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Current time:0:00Total duration:10:31

Video transcript

all right I want you to imagine with me that you're a cell in the brain let's say you remember the hypothalamus right here and as a part of the hypothalamus one of your jobs is to regulate how much fluid is in the blood volume at any given time and so you just got informed by another part of the brain that your buddy cell down in the kidneys right here has been making urine like a madman all day another fluid volume and the blood is a little bit low and so you want to tell them to stop but how do you go about doing that I mean one way the body communicates is through the nervous system and sending messages down the hard wired pre laid tracks of the nervous system through nerves but there isn't really an established connection between you and him and so what you decide to do is you decide to put a message in a bottle of sorts and float it down the blood stream to him and hope that it gets there and and and so you send that message his way and he receives it and he opens that message and he sees that you want him to close the permeability to water and he does that and fluid volume begins to be restored again and so that process of sending a message from one part of the body to another part of the body through the bloodstream forms the basis of the endocrine system the endocrine system and the endocrine system is a system of glands that produce chemical messages called hormones that travel from one part of the body to another part of the body through the blood in order to elicit an effect in order to make a change in what's going on in a different part of the body in the effects that are caused by the endocrine system cooperate with the nervous system in order to control the body's internal environment in homeostasis and so the endocrine system and the nervous system are really related they're almost like cousins they're really similar but they they're kind of unique the nervous system is kind of like the hair and the children's story with the The Tortoise and the hare and the endocrine system would be the the tortoise and so the nervous system is really really fast and you you see results in milliseconds and the endocrine system in comparison is fairly slow and it might take minutes to even even days or weeks to see the effects of these hormones but like the children's story with it with The Tortoise and with the hare the the tortoise as fast as you go he kind of runs out of steam pretty quickly and the indican system as it goes a little bit so it'll last longer instead the effects while slower had a more lasting effect in the body with the endocrine system and so anyway the the chemical message is called hormones that the endocrine system utilizes they can be broken down into three distinct classes first you have proteins and polypeptides and proteins and polypeptides or moans like any other proteins in the body are made up of amino acids and they can be really small as small as three or so amino acids which is pretty tiny when you think about it because an amino acid is a fairly small collection of atoms and if you're talking about three amino acids that's only a few atoms all the way up to hundreds and hundreds of amino acids in a in a polypeptide chain and so typically after you get about 100 amino acids in a chain you start calling it a protein and and that holds true for hormones as well into the second class after proteins and polypeptides are steroid hormones and unlike proteins and polypeptides that are made up of amino acids steroid hormones are typically derived from cholesterol which is a lipid so from cholesterol into Seward's are made up of lipids and have lipid like qualities like they're not charged and they can pass through cell membranes and so that might mean the receptor instead of being on the outside of cells on the inside of the cell and so you've got proteins and you've got steroids and then you've got a class called tyrosine derivatives and tyrosine is an amino acid and this class of hormones the reason it's separate is that they're they're derived from tyrosine tyrosine can be manipulated in order to make a couple different hormones okay so the two main classes of tyrosine derivatives are thyroid hormones and catecholamines catecholamines I hope I spelled that right catecholamines and so catecholamines are the hormones that are made in the adrenal medulla and they include epinephrine and norepinephrine and a little bit more common name outside of the medical community for epinephrine is adrenaline and adrenaline is a little bit more familiar because we hear it when you know when you're really excited in your fight-or-flight response and so these are the three main classes of hormones and we see that they're classified by structure but they're also classified by function in a separate system and so even though all these hormones are functioning in the endocrine system not all of them have endocrine function there there is a class of hormones that are considered to have autocrine function and these are hormones that that elicit a response at the cell that they're made or in the cell immediately next to the cell that makes the hormone and then they're in addition to autocrine signaling there's paracrine signals and this is this is kind of more the the regional effect one example of paracrine signals are between the hypothalamus and the pituitary gland which I'll show you in a second those are really close and so and so yeah this is there's not a hard line that gets drawn with where paracrine signal function ends but generally these are regionally acting signals and then the last class are the endocrine signals and those are the classic hormones that are said to function at a distance in the body and their response is elicited somewhere far away let's say pituitary gland traveling all the way down to the gonads that's a pretty long distance in terms of hormone size and blood vessel linked and so those are called endocrine glands and so now that we've we've kind of covered how hormones are classified I want to talk about the main organs of the endocrine system that use these hormones to communicate and so I went ahead and and pre wrote out to save a little bit of time and so the first organ that I want to talk about in the endocrine system is the hypothalamus and the hypothalamus is a member the inter consistent but it's also a member of the nervous system it's right here in the brain and it's about the size of a grape and as a member of the nervous system it's taking in the signals that are being stimulated by the sensory nerves and it takes those signals and it kind of funnels them into the indicator gland by controlling the pituitary gland and the pituitary gland is often known as the master gland and it's situated right here below the hypothalamus and if the hypothalamus is about the size of a grape in the body the the pituitary gland is about the size of a green pea and it's tiny but its role is huge and that it is is principally involved in stimulating the other endocrine glands which are ultimately going to cause any of the effects that are happening in the body and so the first organ that it stimulates going down the list here is the thyroid gland and it stimulates the thyroid gland through the thyroid stimulating hormone and the thyroid gland is a gland that that wraps around the trachea which is your windpipe and you can feel it when you smoke swallow but the thyroid glands main role is regulating our body's metabolism so kind of regulating or down regulating the entire body and it does that through the thyroid hormones t3 and and t4 another name for T 3 is triiodothyronine and another name for t4 thyroxine but those are the those are the thyroid hormones that I remember the tyrosine derivatives that I was talking about a little bit earlier and so behind the thyroid gland are four spots that are kind of collectively known as the parathyroid and I'm drawing them on the front but I want to be clear that these spots are in the back of the thyroid gland and the parathyroid gland is principally or kind of chiefly involved in regulating our body's calcium levels and it does that through its hormone parathyroid hormone and so moving down the list we had the adrenal glands right here on top of the kidneys and we called adrenal glands because they're adjacent to the kidneys and another name for the kidneys are the and that the whole kidney system is there the renal system and the adrenal glands are stimulated by the pituitary's release of adrenocorticotropic hormone and then they ultimately release their hormones and there are there are two kind of separate areas of the adrenal glands you've got the cortex of the adrenal glands which is the outside in the medulla which is the the inside of the adrenal glands but the cortex is where the adrenal steroid hormones come from and so you've got your glucocorticoids in your mineral ah corticosteroids and those are things like cortisol and aldosterone and those have a lot of functions in the body as far as regulating fluid volume and the stress response and in the middle the medula that's where the catecholamine hormones are made and again there's catecholamines were the second class of tyrosine derivatives that I mentioned earlier so moving moving down the list even further we have the gonads and females those are your ovaries and in males you testes and the gonads are stimulated by the pituitary release of FSH and LH which is follicle stimulating hormone and luteinizing hormone and the gonads then take that stimulation and release their their hormones the sex hormone and so in in ladies that that's mostly progesterone and estrogen and a male's testosterone and those are your those are your gonads and then kind of outside of that pituitary signaling system is the pancreas right here the pancreas isn't isn't stimulated by the pituitary gland directly but it does release some pretty important hormones insulin and glucagon which function to regulate the blood sugar level again the blood sugar level is pretty tied in to metabolism as glucose is kind of the backbone molecule that we get all of our energy from