The whole of AQA HOMEOSTASIS and RESPONSE. 9-1 GCSE biology or combined science revision for paper 2

hey guys this video takes you everything you need to know for a co-ed body homeostasis and response now if you want to get a checklist make sure you cover absolutely everything then you get both fresh and garbage over my website or you can get the line Amazon homeostasis is the maintenance of a constant internal environment [Music] and keep your body functioning properly we need to control our blood glucose levels our water levels and our temperature the brain is the control center and that's going to be sending signals and to various parts of the body for

example to the pancreas which is responsible for producing insulin mmm effective muscles are going to do things like moving for example shivering and then glands are going to be responsible for the production of other hormones nervous system is incredibly complex and is overlaid on our spinal and muscular system it consists of the brain spinal cord which today are going to make the central nervous system or CNS and all the neurons the receptors and effectors when you pick up stimuli that signal needs to travel from where we picked up so your fingers all the way up

to your nervous system your central nervous system sometimes just stopping at your spinal cord and then coming straight back again that is going to be a reflex this is going to happen when you touch something hot so you move your hand away without even thinking about him other time something is going to happen the signal grabs your brain you'll think about it and then you'll decide to move the nerve cells involved in this I've a really long so this cell body here is incredibly long and this can send a fast electrical signal however when we

come transfer a signal from one nerve cell to another nerve cell things slowed down a bit because they have to cross a synapse this is going to be a slow chemical signal as the chemical has to be released diffuse across the channel and then be picked up and then initiates another electrical signal the brain is control central body it makes sure everything's functions properly and tells various different parts watch do we have the cerebral cortex the cerebellum and the medulla the brain is an incredibly complicated thing study because for it to be functioning properly it

needs me inside a living person doctors can work on mapping various different things by using MRI scanning and CT scanning and giving their person different stimuli to see which parts of the brain light up here we have our beautiful picture of the eye sclera which is the white bit the retina which is where the image is focused the optic nerve which sends message to brain the ciliary muscles which change the shape of the lens the cornea which is a protective covering pupil lets light in the lens is responsible for focus and the suspensory ligaments hold

the lens in place if you are short-sighted you can't see distant objects and if you're long sighted you can't see make subjects in an eye that can see correctly the lens would take the light and will focus the image on the retina whereas someone is short-sighted the image focuses before the retina and someone that is long sighted the image focuses behind the retina to correct shortsightedness we need a diverging lens and quite long sightedness we need a converging lens body temperature is going to be regulated by the right right story thermoregulatory Center in the brain

if you are too cold that hairs on your body will stand up this is to trap a layer of air you're going to stop sweating raise a constriction will starts so your blood vessels walking strict so that they're further away from the skin less blood is going to flow close to the surfaces skin so less heat is going to be lost from it and your muscles are going to start to shiver and movement it's going to produce energy if you are too hot your hairs are going to lie flat so they're not trapping any air

you're going to start sweating and the water is going to evaporate leading to heat and energy loss and your brothers are going to undergo they say dilation means you're going to get wider so that blood can flow closer self is the skin so that he can be lost here we have male and female an endocrine system the pituitary gland is in the brain the roid is in the neck your drain applies when the kidneys pancreas is hiding behind the stomach ovaries are kind of like hip level and then testes Hanalei the penis the testes produced

testosterone which has the effects of growing muscles making the Bulls and penis drop and grow larger increasing the rate of hair growth East Asian is producing the over that is responsible for the maturation of eggs and the menstrual cycle the pancreas produces insulin which is important for creating blood glucose levels the adrenal glands produce adrenaline which is reporter for our fight-or-flight response the thyroid produces thyroxine which is important in regulating our metabolism the pituitary gland is very busy among other things it produces follicle stimulating hormone FSH and luteinizing hormone LH control of blood glucose is

very complicated after a meal has been eaten a blood glucose levels start to rise this is picked up by the pancreas the pancreas produces insulin which is sent out into the blood the insulin in the blood stream is going to cause our body cells to start to remove glucose from the blood liver and muscle cells can take the glucose and convert it into glycogen and store it removing glucose from the blood will cause blood glucose levels to fall if blood glucose levels gets too low this is also picked up by the pancreas the pancreas will

start to produce glucagon the glucose has previously been stored in muscle and liver cells starts to return to the blood the most complicated part this is getting all the names right the stored form of glucose is glycogen glucagon will convert that into glucose and this returning the glucose will cause blood glucose levels to rise again there are two different types diabetes type 1 and type 2 in type 1 diabetes the pancreas doesn't work properly so it doesn't produce the right amount of insulin in that type 2 diabetes cells starts becoming sensitive to insulin symptoms for

both are going to be a loss of whites and increased needle we being at very thirsty blurry vision fatigue so being very sleepy and hunger treatment for type 1 diabetes is going to involve intern injections type 2 diabetes it's going to be controlling diet exercise the kidneys have three functions they remove urea they control the iron content and they control the water content of the blood there are three ways we can lose water from our body in urine and sweat and when we breathe out it's important to control the level of water in the body

because there is there's too much water to use too much water taken up by cells by osmosis and they might pop or there's not enough water then the enzymes the functions the reactions won't we have to take place there are three steps away that they kidneys function ultra filtration reabsorption and then the release blood enters the kidneys under high pressure and water irons UV and sugar are going to be squeezed out into the capsule which is it starts at the nephron as this all flows along upon useful things they'll be absorbed all of the sugar

is going to reabsorb by active transport some ions there mattifies that we need the tyre finds that we need I can be reabsorbed by active transport and enough water that we need is going to be reabsorbed the hormone that controls how much water is going to episode is 8 D H which is antidiuretic hormone and then anything that isn't reabsorbed is going to come out as we its kidneys aren't working properly a person can undergo kidney dialysis the dialysis machine will take over the function of the kidneys but it is very time consuming it takes

about 4 hours and has to be done 3 times a week so this has a huge impact on someone's life and it's not a lot of fun an alternative to dialysis could be kidney transplants but these come with very long waiting miss and there was always the risk of rejection one of the reasons periods feel so rubbish is cause your hormones are literally all over the place starting with follicle stimulating hormone it rises Peaks and its job is to make the small egg grow up to a larger egg and then be released luteinizing hormone is

only active for a very very short period it's job is to release the egg Easter Jim builds up until it stimulates luteinizing hormone progesterone builds up slowly as it builds up the lining of the uterus and if there is no eight of his original embryo implanted in it that would decrease and the lining of the uterus will break down there are a number of different methods of contraception some hormonal some non hormonal that will stop be getting pregnant but not all of these will protect against sexually transmitted diseases so is always very very important that

you wear a condom this is a barrier method of contraception this will stop the sperm and getting and the woman pregnant and it will also stop any nasties that occurring to introduce it from her to him or from him to her the pill and the coil IUD into trying device our hormonal methods of stopping getting pregnant they're going to stop the egg being released or the egg being implanted the diaphragm is a barrier method because it will stop sperm entering the vagina but the semen will still be transferred into the vaginal entrance so that you

can still get sexually transmitted diseases this way if you're sure that you don't want to have children even like those to be sterilized you could have a sex me have your tubes tied which will mean that no sperm will get from the testes out to the penis or the woman no egg will be released around one in six people will find themselves in the unfortunate position where they can't have children naturally about half this dude mail relay to me and half Lisa G - female related reasons as you can see only on one of those

people and last year 2016 we did IVF and these is my massive bump so the obvious advantages for IVF are you get the baby out spend it and and if you've been in a situation where you can't have something that you really really want you know it's very very sad individual might house quite a lot so having a baby is gonna be good for people that wants have the baby that mental house however the disadvantages are you have to take a large large number of drugs for a very very long period of time and that

these have very nasty side effects as well as the daily injections which leave you horribly braised and you there are long-term consequences for these because taking these IVF drugs increases your chance of various different types of cancer it is very it's very very expensive I had to have it twice that's twice as expensive doesn't always work there was about a 40% success rate with IVF with each round of IVF costing a minimum 5,000 pounds we the food since exists right here with a large number of drugs are today a good day by day it's a

very costly time-consuming painful process phototropism that means something is gonna go towards the light geotropism or gravitropism means something is going to grow towards gravity meaning your wreaths always concave downwards and your shoes always going to get upwards gibberellins are important for growth Ethan is important for ripening plants and auxins are important for growth at a nagging area growth in the right direction [Music]