Homeostasis Flashcards
to survive, organisms require conditions of…
a suitable temperature/pH, an aqueous environ that keeps substrates/products in solution, freedom from toxins/excess inhibitors
a good communication system will
cover the whole body, enable cells to communicate/specific/rapid communication, short and long term responses
cell signalling
process in which one cell will release a chemical detected by another cell, the second cell will respond to signal released by first cell
neuronal system
interconnected network of neurones that signal to each other across synapses very quickly and enable rapid responses to stimuli that may be changing quickly
hormonal system
uses blood to transport its signals via an endocrine organ releasing signal directly, transported throughout the body but only recognised by specific target cell, enables longer term responses
what is maintained by homeostasis
body temp, blood glucose concentration, blood salt conc, water potential of blood, blood pressure, carbon dioxide conc
feedback
when effectors respond to output from coordination centres they bring about a response that will change conditions, detected by receptors having an effect
changes in body temp affects
activity of cell processes (rises=more KE=faster), structure of enzymes (tertiary changes=ability to function), as cools less able to function normally
endotherms
control their body temp within very strict limits, use physiological and behavioural mechanisms to control body temp, largely independent of external temp
ectotherms
rely on external heat and body temp fluctuates with external temp using behavioural mechanisms
peripheral temperature receptors
monitor temp changes in extremities in the skin of which info is fed to thermoregulatory centre to initiate behavioural mechanisms to maintain temp
effector
a cell, tissue or organ that brings about a response
homeostasis
maintaining a constant internal environment despite changes in external and internal factors
negative feedback
the mechanism that reverses a change, bringing the system back to optimum
positive feedback
the mechanism that increases a change, taking the system further away from optimum
