Homeostatis and Feedback Flashcards
What is homeostasis?
maintenance of the internal environment in a constant state despite external changes
What conditions need to be kept constant in the body?
temperature, glucose concentration, salt concentration water potential of blood, blood pressure, carbon dioxide concentration
What is negative feedback?
reversal of change in internal environment to return to steady state/optimum position
What is the standard pathway used to produce a response to a stimuli?
stimulus, receptor, communication pathway (cell signalling), effector, response
Why are sensory receptors needed for the pathway?
(e.g. temp, glucose receptors) internal and monitor conditions, detect change = stimulated to send message
Why is a communication system needed for the pathway?
hormonal/neuronal, used to transmit receptor message to effector cells, can pass through coordination centre (e.g. brain)
Why are effector cells needed for the pathway?
(e.g. liver, muscle cells), bring about response to reverse change detected by receptor
What is positive feedback?
less common than negative, response is to increase change to internal environment, destabilises system, usually harmful
What is a negative example of positive feedback?
when body is too cold, enzymes become less active, exergonic reactions that release heat are slower = les heat = less enzyme action
What a beneficial example of positive feedback?
end of pregnancy to dilate cervix, as it begins to stretch the change is signalled to the anterior pituitary gland, secretes: oxytocin, increases uterus contractions, cervix stretches more then baby born at full dilation
