GCSE Biology - Homeostasis #54

in this video we're going to look at homeostasis which can seem complicated but really it's just a process of maintaining a stable internal environment if you think about one of the cells in your body it needs certain conditions for it to be able to function properly for example it can't be too hot or too cold it can't be too acidic or too alkaline and it's going to need a good supply of things like glucose and water to achieve all of this our body regulates everything and makes sure that everything is kept around the right levels

that said we don't keep everything exactly constant for example our temperature and glucose levels do fluctuate but only within small bounds as for definition we can say that homeostasis is the regulation of conditions inside the body to maintain a stable internal environment in response to changes in both internal and external conditions now this last bit about being in response to changes in both internal and external conditions just means that we can maintain our internal environment even if changes are taking place outside of ourselves for example if we walk out in the snow or we run

in the sahara desert we can still keep our cells at 37 degrees by regulating our body to do this our body uses automatic control systems that can basically recognize when there's a change from optimal conditions and then send a signal to reverse that change so that the levels go back to normal automatic control systems have three main components to know about receptors which detect a change such as a rise in temperature coordination centers such as the brain or spinal cord which interpret that change and decide what needs to be done about it and finally effectors

which the things that carry out the change generally these are either muscles that might contract or glands that can release hormones a problem though is that these three components might be in different parts of the body so we need some way to send signals between them and this is where the nervous and endocrine systems come in we look at each of these in more detail in the next two videos but basically the nervous system sends very fast and precise electrical impulses through nerves which allows us to respond to things very quickly such as when we

touch a sharp object the endocrine system meanwhile relies on hormones these are small chemicals released into the bloodstream and although they travel throughout the entire body they only affect certain cells that have the right receptors the thing to remember is that the endocrine system is generally slower longer lasting and more generalized than the nervous system okay so we've now looked at the different components of the automatic control systems and also how they communicate with each other the last thing we need to consider is how these systems actually work in real life the mechanism is called

negative feedback and it's actually pretty simple once you understand it basically whenever the level of something gets too high like the level of glucose in our blood negative feedback actually decrease it again to return it to normal but let's say that the glucose or whatever it is gets decreased too much and the level is now too low well negative feedback will just increase it again so it basically just does the opposite of whatever the change was to demonstrate this let's imagine a scenario say we walk into a room but it's really cold the low temperature

will be detected by receptors such as in our skin and the nervous system will then send impulses to coordination centers like the brain and spinal cord these interpret the information and then send another set of signals to the effectors such as our muscles that can carry out useful responses like shivering given a bit of time this shivering will increase our body temperature and will return to normal but what if this goes too far and instead of returning to normal we actually get too hot well now a different set of receptors would detect this rise in

temperature and send their own signals to our coordination centers this in turn would cause a different group of effectors to carry out their own response such as sweating in time our temperature would go back to normal and then if we got a bit too cold the whole process would start over again so really what we have overall is a loop if the levels of something get too low our automatic control systems bring them back up to normal through negative feedback and if they then get too high another control system will bring them back down and

that's homeostasis for you basically the overall process of maintaining a stable internal environment for us that's it for this video so i hope you enjoyed and we'll see you next time