5 - MZH - Homeostasis 1 - Introduction Flashcards
Define Homeostasis
The control mechanisms involved in maintaining a constant internal envionment despite changes in internal and external factors
Define stimulus
A change in an organism’s internal or external environment that brings about a response
Name the 2 majoy communication systems in animals?
Nervous and endocrine
Why do multicellular organisms require communication body systems?
Coordination ebtween different system sis required for functions. There’s a large distance between cells.
What communication system do plants use?
Plant hormones or plant growth substances
How are stimuli brought about in the body?
Changes are brought about by communication within the body, which may be chemical and/or electrical and is an example of cell signalling which may include signalling between adjacent cells and signalling between distant cells
Why is homeostasis important to living organisms? (3)
Biochemical reactions in living organisms are enzyme controlled - Fluctuations in pH and temperature have a sig effect on these reacitiosn and in extreme cases can lead to denaturing in enzymes and other proteins.
External factors e.g. temperature can often fluctuate considerably - A constant internal environment allows indepenence from these fluctuations.
Water moves in/out of cells by osmosis - By maintaining a constant water potential in the surrounding tissue fluids, osmotic problems are avoided.
What are the different stages of a homeostatic control mechanism?
What stages are involved with cell signalling?
What is:
Negative feedback and positive feedback?
Negative feedback = Mechanism that reverses a change bringing the system back to its optimum level e.g. blood glucose conc and insulin secretion
Positive feedback = Mechanism that increases a change further away from its optimum e.g the increased releasing of oxytoxin during child birth
What is the general diagram to describe negative feedback?
