Male Reproductive System | Erection & Ejaculation

all engine in this video we're going to talk about the erection and ejacular to response so just real quick to make it a lot easier for you uh because this is one of the the just one of the ways that I always remember uh which system controls erection and which one controls ejaculation when you're talking about the autonomic nervous system the parasympathetic is actually going to be able to control the erection you can remember that by parasym atic Point okay sympathetic nervous system is going to control ejaculation you can remember that by shoot so parasympathetic

Point sympathetic shoot so we already know right off the bat that erections are caused by or controlled by your parasympathetic nervous system and ejaculation is controlled by your sympathetic nervous system all right so let's go ahead and start off first with erection what triggers an erection to occur now the first stimulus for an erection is usually like the sight or the thought of certain types of erotic stimuli or maybe the touch like tactile stimuli activation of like mechano receptors so touching of the genitals or the skin or touching of specific areas around the body that

activate erotic Sensations right so it could be the sight it could be the thought some people if it floats your boat might even be the smell or it could be due to the tactile stimuli due to the touching right and when it does that what happens is it triggers some specific areas in your brain to activate the specific part of your spinal cord so let's come over here let's say this is the part of the spinal cord and let's say that this is the spinal cord region of S2 so sacral region S2 to S4 okay

now in the sacral region of the spinal cord you're going to have these parasympathetic neurons that are coming out so let's say here I draw here in Black here's going to be my parasympathetic neurons so they're coming out here and this is going to be as the pelvic nerve right so it's going to be as the pelvic nerve and what it's going to do is it's going to come to a specific area in the penis so in the penis before I show where it actually affects in the penis you have uh so let's say right

here here's the whole penis right here right here's the shaft of the penis this is the bulb of the penis and this is the tip which is consisting of the glands penis this blue tissue in here is called the corpora cavernosa so we call it the corpora cavernosum I'm just going to call it the cavernosum but it's basically erectile tissue now what is erectile tissue erectile tissue is actually kind of like a spongy um meshy like connective tissue that's riddled with a lot of vascular tissue so in other words what I mean it's connective tissue

with a lot of blood vessels supplying it but it's more of like a spongy connective tissue so again we would say erectile tissue is a spongy connective tissue riddled with a lot of blood vessels this outer one out here that's on both sides is the Kora cavernosa there's another one that's just surrounding the actual urethra you see this red one that I'm drawing here it's literally surrounding the Ure urethra and specifically the penile or spongy urethra I should actually say and what it's actually doing is it's helping to be able to keep the actual urethra

open during ejaculation now what's actually happening this nerve what is this nerve again called this nerve is actually called the pelvic nerve and it's actually coming from S2 to about S2 to S4 so these nerves are coming out of sacr Region 2 to four and it's coming in here and it's innervating specific blood vessels located within the corpora cavernosa so there's a lot of blood vessels here in the corpora cavernosa that it's going to be inating so look here's all these actual Kor cavernosa right there right it can innervate a little bit of the Corpus

spongiosum too right but the Corpus spongiosum isn't going to fill up too much because his main job is being able to keep the urethra open during ejaculation so actually let's let's zoom in here and let's see what these neurons are actually doing to the copor cavernosa okay so now we're zoomed in and we're actually looking at a blood vessel that's supplying the corpor cavernosa so these blue bodies that you see here this is the corpora Cavern this is basically the corpor cavernosum right so this is the erectile tissue but the erectile tissue is connective tissue

with blood vessels like are riddling within them right so this is going to be a blood vessel and here's the actual endothelial layer and then this is going to be the smooth muscle layer all right so now let's follow this nerve let's say here was that nerve that we had right it was coming from the sacral region of the spinal cord and what it actually can do is it can actually release specific chemicals you see how this is this endothelial cell what it does is it secretes a chemical called acetylcholine right so these parasympathetic neurons

release acetylcholine what the acetylcholine does is it binds onto this receptor here so it binds onto this receptor and it triggers this intracellular pathway and the overall result is that what happens is you're going to take an amino acid called arginine and you're going to convert that you're going to break off a piece of it actually it breaks off into two pieces you're what's going to happen is a is going to stimulate this receptor that's going to activate specific Pathways that activate enzymes enzymes that are going to trigger this conversion if you want to know

it it's actually called nitric oxide synthes enzyme but arginine is acted on by nitric oxide synthese what it does is it breaks Arginine into two components one is actually called citruline which isn't important here and the other one is nitric oxide this is really important okay so what has this neuron done so far it's secreted a cocoline activated this endothelial cell to convert Arginine into nitric oxide where does that nitric oxide go it actually flows right into this smooth muscle cell so in this smooth muscle cell let's say we bring this nitric oxide in here

in this smooth muscle cell we have a specific enzyme embedded into the cell membrane so let's say here's this enzyme this enzyme is called guol Guan cyclas okay guol cyclas this nitric oxide is going to act on this guano cyclas it's going to stimulate the Guan cycl when it stimulates the guol cyclas the Guan cyclas converts GTP into cyclic GMP and what that cyclic GMP will do is it'll actually go and actually help to activate other different types of enzymes enzymes that are basically going to cause the actual smooth muscle cell to relax so it's

actually what it's going to do is it's going to activate specific channels maybe that'll cause like potassium ions to maybe leave the cell right and then what's the overall result if the cell actually is losing potassium ions it's actually going to hyperpolarize right and it's going to lead to this Vaso dilation response right so the smooth muscle cell will actually relax when a smooth muscle cell relaxes what happens to this blood vessel it starts dilating and getting bigger and bigger and bigger and then what happens to the erectile tissue is it starts expanding so this

erectile tissue starts expanding and expanding and expanding there's veins over here little veins that actually drain the actual blood from this corpor cavernosa it drains it but if you think about it let's say here's the vein as we start dilating this blood vessel and dilating and dilating and dilating and expanding the corpora cavernosa the corpor cavernosa starts pinching those veins squeezing those veins and now the blood can't drain out so the blood that's supposed to be draining out of here is actually being inhibited and so if the blood can't be drained what's going to happen

the actual penis is going to get engorged with blood blood and that's going to trigger the erection okay so again what triggered the erection parasympathetic neurons within the sacred region of the spinal cord are activated by the different types of erotic or tactile stimuli or the sight or the smell or even the thought of different types of erotic stimuli and then that nerve is going to go release acetylcholine on the endothelial cells in those blood vessels and actually activate enzymes that are going to convert Arginine into nitric oxide nitric oxide will go into the smooth

muscle here near smooth muscle cells nearby activate guol cyclas who converts GTP into cyclic GMP and the overall result from that is it might cause potassium to leave and cause the smooth muscle cell to relax and that causes vasod dilation the corporo cavernosus and this whole erectile tissue starts expanding squeezes and pinches off the drainage veins which prevents blood from leaving and maintains the engorgement of the penis with blood and that's the erection now obviously some people who can't get it up have a hard time with this Vaso dilation response so you know what they

give you they give you Viagra and when they give you Viagra specifically what the Viagra is doing is Viagra is there's an enzyme there's an enzyme that actually degrades this cyclic GMP let's show you that enzyme here let's say here's the enzyme and this enzyme is degrading the cyclic GMP it's eating it up right what is the name of this enzyme this enzyme is called phosphodiesterase and it's actually type five pde5 what Viagra does is it comes over here and inhibits the phosphodiesterase so then what happens your cyclic GMP levels remain high so that you

continue to push pottassium ions out and cause the actual smooth muscle cell to relax and cause Vaso dilation so for these those of you who can't get that sucker up you give them Viagra it'll inhibit the phosphodiesterase type five which will keep the cic GMP levels up which will keep the actual smooth muscle cells relaxing and dilating all right so now now we have undergone the erection response so now this area is filled with blood so it's engorged with blood now now what triggers this ejaculation response everyone has a threshold right so whenever a person

an individual has these these reflexes because this is what it is it's just a reflex this tactile stimuli is triggering the parasympathetic nervous system who's causing this erection whenever the person is actually getting a a large influx a large flow of parasympathetic flow to that actual erection right causing the erection whenever there's a large outgo to the actual from the parasympathetic nervous system eventually the cerebral CeX stops this from happening so let's say here's the cerebral cortex let's say I just draw like a chunk and let's say this is the cerebral cortex so here's your

cerebral cortex what happens is the cerebral cortex will send down these descending fibers that will inhibit the parasympathetic nervous system but then what it's going to do is it's going to say okay this guy's had enough fun for today I'm going to inhibit the parasympathetic nervous system and stimulate the sympathetic nervous system and what's really triggering this it's whenever the person has so much parasympathetic outflow going to cause the erection that eventually this the central nervous system says okay we've reached High thresold let's inhibit parasympathetic and now stimulate sympathetic and what does sympathetic cause shoot

remember that ejaculation how does it do it okay we go back to the spinal cord but now the spinal cord is in a different part it's at a different level this is at the level of about T12 to about L2 okay so about T12 to L2 is this level what happens here now these actual neurons so it stimulates what happens is these descending fibers stimulate the actual cell bodies in the lateral gry Horn of the spinal cord right and then it comes out here and it synapses on a ganglia this ganglia that it actually synapses

on is called the inferior mesenteric gangon and then what happens here this inferior mesenteric ganglion has cell bodies of the post ganglionic motor neurons and where do these guys go they go all over the freaking place look what happens with this guy one of them is going to come over here one of them's going to come over here another one's going to come over here another one's going to come over here and let's actually have one more over here I'm going to kind of loop puppy around here and it's going to stimulate this guy okay

lot of different axons here what are all of these guys doing okay so you've reached the point the peak point right of the erection now the sympathetic nervous system comes into play we got to remember where was sperm being made it was being made in the testes right so this is the testes where the seminiferous tubules are this black c-shaped structure right here is called the epidemis and that's where it's being stored and maturing right it's being stored here and then whenever the individual is getting ready to ejaculate this sympathetic this adrenergic fibers release what

chemical norepinephrine right so it's going to release norepinephrine what's norepinephrine going to do it's going to stimulate these adrenergic receptors on the smooth muscle cells and cause it to contract so what's going to happen here it's going to undergo contraction and if this undergo contraction what is it going to start doing it's going to start squeezing the sperm out of the epidemis and into this long tube here what's this long tube here called This is called the vast Defence so again what was this structure here called the epidemis didmus and again it was this whole

c-shaped structure here then what it actually contracts it pushes it into this structure here which is called the vast deference but now there's receptors on the actual vast Defence smooth muscle and where is that going to be at so it's going to be contracting continuously squeezing it up this is actually the inguinal Canal that it moves through so look right there this is the vast erence what is it going to be doing secreting what chemical noro epinephrine what's norepinephrine going to be doing binding onto that receptor causing what causing contraction continuously moving the sperm now

then the sperm meets another structure you see this blue gland right here this blue gland is called the seminal vesicles so it's called the seminal vesicles and again what was this long tube here called this long tube is called the vas deference the vas deference has this little dilated region called the ampula that joins with a little duct coming off of the seminal vesicles now the seminal vesicles actually make what's called they make semen they make a lot of different chemicals that we'll talk about in the fertilization video but basically they're producing this different types

of chemicals that are are going to help to make up semen right how do we get that semen out well this nerve right here coming from the inferior mesentary gangon right this is actually going to secrete what chemical norepinephrine what's norepinephrine going to do it's going to act on that adrenergic receptor and cause the actual smooth muscle to contract what's it going to do it's going to expel the actual semen out of the seal vesicles and into this little this whole little tube here that we come have coming here which is the combination of the

vast Defence and the seminal vesicle duct what's this long tube that's running here this little tube is called the common ejaculatory duct and what forms it again it's the vast Defence and a duct of the seminal vesicles fuse vast Defence is Contracting and moving the sperm along seminal vesicles contracts and pushes the seam in and now you have this actual the seminal fluid that it actually makes so seminal vesicles are actually making seminal fluid but when you combine seminal fluid with sperm you actually get seen so that's what Sean is so let's actually write that

down so seen is actually going to be sperm and seminol fluid and we'll talk about the components of the seminol fluid for the seminal vesicles and fertilization now it's moving through this common ejaculatory duct and then it moves through this little doughnut shaped gland you see this little dut shaped gland right there it's called The Prost the prostate right and then there's little tube right here that the actual prostate gland has the urethra here it's called the prostatic urethra what happens is it's going to squeeze and push that actual semen into the prostatic urethra what

Els helps to assist this process now there shouldn't actually be receptors here on the bladder there should only be receptors here for this smooth muscle right here so you know the bladder is actually having an epithelium of transitional but then outside of that has a nice smooth muscle a called the det trusser there's a little like uh kind of continuation of that smooth muscle here right around this point here called this actual urethra right so it's getting ready to empty the bladder and go into the urethra there's this little smooth muscle area that's consisting of

What's called the internal urethro schiner what happens is this releases neuro epinephrine and what nor epinephrine does it binds onto that receptor of the uh internal urethal sphincter and it causes it to constrict why you don't want freen seaming going up into your bladder you want to have just urine in there so what it does is it causes these actual this internal Ure sh to contract and if it contracts it actually squeezes this part here and then prevents the actual reflux of the cement up into the bladder so so far it's caused contraction of the

epidemis contraction of the vast deference Contracting of the seminal vesicles to push the seminal fluid in here it squeezed the common ejaculatory duck squeeze that sperm out into the prostatic urethra and it's preventing the the reflux of the semen into the actual bladder by Contracting the internal ureal sphincter now one more thing once we've get we've gotten to this point now we're getting ready to reach the climax there's one more thing that happens out of the Sacred region of the spinal cord also you're going to have these actual cell bodies in the actual anterior gray

horn and look what's going to happen it's going to come out here it's going to move and it's going to inate this guy right there so it's going to come in and it's going to innervate right there what is this nerve right here this is the sutic nerve of system this is a this right here is actually the sematic nerve so it's like the pendal nerve right so it's the pendal pendal nerve it's going to come once you've actually getting ready to ejaculate it's going to release specific types of chemicals what chemical it's going to

release acetylcholine right cuz this muscle right here that you're going to see around the bulb of of the penis this muscle right there is called the bulbo spongiosis bulbo spongiosis the sematic nerve is going to release acetylcholine and guess what it's going to do to this actual Bulba spongiosis cause it to contract when it starts Contracting where's the sperm at we said the sperm were right here right they were actually in the prostatic urethra well then what's going to happen is we got to get this sperm out so this Buble spongiosis is Contracting and when

it's Contracting it's helping to propel the sperm through the actual urethra and out blasting those puppies out of about 11 miles an hour okay so suckers are flying all right so bobal spongiosis is Contracting who's causing that the sematic pendal nerve right it's coming over here innervating this actual bubble spongiosis releasing aceto choline causing the influx of sodium ions Contracting and helping to expel the sperm out once the sperm is expelled that is the ejaculation and that is the climactic point so whenever they actually ejaculate they've reached the climactic point right the peak point in

their orgasm once that happens once they've actually had the orgasm you know how the parasympathetic nervous system was actually causing that intervation of the blood vessels and stuff like that well this ejaculatory response is is so fast once the ejaculation has actually ended those blood vessels that were actually if we actually come back here these blood vessels that we're dilating right after ejaculation is occurring they actually start going back to their normal size because they have no parasympathetic enervation as they start going back to their normal size it's actually going to start causing the cororo

cavernosa right the erectile tissue to start decreasing in size as it starts decreasing in size what starts happening to these drainage veins they open if they open what starts happening Blood starts flowing out what happens the little PP goes flaccid then okay so then this is actually going to cause the actual uh the lymph of the penis right so it's going to cause it to become flaccid and again to wrap everything up here erection is triggered by a parasympathetic reflex how can you remember that parasympathetic Point ejaculation is triggered by a sympathetic reflex which is

going to be ejaculation you can remember sympathetic shoot what part of the spinal cord is the sympathetic coming out T12 to L2 and it's coming out to the inferior mesenteric gang gland and all these nerves that you actually see here it's actually a bundle of them it's a plexus it's actually called the hypogastric plexus just in case you want to know that and then what part of the spinal cord is coming for parasympathetic S2 to S4 what is it doing it's inating the actual copor cavernosa right the blood vessels causing them to dilate causing the

engorgement of the penis then whenever that erotic stimuli has reached a maximum point it activates the sympathetic nervous system and inhibits the parasympathetic nervous system this reflex is so fast what happens the sympathetic nervous system caus contraction of the epidemis contraction of the vast defrin contraction of the seminal vesicles to expel the seal fluid the sperm is actually going to combine with the seminal fluid and make semen get put into the common ejaculatory duct and then what happens the sematic nervous system the pudendal nerve coming from the ventral grey horn is going to come over

innervate the bulbo spongiosis which is a skeletal muscle as well as the isio cavernosus and The Superficial transverse perennius and cause those muscles to start Contracting they're going to help to BU Buble spongiosis is going to be one of the main ones that's going to help to be able to propel the sperm out but they also help to be able to provide a lot of pleasure okay then once you've reach the orgasmic Point sympathetic nervous system turns off parasympathetic nervous system has actually already been inhibited the blood vessels start actually going back to normal size

corpor cavernosa starts shrinking drainage veins open Blood starts actually draining from the actual rectile tissue and the penis and causes it to return to its flaccid point point and then you reach the latent period all right Niners I hope all of this made sense I hope it helped guys all right until next time