5.1 Communication and homeostasis Flashcards
What do all living things need to maintain? (4)
Suitable temp
Suitable pH
Aqueous environment keeping sub and products in solution
Freedom from toxins/ excess inhibitors
How may the internal environment of an organism change? (2)
Unwanted products
E.g. CO2 alters pH affecting enzymes acts as stimulus causing removal of CO2 by increasing breathing rate
Define homeostasis.
Maintaining a constant internal environment despite internal and external changes
How may an organisms external environment change gradually and rapidly? (2)
Gradual response- Season changing= thick winter coat
Rapid resoonse= rabbit runs into burrow pupils dilate
What 5 things does a good communication system need?
Cover whole body Enable cell communication Enable specific communication Enable rapid communication Enable short and long term responses
What is the difference between negative and positive feedback? (2)
Negative feedback is reversing a change back to the optimum
Positive feedback is increasing the original change
What is an endotherm?
An organism that uses heat from metabolic reactions to maintain body temperature
What is an ectotherm?
An organism that relies on external sources of heat to maintain body temperature
What 3 things might an ectotherm do when too cold?
Move into sun
Lay on warm surface
Expose larger SA to sun
What 3 things might an ectotherm do when too hot?
Move out of sun
Move underground
Reduce body surface exposed to sun
What are 2 advantages of being an ectotherm?
Do not use energy to keep warm
Need to find less food/can survive longer without food
Decribe the process of what an endotherm would do when too cold. (5)
thermoreceptors stimulated by temp decrease impulse to hypothalamus vasoconstriction of arterioles prevents heatloss by radiation increase respiration to generate heat release adrenaline/thyroxine hair raises
Where is the core body temperature monitored in endotherms?
hypothalamus
Name the type of sensory cell in the skin that detects changes in environmental temperature.
thermoreceptor / peripheral temperature receptor
How do you calculate percentage change? (3)
difference (increase) between the two numbers
Divide the increase by the original number
Multiply the answer by 100
