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MCAT
Course: MCAT > Unit 7
Lesson 18: Reproductive system- Reproductive system questions
- Reproductive system questions 2
- Welcome to the reproductive system
- Anatomy of the male reproductive system
- Transport of sperm via erection and ejaculation
- Spermatogenesis
- Testosterone
- Basics of egg development
- The ovarian cycle
- Meet the placenta!
- Reproductive cycle graph - Follicular phase
- Reproductive cycle graph - Luteal phase
- Estrogen
- Maternal changes in pregnancy
- Labor (parturition)
- Breast anatomy and lactation
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Anatomy of the male reproductive system
Explore the male reproductive system with a focus on the testes' role in sperm production and testosterone creation. Discover the importance of temperature regulation for sperm production, the journey of sperm from the epididymis to the urethra, and the role of accessory glands in supporting sperm's journey. Created by Vishal Punwani.
Want to join the conversation?
- At, Isn't it supposed to be ventral? and dorsal instead of posterior? 0:36(8 votes)
- Anterior is the same as ventral, posterior is the same as dorsal.
They are just different names.(46 votes)
- Atisn't it cowper's gland instead of bulbourethral? 9:21(4 votes)
- The Cowpers Gland and the Bulbourethral are the same gland. One gland with two names.(28 votes)
- What about the seminiferous tubules?(6 votes)
- They are part of the testes where the production of sperm by meiosis occurs.(7 votes)
- What happens if the testes do not descend into the scrotum and remain in the abdomen?(2 votes)
- The condition is bilateral cryptorchidism, when neither descend through the inquinal canal. The testes will remain smaller than typical and the sperm numbers will be poorer due to the higher body temperature. Surgery to bring them into the scrotum and improve fertility would be recommended. Some studies have also linked cancer to this condition, however it is also true that internal gonads are more difficult to monitor for growths.(10 votes)
- Is there any for female?(2 votes)
- No, there is no similar video for females.
http://www.ourbodiesourselves.org/health-topics/anatomy-menstruation/
https://medlineplus.gov/femalereproductivesystem.html
Khan is concerned about giving too much information in this area. The next video is on the menstrual cycle. They only discuss ovaries. Seriously sexist and strangely Victorian. In fact, if I use the words for a woman's anatomy in this answer, they tell me my answer is low quality. Males have anatomy they can see, while women do not and yes, it includes more than ovaries. Obviously, the internet is full of incorrect information that abuses women and I do not want to encourage that. I do want women and girls to know the truth about their bodies and have access to reliable truthful information. To that goal, I have included the website from a non-profit women's health oriented website called Our bodies Ourselves and a U.S. government website for you to use that will be safe. Ourbodies Ourselves is a group dedicated to educating women and published a book that continues to be updated so that women do not have to rely on doctors or websites or other resources that are too embarrassed or repressive to clearly explain simple facts using simple words that every women should understand. I teach biology to adult women that often have no understanding of their biology although some of them have had children. There is no excuse for this lack of education that is literally life saving on a site that says it promotes education for all. It can be done simply and respectfully.(7 votes)
- Is there any difference between penis and urethra ?(2 votes)
- The penis is the male sex organ. The urethra is a tube inside the penis that goes from the bladder to the surface of the 'head' of the penis and allows the passage of urine out of the body.(6 votes)
- are those cremaster and dartos muscles voluntary?(2 votes)
- Cremaster muscle is skeletal hence voluntary muscle
dartos muscle is smooth muscle hence its involuntary
but both function is to raise and lower the testes . this reflex is called as CREMESTERIC Reflex due to sexual arousal, sensory fibers on upper thigh, sudden change in temperature and fight or flight situations(3 votes)
- Is there one about the FEMALE reproductive system?(3 votes)
- hey here the sperms move from the testes to the epididymis. then where are the rete testes and vasa efferentia?(2 votes)
- http://web.archive.org/web/20080830004749/http://trc.ucdavis.edu/mjguinan/apc100/modules/Reproductive/mammal/testis0/testis3.html
The sperm are formed in the seminiferous tubules, which are connected to the rete testes and the rete testes are connected to the vasa efferentia, which then connects to the epididymis. The sperm mature in the epididymus. http://nongae.gsnu.ac.kr/~cspark/teaching/chap3.html(3 votes)
- Hello sir ,why haven't you talked about vasa efferentia, seminiferous tubules and seminal vesicle?(2 votes)
Video transcript
- So let's look at the
male reproductive system. And so when we learn about
the male reproductive system it's useful to actually look at it from two different points of view and so the first view we'll take a look at is called an anterior view. And what that is is basically we take everything in this box here and so what we'll do is -- it's a little bit tough to see there. This is zoomed out. So we'll blow it up for you and that's basically what you see there. And so that's called an anterior view. Looking at it from the front. And that's sort of the
opposite to a posterior view which is looking at it from behind. That would be a posterior view. And so there's two points
of views like I mentioned. So the other one is
called the sagittal view and what a sagittal view is is let's look at this guy over here. Let's say that this is his left side because this is where his left hand is and this is his right side. And so in a sagittal
view what you do is you sort of make a cut right
down the middle here and you sort of cut away
everything on one side. So in this case it would be the left side
that we're cutting away because what we want to do and I'll draw the -- I'll draw a little eye here. What we want to do is
look toward the right side toward what's remaining on the right side. So we're seeing this cut surface here. And so what that ends up looking like is something like this here and so this is called a sagittal view and to reorient you this here in the background
this is the right leg because remember we're looking -- we're looking this way so this ends up being the right leg. So those are the two
views that are important when we're learning about
the male reproductive system. And actually it's also
important to mention that most of what you see here is actually contained within the body so you don't actually see that when you look from the outside. What you do see is just the penis and the scrotum that contains the testes and we'll come to what
all of that is soon. Now that we've taken a look
at the two different views let's clear away some of this stuff and meet the organs. So the first set of organs we'll look at they're actually paired organs. They're the testes and they're sort of the key organ in the male reproductive system. I'll just shade them in for you here. And the testes are pretty interesting. What happens in the testes is the process of spermatogenesis and so what spermatogenesis is is the creation of sperm and sperm are the male
contribution to a baby. So sperm production in the testes has to happen at a certain temperature. It has to be at a temperature
that's a bit lower i.e., a bit colder that
core body temperature which is pretty warm. And so the testes have to
be kept at a temperature that's a little bit lower
than body temperature and they do that by hanging out in this -- this fleshy sac outside of the body called the scrotum. And so I'm just pointing at it now. And so this is called the scrotum and the way that the scrotum regulates the temperature of the testes is by sort of retracting
upward toward the body if it gets a little bit cold so that they can stay a bit
warmer closer to the body or by descending a little bit
if it gets a little bit warm and so it does that -- the retracting upward and the
descending via two muscles. The first one is called
the cremaster muscle -- cremaster -- and the second one is
called the dartos muscle. Kind of a cool name. And so those two muscles help to regulate the
temperature of the testes so that sperm can be produced. And interestingly there's something called the cremasteric reflex where if you sort of
lightly brush on the -- on the upper and inner part
of the thigh here on a male instinctively or reflexively rather the cremaster muscle will contract and pull the testes slightly
upward on that side. And that's called the cremasteric reflex. Now the testes also have another
really important function besides producing sperm and that's the creation
of the major male hormone called testosterone. And the testosterone that
you produce in your testes is actually responsible for all of your secondary
sexual characteristics and when I say secondary
sexual characteristics I mean things like hair growth. So when you hit puberty
around 12 or 13 years old and you start to produce
testosterone in greater amounts you sort of get an outbreak of body hair. So you get hair on your knuckles and on your arms and on
your legs and your face and you'll start to grow pubic hair and so testosterone is the main
driver of that hair growth. In addition to that you get sort of muscle growth and you also get a
deepening of your voice. And so next up what we
have is the epididymis and so I'll just color those in. Those sit right on top of
the testes on either side. And so the role of the epididymis is to sort of provide
a place for the sperm to sort of hang out and develop and so the epididymis is this really long convoluted really wavy set of tubes that sperm sort of spends a lot of time in before it goes off on its journey. And so if you were going off on a journey you'd sort of pack a few
things in preparation and sperm sort of do the same thing. And so when the sperm are
hanging out in the epididymis they gain more mitochondria, the organelle in the cell that provides the cell with energy. And so the sperm are about to
embark on this huge journey and they have to be ready at
basically a moment's notice to sort of shoot out and swim a long way and they're going to need mitochondria because they're going
to need a lot of energy. In the epididymis they also develop really long tails called flagella and that sort of helps to propel them on their journey as well. And so from the epididymis sperm sort of drains out of the epididymis and into this tube called the vas deferens and so the vas deferens actually drains the epididymis of sperm and brings the sperm
upwards behind the bladder and into the urethra which is the next part of
the reproductive tract. Now the vas deferens
actually runs within a bundle called the spermatic cord and inside the spermatic cord you actually have an artery
that serves the testes and you also have a vein
that serves the testes. And so all of that together -- and you have that on either side that's called the spermatic cord and let me just draw one
on this side as well. So there's your artery and you've got your vein as well. So before we move on let's just clear off a few things or everything, that's fine too and next we'll talk about
the accessory glands. And so what the accessory glands do is basically provide sperm with things that they
need along their journey. And so if you were going on a journey you might make a few
pit stops at a few shops and pick up some things and that's basically what's
happening with sperm. And so I'll point out
some accessory glands here but before I do that I'll just orient you to where they are with respect to the bladder. And so this yellow object
here is the bladder and you can see it on
the sagittal view here. And so the first accessory gland
that we're going to mention is called the seminal vesicle and there are actually two of them and I'll shade it in here. So on the sagittal view you can see it behind
the bladder quite nicely and on the anterior view you have to sort of imagine that it's behind the bladder in there and about there. And so those are the seminal vesicles. And what they do their contribution to
sperm is a lot of fluid and in fact they actually
make up 60% of semen volume and just to hammer out
some terminology here semen is different from sperm in that semen equals sperm plus the fluid that it picks up on the way from the accessory glands. And so the fluid that the sperm pick up from the seminal vesicles is actually somewhat alkaline. And that's to neutralize the somewhat acidic environments of the male's own urethra and the vagina where the sperm will end up and to be alkaline that just means that
your pH is greater than 7 which is what water is. The fluid is also rich in fructose and that's so that the
mitochondria have sugar that they can use to produce ATP and ATP is what the sperm use for energy to complete their long journey. Now the other two
accessory glands are called the prostate gland and
the bulbourethral glands and there are actually
two bulbourethral glands, one on either side of the penis. These three glands actually contribute more fluid to semen. The prostate gland actually
makes prostatic fluid and that increases the mobility of sperm once it reaches inside the vagina and the bulbourethral gland sort of just makes a thick lubricant for both the urethra and the vagina. Now semen actually travels through a tube called the urethra which you can see here in red to get to the outside of the body and it travels through the urethra through the penis which
is here in purple blue and so in reproduction
the role of the penis is to actually penetrate the vagina so that sperm can be deposited inside.