2 A Cooling Glove The heat extractor increases heat loss and allows the body to perform at a higher level in severe conditions.
3 Core TemperatureHumans have a normal temperature of around 36.2 to 37.2 degrees CelsiusAbove (hyperthermia): infectionBelow (hypothermia): cell death
4 What is Homeostasis?The body’s attempt to maintain “normal” levels within your body, despite environmental differencesdynamic equilibrium- a mechanism to ensure that all body systems function within an acceptable range to sustain life
8 Homeostatic control systems 3 components:Monitor(receptors)Coordinating centre(brain)Regulator(muscles, glands etc.)Monitors send signals to the coordinating centre that the normal levels have changed (sensory pathway).The coordinating centre then messages the regulator which helps restore normal balance (motor pathway).MonitorCoordinating centreRegulatorNormal balanceChange in balance
9 Homeostasis Example: household thermostat Room T at 22 oCT below: thermostat turns on the furnaceT above: thermostat turns off the furnace
10 Example: household thermostat Detects decrease in temperatureMonitor- ThermometerCoordinating centre- Thermostat switches on furnaceRegulator- FurnaceThermostat detects temperature increases over “normal”Furnace turns offWhole control system is called a negative feedback system
11 Negative feedbackProcess by which a mechanism is activated to restore conditions to their original stateIt ensures that small changes don’t become too large.Why is a thermostat a negative feedback system?
12 Negative Feedback Example: Thermoregulation of body The maintenance of body temperature within a range that enables cells to function efficientlyHeat StressCold Stress
13 Heat stressThermoreceptors (PNS) detect an increase in body temperatureHypothalamus (CNS) signals to the sweat glands to initiate sweating.Evaporation of the sweat off the skin causes cooling.
14 Dilation allows for more blood flow to the skin. Heat StressThe hypothalamus also sends message to blood vessels in the skin causing them to dilate.Dilation allows for more blood flow to the skin.Heat from the blood is lost to the skin so blood can return to core of your body & cool the internal organs.
15 Heat StressMonitor: thermoreceptorsCoordinating centre: hypothalamus turns on cooling systemRegulator: skin blood vessels dilate and sweat glands initiate sweatingResult: body temperature decreases; hypothalamus turns off cooling system
16 Thermoreceptors message the hypothalamus Cold stressThermoreceptors message the hypothalamusHypothalamus sends a message via the nerves:Arterioles of the skin constrict therefore limiting blood flow =reduced heat loss from the skin and retains heat in the body.Smooth muscle contract that surrounds the hair follicles in your skin causing the hair to “stand on end” trapping warm air.Skeletal muscle to contract causing shivering and increasing your metabolism to make heat.
17 Cold stressMonitor: ThermoreceptorsCoordinating centre: HypothalamusRegulator: skin blood vessels constrict and skeletal muscles contractResult: body temperature increases and hypothalamus turns off.