hey class let's talk about the endocrine system this is a great organ system lots of cool structures and functions in your body now the first thing we want to do is figure out overall what are we going to be talking about and the two words are endocrine course and hormones and usually we're talking like this there's an endocrine gland that makes this hormone that does this thing and that's a pretty good starting point I want to tell you it's a little more nuanced than that meaning some endocrine clamps are in the brain which means their brain matter so are they really Glantz maybe not in the stuff they're making well maybe they're not really hormones if they're not really glands so there's other names for those the point is we're just gonna keep it simple yeah we'll call them glands will call them hormones but there's a lot of complexity here especially when you start talking about these glands and hormones in the brain but to keep it simple look at your screen here you'll see there's this figure with all of these different glands listed starting way up in the brain all the way down to the gona so those are our major endocrine glands but a note here on the side shows you that there are other organs in your body that have secondary endocrine functions like the heart can make a hormone that can make a hormone that helps regulate appetite your digestive tract your kidneys some of these parts of your body we will talk about the hormones that they make later on but mostly we'll just hit the major ones now over on this side of your screen so what is it gland is just a bunch of cells that make something cluster of cells that secrete a product exocrine glands we've already talked about back in unit 1 they secrete their product onto the surface of the body or maybe indirectly into some passage that can reach the surface of the body through ducts right so this concept of ducts is a major element here in fact in this picture over to the side here of this exocrine gland you can see that there are cells secreting a product and things go into these ducts to the body surface or whatever so Ducks are crucial to exocrine glands you already know about exocrine glands at least seven so that was a good time to pause it think about how many you can name you didn't pause it you're just gonna wait for me to tell you it's fine that's fine if that's what you want to do sweat glands oil glands lacrimal glands mammary glands earwax glands mucus glands gastric glands there's probably even more salivary glands so we say that uh you maybe you can think of even more but we've done a bunch of these exocrine glands already well we'll talk about today is endocrine glands but they are very different mainly they have note ducts and they make hormones they make no ducts because if you check out this uh endocrine gland on your screen there's a cluster of cells here in the middle and hormones travel in the blood so you don't need any ducts they're just gonna defuse it out of the cell membrane or if you transported out of the cells and into the blood some glance by the way can be both exocrine and endocrine so like gonads they make sex hormones that's endocrine but sperm and eggs can eventually leave the body so maybe as a fertilized egg person but also just as eggs and sperm so endocrine and exocrine the pancreas makes insulin and glucagon these are two different hormones so that's endocrine but they also make digestive juices squirt into the intestines and the intestines are more or less open to the body through the long long process of food going through the digestive tract but eventually we'll reach the exit of the body so both of these structures gonads meaning testes and ovaries and pancreas are dual purpose endocrine ES and exocrine and finally a hormone is a chemical messenger made by endocrine gland that affects the behavior of they're glands or tissues so hormone means to excite so they're causing some excitation now these hormones only affect the parts of your bodies that have target cells that let our receptors have receptors if they don't have receptors the hormones just swish right past the cells they don't bind to anything nothing changes but if they find a receptor on a target cell then they can alter metabolic activities and what I mean by that are things like this like change the cell membrane permeability so suddenly more things can come in or come out of the cell everything about this we can activate the synthesis of proteins you know proteins do a lot for the cell enzymes they can stimulate cell division lots of cellular processes are affected by hormones now as with most of the organ systems here we don't really have a super firm grasp on how everything in this system works this paper is back from 1994 it's called the effects of gender and birth control pill use on spontaneous blink rates so what they did here was some researchers took 59 men and 86 women and they just monitor them to see how much they blinked probably they pretended they were doing some other study because if you know someone's watching you blink you might not blink so much but so they they counted their blinks and they knew that some of the women were on birth control and some weren't and at the end of the study they found females on birth control blinked about nineteen point six times per minute but females not on birth control blinked about fourteen point nine so about twenty if you had birth control fifteen if you didn't and males blinked about fifteen times if you did it so something about taking the birth control affected blink rate and presumably it wasn't the act of putting the pill in your mouth and drinking a sip of water right something about the hormones in the birth control effected birth rate and so that the researchers as you can read they monitored for differences in like the women wear contact lenses or how fast their tears break up these Shurmur tests these are like dry eye tests they looked at temperature and humidity in their research room their age menstrual cycle phase all of that stuff and nothing explain this difference except the birth control pills so the reason that birth control pills and their hormones affect blink rate is totally unknown because I don't know no one can figure it out and I've looked to see if in the past almost 20 years whether or not we've figured this out and there's nothing we have looked at blink rate in infants to see if that can give us a clue about their health we've looked at blink rate and smoking weed and driving and whether or not the cops could figure out if you were under the influence of weed by Counting your blinking stuff like that but as far as birth control and how hormones affect blinking there's nothing else out there so it's interesting stuff still confusing a little bit more housekeeping about hormones there's two main types of hormones steroid hormones and peptide hormones so the difference between these thurid and peptide hormones is where do they affect their target cells where do they find receptors steroid hormones can actually enter the cell I kind of think about like steroids like you know anabolic steroids that build muscle and like the steroid hormones like bust into the cell and they make it all the weight into the nucleus inside the nucleus they can affect like what the DNA is up to so they can have a really major indirect influence on the target cells peptide hormones on the other hand which just means proteins protein hormones they can't get through the cell membrane so they definitely can't get to the nucleus all they can do is bind with a receptor on the surface of the cell and then initiate some cascading reaction you know it causes this to happen which to happen so very different abilities to influence cellular activities there's also this concept of how hormones are released so we have three types of hormone release here humoral neural and hormonal humour is a fluid so this is a fluid based release of hormones and more specifically what that means is you have something in your body a little monitoring station and it's watching the fluid let's say blood there's little cells monitoring your blood if there's a sudden change in the concentration of something in your blood like maybe calcium then these monitoring stations will identify that problem in your fluid and cause a hormonal release to fix the problem so humor is fluid the fluids being monitored and if something's off hormone gets released to fix it neural control app hormone release is that the nervous system is involved and it's going to basically zap something and tell it to release hormones and the example here is the adrenal medulla so the adrenal glands sit on the kidneys that's what adrenal means above or on top of the kidneys and these glands have an outer part called the cortex and an inner medulla and are very very very very very different so that's important it's the medulla the inside of the adrenal gland in which the nervous system is directly connected as longer on comes all the way down through the central nervous system into the adrenal medulla and it'll zap it when it wants to release it's really some epinephrine so that's a neural control the last way that you can control when hormones are released is through hormonal control of hormone release so hormone control means that you have some regulatory hormone and that hormone caused the release of a different hormone as we'll discuss soon the pituitary gland it used to be called the master gland I'll talk about why later but this master gland made all of these hormones that could regulate the behavior of other hormones or regulate their when they're released so as you can see in our picture here this pituitary gland appear whether or not it releases these hormones and these hormones and these hormones determines whether or not these hormones and these hormones and these hormones get released so it's these regulatory hormones made by the pituitary gland control the hormonal release of these other hormones a last concept here before we move into actually looking at the endocrine glands and the specific hormones they make is to remember that hormone release uses this negative feedback mechanism and I have a video about this that I posted earlier of me standing in front of a thermostat kind of talking through this but this concept of negative feedback and be described kind of like a thermostat in that if things are out of whack in one direction like your house is too cold your thermostat can automatically kick on and it'll heat up the house and heat up the house until you get to a certain point and then the thermostat will kick off the hood if things drop too low again the thermostat will kick on and it'll kick off and on and off so that's the concept of negative feedback in hormone release