Lecture 10 - Reproductive System

hi everyone dr mike here in this video we're going to go through an overview of the male reproductive system the purpose of the male reproductive system is to produce and supply sperm when we look at the external anatomy you see two things you see that of the penis and the scrotum inside of the scrotum is the testes and this is where we should begin our discussion because the testes is the site of sperm production so let's begin we'll look at the scrotum itself now the scrotum is a sac that houses the testes now testes plural t-e-s-t-e-s the testes is a side of sperm production now if we were to have a look at the testes and have a look inside you'll find that it's made up of these individual lobes and within each lobe you're going to find something called seminiferous tubules so these are just convoluted tubes inside each of these lobules of the testes and if you have a look within these tubes there's two major cell types that you should be aware of first cell type are the latex cells the second cell type are the sertoli cells now what do these cells do within the testes specifically at the seminiferous tubules the latex cells produce testosterone and the setoli cells produce something called androgen binding protein androgen binding protein also known as a b p now and androgen is a male sex hormone i.e testosterone so it binds to testosterone if they bind together what they do is they promote the production of sperm sperm production now this is important because you're going to have signals coming from the brain specifically from these glands that sit underneath the hypothalamus in the brain called the pituitary glands and the pituitary gland has two lobes and anterior and posterior the anterior lobe of the pituitary gland releases a hormone anterior pituitary releases something called gonadotropins there's two types of ganadotropins there is luteinizing hormone and follicle stimulating hormone now once a male hits puberty these hormones begin to be released luteinizing hormone i've drawn in red as you can see luteinizing hormone stimulates the latex cells think of the l and the l the follicle stimulating hormone stimulates the setoli cells they produce testosterone and antigen binding protein respectively and sperm production begins in the seminiferous tubules of the testes sperm is starting to be produced this is happening at puberty now this the sperm that's produced is transported into this structure here that lines the outside of the testes called the epididymis the epididymis and the role of the epididymis is to store sperm mature sperm and then transport sperm into this next tube which is called the vas deferens also known as the ductus deferens vas deferens also known as the ductus deferens so if you've ever heard of a vasectomy so if a male no long no longer wants to produce children they can have a vasectomy ectomy as a suffix means to cut so they cut the vas deferens so a vas deferens or ductus stefans that is intact will transport sperm via the ductus difference you can see it loops around you can see it loops around the bladder here that's the bladder which is part of the urinary system not the reproductive system and then it joins together with a gland here now this gland is called this gland is called the seminal vesicle and this seminal vesicle or seminal vesicles what that does is it produces a really important fluid it actually produces two-thirds of the volume of two-thirds of the volume of semen and one of its major components is that of fructose which is an energy source so fructose very similar to glucose is what sperm uses as its energy source each your fruit gentlemen so seminal vesicles produce this sperm produce this fluid the seminal fluid it mixes with the sperm that's coming from the testes via the ductus deferens and it enters the ejaculatory duct the ejaculatory duct right here now you can see the ejaculatory duct will merge together with part of the urethra which is coming from the bladder and it forms the prostatic urethra now this structure here is the prostate not prostrate which means to lay down but prostate the prostate you can see houses both the ejaculatory duct which is coming from the seminal vesicles and from the vas deferens but also the urethra and the urethra is going to be sharing a a pipe that houses urine but also this semen which has sperm and also the fluid from the seminal vesicles now the prostate what isn't drawn here is the rectum which means the rectum sits right next to the prostate and that's why a digital examination of the prostate can occur occur because you can feel the prostate you can feel its size you can feel its hardness and you can feel its texture is it lumpy or bumpy or whatever it may be because as males age the prostate grows and as it grows the tissue and cells develop and it can impede and squeeze on the urethra which makes it very difficult to urinate and so this is known as prostatic hyperplasia then from the prostate we have the urethra and the urethra travels through the penis and you can see the pain is here now the penis is made up of spongy form tissue at the very end of the penis we've got what's called the glands penis now it's made up of spongiform tissue and what happens is this when it's time for erection and ejaculation so erection and ejaculation needs to occur in order to eject that sperm into the vagina of the female when we look at erection think of the word point when you think of ejaculation think of shoot point and shoot why because the p for erection is going to be parasympathetic nervous system the parasympathetic nervous system is responsible for erection and the s is sympathetic nervous system that is responsible for ejaculation the parasympathetic nervous system will tell the blood vessels to dilate blood enters the penis and it compresses the vein so blood can't leave so the erection is blood filling the spongiform tissue of the penis then the ejaculation is coming from stimulating the sympathetic nervous system telling the smooth muscle of this tube to contract pushing the sperm and the semen through and this is a quick run through our overview of the reproductive system of males hi everybody dr mike here in this video we're going to take a look at the female reproductive system now to begin with i think we should look at the external anatomy or the external genitalia also known as the volvo of the female reproductive system and then we'll move through and have a look at the female reproductive tract so when we look at the external anatomy a couple of things first of which you can see that we have what's called the mons pubis now the mons pubis is this fatty pad mons pubis is a fatty pad that overlays that of the pubic symphysis so the very front of the pubis itself we can see that there are two skin folds in actual fact there are two lots of two skin folds which we call the labia and the most external aspect is going to be called the labia majora labia majora which are two skin folds that basically begin at the mons pubis and they finish down at the perineum now the labia majora is homologous to that of the scrotum so they are skin folds and they have muscle in them similar to that of the dartos muscles of the scrotum itself then there are more internal skin folds that we call the labia minora labia minora and these skin folds move from the clitoris down to the vaginal orifice itself now what you'll find is that the mons pubis the labia majora labia menorah and then as we start to move in to what we call the vestibule now the vestibule is the recess that sits within the skin folds of the labia majora okay the vestibule and what you find with the vestibule is it contains most superiorly that of the clitoris and the clitoris is highly innovative with sensory neurons so it is extremely sensitive and it plays a very important role when it comes to sexual arousal when it comes to female reproduction as we move down you'll find that there's the external urethral orifice external urethra urethral orifice which is obviously going to be where the urethra coming from the bladder moves through to move urine out of the body and then we've got the vaginal orifice itself vaginal orifice now the vaginal orifice as we can see here so here is the vagina it plays an extremely important role in separating out the external environment from the internal environment of the female reproductive tract really important and because of that it actually has a ph that's quite acidic and this is important to maintain the vagina when it comes to keeping it clean because again it's playing an important role separating the external from internal environment but because it's acidic any sperm that enters may be damaged or killed off and therefore that's why sperm moves through in semen which is slightly alkaline to neutralize the acid of the vagina now as we move from the vagina we get to that of the cervix cervix now cervix or cervical or cervical you've probably heard of being referred to as the neck here and that's what cervix means cervix means neck because the cervix is the neck of the uterus which we have here now the uterus is a muscular body and it comprises of a couple of important layers the two that i want you to be aware of is the most internal layer of the uterus which is a layer that thickens when a woman becomes pregnant and this is called the endometrium endometrium and then a thick muscular layer which is called the myometrium now the important role of the uterus and that of the endometrium is that when an egg becomes fertilized and then implants it implants in the uterus and specifically implants in the endometrium but the endometrium in a woman who's not pregnant is quite thin so during the process of fertilization the endometrium prepares itself it becomes thickened and more vascularized because of the important roles of estrogen and progesterone so it thickens vascularizes and that egg implants in the endometrium to nourish that fertilized egg the myometrium being this thick muscle is important for when that embryo is developed into and basically that embryo has developed into an unborn child and it's time for that child to be pushed out so this baby that's now developed when it's time full term baby needs to be pushed out because of the role of oxytocin it's going to contract the myometrium of the uterus and help push the baby out through the cervix through the vagina now as we can see we've got the top of the uterus which is called the fundus and it starts to enter these two tubes which are called the uterine tubes the uterine tubes also known as the fallopian tubes so the fallopian tubes carry both sperm and egg right there's a couple of different areas the most the thinnest portion of the uterine tube is known as the isthmus and that's this area here and as it moves through you've got this region here called the ampulla and the ampulla in actual fact is the most common area for the sperm to fertilize the over more egg that's been pushed out by the ovary so when sperm enters the vagina it then has to swim through the cervix it has to swim through the uterus has to go through the isthmus has to go through most of the fallopian or uterine tubes and it's at the ampulla in which it'll fertilize the egg which means the egg or oocyte will be ovulated here from the ovary and move through to the ampulla okay so the end of the fallopian tube is called the infundibulum infundibulum nice name infundibulum which has these little fingertip-like projections called fimbre when it's time for ovulation so for that egg to leave the ovary to go into the uterine tubes these fibres swell and they play an important role in help moving that egg into the fallopian tubes which means that this structure here on both sides is that of the ovary and it's the ovary that contains the egg and ovulates that egg approximately every 28 days or every month extremely important now the ovary also plays important roles in hormone production so it plays a really important role in producing progesterone and estrogen really important role and both of these two hormones are important when it comes to producing maintaining that of the thickened endometrial lining so what we've worked through at the moment is the external anatomy of the female reproductive system which is called the vulva and the internal anatomy also known as the reproductive tract so today we're going to focus on the female reproductive system and have a look at the female reproductive cycle so before we begin we need to have a look at some of the important anatomical features of the reproductive system so what i've drawn up here very quickly is first of all the vagina which then moves up into the cervix and then up into the uterus now the uterus has a number of different important anatomical structures such as the body of the uterus the fundus of the uterus and also the uterine walls which is made up of a number of different layers one layer which we're going to focus on today is the internal layer called the endometrium now you can see that the uterus feeds through into two tubes these are called uterine tubes also known as fallopian tubes and i've exaggerated just one of these uterine tubes so you can see as we follow it through it starts to branch out like little fingertips now these little fingertips are called fimbre and what's the importance of these fembrae these fembrae hold the ovary okay so you know that you've got one ovary on either side now the ovary holds oocytes so what's an oocyte an uber site o o c y t and oocyte is basically an egg now which is also known as an ovum now for females you'll find that there are thousands of oocytes what we call primordial oocytes in one ovary where they come from and how long have they had them well basically females when they are in utero themselves so for example when a female is within them their mommy's tummy so to speak they already have all the oocytes they need for their entire life their ovaries even when they are in utero their ovaries already contain all the illusions they need okay thousands of them so if i were to take this ovary and just draw up a couple of oocytes to begin with there's going to be thousands and thousands of them and we know that every single month the reproductive cycle begins and these oocytes start to prepare themselves for fertilization and the uterus starts to prepare itself for fertilization so what we're going to talk about today is how does the body do this so we know that many hormones are involved this interplay of systems is involved and we need to look at exactly what happens with stimulating those hormones and what happens as a response to releasing those hormones so i've drawn up a little graph here or at least the start of the graph where we're going to have a look at hormone levels over the reproductive cycle so how long does a reproductive cycle go for well on average it's 28 days but it can be as short as 21 days or as long as 35 days but the average is 28 days so i've drawn one to 28 days here and this is going to represent hormonal levels of the reproductive cycle okay so what are we beginning with well day one of the reproductive cycle the ovary has a number of oocytes and we call them primordial follicles so these oocytes are called primordial follicles and at day one these primordial follicles between 10 to 20 of them okay but i'm just going to draw one for reference between 10 to 20 of them start to develop now what does a primordial follicle develop into it develops into something called a primary follicle now primary follicle again has the oocyte or the ovum and this philocyte is surrounded by some cells some flat looking cells which are called follicle cells or follicular cells and again the whole structure is called a primary follicle now these follicular cells what's the point of them being around the oil side well they basically provide nourishment for the usa they keep it alive now this primary follicle or at least between 10 to 20 of these primary follicles that have just been made starting at day one they will not turn into the next form which is called a secondary follicle unless there is a stimulus to tell it to do so now this stimulus is going to be a hormone so we need to talk about the first hormone that's released within this process now what we need to talk about quickly is where's this hormone released from and what's its stimulus so if we were to draw up very quickly central nervous system we've got the cerebrum and the cerebellum and we've got the midbrain pons and medulla and then the brain stem there's a very important part which you've spoken about before and this important part is called the hypothalamus now the hypothalamus is located around about here and you know that just below the hypothalamus is a projection called the anterior pituitary gland and the posterior pituitary gland so this is what we need to focus on to begin with so i'll just get rid of this and i'll draw them up in more detail so i've got the hypothalamus i've got the anterior pituitary gland and posterior i'll just light them up for reference hypo thalamus anterior pituitary gland and this one's the posterior pituitary gland okay so what's happening well the primordial follicles are now turned into primary follicle follicles with these follicular cells providing nourishment to the oocyte now they want to go to the next form which are called secondary follicles but they can't unless a particular hormone is released now the hypothalamus has a number of different hormones that it releases one is called gonadotropin releasing hormone getting out of tropon releasing hormone so let's write that down gonadotropin releasing hormone what this means is this hormone releases gonadotropins because it's a good anatomy releasing hormone what are gonadotropins well gonado refers to sex cells so this is going to be either the ovaries for women or the sperm cells for males or testis i should say the ovaries for women are the testes for males so that's gonado tropin means it's a hormone that stimulates the release of another hormone okay so gonadotropin means it's a hormone that goes to the gonads to tell it to release another hormone and this gonadotropin releasing hormone without trying to confuse it releases gonadotropin so the hypothalamus produces gonadotropin releasing hormone and this travels down to the anterior pituitary gland to tell it to release get natatropins because that's again atropine releasing hormone so here in the anterior pituitary gland we have gonadotropins which are released now these gonadotropins there's two one is called follicle stimulating hormone and one is called luteinizing hormone so let's write that up very quickly fsh is follicle stimulating hormone and lh is luteinizing hormone so which one of these two do you think is going to stimulate this follicle from going from primary to secondary well it's going to be the follicle stimulating hormone so the primary follicle will not turn into a secondary follicle until fsh is released from the anterior pituitary gland and fsh like i said is going to travel to the ovum or to the ovaries and stimulate primary movement to secondary follicle now a secondary follicle cell again it has these follicular cells but these follicular cells have now turned into something else there's something else it's called granular cells so the ovum what will site the granular cells which are now surrounded by another group of cells called thicker cells and very importantly surrounding the oocyte is a layer called the zona pellucida so i'm just going to write that down here zona pellucida what's the importance of this zona pellucida layer surrounding the oocyte well when this oocyte has been released from the ovary into the uterine tube this zona pellucida allows for because remember it's going to be hopefully a number of sperm coming in to try and fertilize that oocyte and what the zona pellucida does is as soon as one sperm gets in to the zone of pellucida it shuts all the doors and doesn't allow any more sperm in so if i were to draw that up very quickly if after all this has happened so i'm jumping forward a little bit we've got the oocyte surrounded by the zona pellucida we've got all these sperm cells coming in once one sperm cell has penetrated through the zona pellucida no other sperm cell can get into the egg to fertilize it okay very important that's the function of the zona pellucida now once the follicle stimulating hormone released from the anterior pituitary gland has told the primary follicle to turn into the secondary follicle i said that there's the oocyte in the secondary follicle there's the zona pellucida important for letting sperm in there's granular cells on fecal cells now together the granular cells and fecal cells produce something very important and this important something is estrogen the hormone estrogen and what does estrogen do well estrogen will travel to the uterus and will tell the uterus to start to prepare its uterine lining why is it doing this because it's saying hey there's a baby coming fingers crossed we need to prepare the uterine lining for implantation so that's what this estrogen does so estrogen will travel and prepare that uterine lining for implantation now let's go to this graph which we haven't drawn up yet what two hormones have i've spoken about predominantly i spoke about fsh being released and i spoke about estrogen being released so if we were to first focus on fsh so let's put fsh in blue what you'll find is from day one fsh starts to increase okay why well because once this primary follicle cell wants to turn into secondary we need fsh to be released and it's happening a couple of days after day one starting from day one and moving forward once this has happened and we produce secondary cells estrogen is being released which means that so let's write estrogen in green estrogen starts to release and starts to go up now this secondary cell turns into something called a mature follicle so primordial follicle primary follicle secondary follicle mature follicle also known as a graffian follicle and what happens with this follicle is that again has the oocyte there's the zona pellucida remember important for letting sperm in has granular cells and these granular cells start to really grow really get thick and then has the thicker cells as well on the outside and what you see happens is it starts to protrude against the wall of the ovary okay and this is a mature follicle now this mature follicle because it's producing so many remember thicker and granular cells it again starts to release more estrogen so estrogen levels start to go up and up and up so that means estrogen goes up and up and up and up and up now the important point is as estrogen goes up it feeds back to the hypothalamus and stops what follicle stimulating hormone from being released so negative feedback so this follicle stimulating hormone starts to drop down again however once these mature follicles start to produce more and more and more and more estrogen what happens is the estrogen levels get so high that it hits a point in which for some reason we don't know why instead of negatively fading back it positively feeds back and so what do you think happens well we get a surge in the production of both follicle stimulating hormone and especially luteinizing hormone so higher levels of estrogen have now told follicle stimulating hormone to peak and i've now told luteinizing hormone to surge and before that luteinizing hormone was quite low but now what's happened is luteinizing hormone is bumped up like that really important so just before day 14 luteinizing hormone has bumped up now what does luteinizing hormone do luteinizing hormone travels to this mature follicle and it starts to weaken the wall of the ovary that's the first thing loot nosing hormone starts to weaken the wall of the ovary here where that mature follicle has started to protrude out and what does this do well this results in the oocyte or the egg from being released oops now once that egg has been pushed out and released it's surrounded like i said by that zona pellucida and what's remaining well the granular and thicker cells so what you end up having is a remnant group of cells that look like that now this remnant group of cells because remember we've got the oocyte has just been injected so now we've got the oocyte with the zona pellucida and now we've got these granular cells with thicker cells here okay now the continual release of luteinizing hormone at this point here continues to stimulate this little remnant group of cells what's it tell these groups of cells to do it tells them to release another hormone and this hormone that it's telling it to release is called progesterone just progesterone do progesterone travels again to the uterus and it tells the uterus to really start to prepare its lining for implantation because think about it that egg's now being released it's going okay baby's coming really starts to prepare for implantation so it thickens up that endometrium and this is also what progesterone does is it makes it highly vascularized we've now got a huge amount of blood vessels in this endometrial wall really important now think about what's going to happen this thing here which is now called the corpus luteum about it luteinizing hormone luteinizing means it turns it into something called the corpus luteum so the lutean body means yellow body because this yellow stuff is fat and cholesterol and produces progesterone and as this progesterone is released it further thickens up the endometrium makes it highly vascular vascularizes saying okay babies coming baby's coming it will continue to do this for about 10 days so think about it at day 14 what happened luteinizing hormone was released to tell the ovum to come out that's ovulation so day 14 was ovulation and we've got follicle stimulating hormone has dropped off luteinizing hormone is continually telling this system to release progesterone progesterone progesterone the estrogen levels have gone up and then start to drop back down again but for 10 days progesterone is continually being released by the corpus luteum to continually prepare this endometrial lining which means that if i want to now draw progesterone up it starts off low and then jumps up high and then jumps back down again now for 10 days because think about it if no sperm comes to fertilize the egg what happens at the end of the 28 days menstruation occurs so let's talk about that very quickly no sperm has come in do you think this corpus luteum has any idea that no sperm has come in has no idea so what it's thought what's going on is that it goes like i've released the oval and that ovum is going to get in fertilized by sperm and then implants itself into the endometrial wall that's what it thinks and so he goes okay i'll keep preparing the endometrial wall for 10 days and then what should happen is if that ovum does get fertilized and implants once that fertilized egg is implanted in the wall a signal should get sent if it doesn't happen no signal gets sent now after 10 days this corpus luteum if no fertilization has happened it goes uh you're not hearing anything what's going on so it starts to degenerate and starts to die and what happens to progesterone levels starts to drop off as progesterone levels start to drop off this endometrial lining which is now thick thickened and highly vascular vascularized also starts to die off and it begins to slough off that means it starts to fall away from the wall and this highly vascularized tissue starts to bleed out at day 28 and this is called menstruation so if no fertilization occurs what happens well what happens is no signal is sent progesterone drops off and menstruation occurs so just as a very quick recap what's happened well every female starts off with thousands of primordial oocytes primordial follicles at day one of their cycle reproductive cycle these primordial follicles between 10 to 20 of them turn into primary follicles these primary follicles under the influence of follicle stimulating hormone turn from primary follicles into secondary follicles these secondary follicles have granular cells and thicker cells which release estrogen this estrogen prepares the endometrial lining for implantation of a fertilized egg in addition to that it also sends a negative feedback signal to the hypothalamus saying stop releasing fsh and lh but as this secondary follicle turns into mature follicles it produces so much estrogen that for some reason that negative feedback reverses and becomes positive feedback and you get this huge influx of both fsh and lh specifically this lh results in this surge of luteinizing hormone that's been released this luteinizing hormone is important because it tells the egg to ovulate so that's what luteinizing hormone does tells you to ovulate and also tells the corpus luteum to release progesterone this progesterone will continue to be released for about 10 days and will further prepare the endometrial lining for implantation if that egg does not get fertilized and does not implant itself progesterone levels start to drop off this happens at around about day 28 once this progesterone levels start to drop off the endometrial lining starts to die and slough off and this is called menstruation in the next video i'll talk about what happens if that egg does get fertilized so in this video we're going to talk very briefly about the testes and sperm production so before we begin just remember that there are two testes and they are around about four centimeters in length two and a half centimeters in width and weigh around about 10 to 12 grams each the purpose of the testes is twofold predominantly they are there for sperm production and they are also there for androgen production now androgens are male sex hormones for example testosterone so what we're going to look at here first of all is i've drawn to the best of my ability a testy and you can see that well at least i've tried to cut out a wedge from the tester to see what's happening internally in regards to internal anatomy and also some of the physiological processes that occur within the teste so to begin with let's talk about some anatomy what you can see up here above so superior to the is what we call the spermatic cord and the spermatic cord moves from the testes up into the abdomen so this whole region here is the spermatic chord and within the spermatic chord are a number of different anatomical structures for example there's the ductus deferens the ductus deferens is sometimes called the vas deferens and that is a tube that carries sperm that's produced in the testes and carries it up to the rest of the ductal system for the male reproductive tract so that's the ductus deference is the tube carrying the sperm okay what else is within this spermatic cord is the testicular artery the testicular artery is obviously going to be a branch of the abdominal aorta coming down and going to provide nutrients to the testes so if there's going to be an artery that also means it's going to be a venous system so a vein now the veins that come back up and out of the testes are actually a plexus so they're like a braiding that comes out now it's not called the testicular artery per se but it's called the pampiniform plexus so remember i said plexus is like a braiding remember you've got the various spinal plexuses of the the spinal nerve plexuses and remember it's sort of going to come out like this and then it's going to look a little bit like that and then come back so this pampiniform plexus so remember you're going to have the aorta sorry the branch of the abdominal aorta which is the testicular artery coming down providing warm nutrient-rich blood to the testes and then you've got this pampiniform plexus coming up right next door to it now the reason why we have this pampiniform plexus is because this venous supply cools the arterial blood coming down why do we want to cool this blood well testes when it comes to sperm production the ideal temperature for sperm production is around about two to three degrees lower than internal body temperature which means the ideal temperature has to be two to three degrees lower than the blood that's coming in to feed it so this blood is going to be too warm for the testes and so this venous supply cools it down that's another reason why the testes are found exterior to the body okay all right what else can we find well we can find the testicular nerve and we can also find the cremaster muscle now the cremaster muscle is a muscle that comes down through the spermatic cord and what does it do well when it's relaxed the testes drop when it contracts the test is lift up again this has to do with temperature regulation so when the body is hot or when the temperature is hot again testes need to be two to three degrees cooler than the internal body temperature so the cremaster muscle relaxes and the test is dropped if it's cold well the testes need to be warmer contracts lifts the testes up now this is the spermatic chord you've got a couple of different layers surrounding the testes which we won't really go through but it's important that you know that there is a muscular layer surrounding the testes and that muscle is called the dartos muscle and the reason why i'm bringing this up is the dartos muscle plays another important role in temperature regulation of the testes so when it is cold the dartos muscles contract and wrinkles up the scrotum when it is warm the dartos muscles relax and the scrotum becomes less wrinkly and again has to do with temperature regulation when it's cold and wrinkles up well that means that it holds on to the temperature and vice versa when the temperature increases so what are the two muscles involved in temperature regulation for the testes the cremaster muscles which raise and lower the testes and the dartos muscles which change the scrotum in regards to wrinkly or less frankly okay now let's talk about sperm production now what you can find here is i told you that you've got that ductus deference which is in the spermatic chord and that ductus deference is attached here and what we're going to find is that this ductus deference is attached to the epididymis and the epididymis which you can find this part that i'm coloring in here is where sperm is stored and further matures okay the epididymis which i'm coloring in here is where sperm is stored and also further matures now there are some ducts or branches of this you go into the testings and these branches further branch off into individual lobes of the testes so you can see i've drawn individual lobes here there's actually around about 200 to 250 lobes within the testes and these lobes turn into smaller tubules and this is where sperm is produced these tubules are called seminiferous tubules now again let's label a couple of things first of all we've got the epididymis where sperm is stored and matures and here we've got tubules and this is where sperm is produced and therefore sperm being produced in the seminiferous tubules travels through these ducts into the epididymis and then up into the ductus deferens now what i want to do for the rest of this video is focus on what's happening right here in regards to sperm production so if i were to take one of these seminiferous tubules and have a look that's going to be inside of that tubule actually a little bit smaller so that's inside the seminiferous tubule and this is the wall of the seminiferous tubule and then you're going to have all the area outside of the seminiferous tubule now what you're going to find is that there's a number of different cell types that you need to be aware of first of all you've got cells present around here in the walls of the seminiferous tubules these cells are called sustentacular cells isn't that a good name sustentacular sustain tacular cells which we also call sertoli cells so told me okay what's the importance of cetaly cells they produce a very important hormone called abp and we'll talk about that in a sec a b p androgen binding protein in addition to that there are cells that sit outside of the seminiferous tubular walls so in the interstitium and therefore these cells are called interstitial cells so these cells are called interstitial cells but again they have another name and they're called lady cells and what a lady cells do roladex cells produce testosterone okay what else do we have we have stem cells in the walls of these seminiferous tubules sperm stem cells so these can't obviously turn into sperm so how does this process occur okay well once a male has reached puberty remember if we look at the brain your cerebellum uh cerebrum cerebellum uh midbrain ponds medulla so forth and that right here you've got your hypothalamus and you've got two danglies here which aren't the testes but is the anterior and posterior pituitary glands remember that the hypothalamus and the anterior pituitary gland is very important when it comes to sperm production so if we were to draw the hypothalamus up here here's the hypothalamus let's say that this one on this side is the anterior pituitary gland well remember similar to when we spoke about the femoral reproductive cycle you have gonadotropin releasing hormone which is released by the hypothalamus travels down through the blood supply to the anterior pituitary gland and tells the anterior pituitary gland to release two hormones called gonadotropins remember these hormones are follicle stimulating hormone and luteinizing hormone now what happens here is that these two hormones when a male reaches puberty is that they travel to the seminiferous tubules and if we have a quick look what you'll find is that the follicle stimulating hormone travels to the setoli cells and stimulates the tolly cells luteinizing hormone travels to the latex cells and stimulates the latex cells which means what happens when a mouth is puberty is that the sustentacular cells or the cetoly cells produce abp so now abp is released in here into the walls of the seminiferous tubules and luteinizing hormones stimulates the latex cells outside here in the interstitium to produce testosterone and this testosterone moves in as well together these two hormones stimulate these stem cells the name of these stem cells is spermatogonia okay spermatogonia or spermatogonium and together abp and testosterone stimulate their cells to start producing sperm and so this sperm is pre and what happens is as this sperm is produced it starts to move towards the lumen or the hollow inside of the tube so the hollow inside of that tube and as this sperm is being produced and starts to mature a little bit more it then gets into the tubule and what do we find we now have sperm within our seminiferous tubules and what did i say happen to those sperm they travel into the epididymis or they further matured and they're stored and then when it's time for ejaculation they'll move up to the ductus deferens so just to summarize this particular part here follicle stimulating hormone stimulated certainly cells and the setoli cells released abp luteinizing hormone stimulated the latex cells and they released testosterone together these stimulated spermatogenesis which is sperm production so if you have any questions pop me an email i hope that made sense hi everybody dr mike here in this video i want to discuss the really important role that the gonadotropins a set of hormones produced by the brain what role they play in both the male and female reproductive systems so to begin with we know that there is a part of the brain called the hypothalamus and there is a projection of the hypothalamus called the pituitary gland and it has an anterior and posterior lobe we're going to focus on the anterior lobe of the pituitary gland because that is where the gonadotropins are produced so the gonadotropins firstly gonad is referring to the male and female reproductive organs so for the males test these females ovaries tropins tells you that this hormone or these hormones are going to travel to these tissues the gonads and tell them to release more hormones all right now what are the gonadotropins the gonadotropins are follicle stimulating hormone so it's follicle stimulating hormone also known as fsh and luteinizing hormone also known as lh now these two gonadotropins follicle stimulating hormone luteinizing hormone they're named after what they do in the female reproductive system so let's focus on that one first so what do they do all right firstly let's look at follicle stimulating hormone and we know they play their role at the ovary so let's draw an ovary up here and what we need to know is that every month through the menstrual cycle the reproductive cycle what's happening is that there are these primordial follicles so there's a whole number of eggs and they need to begin to mature now what you're going to find is that around about 14 days of this cycle an egg will be ovulated this egg will be taking up into the uterine tubes or the fallopian tubes and we'll be waiting for fertilization for a sperm to come along now in order for this process to happen you're going to have a number of primordial oocytes that will turn into something called a primary follicle so this is a primary follicle right here now the primary follicle will be frozen it's stuck there until follicle stimulating hormone comes along that's unsurprising right it's named after what it does it stimulates the follicle so follicle stimulating hormone comes along and stimulates the primary follicle to turn into something called a secondary follicle and this secondary follicle will start to grow and develop a number of different cells around it now these cells are going to produce a hormone called estrogen really important estrogen that's the first thing the second thing is that this secondary follicle is going to begin to turn into a more mature or graphene follicle and this more mature follicle is going to really start to thicken up these cells now these cells are called granular cells or thicker cells they're going to start to thicken up really pump out that estrogen but now we're at around about day 14 and something needs to happen that egg inside needs to be ovulated this is where luteinizing hormone comes along luteinizing hormone stimulates ovulation this egg then becomes then gets ovulated and it's going to ovulate into the fallopian tubes right now the thing is this once luteinizing hormone has told that egg to ovulate these cells remain now we said that follicle stimulating hormone stimulates the follicles what does luteinizing hormone do so lutein means yellow luteinizing means to make something yellow what happens is these cells that are now remaining so there's a little group of cells that are now remaining they start to become yellow and they are called the corpus luteum corpus meaning body lutein meaning yellow now haven't drawn it up as yellow but it is and what these cells do is they start to produce progesterone so what have we found we've found that follicle stimulating hormones stimulate a primary follicle to go to a secondary follicle and that produces estrogen luteinizing hormone tells the egg to ovulate and the remaining cells called the corpus luteum produce progesterone what does both estrogen and progesterone do they prepare the uterine lining for implantation so uterus preparation endometrial thickening starts to become more vascular starts to thicken and this is going to obviously be beneficial for egg implantation or some fertilized blastocyst implantation let's now focus on what's happening in d so again let's just label this because this is the ovary this is going to be female let's now have a look at what's happening in the male reproductive system so we're going to have a testy not an ovary we're going to have a testing and in the testy we're going to have something called seminiferous tubules this is where sperm is produced and that's going to give you an indication as to what these two particular hormones are going to do so what we're going to find is in the test we're going to look inside the test is we're going to have a look inside the seminiferous tubules and it's going to be a hollow tube like this what you're going to find is there's a couple of different types of cells all right first type of cell is going to be a group of cells that sit inside this tube like this these cells are called sustentacular sustain tacular cells also known as sertoli cells really important then there's going to be a group of cells that sit outside the tubules they're called interstitial cells interstitial cells also known as lady cells all right what happens follicle stimulating hormone gets released what does follicle stimulating hormone do follicle stimulating hormone stimulates the setoli cells all right what does it stimulate the setoli cells to do stimulates them to produce something what does it stimulate them to produce something called a b p abp is androgen binding protein androgen binding protein all right what does luteinizing hormone do i'll tell you what it does in a sec luteinizing hormone stimulates the latex cells so think of the l in luteinizing stimulating the lady cells and what do they produce they produce testosterone testosterone all right here's the thing androgen an androgen is a male sex hormone testosterone is the male sex hormone antigen binding protein so it must bind to testosterone and that's exactly what it does abp and testosterone bind together and what do they do together they start to produce sperm so what do we have we've got estrogen and progesterone preparing the endometrium or the uterus for implantation and abp and testosterone producing sperm so luteinizing hormone stimulates latex cells to produce testosterone follicle stimulating hormones stimulates setoly cells to produce abp there's going to be a quick and easy way to present this now let's have a look what we can now do is take this information that we've learnt we can say all right here's male reproductive system his female reproductive system follicle stimulating hormone for the male reproductive system follicle stimulating hormone for the female reproductive system what did it do let's start with female stimulated primary to secondary follicle then what did that secondary follicle do it produced estrogen what about the male reproductive system follicle stimulating hormone stimulated what cell type was it it was the was it interstitial was it certainly it was setoli stimulated the setoli cells and these setoli cells produced do you remember what it was androgen binding protein a b p luteinizing hormone luteinizing hormone stimulated ovulation in the female reproductive system and that corpus luteum that was remaining what did that so led to a corpus luteum what did that corpus luteum do it produced progesterone what about in the male reproductive system luteinizing hormone latex cells what do the latex cells do testosterone testosterone and together what did these two do sperm production and what did these two do in the female reproductive system prepare the uterus so there we go this is the role that the gonadotropins fsh and lh play in the male and female reproductive systems you

Channel: Dr Matt & Dr Mike

Views: 49,980

Keywords: lecture, university, college, biology, reproductive, system, reproduction, hormones, testis, testes, testicle, ovary, uterus, baby, implantation, menstrual, cycle, gonad, gonadotropins, lh, fsh, sperm

Id: bqZAYZTeMbk

Length: 69min 9sec (4149 seconds)

Published: Mon Sep 07 2020