okay we're we're talking about the endocrine system and this material is material that you'll need to know for your final test okay so hormones which of course are the chemical messengers that stimulates um or bind to some sort of receptor on a cell to cause some sort of change in the body but they do it primarily through going through the blood so what we're going to look at in this chart here which is kind of an introductory chart to the chemical nature and structure of the different types of hormones so notice in this column we have hormones that are derived from amino acids so this area right through here would be hormones derive from amino acids our next column which would be our largest group of hormones or hormones that are peptide hormones in other words they're made up of chains of amino acids and they would include this group color glycoproteins and this group called short polypeptides and small proteins and then finally our last big category of what hormones are can't how they are chemically structured water they derive from or what is their chemical nature would be our lipid derivatives so notice again then that would include our steroid hormones and our eicosanoids so again our three major categories of hormones would be hormones derived from amino acids hormones that are basically made up of chains of amino acids called peptide hormones and finally hormones that are made up of lipids and here we already see a cholesterol backbone as being one of the building blocks for lipid derivative hormones okay well let's look first then at our amino acid derivatives and we see that I hormone that is an amino acid that actually has several hormone derivatives is the amino acid tyrosine so our catecholamines which you will hear that term a lot if you continue in Visio anatomy and physiology the catecholamines are things such as epinephrine and norepinephrine of course we know there that's that's what makes up adrenaline and these would be created by the adrenal medulla and then a very similar in structure because again they're all derived from tyrosine so if you notice this chemical structure looks very similar to that chemical structure which looks very similar to that chemical structure dopamine is another catecholamine but it's secreted by the hypothalamus okay next let's look at our thyroid hormones which are also derived from tyrosine and again you will notice there is a common ring structure and you know carbon chain attached to it very similar because that we're taking tyrosine and we are chemically altering a little bit to make these different these different structures well T 4 and I wish they had drawn a picture of T 3 because those were those triiodothyronine and thyroxine and T 4 we can actually see the reason why it's called T 4 we can say 1 2 3 4 iodine's in the chemical structure and T 3 would actually have 3 iodine's but I bet you guessed that already okay our last amino acid that we derive a hormone from is tryptophan and our hormone is melatonin no I bet a lot of you've heard the heard somebody say in the past that Turkey makes you sleepy well the reason why Turkey makes you sleepy is because Turkey has a lot of tryptophan in it that makes up the proteins found in turkey meat and that tryptophan then is it can be used to make melatonin which of course is secreted by the pineal gland or pineal gland and melatonin we know helps us become sleepy ok our largest group of hormones comes from the peptide hormones which instead of just being a single amino acid would be you know a an actual peptide I grew a chain of amino acids we divide these into two groups the short polypeptides and small proteins in other words these would be under 200 amino acids and then we divide them into the glycoproteins so we know these would have the glucose chains hanging off of them well here we can see in from the glycoproteins our pituitary glands Tim you know secretes thyroid stimulating hormone the T&I zhing hormone and follicle stimulating hormone a kidney secrete erythropoietin that really important hormone that causes to to you know make more red blood cells and then our reproductive organs secrete inhibit and kind of a negative feedback loop hormone now our short polypeptides and small proteins under under 200 me know acids our hypothalamus remember antidiuretic hormone and oxytocin and ret are regulatory hormones are all made in the hypothalamus the regulatory hormones are secreted to the anterior pituitary to trigger the anterior pituitary hormones to be made but antidiuretic and oxytocin are actually released from the posterior pituitary even though they are made in the hypothalamus but these are or either short polypeptides or small proteins okay our pituitary gland notice a lot of those anterior pituitary gland proteins adrenocorticotropic hormone growth hormone will add a size same Langhorne and prolactin fall in this category insulin and glucagon from our pancreas follow this category parathyroid hormone that does the opposite of calcitonin and so parathyroid hormone obviously being from the parathyroid calcitonin being from the c cells of the thyroid gland okay then the two hormones from our heart and hormones from our adipose tissue and even the lymphatic the hormones that are from our lymphatic system those chemical those chemical products that are literally causing some of the changes like the interleukins and then the digestive tract hormones which we'll be talking about separately now finally our last category are lipid derivatives which are the steroid hormones which as it says here related cholesterol we see our cholesterol backbone in this example of estrogen and then we know that our androgens which is mainly testosterone estrogen and progestin x' are all steroid hormones of course we notice we know that if you're a steroid hormone cholesterol base you have the ability to go directly to a phospholipid membrane but look we also have our cortisol's our aldosterone and again androgens from the adrenal cortex because remember ladies you get your testosterone from the adrenal cortex also and then calcitriol from the kidney which actually helps us conserve calcium now our okosan lloyd's lipid reviews from arachidonic acid well this structure here which looks kind of like it's got legs on it like a spider it's called a Rekha donek acid and so these things will be like our leukotrienes and of course those are secreted from leukocytes prostaglandins which are sometimes referred to as local tissue hormones ROM axons and across the Cyclones okay now but the bottom line is my biggest concern is that you understand that because hormones are derived from different chemical structures then they're going to have different chemical properties and that is going to affect how they interact with cells and the receptors in the cells now I wouldn't expect you to memorize all of this but I would you know I would want you to be familiar with this chart enough to where you know if I were to blank out you know which of these belong to the amino acid derivatives or or even which of these would be considered catecholamines I would expect you to you know be able to fill in the large categories into any of these boxes that are you know circled so you know if I had that blanked out you saw that it included steroid hormones and eicosanoids I would expect you notice it's lipid or if that's or if I had that blanked out and it says structurally related to cholesterol and here you see a cholesterol backbone I would expect you to know that that's a steroid hormone so those are the type things Vantage - the big categories and what would be included in those categories now since hormones are most often distributed to the blood then they're going to be released where there are a lot of capillaries so they can go into the blood or be released from capillaries to go into the tissues now they can either circulate freely which means by themselves which means they will not circulate very long at all because they'll probably be broken down by an enzyme or if they need to last longer they will bind to some of those plasma proteins which are the protein carriers but they'll always be an equilibrium between what is found and and what is releasing so as soon as they're bound they go to be released as soon as they're released they go to bind more okay so so again when the free are inactivated then they are replaced by the bound hormones so they will either be inactivated when they actually bind to the receptor in the cell that will trigger the events in the cell so we'll get the effects of what the hormone is supposed to do or they may be broken down and absorbed by the kidneys or the liver because they you know aren't necessarily going to be there forever and there's so many different hormones they're going to do different things but remember our kidney is filtering things that's in our blood and our livers also filtering and breaking down things that's in our blood or they can be broken down by the enzymes that's you know enzymes are there to put stuff together rearrange stuff or in this case break things down now this is extremely important that you get these two different mechanisms of how hormones work so they will either work primarily by what's called a fixed receptor mechanism which I will show you what that means in a second and then here's kind of a list of the hormones that are basically uses fixed receptor mechanisms and/or they will be mobile receptor and here's kind of a list of the hormones that will be mobile receptors so what do we mean by fixed receptor mechanism or mobile receptor mechanism okay in this picture we see a cell cell with this phospholipid bilayer membrane and a receptor that is fixed into the membrane so the hormone actually attaches from the outside that just like we talked about neurotransmitters opening up norway's or causing some sort of reaction here we say the hormone is in this case the hormone doesn not go into the cell but the hormone is the hormone attaches to the receptor and the receptor is fixed into the membrane but when the hormone activates the receptor then there are several activities that can happen that can go forth inside of the cell even though the hormone itself doesn't go in the cell so first thing we won't understand is that hormones either act as fixed receptors or other types of hormones can act as mobile receptors now notice them this mobile receptor is inside the cytoplasm of the cell and it is actually moving around in the cell especially it's moving around because it's going to end up being what's going to carry the hormone to the to basically the activation area so it can activate the DNA and actually cause transcription and translation so again this is a mobile receptor not a fixed receptor okay so hopefully now you kind of see what a fixed receptor is versus a mobile receptor and again notice our catecholamines peptide hormones and eicosanoids bind to receptors in the membrane well that kind of makes sense overall when you understand that the chemical nature of those things are not going to allow them to easily pass through a membrane because remember look it's compacity lipids but in this case that hormone can't just pass into that membrane it would have to bind to a receptor but remember receptors are very specific for specific hormones that's why hormones can go all over the body but they're not gonna actually you know necessarily cause the same effect in every cell they're only going to affect the cells that have a receptor for them now what is it that hormones are actually going to do for the body so ultimately what all hormones are basically going to do is they're either going to activate they're going to cause a cascade of events that activate enzymes in other words turn enzymes on so certain metabolic reactions can occur in the cell or they're going to create the opposite effect and they're going to basically lead to the reduced enzyme activity or basically turn off enzymes so notice here where they're going to activate enzymes turn off enzymes here we see activation of enzymes and then the other thing that we can do is actually open up ion channels either open them up from the inside where ions can leave or open them up from the enzyme where ions can enter so again notice in this case this this hormone this hormone is actually eventually opening up it's activating enzymes but it's also opening up ion channels kind of similar to how neurotransmitters would open up ion channels but instead of this necessarily doing it directly it's doing it indirectly now notice it says fixed receptor membranes use a second messenger system where the hormone is the first messenger but never enters the cell so again notice this hormone right here is the is the first messenger but it attaches to the receptor and never under cell what it does it triggers a cascade of chemical events where it activates a second messenger notice this acts as a second messenger second Mester and what's significant about that is we get a lot more second messengers than the original hormone so the first messenger is limited the second messenger is amplified we actually call this process amplification so fixed protein receptors first messenger activates a chemical reaction of activating a lot of second messengers