Homeostasis Flashcards
Why do we need communication systems
Changing external environments
Changing internal environments
Co-ordinating different organs
What is a stimulus
Any change in environment that causes a response
What is a response
A change in behaviour or physiology as a result of a change in the environment
What are the 2 major systems for cell signalling
Neuronal
Hormonal
What is a neuronal system
A network of interconnecting neurones that produce rapid responses to stimuli
What is a hormonal system
Uses the blood to transport hormones from endocrine glands to target organs
What is homeostasis
Maintaining a constant internal environment despite external changes
What is negative feedback
Reversal of any change in internal environment to return to an optimum steady state
What is a receptor
A cell that responds to a stimulus
What is an effector
A muscle that contracts or a gland that releases a hormone
How is body temperature maintained by endotherms
Maintain body temperature within strict limits
Independent of external temperature
How is body temperature maintained by ectotherms
Body temperatures fluctuates with external temperature
Advantages of ectotherms
Use less food in respiration
Need less food
Greater proportion energy used for growth
Disadvantages of ectotherms
Less active in cooler temperatures
May not be capable of activity in winter months
Advantages of endotherms
Constant optimal body temperature
Activity possible when cool
Inhabit colder parts of the planet
