hey everybody in this video we're going to go through the male reproductive system we're going to start by talking about sexual reproduction and development so we're first going to look at um sex disting distinctions so the male and female gametes or the sex cells are combined to form a zygote during fertilization so the two gametes are the sperm or the Egg the sperm is the one that has um motility um and the parent producing the sperm is considered the male um or in humans they have a y chromosome genetically the other gamate contains the nutrients for the developing embryo and that would be the egg or the ovam and so this would be produced by the female and they are lacking a y chromosome again in humans um so when we're looking at our embryonic development um the sperm will determine gender so the purposes of the male reproductive system is to produce the sperm and introduce them into the female body the female reproductive system is a little more complex and involves multiple um processes because it needs to produce eggs as well as receive the sperm and provide a place for fertilization and then also Harbor the fetus and nourish The Offspring um which would also include lactation as well the reproductive system can be simply divided into the primary and secondary sex organs the primary sex organs are the gonads are the ones that produce the gametes so that would be the tesses in the male and the ovaries and females the secondary sex organs are all the other organs that are necessary for reproduction um and so the male that's going to include the Ducks the glands the penis for the female the uterine tubes uterus vagina reproductive organs are also classified by location so we have both external and in and internal genitalia the external genitalia are externally visible um except for some of the accessory glands and then the internal genitalia is look could in the pelvic cavity um the cheses are considered internal genitalia because they um develop in the pelvic cavity and then later move into the scrotum secondary sex characteristics these are the things that um visually distinguish the Sexes and influence mate attraction so some examples of things like this would be like the peacock versus the peen the peacock has the real pretty tail the peen is brown we see this a lot in in Birds but we also see this in humans too um so these secondary sex characteristics in humans develop at puberty um so both sexes get pubic and axillary hair um and increased scent glands and pitch of the voice will change males will also get facial hair and hair on the Torso and limbs that becomes thicker and more visible and increased muscle mass females get distribution of fat in the hips and the thighs breast enlargement and then their body hair will become ther and thinner so looking at at the genetic sex determination so again in humans our cells contain 23 pairs of chromosomes um the first 1 through 22 are autosomes and then the last pair are the sex chromosomes so again in humans if you have XY that would make you male if you have XX that would make you genetically female so males produce sperm that have um half Y chromosomes and half X chromosomes all eggs so from the female always carry an X chromosome so gender of the baby would be determined by which sperm cell they get okay so if you get a x carrying sperm then you have two x's and you would be female if you have a y carrying sperm you would have a x y and you would be male so again you can see this right the egg is always an next chromosome and then the sperm either carries an X which will give you two x's and make you Fe genetically female or the sperm carries a y and makes you XY which would make you genetically male sex determination also results from an interaction so between genes and hormones um so initially our fetus is sexually undifferentiated meaning we can't tell if it's going to become male or female um and so this sexual differentiation will start at 5 to six weeks so the undifferentiated fenus fetus has two sets of ducks um we have Meson nephric Ducks which would develop into the male reproductive tract and we also have the paramone nephric ducts which would develop female reproductive tract Meson nephric ducts are also called wolfian ducts and the paramone nephric ducts are also called the malarian ducts so these undifferentiated uh fetus at five to six weeks has both of these ducks so then we have to have some sort of signal to to cause development of one duct and regression of the other and this is actually determined by the s r y Gene um which stands for sex determining region of the Y chromosome and this is found in males because it is found on the Y chromosome so the SR y Gene is then going to code for a protein which is testes determining Factor this will initiate the development of the testes then the testes will begin to secrete testosterone and this test stimulates those Meson nephric ducts to develop into the male reproductive tract the testes will also secrete malaran inhibiting factor which causes degeneration of the perinephric duct so we will the testosterone will stimulate the mzc decks to develop male and the malarian inhibiting factor will cause degeneration of the parom mesc Ducks so then the male genitalia would develop development of the female results from an absence of androgens rather than the presence of estrogen so estrogen is always high during pregnancy because it's a maternal estrogen so if we have an absence of androgens then it would develop female about 1% of individuals are intersexual so there's a disconnect between the um genes so the chromosome the gonads and the genital genitals um so they may be male in some of those and females in other and there's a lot of ways that this can occur but some examples um you can get a Sr y Gene it's transferred from a y to an X chromosome so you could have a sperm that is actually X um and pass the sry gene to an XX child so they would genetically would be have female because it's XX but then the gonads and genitals would actually develop male um an XX fetus so again genetically XX can also be ma masculinized by abnormally High Androgen exposure this is called adrenogenital syndrome and then we also another example of this is Androgen and sensitivity Disorder so in this case the individual genetically is XY so they would genetically male and they have testes internally that would secrete testosterone but they would show a a feminine phenotype and it's because they have um a lack of testosterone receptors so this is would be a person with Androgen and Sensi Sensitivity Syndrome externally they look female internally they have testes and they have XY chromosomes um and so this person would um look like a girl externally so again we would assign them female um but they would fail to menstrate so we would see this would be one of the first um things that we would see okay um and then upon examination we would see the presence of testes in the abdomen and you could do DNA taste and they would have XY chromosomes in this condition the testes produce normal levels of testosterone but we don't have the receptors so go back to our endocrine system if we don't have receptors it's as if the hormone doesn't exist and so the external genitalia actually developed female anatomy um there is no uterus or ministration um so again they would be male as based off of their chromosomes and the gonaz but not with respect to the genitalia also just want to take a note to talk about um gender versus biological sex so gender and biological sex can be different gender is our psychological sense of masculine feminine or other sexual identity and sex and social role humans don't fall into two simple binary categories male and female and there is a wide range of biological variation that creates this spectrum from feminine to masculine both um in anatomy and physiology and and psychology so you saw we've already talked about some examples of that so the development of the external genitalia of males and females is is similar um to the internal genitalia that we just talked about so we have we start with a embryo that has undiff shed tissues and then based off of the hormones those tissues will develop into either an external male or female part so we have the genital tubal um and so if that is stimulated by uh testosterone it would become the head or the glands of the penis if it is stimulated by estrogen it will become the glands clitorus the second embryonic tissue is aale of urogenital folds if it is simulated by testosterone it will it becomes a tube that encloses the male urethra if it is stimulated by estrogens um it's going to form the labia minora and then the third embryonic tissue are the labioscrotal folds um and so the labioscrotal folds if they're stimulated by Androgen and testosterone will become the scrotum if it's stimulated by estrogens would become the labia majora and so this process of sexual differentiation is usually completed by week 12 so this all happens in that first trimester okay these organs that develop these external genitalia organs that develop from the same embryonic tissues are homologous because they came from the same embryonic tissue so if you look at here's our embryo okay and you can see that they have right this is going to be the mesonic duct and then your paramone nephric duct okay and so as we go through right this starts at five to six weeks okay so you can see if we have testes that are secreting testosterone and the malarian in inhibiting Factor then we're going to get um the Meson nephric duct is going to develop and form the glands and the and the ducts that are necessary for sperm and for the male reproductive system okay and the tessis are going to secrete the malarian inhibiting factor which is going to cause the parone ducts to degenerate conversely without testes right we don't have testosterone we don't have the malarian inhibiting factor therefore the Meson nephric ducts degenerate and the parone nephric ducts will develop into the uterus vagina and the uterine tube with the ovaries for the female that's the internal genitalia then looking at the external genitalia um again our undifferentiated embryo we have a genital tubic we have two urogenital folds into two Laos scrotal folds so again 5 to six weeks it's undifferentiated okay by the time we get to 10 to 12 weeks we have differentiated sexual differentiated tissues so again um the EUR we'll get the uh glands penis or the clitorus and then you have the tube that surrounds the urethra or the labium or or the scrotum or the labia majora remember this is again dependent upon hormon so this is completed by 10 to 12 weeks so the gonads initially are going to develop in the abdominal cavity and then migrate to the pelvic cavity so they are considered uh internal genitalia we have this gacul which is an embryonic connective tissue core it goes from the gonad to the pelvic cavity floor um in males it does pass between the internal and external oblique muscles into the scrotal swelling so it's going to go into the scrotum um uh vaginal process forms which extends into the scrotum um and then the gubernaculum and vaginal process create this inguinal Canal which is basically a a pathway okay of low resistance through the groin through the groin um so that we can get the tessi pulled into the scrotum um but it also is a common site for hernas in males because it does it it's it has low resistance and so it does can cause herniation later on so The Descent of the testes will begin as early as six weeks um in the seventh month again this is embryonic development so in the seventh month of pregnancy right the tesses will pass through that ininal Canal into the scrotum Again by that we just shorten that gubernaculum um and as the testes get pulled into the scrotum we're going to elongate the testicular arteries veins lymphatic vessels Nerf spermatic ducts all that's going to elongate to allow the testes to drop down into the um scrotum about 3% of boys are born with undecided testes this is called cryptorchism um we can monitor this uh we may need to go in and pull out pull the testes down into the scrotum if they don't descend on their own after about a month of being born um teses that remain in the pelvic cavity are not able to produce viable sperm and increase the risk of testicular cancer the ovaries will also descend but to a much lesser extent they just um end up on the pelvis and then the gacula becomes ligaments that will help support the ovary and the uterus so here if we look at the chest sees because it's a little bit more dramatic okay so here is the chesses so the green here is the gacula and then you can see the um hole here right okay and so the gacul is going to just shorten and as it shortens right the blood vessels and the spermatic cord and all the things that are in it are going to lengthen okay and the gacul is going to shorten and it pulls the testes down into the scrotum through the ininal canal okay so now we need to look at Focus just on the male reproductive Anatomy so we're going to go through each structure and function so the male external genitalia includes the scrotum and the penis um so the scrotum is the pouch of skin muscle and fibbr tissue that contains the testes okay the left testicle usually descends lower than the right um the scrotum does has have sebaceous glands hair sensory innervation and darker pigmentation deep to this skin is this dartos fascia this is a layer of smooth muscle this is the dartos muscle and connective tissue this is going to be important for helping temperature regulation okay so you can see looking at the external genitalia we have the penis and the scrotum and the anus um inside of the scrotum then we have the internal medium septum we've talked about a septum before physically divide so this divides the scrotum into the right and left compartment and we have these uh perennial R which is a midline seam on the scrotum so it marks it's external marking of that Medium septum um the scrotum also contains the spermatic cord this is important because it it houses um the ductus defrin the blood the lymphatic vessels the testicular nerve and again this will go through that inguinal Canal okay um and then we also have within the spermatic cord we have uh internal oblique muscles called the creamy stir and this also is going to help with temperature regulation so the reason that the testes are located in the scrotom is because it is cooler um and so we can't produce sperm at our core body temperature of 37 degre C so we need to drop that temperature a few degrees to about 35° CSI um and so having the tesses located outside the body helps that but then we also have um some other mechanisms to help regulate the temperature so we I briefly talked about them let's talk about them more so the Chaser um when it's cold this will contract and pull the testes closer to the body when it's warm it will relax and the tessis will move further from the body the dto fascia the D muscle is smooth muscle and so it controls the surface area of the skin of the Tess so when it's cold it will contract which will wrinkle the scrotum which again holds the tesses against the body and then when it's warm um it will relax which flattens out that which allows for increased heat loss we also have this pampiniform plexus um this is a Venus plexus around the testicular artery and so it's it's a countercurrent blood flow we've talked about counter current before essentially what happens is the pampan plexus as the um as the testicular arterial blood goes into the testes right it's coming from your core body temperature it needs to cool as it goes into the testes and so it does that by passing off the heat to the testicular um Venus blood which was cool which will then heat up back to core temperature so arterial blood cools down and passes the heat onto the Venus blood so it will warm back up is pretty interesting um the testes are we did talk about them with the endocrine system right they are both an endocrine and an exocrine gland um so endocrine they produce the sex hormones and exocrine is the sperm um the testes is covered by the uh it's it's an oval okay it's covered by the Tunica of vaginalis uh anterior and laterally and then the tunic Albania which is the white fers capsule around it inside the testes it's divided into these seminiferous tubules which are where sperm produced between the seminiferous tubules then we have our interstitial cells that will produce testosterone always looked at this before but we can look at it again okay so here is our cies with our spermatic cord here's our epidemis this is covered by the tuna alenia so the scotum has been folded down here so again here's your spermatic cord okay vast deference epidemis eer ductil okay Tunica alenia and then the Tunica vaginalis is okay the anterior it's got two layers here and then you can see the seminiferous tubules here that are divided okay each seminiferous tubule then has a thick epithelium um and the epithelium is composed of several layers of developing uh sperm cells and then also has these Nerf cells um which are called sustentacular or ctoi cells um they will protect the sperm cells okay um so they will actually secrete two hormones Androgen binding protein which promotes spermatogenesis and then inhibin which is going to inhibit spermatogenesis additionally um these cells are held together by tight junctions and form our blood testes barrier this is important because it prevents our antibodies and immune cells from attacking the germ cells so the body is no longer able to recognize the sperm cells as belonging to them and so the immune system will attack it so we have this ctar these Nerf cells that separate this Blood testes barrier so we keep the immune cells away from the SPM cells so again here if we look at our cross-section of our tesses we have a seminiferous tubule okay um a lot of these cells here are those spermatogonia speratti sites and spermatids so these are all the developing cells okay um we have the interstial cells are going to be outside the seminiferous tubule and you have the uh Nerf cells right that are going to help form that blood testes barrier and promote spermatogenesis regular spermatogenesis so after the sperm are produced then they need they're going to go through these ducks to to leave the body okay um and so they are going to go the C tubules are going to lead to a network of re testes so this is going to collect the sperm from the tubules um the sperm do not swim while in the male reproductive tract so we have fluid and we have cyia we have pistolic contractions that will help move the sperm through um each arter each testicle also has a testicular artery okay um remember this is going to cool um it also there's a low blood pressure so there's actually kind of a a poor oxygen supply um but the sperm are going to develop mitochondria to help cope with that um and they need that anyway because they need it to um be able to produce energy in the hypoxic environment of the female reproductive tract um then the blood will leave the tesis so we drain blood through the testicular vein again through that pampiniform plexus so we're going to um heat it back up the right testicular vein will drain to the inferior vnea the left one will go into the renal vein we ALS o have our testicular nerves so these come from our spinal cord from T10 to t11 um and this will carry a sensory fibers so pain and also sympathetic fibers for blood flow the spermatic decks then are then where the the sperm are going to go through when they after they leave the testes so the first place they're going to go is the eant ductal this about 12 small ciliated ducts so again the cyia will help collect the sperm from the Reet tesses and then they deliver them into the epidemis um the epidemis does have a head body and tail but the epidemis is the site of sperm maturation or storage so the sperm have to be here for at least 12 days to mature and then they can be stored here for up to 60 days if the sperm are not ejaculated they disintegrate and the epidemis reabsorbs them after um so during ejaculation then the sperm will enter into the ductus Defence or the vast Defence um this goes from the tesses okay um urinary bladder and then it's going to come in contact with the simal vesicle and the ejaculatory and then into the ejaculatory duct um the ductus defin will do peristalsis again that's going to be those smooth muscle contractions to help move the sperm and then once into the ejaculatory duct um this is where that ductus deference and the semal vesicle are going to merge this goes through the prostate and then into the urethra uh remember we've talked about the urethra before because it is part of both reproductive and urinary system just as a reminder the male urea has has three regions prostatic membranous and spongy urethra so let's look kind of quickly so we have our tesses okay you can't see the eer ductal but then it would go into the epidemis into the vast Defence ejaculatory duct and then the urethra okay that's how the sperm would travel through the Bonnie again different view testes eent ductal epidemis vast Defence okay ejaculatory duct urethra so besides the ducts we also have the glands that are going to produce um fluid and Secret ions um so we have the seal vesicles this is a pair of glands this forms about 60% of the semen we have the prostate which remember surrounds the urethra and the ejaculatory duct it's going to make a thin milky secretion which forms about 30% of the semen the other 10% of the semen is sperm cells and then we also have the bulbo urethal gland it's called this because it's near the bulb of the penis um it produces a clear uh lubricant um in preparation for intercourse it also is alkaline so it is um will help neutralize the acidity okay and this is not part of the simal fluid the bobal urethal gland secretion is secreted preejaculation so prostate cancer and prostate diseases are um important things to consider especially for people that have a prostate so um you can have benign prostatic hyperplasia this is a non-cancerous enlargement of the prostate because the urethra and the ejaculatory duct run through the prostate enlargement of the prostate can compress the urethra um which can lead to increased um bladder and kidney infections prostate cancer typically goes unnoticed until it becomes painful um and so again cancer early detection is best right so we check for tumor for tumors with a digital rectal exam so we palpate um the prostate through the rectal ball and we can also diagnose it through a blood test we look for elevated levels of seran proteas to PSA and acid phosphatases in the blood okay and then the penis is job is to deposit the C into the vagina um half of the penis is internal root the other half is externally visible which is the shaft and the glands okay the skin over the shaft Loosely attaches to allow expansion and and extends over the glands as the preuse or the foreskin that can be removed during circumcision um and it does it is held in place by the frenulum which we've seen frenulums before uh the penis contains three cylindrical bodies of erectile tissue um that fill with blood okay um so we have a single Corpus spongiosum this is along the ventral side this is um encloses the sponge your penile urethra and forms the glands penis and then you have two corpa cavernosa and they are like arms of a y um and so the three cylinder cylinders of rectile tissue are spongy again it's got lots of blood sinuses and spaces so that it can fill with blood during erection so if you look at this you can see the Corpus spongiosum and then the Corpus cavernosum so again here's the Corpus spongiosum and we go into the head of the penis and then the Cor F this CERN of some on each side all right let's talk about um puberty and hormone control and climac ter so reproductive systems remain dormant from birth until until puberty um puberty is that onset of an increase in gonadotropin so triggered typically by G&R secretion um tend 12 year old is when this is going to probably start in males until we get the first ejaculation of viable sperm which is about 14 years old adolescence then is the period that includes puberty until until you retain your full adult height for males the hormones that are primarily responsible for this are testosterone and DHT this is where we're going to start to get those secondary sex characteristics as well so growth of sex organs the secondary sex characteristics increase in libido or sex drive sperm production and body growth um we're going to go back and look at how this is regulated through reminding ourselves of the endocrine system so this is regulated through the hypothal pituitary gonad ex AIS so we're going to start in the hypothal hypothalamus we're going to get an increase in GnRH remember that G&R then triggers the release of FSH and LH okay FSH stimulates those Nerf cells or those SOI cells to secrete Androgen binding protein that will stimulate spermatogenesis those Nerf cells or ctoi cells can also secrete inhibit which will suppress FSH which would slow down spermatogenesis G&R also triggers LH okay LH from the interstitial cells or the LI egg cells to produce our androgens mainly we're talking about testosterone here so that's hypothalmic and pituitary hormones that act on the gonads so again we can look at it this way right so here's our hypothalmus okay going to produce G&R goes to our anterior pituitary to release F FSH the nurse cells secrete Androgen binding protein and promote spermatogenesis GNR also triggers LH goes to the interal cells to secrete testosterone with which uh increases spermatogenesis the nerve cells can secrete inhibin which will inhibit FSH so that will reduce um spermatogenesis okay um also if we have low testosterone levels right that's going to inhibit GNR from the hypothalmus as well testosterone secretion will decline with age due to the decline in the number of interstitial cells so some effects that we see is reduced libido a decline in seam and volume sperm count and sperm motility um elevation of FSH and LH because there's a lack of of negative feedback so it can cause mood and personality changes um also more likely to develop erectile dysfunction these changes are called andropause okay next I want to talk about sperm and semens so we want to talk about spermatogenesis so this is the process of producing sperm in the seminiferous tubules there kind of three main events that are happening here so the first is the division and remodeling of these large germ cells into the small mobile sperm cells that you're used to seeing we have to reduce the chromosome number by half so we have to produce haid cells and this is where we get shuffling of genes so that we get genetic variation so that each sperm contains genetically variable DNA um and so we're going to use meiosis here to do this cell division to reduce our chromosome number so that we end up with four um capoid sperm cells so they have 23 chromosomes so just a reminder um mitosis versus meiosis okay so you should have learned this but let's just do a real quick reminder U mitosis is when we have a diploid cell it doubles its DNA and divides into two genetically identical cells so you start with a diploid cell and you end up with two genetically identical diploid cells okay remember that there are four phases of mitosis prophase metaphase anaphase and telophase um mitosis is used for um growth tissue repair those types of things okay meiosis is our specialized type of cell division that only occurs in the G in the gonads this is when we have a diploid cell that ends up producing four haid gametes so we go through two divisions and then you end up with four haid gtes and meiosis okay so it's this is sometimes called redu reduction division okay but this only happens meiosis only happens in the gonets to produce sperm and eggs so looking at sperm production okay um we'll just start embryonically you have primordial germ cells in the Yol sack of the embryo they're going to colonize the scadal ridges and these become stem cells which are called spermatogonia they're going to hang out and do nothing until puberty okay puberty then will initiate spermatogenesis um because with this increase in testosterone level this is going to activate those spermatogonia so once we have high testosterone levels the spermatogonia are going to divide by mitosis first okay so you got have a spermatogonia it's going to divide and you're going to get two cells so you have a type A and A type B spermatogonia the type A is going to stay in the tubular wall and remain as a stem cell to keep undergo mitosis type B will come come away from the wall and it is going to continue on and undergo meiosis so the type B spermatogonium enlarges it changes into what's called a primary [ __ ] this will go through that blood testes barrier so now it's protected from the immune system before it becomes genetically different the primary two haid secondary spermatocytes okay meiosis has two phases okay so each um secondary [ __ ] under goes meiosis to it to produce two more two haploid spermatids so you actually end up with four spermatids okay and then we have another process where each spermatid must undergo spermiogenesis this is where it's going to go under a transformation shape change from that round cell into the sperm shaped cell that has that um flagellum in it so let's look at spermatogenesis first so we have our type A spermatogonium it's going to undergo mitosis and divide right and becomes a type B spermatogonium okay the type A is going to stay here and keep dividing so we can keep getting type D okay the type B is going to enlarge and become a primary spermatocyte it's then going to go through the blood testes barrier so here's our blood testes barrier so it's protected okay it's going to undergo meiosis one and divide into two haid secondary spermatocytes it will then undergo meiosis 2 and those two cells will split into two more cells and become haid spermatids so you end up with four spermatids and then they're going to undergo the shape change during spermiogenesis become sperm cells spermatazoa so the spermatazoa has two parts so it has the head and tail um and then within the head we have the nucleus which is contains the haid cells um and we have the basil body which attaches the flagellum we also have the acome which is the enzyme cap this is important because it has the enzymes that are needed to penetrate the egg the tail then has three regions the mid piece which contains the mitochondria this is important for being able to produce that fella movement the principal piece which makes up most of the tail and then you have the very narrow end piece of the tail so looking at spermiogenesis where we're doing that shape change right we have uh the appearance of the acromo vesicle and flugum in the spermatid we have the growth of the acrosome and the selum we're going to shed the excess cytoplasm and organel okay and we end up with our sperm we have the head that has the nucleus the acrone and the basal body the tail the mid piece is filled with mitochondria the principal piece and then the end piece of the tail semen or seal fluid is the fluid that's expelled during ejaculation um most of this is simal plasma which is a mixture of the glandular secretions from the seminal vesicles and the prostate and then also a percentage of the sperm cells right you're normal sperm count is 50 to 120 million per milliliter infertility can occur if the sperm count is less than 20 million per milliliter the seman is composed has um a lot of different things in it so let's start looking at them okay so it is sticky to promote fertilization so inside the seamen we will have clotting enzymes um called Pro proen oeline okay and so this converts to a sticky fibrin like protein called cogelon um and this entangles the the sperm it sticks to the wall of the vagina and cervic ensures that the semen doesn't drain back out of the vagina so what this does is it makes the semen sticky so that it promotes the uptake of the sperm Laden clots of cement into the uterus after about 20 or 30 minutes we have serin serin protease um this from the seminal fluid as well breaks down and reifies the semen um Serum protease is also known as prostate specific antigen or PSI PSA sorry antigen a um and this can indicate um prostate cancer if the ele levels are elevated so in order to have sperm motility we've got to have two things um we have to have a elevated pH and we had to have an energy source um and so the prosthetic fluid buffers the vaginal acidity from 3.5 to about 7.5 um the seminol vesicles then provide fructose and citrate to the ATP um to make ATP right and calcium um we also will have prandin secreted from the seminal vesicles that can help thin the mucus of the cervical canal and stimulates waves of contractions in the uterus and the uterine tubes to help spread the semen all right the next thing then we need to talk about is the male sexual response sexual intercourse also known as as quitus or culation there are four phases so excitement Plateau orgasm and resolution so we're going to look at each phase so during the excitement phase we're going to get Vaso congestion this is where we're going to get swelling of the genitals with blood and myotonia we're going to get muscle tension tension you'll also see increased heart rate blood pressure and pulmonary ventilation uh the bulbo ureal glands are going to secrete that lubricant fluid um we're going to get erection which is primarily due because of parasympathetic triggering of Nitric o oxide um that Nitric o oxide will dilate the arteries and fills them with blood Um this can also this phas of congestion can also increase the size of the testes um and then the erection is important because it allows for intermission or entry of the penis into the vagina the plateau phase then um your respiratory rate heart rate blood pressure are going to stay increased um we're going to get increased phas vasocongestion and myotonia um and this will be a few seconds to a few minutes before orgasm so then our third phase is orgasm or climax this is short 3 to 15 seconds um but it's an intense reaction usually marked by ejaculation um heart rate blood pressure breathing are going to increase further and then ejaculation occurs in two phases so we have emission so this is when the sympathetic nervous system is going to stimulate that parsis which is going to move the sperm through the ducts and we're going to add the glandular secretions and then we have expulsion which is when the um semen in the urethra is going to activate sematic and sympathetic reflexes um so that we get muscular contractions for expulsion um during expulsion sympathetic reflexes also constricts that internal Ural spinor so that urine doesn't enter the urra and semen don't B back up into the bladder so it separates the it closes to separate the reproductive from the urinary tract okay so looking at this um neural control okay so um during excitement the Deep artery of the penis is going to dilate erectile tissues are going to fill with blood and the penis becomes erect the tricular muscle of the erectile tissue relaxes allows for enlargement of the erectile tissues and the B Buble you reach gland is going to secrete um it's that lubricant fluid during orgasm then the ductus defer are going to do peristalsis and move the sperm into the urethra the prostate and simal vesicles are going to secrete their fluids and contribute to the seminal fluid the resolution phase then this is where the body variables are going to return back back to normal um sympathetic signals will uh reduce blood flow to the penis and then the penis becomes soft and flaccid cardiovascular respiratory function returns back to normal um the refractory period Then is the period following resolution in which it is usually impossible for male to attain another erection or orgasm so this may last from 10 minutes to a few hours this refractory period so looking continuing on then reviewing orgasm right the prostate will and seminal vesicles release secretions the internal ureal spincter con con constricts so that urine is retained and semen doesn't back up into the bladder um and then the bulbo spendo muscle contracts and we get compression of the root um of the penis so that SEMA will be expelled and then during resolution we reduce blood flow to the penis the muscles will contract and the penis will become lacid um erectile dysfunction we talked about again is common with aging um treatments include Viagra levara and Calis um these are phosphodiesterase Inhibitors um and so sexual stimulation triggers that n nitric oxide secretion which activates cyclic GMP which increases blood flow to erectile tissue this is what happens normally these drives are phosphodiester Inhibitors um and so it slows the breakdown of the cyclic GMP and prolongs the erection so it kind of looks like this so sexual stimulation nitric oxide inactivated um gcp okay activates the Cy GMP phosphodiesterase Inhibitors inhibit the degradation of this so the CYCC GMP stays which increases the V Vasa dilation and erection so basically just inhibiting the B breakdown of the cyclic GMP which causes the loss of erection okay and then the last thing that I want to talk about are sexually transmitted diseases um these are infectious diseases that are transmitted through sexual contact um they have incubation periods where pathogen multiplies without symptoms um and they also have a commun communicable period um where it can be transmitted to others even in the absence of symptoms um STDs can also cause fetal deformities still births and neonatal death as well and so it's important to pay attention um so let's talk about a few there are some that are bacteria and so garia is a bacteria um it will have be painful and have a pus discharge could result in sterility because of pelvic inflammatory disease chyia may cause ureal discharge and testicular pain um syphilis is going to be form hard lesions at the side of section um and going to disappear and then during the second stage you're going to get this pink rash um and then you can also get tertiary syphilis which would be the third stage which affects um the cardiovascular uh damage and brain we also have viral sexually transmitted diseases um and these would include things like genital herpes this is the most common STD in the US blisters and pains and it's caused by the herpes simplex virus uh genital warts which is caused by HPV and then Hepatitis B and C which can um which is an inflammatory liver disease all right that is it for the male reproductive system