Homeostasis Flashcards
Define homeostasis
Maintaining a constant internal environment despite changes in internal/external factors
What variables need to be kept constant?
Body temperature
Blood glucose concentration
Blood salt concentration
Water potential of the blood
Blood pressure
Carbon dioxide concentration
What is the mechanism of homeostasis?
Stimulus, receptor, communication pathway, effector, response
What are sensory receptors?
May be on surface of the body eg temperature receptors on the skin
Monitor changes in external environment
Detect any deviation from the set point
What is the communication system?
Coordinates information from various sources and send instructions to effectors
What are effector cells?
Cells that bring about necessary changes to return system to set point
What is a feedback loop?
It informs the receptors of changes to the system brought about by the effectors
Define negative feedback
Process that reverses a change bringing the system back to the optimum eg. Body temperature
What is the negative feedback loop?
optimum condition- change away from optimum- receptor detects change - communication system informs effector- effector reacts to reverse change- return to optimum
Define positive feedback
Process which increase and change detected by the receptors taking system further away from optimum- does not lead to homeostasis eg. Child birth as increase pressure on the cervix
What is the positive feed back loop?
optimum condition- change away from optimum- receptor detects change- communication system informs effector- effector reacts to increase change- change away from optimum
What processes must occur for negative feedback to work?
A change to the internal environment must be detected
The change must be signalled to other cells
There must be an effective response that reverses the change in conditions
