homeostasis and temp control Flashcards
what is homeostasis
the maintenance of a constant internal environment despite fluctuations in both the body’s activities and external environment
essential for maintaining an optimum internal for cell function + metabolism
what is the internal environment
the internal environment is made up of tissue fluids bathing each cell supplying nutrients and removing waste
describe the stimulus pathway- control mechanism in homeostasis
1.stimulus = change to system
2. receptor= measures level of a factor
3.coordinator = operational information is stored here and used to coordinate effectors
4. effector= brings about changes to the system n order to return it to the set point
5. response = system returned to set point
=feedback loop
what factors need to be kept constant and why?
-maintaining blood glucose concentration= needed for respiration, too much can affect water potential blood and cells
-maintaining blood pH= changes can impair enzymes action
-maintaining temperature= changes can impair enzyme action
-water regulation= too much or too little can cause cells to burst or shrink due to osmosis
what is the difference between receptors and effectors
receptors= sensory receptors detect stimuli and send signals to the brain about changes in internal environment
effectors= muscles or glands that act on signals from the brain and cause responses to reverse changes and regain equilibrium
what are positive and negative feedbacks
negative= reversal of a change and a return to the optimum or norm, switches off corrective mechanism
positive= increase in the change/ further deviation. usually harmful as it destabalises the control system. can be beneficial e.g oxytocin during birth
explain why it is important to regulate temperature in living organisms
-changes in body temp can effect structure of proteins including enzymes
-enzymes are globular proteins with structures specific to their function
temp either side of optimum affects enzyme activity
name 3 physical methods by which body can lose or gain heat
-conduction
-convection
-radiation
what is meant by endotherms and ectotherms
endotherms= organisms that use heat from metabolic reactions to maintain body temperature
ectotherms= organisms that rely on external sources of heat to maintain body temp
what is the coordinator in endotherms and what is its role
-hypothalamus in the brain
-monitors temp of blood passing through it as well as receives nerve impulses from the peripheral temperature receptors -thermoreceptors- in dermis of skin
what happens when blood temperature is too high or low
-too high= nerve impulses are sent from the heat loss centre to switch on cooling mechanisms such as vasodilation and sweating
too low= nerve impulses from the heat gain centre stimulate warming mechanisms such as shivering and hair erector muscle contraction and vasoconstriction
what are the physiological adaptations for endothermy
-capillaries regulate temperature through vasoconstriction and vasodilation
-hairs/feathers on skin can be raised to trap a layer of air to provide extra insulation
-sweat glands-when hot= the water in sweat evaporates taking heat out of the skin
-panting increases evaporation of water from mouth and airways using latent heat of vaporisation to cool
-liver cells; changes in metabolism of liver cells can be used to generate heat through exergonic reactions like respiration
-skeletal muscles= spontaneous contractions: shivering, generate heat as muscle cells increase respiration rate
-blood vessels; dilation directs blood to extremities for heat loss or vasoconstriction
what are behavioural responses to temperature in endotherms
-move into shade or sunlight to cool or warm
-orientate body to alter surface area exposed to sun
-if too hot, can spread out limbs to increase surface area and reduce activity to cool
-some animals wet skin to use evaporation to cool body e.g cats lick their fur
-increase activity to generate head in muscles
what are the pros and cons of endothermy
pros:
-constant body temp independent of external temp
-can remain active at night and in cool environments
-can inhabit cold parts of eart
cons;
-significant energy intake used to maintain body temp when cold
-more food required
-less energy from food used for growth or more food needed to gro
what are ectotherm behavioural responses to temp
-sunbathe or seek shade or burrow underground to warm or cool
-orientate body to alter surface area exposed to sun
-alter body shape to change surface area
-if to hot increase breathing movements to increase evaporation of water and aid cooling
