- 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.