is the erectile organ of the male. It’s a
copulatory organ. And if you section through
the penis, you can see the erectile tissue.
The main erectile cylinders or tissues are
called the corpora cavernosa. They are really
just large spaces that engorge with blood,
and those large spaces are lined by endothelium,
the normal line you’d expect in blood vessels.
The urethra is within another tubular structure
called the corpus spongiosum. That doesn’t
become erectile tissue. It maintains the patency
of the urethra. So during ejaculation, erection
is maintained but also towards the lumen of the urethra
maintained open. If we now look at the erectile
process, in this diagram, you see pictures
or diagrams of the penis, the flaccid penis,
when it’s usually acting as part of the
urinary system, and then the erect penis when
it’s acting as part of the reproductive
system. And on the right-hand side, you see
a section through the penis, all be it rather
faint, just to point out the corpora cavernosas,
the erectile components of the penis that
become engorged with blood. And on the right-hand
section through the penis, you can see a very
faint outline of the male urethra enclosed
by the corpus spongiosum. Normally in the
flaccid penis, when blood comes down, it flows
a little bit into the corpora cavernosums
but it’s diverted mostly into the venous
system and returned back towards the heart.
Sphincters close down so that blood tends
to be diverted from the corpus carvenosums or at
least a lot of blood. Under sexual stimulation,
though, that sphincter can then open up. So more
blood is diverted into the corpora cavernosums,
and so the penis becomes erect, that area
becomes engorged with blood. And it becomes
engorged with blood because of the relaxation
of muscles, smooth muscle cells around the
vessels and the opening of that supply to
the corpora cavernosums. But at the same time,
the venous return out of the penis is restricted,
because the vein coming out of the penis through
the penile areas comes out at an oblique angle.
And so when the penis becomes erect, that vein
is closed off, and therefore, blood is not
then continually flowing through the penis,
hence, the erection. Here again is the corpus
cavernosums that is the erectile tissue, and
the corpus spongiosum is the area around the
urethra. Well, let’s now summarize what
I’ve covered in this lecture. It’s important
to understand that the epididymis is the location
for sperm to become mature. Sperms tend to
spend 10 to 12 days in the epididymis going
through this process, and they gain motility.
Then there's all duct system that leads the sperm
to the epididymis coming from the testis.
It’s important to understand those as well.
And then there’s a seminal vesicle that
secretes fructose, the main energy source
for the sperm, understand its structure.
It’s a tubular convoluted glandular tissue.
And then make sure you recall the importance
of the prostate gland, its secretory product,
and also the way in which the glands are arranged,
and therefore, the occurrence of conditions that
can restrict the flow of urine, and also the
conditions that can lead to cancerous lesions
in the prostate. And finally, recall the structure
of the penis, the erectile tissue, and the
process in which that erectile tissue becomes
engorged, and therefore, leads to erection
of the penis, so it become into the copulatory organ.
Well, thank you for listening to this lecture.
I hope you now know something about the duct
systems in the reproductive system of the
male, and also knowledge about the very important
accessory glands. And, of course, the structure
and function of the penis.
So thank you again for listening to this lecture.