Anatomy of the male reproductive system | Reproductive system physiology | NCLEX-RN | Khan Academy
Summary
TLDRThis educational script explores the male reproductive system, focusing on its key components and functions. It introduces anterior and posterior views, then dives into the sagittal view, highlighting the internal organs. The testes, responsible for sperm production and testosterone, are detailed alongside the scrotum's role in temperature regulation. The script also covers the epididymis, vas deferens, and accessory glands, explaining their contributions to sperm's journey and function. Finally, it touches on the seminal vesicles, prostate gland, and bulbourethral glands, emphasizing their role in semen composition and sperm mobility.
Takeaways
- 🔍 The male reproductive system can be viewed from two perspectives: anterior (front) and posterior (back) views.
- 📐 A sagittal view is a side view that involves a vertical cut through the middle of the body, showing the internal structure on one side.
- 🌡 The testes are the key organs for sperm production and must be kept at a lower temperature than the body for proper spermatogenesis.
- 💼 The scrotum is the sac that holds the testes and helps regulate their temperature through the action of the cremaster and dartos muscles.
- 🏃♂️ The cremasteric reflex is an involuntary response where the cremaster muscle contracts, pulling the testes upward when the thigh is lightly brushed.
- 🤺 Testosterone, produced in the testes, is responsible for secondary sexual characteristics such as body and facial hair growth, muscle development, and voice deepening.
- 🛤️ The epididymis is a series of tubes where sperm mature and gain energy through additional mitochondria and develop flagella for propulsion.
- 🚰 The vas deferens is the duct that transports mature sperm from the epididymis to the urethra, running within the spermatic cord alongside blood vessels.
- 💧 Seminal vesicles contribute the majority of semen volume, providing an alkaline fluid rich in fructose to nourish sperm during their journey.
- 🚿 The prostate gland and bulbourethral glands add fluid to semen, enhancing sperm mobility in the vagina and providing lubrication.
- 📍 The urethra is the tube through which semen travels to exit the body, passing through the penis, which plays a crucial role in depositing sperm inside the vagina during reproduction.
Q & A
What are the two main views used to examine the male reproductive system?
-The two main views used to examine the male reproductive system are the anterior view, which is a front view, and the posterior view, which is a back view. Additionally, the sagittal view, which is a vertical cut through the middle of the body, is also important.
What is the primary function of the testes in the male reproductive system?
-The primary function of the testes is spermatogenesis, which is the production of sperm, the male reproductive cells, and the production of the male hormone testosterone.
Why is the temperature inside the scrotum important for sperm production?
-The temperature inside the scrotum is important for sperm production because it needs to be slightly lower than the core body temperature to facilitate the process of spermatogenesis.
What is the cremasteric reflex, and what causes it?
-The cremasteric reflex is an involuntary contraction of the cremaster muscle that pulls the testes slightly upward when the upper and inner part of the thigh is lightly brushed. It is a protective reflex to prevent injury.
What role does the epididymis play in the male reproductive system?
-The epididymis provides a place for sperm to mature and develop before they embark on their journey. It is a long, convoluted set of tubes where sperm gain more mitochondria and develop flagella for propulsion.
What is the function of the vas deferens in the male reproductive system?
-The vas deferens is a tube that transports mature sperm from the epididymis to the urethra, which is the next part of the reproductive tract leading to the outside of the body.
What are the accessory glands of the male reproductive system, and what do they contribute to the sperm's journey?
-The accessory glands include the seminal vesicles, prostate gland, and bulbourethral glands. They provide fluids that nourish and protect the sperm, enhance its mobility, and provide energy for its journey.
How does the fluid from the seminal vesicles benefit the sperm?
-The fluid from the seminal vesicles is alkaline, which helps neutralize the acidic environment of the urethra and vagina, and it is rich in fructose, providing a sugar source for the mitochondria to produce ATP, the energy currency for sperm.
What is the role of the prostate gland in the male reproductive system?
-The prostate gland produces prostatic fluid that contributes to the semen's volume and increases the mobility of sperm once it reaches the vagina.
What is the function of the bulbourethral glands in the male reproductive system?
-The bulbourethral glands produce a thick lubricant that facilitates the passage of semen through the urethra and provides lubrication for the vagina during sexual intercourse.
How does the urethra play a role in the reproductive process?
-The urethra serves as a channel through which semen travels from the reproductive system to the outside of the body, facilitating the deposition of sperm during sexual intercourse.
Outlines
🔍 Exploring the Male Reproductive System Views
This paragraph introduces the male reproductive system, emphasizing the importance of understanding it from two distinct perspectives: anterior and posterior views for a comprehensive understanding. It then explains the concept of a sagittal view, which involves a vertical cut through the body to observe internal structures. The paragraph also mentions that most of the male reproductive organs are internal and not visible externally, with the exception of the penis and scrotum, setting the stage for a deeper dive into the organs' functions.
🌡️ The Testes: Sperm Production and Temperature Regulation
The second paragraph delves into the function of the testes, the primary organs in the male reproductive system, where spermatogenesis, the creation of sperm, takes place. It explains the necessity of a cooler temperature for sperm production, which is facilitated by the scrotum's ability to regulate temperature through the cremaster and dartos muscles. The paragraph also touches on the cremasteric reflex, a protective response to stimuli, and the production of testosterone, which is responsible for secondary sexual characteristics such as body hair growth, muscle development, and voice deepening.
Mindmap
Keywords
💡Anterior view
💡Posterior view
💡Sagittal view
💡Testes
💡Spermatogenesis
💡Scrotum
💡Epididymis
💡Vas deferens
💡Spermatic cord
💡Accessory glands
💡Semen
💡Urethra
💡Penis
Highlights
Introduction to the male reproductive system from two different viewpoints: anterior and posterior.
Explanation of the anterior view, focusing on the front aspect of the male reproductive system.
Clarification of the posterior view, which examines the system from behind.
Introduction of the sagittal view, emphasizing the lateral perspective by cutting through the middle.
Description of the organs visible externally: the penis and the scrotum containing the testes.
Discussion on the importance of the testes as the key organ for sperm production and testosterone generation.
Explanation of spermatogenesis, the process of sperm creation within the testes.
Details on the necessity of a cooler temperature for sperm production, facilitated by the scrotum.
Functioning of the cremaster and dartos muscles in temperature regulation for the testes.
The cremasteric reflex, an involuntary response to stimulation of the inner thigh.
Role of testosterone in developing secondary sexual characteristics such as body hair growth.
Introduction to the epididymis as a site for sperm development and storage.
The process of sperm gaining mitochondria and flagella for energy and propulsion in the epididymis.
The vas deferens' role in transporting sperm from the epididymis to the urethra.
Overview of the spermatic cord containing the vas deferens, artery, and vein for the testes.
Importance of accessory glands in providing fluids and nutrients for sperm during their journey.
Function of the seminal vesicles in producing alkaline fluid rich in fructose for sperm energy.
Role of the prostate gland in enhancing sperm mobility within the female reproductive system.
Contribution of the bulbourethral glands in producing a lubricant for the urethra and vagina.
The urethra's role in transporting semen, a mixture of sperm and glandular fluids, out of the body.
The function of the penis in reproduction, specifically in penetrating the vagina for sperm deposition.
Transcripts
- 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.
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