How An Erection Works

i think we can all agree that erectile function is pretty important i mean think about it from the reproductive standpoint it can be pretty challenging to participate in the act of creating a baby or practice creating said baby without a proper erection also many people suffer from erectile dysfunction and i always tell my students you first have to understand how things are supposed to work inside the human body before you can really dive in and understand how things aren't working so in today's video we're going to utilize the cadavers behind me to go over some of the amazing anatomical structures as well as the physiology involved in creating an erection also think how amazing this is gonna be you're gonna be able to explain to your spouse partner or special friend what's going on in the nether regions when you choose to participate in certain extracurricular activities it's going to be a fun one so let's do this [Music] so i'm assuming that most of us have a general idea of what a male erection is but just to cover our bases and to be clear a male erection is defined as the enlargement and stiffening of the penis now females have a homologous structure called the clitoris and there's actually more similarities than people realize but we'll save that for a whole segment or video all by itself but for this erection to be initiated typically we need some sort of stimulus now stimulation occurs in two ways this can be psychologic stimulation coming down from the brain as well as stimulation of the actual genital organs now when it comes to this psychologic stimulation this is often in the form of some sort of sensory input or sensory information things like visual input maybe you see someone that's easy on the eyes auditory somebody whispering sweet nothings into your ear olfactory a stimulating smell if you will and all this can even be imagined which is quite the broad category with multiple possibilities now tactile stimulation of the genital structures as well as surrounding areas also initiates the erection however the most sensitive and therefore most important structure is the distal end of the penis called the gland's penis now glands actually means acorn and anyone who's visualized the glands often thinks yeah that name makes sense but as i mentioned this is an extremely sensitive area it's packed with an extensive amount of sensory nerve endings and when this is stimulated it sends a signal into the spinal cord through a nerve called the pudendal nerve now the latin meaning of pudendal actually means that which you should be ashamed of you know because it's bringing sensory information from your genitals but once that signal is in the lower portion of the spinal cord part of that signal or sensation will travel up the spinal cord into the brain so that one becomes aware of such genital stimulation however erectile function is primarily from inherent reflexes built into the sacral portion of the spinal cord that is the lower portion of the spinal cord so what that means is you don't technically need that signal or sensation from the glands or other genitals to actually make it up to the brain in order to have an erection so in theory someone who has a spinal cord injury still could get an erection from stimulation of the glands they may just not be aware of say like the feeling or the sensation the key is this reflexive activation of certain nerve fibers or neurons within that sacral spinal cord and these nerve fibers or neurons belong to part of the nervous system referred to as the parasympathetic nervous system now you may have heard of the parasympathetic nervous system but it's part of the autonomic or automatic portion of your nervous system that controls things automatically almost reflexively in some cases and it's nicknamed the rest and digest system because it's often active in a resting or relaxed state and obviously is going to control the smooth muscle of your digestive tract to move things along even activates salivary glands and yes is going to control erectile tissue within the penis and we are definitely going to take a look at these erectile tissues within the penis but first let me mention a few things about testosterone testosterone is such an important hormone it is a primary male sex hormone and its effects are far reaching throughout the human body it affects things like bone health muscle mass and strength fat distribution red blood cell production and even things like libido sex drive and therefore can influence erectile function and because of this influence i'm excited to say thank you to the sponsor of today's video let's get checked let's get checked provides private convenient testing in the comfort of your own home they offer routine blood work sti tests and yes hormone tests like testosterone all you have to do is get online pick a test say like the testosterone test and they'll ship it to your house with detailed instructions so that you can gather the specimen and ship it back with their prepaid label they also have medical staff on hand so that you can discuss your test results so if you're interested in getting your testosterone levels checked maybe you're concerned about libido sex drive or even erectile function or maybe you're an avid gym goer and want to make sure your testosterone levels are at the levels they need to be for adequate strength gains or maybe you just want to get a routine test like i did and make sure the levels are where they need to be either way go to try lgc.com iha and they'll give our viewers 30 off if you use our code iha 30. we'll also put that link in the description below so back to these erectile tissues within the body of the penis there are three cylindrical masses of erectile tissue and we're going to take a look at these by looking at a cross section through the penis so deep breath so here are these three cylindrical erectile tissue masses one two and three and yes i understand it resembles an alien but moving on to the amazing anatomy here so the first erectile tissue mass is called the corpus spongiosum corpus just refers to like body because it's in the body of the penis like corpse and spongy because it's this spongy erectile tissue and the spongy urethra that's right at the tip of the probe runs through there now one of the main jobs of the corpus spongiosum is to keep the urethra open so that seminal fluid can exit the body now these other two erectile tissue masses are the corpura cavernosa that's just the plural version this would be the corpus cavernosum here corpus cavernosum here that's just singular now we know what corpus refers to but cavernosum is just referring to this cavernous erectile tissue if you look closely there's all these tiny little spaces or blood sinuses within each of these and that's going to be important in a minute but also these little beams of tissue that you can see are lined with epithelial cells as well as smooth muscle cells now within each corpus cavernosum there's also a deep artery of the penis so an important blood supply so we're essentially putting all these structures together so that we can understand how this erection will work but let's kind of talk about two potential scenarios to initiate this process one of these scenarios could be that psychological stimulation so visual auditory the imagination that we talked about earlier starting up in the brain and that signal would be sent down the spinal cord all the way down to the sacral region of the spinal cord specifically at sacral regions s2 s3 and s4 and that's where it would activate those parasympathetic neurons now that could be potentially the only stimulus most males have a pretty good idea that an erection can occur without any tactile stimulation of the glands or other genital structures it could just be from thoughts but yes it can also be from stimulation of the glands and that would come through that pudendal nerve we talked about earlier and that pudendal nerve would go into the spinal cord at levels s2 s3 and s4 and would also activate those parasympathetic neurons so you can see it could be coming from the brain or the genital region and in a lot of scenarios it's coming from both areas at the same time but now that we've activated these parasympathetic neurons we've got to get this signal out to the erectile tissue so how neurons get their signal out of the spinal cord is that they send their axons or extensions of themselves into these spinal nerves which come right off the spinal cord now think of a nerve as like an extension cord and if you were to cut into a nerve you'd see these tiny little copper wires inside and those copper wires would be the neurons in this example so these parasympathetic neurons are going to leave the spinal cord at least their axons are through spinal nerves s2 3 and 4 and eventually make it into the erectile tissues now i know i've mentioned s2 3 and 4 like 300 times but it's probably because we had a mnemonic way back when i was a student and the pneumonic went like this s234 keeps the penis off the floor and we're about to see that happen so now that we've figured out the pathway in which those parasympathetic neurons get to the erectile tissue once they are activated or release their neurotransmitters they cause nitrous oxide to be released within the erectile tissues and nitrous oxide is a powerful vasodilator and remember within the corpora cavernosa were those deep arteries of the penis and that nitrous oxide is going to cause those deep arteries to vasodilate or open up bringing more blood into these tissues not only that nitrous oxide also causes the smooth muscle in this tissue to relax making these little spaces or blood sinuses even larger which again allows for even further expansion now enlargement and expansion can only go so far as you can see there's these white connective tissue bands surrounding the coppora cavernosa and eventually those will limit the amount of blood and enlargement that can take place also you may have noticed some small little veins here on the top or dorsal aspect of the penis as the erectile tissue expands those veins will start to get compressed and collapse which will limit the amount of blood that can leave the penis which actually helps to maintain the erection and that erection will be maintained until either climax or until the stimulus ceases or ends but regardless of how it ends that was the anatomical and physiological awesomeness on how one may achieve a proper erection thanks for watching everyone hopefully you learned some cool things about these amazing reproductive structures if you're interested in getting your testosterone checked be sure to check out that link in the description below for let's get checked and if you feel the need like subscribe leave some comments below let us know what you want to see in the future and what you thought of the video and we'll see you next time [Music] [Music] you

Channel: Institute of Human Anatomy

Views: 8,836,454

Keywords: erection, how an erection works, how does an erection work, how do erections work, what is an erection, what is inside the penis, anatomy of an erection, erections, mechanism of an erection, mechanism of erections, anatomy of the penis, erectile tissue, glans, what causes an erection, male reproduction, male reproductive anatomy, testosterone, erectile dysfunction, brain and spinal cord, parasympathetic nervous system

Id: 3kIncgW_-vI

Length: 10min 31sec (631 seconds)

Published: Fri Jul 01 2022