5.1.1 The need for Communication and Homeostasis COMPLETE Flashcards
Why communication between specialised cells is needed
To ensure correct conditions for enzymes is maintained
Defintion: Stimulus
Any change in the environment that causes a response e.g. season
Define: Response
A change in behaviour or physiology as a result of a change in the environment e.g. changing thickness of a coat/ its colour
Internal Stimuli
Example is when waste products are removed from tissue fluid after being released from metabolic processes by the blood.
Features of a good communication system
- Cover whole organism
- Rapid Communication
- Short and long term responses
- Specific Communication
Two major communication systems
- Neuronal System
- Hormonal System
Defintion: Homeostasis
Maintenance of internal environment in a constant state despite the internal and external changes
Negative Feedback
Reversal of change in the internal environment back to optimum conditions
Cell signalling
Stimulus -> Receptor -> COMMUNICATION PATHWAY -> Effector -> Response
Positive Feedback
A process that increases any change detected by the stimulus, tends to be harmful i.e. when you get cold and during labour
Definition- Ectotherm
An organism that relies on external sources of heat to regulate its body temp.
Definition- Endotherm
An organism that can use internal sources of heat to regulate/ maintain body temp. i.e. heat from metabolism
Advantages of being an ectotherm
- Use less of their food in respiration
- Need to find less food and survive longer without eating
- More of energy obtained used for growth.
Disadvantages of being an ectotherm
- They’re less active in cooler temps and may need to warm up before becoming active, greater risk of predation
- Not capable of activity during the winter so must store sufficient energy
Heat transfer
- Depends on the thermal gradient
- lost of gained via convection, conduction or radiation
- Only lost via latent heat of vaporisation
