract to insulate by trapping a layer of warm air.

• Not very effective in humans; creates goosebumps instead.

Voluntary Responses

• Human behavior adapts to temperature changes:

  • Cold: Add clothing, seek heat sources, exercise.

  • Hot: Remove layers, hydrate with cold drinks, reduce physical activity.

Heat-Related Conditions

Heat Stroke

• Occurs when cooling mechanisms fail, leading to very high body temperature.

• Can cause unconsciousness and potentially death if untreated.

Heat Exhaustion

• Results from dehydration due to extreme sweating and exercise.

• Decreased blood volume can lead to collapse from low blood pressure.