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


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


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


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


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