Hypothalamus and Pituitary Gland

[Music] in this video we are going to look at how the hypothalamus controls the pituitary gland so remember that the hypothalamus and the pituitary play a very important role in homeostasis so they regulate things like growth and metabolism in our stress response so what kinds of factors will affect the secretion of those hormones in this diagram we can see where our hypothalamus is located the hypothalamus contains many many neurons each group of neurons clustered together are called nuclei and they control the pituitary gland the pituitary has an anterior and a posterior region and the pituitary is highly protected in this depression of the sphenoid bone called the cela turcica so the hypothalamus contains groups of cell bodies these groups of cell bodies are called nuclei and how the hypothalamus communicates with the posterior pituitary compared to the anterior pituitary is slightly different so notice that there's axons that extend from the hypothalamus through this stock region called the infundibulum and the axon terminals are in the posterior pituitary gland the hypothalamus will make two specific molecules called oxytocin and antidiuretic hormone we'll look at those details in a second but they are produced and then stored in these axon terminals in the posterior pituitary gland the posterior gland doesn't make any hormones when these molecules when these hormones are released from the synapse they go into the bloodstream and that's why they're called hormones and then they will have their effect whereas the anterior pituitary is controlled by hormones produced by the hypothalamus those hormones will go into the bloodstream which will then flow directly to the anterior pituitary gland through portal vessels so the hormones will then stimulate the pituitary to make a bunch of different hormones we will look at the posterior pituitary hormones first but you have to remember that they are not made in the posterior pituitary they're made in the hypothalamus and then stored in the posterior pituitary so those two hormones are oxytocin and antidiuretic hormone oxytocin is another one of my favorite molecules and it is involved we primarily think of oxytocin as being involved in childbirth it causes uterine contractions until the baby is born but oxytocin does a bunch of other things it plays a really important role in bonding and not just between mom and baby but also bonding between other humans it is important for humans throughout evolution to be able to cooperate in groups and oxytocin is the molecule that allows us to bond with each other to have empathy to feel trust okay so it's not just a love bonding it's any kind of feeling and interconnection with other people oxytocin plays a really important role in that and animals also make oxytocin and they don't just make it to bond with their babies group animals make more oxytocin than independent animals so who do you think would make more oxytocin a dog or a cat right we can actually make oxytocin by bonding with our pets as well so next is anti-diuretic hormone or adh so first i want to clarify a diuretic is a substance that makes you increase excretion through the kidneys so you will increase urination if you took a substance that was a diuretic so antidiuretic hormone decreases excretion so how do you think antidiuretic hormone would impact blood pressure do you think it would make it go up or down if we are going to be decreasing excretion and increasing the amount of water that we reabsorb into the bloodstream we're going to have more blood volume which will increase blood pressure so adh increases blood pressure by acting on the kidneys adh also increases blood pressure by causing vasoconstriction if you constrict blood vessels then that blood volume has less space in the whole body so blood pressure will go up so why do we need oxytocin right how would that be regulated so first if we just think about childbirth oxytocin is regulated by a positive feedback loop so it is one of the main examples in the body where when you produce oxytocin you will cause uterine contractions which stimulates more oxytocin production okay you also make more oxytocin when you're with other people when you are with people you have to like them when you're bonding with pets or people then you will make more oxytocin so oxytocin is primarily regulated by positive feedback so antidiuretic hormone what do you think antidiuretic hormone increases blood pressure when would we make more of that when our blood pressure is low okay so here's a summary chart for those first two hormones now we're going to look at the hypothalamus hormones that stimulate the anterior pituitary gland okay so there's five different hormones that will have a direct impact on the anterior pituitary when a hormone impacts another endocrine gland to affect the secretion of another hormone we call those tropic hormones so the hypothalamus hormones are tropic hormones because they're going to stimulate the pituitary a good trick is that all of the hormones that are coming from the hypothalamus that are stimulating the anterior pituitary we call them releasing hormones so we have growth hormone releasing hormone thyrotropin releasing hormone corticotropin releasing hormone gonadotropin releasing hormone and prolactin releasing hormone so those releasing hormones are going to impact the anterior pituitary so what is the main function the main function will be to make the pituitary produce other hormones now what are those hormones growth hormone releasing hormone will tell the pituitary to make growth hormone thyrotropin releasing hormone tells the pituitary to make thyroid stimulating hormone which will stimulate the thyroid gland we'll talk about the anterior pituitary in a second corticotropic releasing hormone tells the pituitary to make adrenocorticotropic hormone that will stimulate the adrenal gland okay go netatropin releasing hormones will stimulate the pituitary to make hormones that stimulate the gonads and those are follicle stimulating hormone and luteinizing hormone okay fsh and lh and they both have a specific impact on the gonads and then lastly prolactin releasing hormone tells the anterior pituitary to make prolactin its primary role is to stimulate lactation or milk production so before i look at why the hypothalamus makes these releasing hormones i want to look more specifically at the anterior pituitary hormones once you know the function of those hormones it'll be easier to figure out why the hypothalamus would stimulate their production when the anterior pituitary makes growth hormones that is going to stimulate growth but we don't just make growth hormone during development okay so the obvious function is to stimulate bone growth up until we stop growing in height during puberty we also require growth hormone for our whole adult life as well growth hormone is really important for promoting protein synthesis growth hormone is really important for tissue repair and healing and regenerating cells stimulating mitosis okay growth hormone in adulthood is actually like our anti-aging hormone it helps regenerate cells and tissues so it's very important to produce growth hormone it also stimulates the liver to make a hormone called insulin-like growth factor and that also has similar protein synthesizing stimulating effects growth hormone also stimulates the breakdown of fat so that we can increase blood sugar so that we can make energy because growing and replenishing tissues and regenerating cells requires atp next we have thyroid stimulating hormone this is going to stimulate our thyroid gland the thyroid plays a major role in metabolism so we need to have thyroid hormone production whenever we need to have energy okay so when we have an acute stress response when we're exercising we need to increase the amount of atp adrenocorticotropic hormone this is going to affect the adrenal gland and the adrenal gland plays an important role in stress so when we have a stress response we need to have cortisol cortisol is the main hormone produced by the adrenal cortex now our fsh and our lh hormones they both impact the gonads testes in males and ovaries and females follicle stimulating hormone stimulates follicles so it will stimulate the development of sperm and eggs basically follicle stimulating hormone is going to stimulate spermatogenesis and oogenesis or gametogenesis we're going to make gametes and then luteinizing hormone its primary rule is to stimulate the production of other hormones so in the testes luteinizing hormone stimulates the latex cells to produce testosterone in females luteinizing hormone stimulates the the cells to make testosterone but then that testosterone is converted into estrogen because females have an enzyme called aromatase so then we have more estrogen production compared to males luteinizing hormone also has one other really important rule it stimulates ovulation okay so when we have an lh surge around day 14 of the female cycle that stimulates the egg to be released and then lastly actually also the luteinizing hormone will also stimulate the production of that empty follicle after ovulation to become what's called a corpus luteum and that will produce progesterone progesterone is important for uterine lining buildup so that the uterus is ready for a possible implantation so follicle stimulating hormone and luteinizing hormone very important roles in reproduction and then prolactin plays an important role in lactation so there are two hormones that play a role in breastfeeding so prolactin stimulates the production of the milk and oxytocin stimulates the release of the milk so when the baby is suckling that is going to stimulate a positive feedback loop and it will increase the amount of milk that can be released so both of those hormones work together for lactation before i do a summary chart of the anterior pituitary hormones i want to just point out that growth is stimulated by more than just growth hormone there's a few hormones that impact growth okay so all of the things that we said about growth hormone but we also need thyroid hormones in order to be able to make growth hormone so thyroid hormones are also important for growth and sex hormones so during development estrogen and testosterone play an important role in in growth so the anterior pituitary hormones we went through each one and what their main functions are now why are they produced what stimulates the production of the anterior pituitary hormones okay it's the hypothalamus all of the hypothalamus releasing hormones are what stimulate the anterior pituitary to make their hormones so here's a summary okay now that we have looked at the function of all of the anterior pituitary hormones and we know why they are made now i want you to think about why would the hypothalamus produce these hormones what stimulates the release of the releasing hormones so if thyroid stimulating hormone is all about stimulating the thyroid then the hypothalamus is going to need to make releasing hormone when we need to increase our metabolism when we need to increase the production of atp when do we need more atp we need more atp when we are exercising or when we have an acute stress response adrenocorticotropic hormone stimulates the adrenal gland during stress so we need cortisol so we will increase this when we have a stress response and i'm going to skip these for a quick second but prolactin releasing hormone is going to be released during breastfeeding the other thing that has a very important role in regulating the hypothalamus is negative feedback so we talked about oxytocin being regulated by a positive feedback mechanism the hypothalamus hormones that affect the anterior pituitary all those releasing hormones they are primarily regulated by negative feedback so for example when the thyroid stimulating hormone stimulates the thyroid gland the thyroid will make thyroid hormones those thyroid hormones then regulate the hypothalamus so the hypothalamus detects the level of thyroid hormones in the blood and when it goes down it will increase the releasing hormone and when it's higher it will decrease the releasing hormone so negative feedback plays an important role in all of the production of the releasing hormones the last thing that i want to mention but i'll show you a summary chart of the hypothalamus hormones in one second but i want to just talk about what could potentially decrease some of those hormones so there's a few key ones that i want to talk about one the hypothalamus actually makes up another hormone called growth hormone inhibiting hormone and it will actively inhibit the production of growth hormone by the anterior pituitary now why would we ever want to inhibit growth so we can't grow and regenerate cells and do all of those kinds of functions when we have a major stress response our body has to divert its attention and energy to dealing with the stress response so when you have a huge amount of emotional stress specifically you're going to make more growth hormone inhibiting hormone and you will decrease growth when we exercise that is a physical stress that will actually then stimulate growth hormone because when we exercise we cause bits of micro damage to our muscle tissue and then we need to regenerate that and repair that tissue so exercise will stimulate growth hormone the hypothalamus also makes prolactin inhibiting hormone and it produces this most of the time most of the time lactation is inhibited okay except it obviously in the case of lactation the last one is gonadotropin releasing hormone okay the reproduction hormones they will be inhibited with huge amounts of stress and also in females it will be inhibited with a very low calorie intake if there's not enough nutrients to reproduce and make a baby then ovulation will decrease so here is a summary chart of your hypothalamus hormones [Music] you

Channel: Dr. Wendi

Views: 80,799

Keywords: Hypothalamus, pituitary, anterior pituitary, posterior pituitary, oxytocin, antidiuretic hormone, ADH, GHRH, TRH, CRH, GnRH, PRH, prolactin, growth hormone, adrenocorticotropic hormone, thyroid stimulating hormone, FSH, LH, follicle stimulating hormone, luteinizing hormone, positive feedback, negative feedback, Fanshawe College, Biology, Physiology, prehealth, Pre-health, tropic hormones

Id: xCXtcoUxJZc

Length: 17min 40sec (1060 seconds)

Published: Tue Sep 15 2020