Breaking out in a sweat Flashcards
Define homeostasis?
Maintanence of stable internal environment
Describe the role of negative feedback in homeostasis
Each condition has a norm value
Receptors are used to detect deviation from norm value which stimulate effectors to bring conditions back to norm value
As deviation from norm results in a change in opposite direaction back to norm = negative feedback
Define thermoregulation
Control of the body temperature
Describe how temp is maintained
Temp rises of falls, detected by receptors and sends impulses to either heat loss/gain centre in hypothalamus, effectors react and temp rises/falls
Describe heat loss centre
Stimulates: sweat glands to secrete sweat
Inhibits: contraction of arterioles in skin, hair erector muscles (lie flat), liver (reduces metabolic rate), skeletal muscles relax
Describe heat gain centre
Opposite to heat loss centre
Describe vasoconstriction
Colder conditions, muscles in arteriole walls contract causing constriction reducing blood supply to capilaaries,
Blood is diverted through shunt vessel which dilates
Blood flows further from skin surface so less energy is lost
Describe vasodilation
Warmer conditions
Shunt vessels constrict and muscles relax, blood flow through arterioles making them dilate more blood flows to the surface of skin
Describe sweating
Released on skin via sweat duct and evaporates taking heat energy from skin
Describe hairs
Raised in cold by contractions of erector muslces - trap a layer of air to insulate the body
What is convection
Air next to use is warmed due to air expanding and rising its replaced by cooler air which is warmed by the body
Energy loss in bulk
What is radiation
energy can be radiated as our bodies are warmer than the surroundings
What is conduction
Direct contract between objects and energy transfer from one to another
What is evaporation
Energy needed to convert water from liquid to vapour and energy to evaporate sweat is drawn from body cooling it
