the male reproductive system now most people are familiar with the external structures of the male reproductive system but there's actually a lot of structures inside that people are less familiar with in this video we're going to look at all of those different structures of the male reproductive system what each of them does and how they're all connected to each other and to other structures in the urinary system and then we'll identify all of those structures on the torso model to get a better idea of their three-dimensional orientation inside of the pelvic cavity so let's jump to the white board and get started so here we have a sagittal cross section of the pelvic area we can see a leg back here we can see the penis the scrotum and we can also see the colon and the anus where the colon connects to the outside of the body posterior to the colon we have vertebrae of the spinal cord and here on the anterior side we have the front of the pelvis or really the cartilage between the two halves of the pelvis as you can see on mortimer here the main reason that i include these structures in the diagram is to give us a better understanding of where the male reproductive structures are in relation to nearby organs the first structure we'll talk about are the testes the testes are the primary sex organ in the male reproductive system and they're the site of spermatogenesis or the creation of sperm cells before they technically become sperm cells these cells called spermatocytes will undergo meiosis which is going to reduce the number of chromosomes from the normal 46 down to 23. most of the cells in the human body have 46 chromosomes or 23 pairs of chromosomes but after undergoing the process of meiosis that number is reduced down to 23 individual chromosomes whenever fertilization of an egg cell occurs 23 chromosomes will come from the sperm cell and 23 chromosomes from the egg cell creating a new combination of 46 chromosomes for that new zygote inside the testes are these long coiled tubes called the seminiferous tubules as these spermatocytes travel through the seminiferous tubules they'll undergo these processes of mitosis and meiosis and they'll eventually develop into mature sperm cells that have the potential to fertilize an egg now before we move on let's take a look at the structure of the sperm cell itself the sperm cell will have a head which will contain the nucleus and that's where all the genetic material those 23 chromosomes are going to be located in the body of the sperm cell there's going to be a mitochondria that's shaped in this strange sort of coil pattern and that's going to help provide the sperm cell with the energy that it needs and finally there's the tail the tail is in a coil and it's going to rotate and spin that coiled rotation of the tail will help that cell travel through the female reproductive tract for fertilization if sexual intercourse has occurred a couple fun facts about the sperm cells they can only make left turns because of the direction that their tail rotates another interesting fact is that sperm cells are the smallest human cells in the body and egg cells are actually the largest human cell in the body and whereas the egg cells have a lot of nutrients already built into the cell itself the sperm cells have to get all of their energy from sugar that's found in the fluid that surrounds the sperm cells now this process of spermatogenesis or the production of sperm cells takes place at a slightly lower temperature than the body's normal internal temperature and because of that the testes must hang outside of the body in a sac called the scrotum the scrotum is essentially a patch of skin that's going to help regulate the temperature of the testes to maximize sperm cell production whenever it's cold the scrotum will contract and pull those tests up closer to the body to keep them warm and whenever it's warm then the scrotum will relax so those testes can keep farther from the warmer temperatures of the internal body the testes also produce testosterone the primary male sex hormone they're not drawn in the diagram but there's lots of blood cells that go to the testes and whenever the testes produce testosterone it's not going to go through the other tubes that i'm about to talk about that hormone will travel directly into the bloodstream straight from the testes the sperm cells however follow a different path they're going to travel next through a structure called the epididymis the epididymis starts at the top or superior part of the testes and then it's going to travel down and then back up to the vas deferens the epididymis is basically an extension of those seminiferous tubules where the sperm cells will continue to grow and mature and develop until they're ready for ejaculation now during sexual arousal and then ejaculation the sperm cells will travel up through a tube called the vas deferens the vas deferens extends from the testes and the epididymis upward anterior to that pelvic bone and then posterior to the back connected to the back or the posterior part of the vas deferens are a pair of glands called the seminal vesicles that word seminal is the same root as semen and the seminal vesicles are going to produce some of the fluid that the sperm travel through during ejaculation and to clarify a couple terms here sperm refers to the cells produced by the testes that carry genetic information whereas semen refers to both the fluid and the cells that travel during ejaculation the semen acts as lubrication for the sperm cells to travel as well as providing nutrients that supply the sperm with the energy that they need and just past the seminal vesicle the two vas deferens will join with the urethra which is connected to the bladder so here's the bladder which of course stores urine until it's ready to be expelled during urination and the bladder is connected to the kidneys by two tubes called ureters which will bring the fluid from the kidneys down to the bladder to be stored you can see that here in the diagram as well this spot where the two vas deferens joined together with the urethra is also surrounded by a gland called the prostate gland the prostate just like the seminal vesicle will secrete some of the fluid that makes up the semen that the sperm travel through now the prostate gland in the male reproductive system is the common side of a couple disorders an enlarged prostate or even prostate cancer and after a certain age men need to have their prostates checked so let's talk real quick about prostate exams notice on the diagram the location of the prostate it's really close to the colon but it's pretty far from everywhere else and so how does a physician check a prostate to see if it's enlarged or if there's a chance of prostate cancer well they can test through a digital examination or in other words inserting the finger up through the anus into the colon and feeling for the anterior side of the prostate and that way they can tell if the prostate gland is larger than it should be which is indicative of prostate cancer or an enlarged prostate oftentimes one of the first symptoms of an enlarged prostate or prostate cancer is difficulty urinating so let's think about why that would be well notice that the prostate surrounds the urethra just below the bladder if that prostate is enlarged it's going to be pushing on the walls of the urethra making it really difficult for urine to travel through the urethra and out of the body just inferior to the prostate is a pair of glands called the calpers glands or the bulbo urethral glands bubble because they're shaped like a bulb and urethral because they're attached to the urethra just like the prostate and the seminal vesicle the bubble urethral glands will secrete part of the fluid that makes up the semen from there the urethra extends through the shaft of the penis and then out to the outside of the body the penis of course is the main delivery system of the sperm basically the sperm travel through the penis and outside the body during ejaculation the end or the head of the penis is referred to the glands penis and here surrounding the gland's penis is the foreskin which sometimes gets removed during circumcision if we want to follow the path of sperm traveling from the testes to the outside of the body it would go like this the sperm are made in the testes they'll develop as they travel through those seminiferous tubules through the epididymis and then they'll travel up through the vas deferens then back and then down there they'll mix with semen which is produced by the seminal vesicle prostate and bulbourethral glands and then from the vas deferens they'll connect to the urethra where the sperm will travel out through the penis to follow the path of urine out of the body urine will of course start in the kidney travel down through the ureters into the bladder where it's stored then during urination the bladder will contract and that'll expel the urine down through the urethra to the outside of the body and just as a reminder testosterone doesn't travel through any of this testosterone goes straight from the testes into the bloodstream where it travels throughout the body speaking of which while i've got this diagram up let's talk about vasectomies during a vasectomy the doctor will make a little incision in through the scrotum and they'll make a cut into the vas deferens hence vasectomy or cutting of the vast difference when the two ends of the vas deferens are cut and tied off then suddenly sperm are not able to exit the body through that vas deferens any sperm that are produced will just break down and be absorbed now somebody deciding to have a vasectomy might have some concerns about this they could wonder will ejaculation still happen and the answer is yes if you notice the path of semen traveling from the prostate gland and the seminal vesicle in the bulbourethral gland is not obstructed by the vasectomy they could also wonder about testosterone would a vasectomy reduce their body's ability to make and release testosterone the answer to that is no as well because remember the testosterone doesn't travel through the vas deferens at all it just goes straight to the bloodstream from the testes now let's take a look at terry the torso model's reproductive system and see what these structures look like three-dimensionally in the body so let's start with the external structures that we can see here we have the glans penis as well as the shaft of the penis we have the scrotum which is going to surround the testes and we have the epididymis just above the testes right here you'll notice here in the scrotum we have these red lines which are muscles which will pull the testes up closer to the body or let them go farther away from the body depending on the temperature so sperm cells will grow in the testes they'll mature in the epididymis and they're going to travel up the vas deferens which runs up here you can see the vas deferens better on this side as it travels this way and then on this side the vast difference travels back this way and the two vas deferens are going to run in front of the pelvic bone which we can see right there so as the sperm travel up through the vas deferens they're going to reach back here the seminal vesicles where the seminal fluid or semen gets released and then the vas deferens will converge back here i can open up the model here and we can see a little bit better here's the prostate gland and there's the little tube that's the vas deferens where it's connecting to the urethra we have the bladder here and here on the side we can see that's going to be one of the ureters that connects up to the kidney back over here we can follow the urethra as it travels down through the prostate gland here's going to be the bulba urethral gland that tiny little gland right there and then the urethra travels down through here and then out through the shaft of the penis back here of course you see the colon which is really close to the prostate gland and then there is the anus i can also show a cross section of the inside of the penis which looks like this it's going to have the urethra which travels through right there and that's where urine and semen both travel through these other two sections right here and right here are blood sinuses during an erection the arteries in those areas will expand and blood will rush into the penis during the erection so to recap all those structures again we have the scrotum the testes the epididymis that's going to connect to the vas deferens which runs along here we have the seminal vesicle the vas deferens will connect right here to the urethra that's in the prostate gland here's the bladder we've got the ureter back over on this side the urethra extends down through here there's the calpers or bulbourethral gland and then the urethra extends the rest of the way down through the penis all right that was a lot of different structures take a moment pause the video and see if you can identify all of the structures of the male reproductive system as well as what each structure does first we have the testes which are the primary sex organ of the male reproductive system they'll produce testosterone as well as produce and develop sperm the sperm cells travel through the epididymis where they mature and develop and both the testes and the epididymis are contained within the scrotum which is going to help regulate the temperature of the testes during ejaculation sperm will travel through the vas deferens and those sperm will pass by the seminal vesicle the prostate gland and the bulb urethral or calpers gland which all produce some of the fluid that makes up the semen and here on the diagram we have the bladder which is connected to the kidneys via the ureters and the urethra extends down from the bladder it'll connect to the vas deferens in the prostate gland and then run to the outside of the body through the penis the head of the penis is referred to as the gland's penis and it's surrounded by the foreskin so those were the structures of the male reproductive system thanks for watching normally this is the part of the video where i make jokes to fill the time while asking you to subscribe or watch another video but it feels weird to make jokes about the reproductive system so i guess i'll just put this back and uh see you next time