5.1 communication and homeostasis Flashcards
(18 cards)
Why do multicellular organisms need communication systems?
Detect changes in the internal and external
environment (stimuli)
Coordinate responses to maintain internal conditions
Define homeostasis
Regulation of the internal environment in response to internal and external changes to
-maintain cell function
-prevent osmotic damage
-prevent enzyme denaturation
Describe the negative feedback system within homeostasis
Stimulus -> receptor -> Coordinator -> effector -> response
and then apply to too high or low…
Describe negative feedback
A system that resists change
Define an ectotherm
Organisms that maintain their core temperature using external environmental heat sources. They use behavioral responses to control their temperature.
What are the two types of cell signaling?
Neuronal and hormonal
Define positive feedback
A response to increase the initial change
What are some ways ectotherms control their temperature?
Move to sunny area or lie on a warm surface
Move out of sun and reduce body exposed to sun
Define an endotherm
organism that uses heat from metabolic reaction to maintain body temperature
What are the advantages of ectothermy?
- Less food, less respiration
- More efficient growth
- less time hunting
- Survive without food for longer periods
What are the disadvantages of ectothermy?
- Lower activity levels in cold means a higher risk of predation
- Climate-dependent behaviour
How to endotherms detect changes in temperature?
Thermoreceptors on the skin detect changes in temperature, the thermoregulatory center in the hypothalamus cause a response via effectors
What are the three effectors in endotherms?
- Sweat glands
- Muscle around blood vessels
- Skeletal muscles
What is the role of sweat glands in endotherms?
Produces sweat which releases large amounts of energy due to its high latent heat of vaporisation
What is the role of the skeletal muscles in endotherms?
Shivering:
Spontaneous fast contractions of the muscles to generate friction -> heat
Role of muscle surrounding blood vessels in endotherms?
Vaso-constriction or vaso-dilation
Precapillary sphincters close when constricting and open when dilating
Increased blood flow closer to the skin means more blood can radiate heat energy
What are the advantages of endothermy?
- Climate-independent so can occupy colder habitiats
- Remain acitve even at low temperatures, decreasing risk of predation
What are the disadvantages of endothermy?
- High energy requirements from high rates of respiration means more time spent hunting and more food required
- Less efficient growth
- More likely to over-heat
