Where is the kidney
Kidney Location and Structure
so let's take a quick look at the
kidneys and have a look at their
location and their structure and then
also have a look at the urinary system
as a whole so when we talk about the
urinary system or renal system we talked
about the two kidneys that we have so
remember the kidneys are this bean
shaped organ random at the size of the
hand to about the second knuckle they
are connected to two ureters which you
can see here are two tubes that travel
down to the one bladder which is a
storage unit for a urine and then one
urethra which transports that urine from
the bladder out to the external
environment so again two kidneys to your
eaters one bladder one urethra okay
now when we have a look at the location
of the kidneys you can see that they
actually sit relatively high up in the
body now they don't sit towards the
front they sit towards the back so they
actually sit behind the peritoneum
remember the peritoneal cavity is the
cavity that holds the majority of the GI
t the gastrointestinal organs okay so in
that you could say that the kidneys sit
retroperitoneum behind the peritoneal
cavity okay and actually sit to at the
back of the abdominal wall okay now
sitting towards the back of the
abdominal wall the top of the kidneys
are actually resting upon the diaphragm
as well and if you don't have a look at
the kidneys and haven't necessarily
drawn them as well as I probably should
have but you should see that the right
kidney sits a little bit lower than the
left kidney and the reason why the
kidney on the right sits a little bit
lower then the kidney on the left is
because remember that you have that
large liver on the right hand side that
pushes that kidney down
so the right kidney sits a little bit
lower than the left now in this image
you can see that I've drawn the skeletal
system from a posterior view and you can
see the pelvis here and you can see the
vertebrae coming up and you can see two
rooms so looking at this a couple of
reasons why drawing like this is
because you can see that the kidneys
aren't very well protected by the
ribcage okay your lungs are your heart
is by the sternum and ribcage but the
kidneys are in actual fact you can see
that this is the last rib the 12th red
that you can see here
12th rib and part of the 11th rib
protecting the kidney now doesn't
actually protect it very well in actual
fact this can be more dangerous than
helpful a lot of patients may come in
from car accidents and the way that the
car crash and the way that their body
twisted that rib can snap and actually
sever the kidney now because of this
fact the kidneys among other reasons are
surrounded and I haven't drawn here by a
lot of fat and now this fat that
surrounding the kidneys is called peri
renal fat and this paragraph in fact
isn't like the type of fat that you put
around your belly around your thighs and
a ratchet bomb this is functional what
that fat that you put here is called
functional fat but the fact that you
have around the kidneys is called
structural fact there is a difference
functional fat we use for energy
structural fat we often use for
protection and Anchorage for example and
that's exactly why this what this
Peregrine or fad does it protects the
kidneys because the ribs don't do a very
good job of that and therefore it's very
open to being hit but at the flank and
it's there to anchor the kidneys as well
so keep the kidneys where they are so
they don't start floating around there's
been a number of reported cases in which
patients have come in and they've had
scans done and their kidneys are
floating around now why the kidneys
floating around well they found that a
number of these patients were either
malnourished or they were marathon
runners for example now think about that
when you're a marathon runner think
about how much energy you use and if
you're not eating appropriately well
what could happen is that you move
through your glucose glycogen stores and
you start to move on to your fat stores
and you go to your protein stores and
you get muscle wastage but if you've
used up all your fat stores which is
very hard to do your body starts to move
from
functional factor that structural fat
and some of these patients have heard
the structural fat around their kidneys
started to get broken down to use for
energy without this fat that's anchoring
the kidneys these kidneys can be start
floating around okay so we have the
kidneys to sit behind the 12th rib sit
at the little the 12th rib you can see
here and goes down to around about this
third lumbar vertebrae so one two three
four five so one two third lumbar
vertebra l3 so between the 12th rib and
the third lumbar vertebrae is where
these kidneys sit and again attach to
the ureter x' bladder and urethra now
let's have a closer look at the kidney
so let's draw the kidneys and let's
section in and see what we can find
so if you want to draw the kidneys up
you can see that the kidneys are made up
of two predominant layers an outer layer
which I've drawn here which we call the
renal cortex and an inner layer here
which we call the renal medulla you
could also see that there's like an
entry and exit point here which we call
the hilum now this hilum is where we
have you can say here the ureter coming
away also have veins coming away and
lymphatics as well and it's also where
we have the artery renal artery coming
in you have the abdominal aorta the
descending abdominal aorta with a renal
artery branch that comes out okay and
I'm not going to draw that yet but I'll
draw a Shortland when we have a look at
the medulla you're going to see a couple
things first thing you'll see is that
there are a number of pyramids that are
located here in the medulla
now we call these renal pyramids
unsurprisingly
and you have between 8 to 12 of these
rental pyramids so you have the renal
cortex then you have these real pyramids
and I've got these striations there's
lines through them and you can see
between them you have these renal
columns and in actual fact these renal
columns are extensions of the cortex and
come down
and these Radle pyramids or your font
are connected I'll draw it in a
different color like little cups
I'll have to think of it as your hand
place like this as though you're asking
for somebody to pour some water into
your hands and you were to hold it like
that so you could hold the water that's
what these are like and these are called
a calyx or Kellis cease to be plural
I'll write that down Catholics and calyx
does actually mean cup now these smaller
calluses are called minor calyce's but
what you'll find is that these minor
calyce's all connect up with each other
and one of these minor calyce's form
when they connect up with each other
well they form a major calyx a major cup
and that this major calyx forms a funnel
right here which is called the renal
pelvis now what's the whole point of
having these little cups here and
there's big cup here's
renal pelvis here so minor calyce's
major calyx and then renal pelvis but
that's because when our kidneys filter
the blood to create urine what happens
is that the majority of it happens here
in the cortex and the urine or the
filtrate that's been made dripped down
these renal pyramids drip drip into them
minor calyce's
which standeth all pull into the major
comes and goes to the renal pelvis and
then what do you think this goes from
the renal pelvis well this is the ureter
remember you have two kidneys so we're
just highlighting one particular kidney
here okay now I just said that we take
the blood in and we filter it from here
so that means that there must be another
it coming in which we do have remember
you have the descending abdominal aorta
with a renal branch that comes in
now this renal branch will split here in
segments go towards the back and towards
the front and continue to branch a
branch a branch a branch if we look at
these branches okay what you'll find is
as it branches and this image is going
to start to become a little bit messy
I'm sorry so as its branches you'll see
that it starts the branch between the
lobes here between the pyramids there's
renal pyramids and these are these low
bar segments of the arterial of the
artery that's come through so you have
low bar arteries that branch through
okay now these low bow arteries like I
said will go between these renal
pyramids and what do they do they turn
the corner like this
and they go around the real pyramids now
when you take that corner it's called an
accurate okay a turn accurate so these
are accurate arteries
now these accurate arteries have other
branches that come off them in the
cortex now these other branches that
come off
I called lobular arteries okay lobular
so we have to remember we have seek
mental arteries we have low bar arteries
or into lobha arteries because they're
between the lobes into loba then we have
accurate arteries and then we have into
lobular arteries coming up through
that's not the end yet unfortunately
because these interlope Euler arteries
have more branches coming off them like
this and this is where it gets to become
very important because these branches
are no longer batteries they are
arterioles remember arterioles are small
arteries and that these and these are
the only ones I'm going to label for you
these smaller arterioles are called
afferent arterioles okay why is this
important well as this remember this
blood comes in branches branches
branches into these afferent arterioles
but this is when we filter the blood in
the cortex and what we have in the
cortex are the functional unit of the
kidneys so the structural portion of the
kidneys that does all the filtering and
what this thing is called this is called
a nephron okay and you have now what
does a nephron look like I'm gonna wipe
this off here
and show you and therefore looks like
this has a little Pacman head to it and
then starts to look a little bit like a
snake
that's what I'm left for looks like now
this Neff on so let's write that down
and a pH ro and this Neff on this little
cup here is actually here at all these
arterioles so that means if I were to
draw it like this here so you've got
nephrons everywhere now the thing is
that you actually have per kidney around
about one to one point two nephrons so
for both kidneys you have two point four
ish nephrons which means you have a
great capacity to filter okay so you can
see if i want to draw the afferent
arteriole that's coming in comes in like
that like you can see here and then it
forms this capillary bed in that little
capsule like that and then pops out the
other side so and here you have the
afferent arteriole like I stayed and on
the other side you actually have what we
call an efferent arteriole the terminal
talking more detail in the next video
and effort arteriole and it's here at
this little capillary bed is where all
the substances from the blood that are
small enough and are of appropriate
challenge you can get filtered through
okay so this is important so that means
the blood comes in it gets filtered it
gets pushed through into this tube which
we call an f1 okay and follow through
the tube and go down this big tube here
now this big tube here moves down into
the renal pyramids so if I want to draw
a bigger nephron so there's the capsule
there's the afferent arteriole now sorry
there's the capsule there's a proximal
tibia
now like this and then moves down into
the rental pyramid now as it moves down
into the rental pyramid this is where
the fluid starts to move down so the
urine that you've just formed moves down
the renal pyramid and like I said drips
into the minor calyx then drips into the
major calyx and then that means when I
pee okay so this nephron is the site of
filtration the blood gets filtered and
travels through this tubing comes out as
pin okay in the next video I'm going to
focus on the nephron to talk about
exactly what happens but what you need
to know from this video is couple of
things two kidneys - you're eaters one
bladder one urethra the kidneys sit
behind the peritoneal cavity which are
called retroperitoneal at the level of
the 12th rib - the third lumbar
vertebrae okay it's surrounded by this
structural factor of peri renal fat it's
there for protection and Anchorage and
that the kidneys if you segment it if
you cut it you can see that it's made up
of two major components the cortex which
is the outer component and the medulla
which is the inner component the
filtration happens in the cortex and
that the urine that's being filtered
drips down into the renal pyramids and
into these cup-like structures which we
call the minor calyx and then the major
calyx and then out via the ureter the
way it gets filtered is that blood comes
in through the renal artery and this
artery branches and branches and
branches and branches branches into this
segmental arteries into interloper
arteries into arcuate arteries into
inter lobular arteries and they need to
afferent arterioles and it's the
afferent arterioles that enter into the
nephron as capillaries and this is where
the blood gets filtered the nephron will
take all that filtrate the blood that's
been filtered and drip it down the renal
pyramids for us to pay out okay
so hopefully that all makes sense
