- Let's take a closer look
at the renal corpuscle. The renal corpuscle consists
of the glomerulus. The glomerulus was
the capillary bed, so glomerulus contains blood. And Bowman's capsule is
where the filtrate goes. So, blood parts, plasma, flows out of the glomerulus
and into Bowman's capsule. It's caught in Bowman's capsule.
So let's draw this again, so that it's nice and clear. And remember, how did blood get
into the glomerulus? This is my glomerulus
right here, and how did blood get in there? It came in through the afferent
arterial. And this is glomerulus. And it left
via the efferent arterial. So you're good with that? Now we have to draw
Bowman's capsule. Bowman's capsule is
a double-layered structure. You can imagine Bowman's
capsule is like a balloon. And the glomerulus is a net of capillaries that were punched
into the balloon. Is any part of this seeming
somewhat familiar? Yes.
Look at my balloon. The glomerulus is
inside the balloon. The balloon wraps
around the glomerulus that punched inside it, and then still contains the air that was in the balloon
in the first place. What? Yeah, you actually
have a visceral layer and a parietal layer
of Bowman's capsule. And let's make sure
we have our terminology. That's exactly what it's called.
You tell me. My little stick pointer is
on the parietal layer of Bowman's capsule. And now my little stick
is on the visceral layer of Bowman's capsule. The visceral layer
of Bowman's capsule is unique. It's actually a group of cells that are smashed
on the capillary bed, and they have these really
unique characteristics. The capillaries are
really unique. They have these slits in them, so they're super
leaky capillaries, which is very unusual.
And then the visceral layer of Bowman's capsule has these
parts of the cells that kind of, like, these little fingers
that come out and interdigitate, and create this sieve, like a filtering system.
Well, that's exactly what it is. It is a filtering system. Like, remember when you were a
kid, and you'd go to the beach, and you'd have that little tray with all the holes in it?
What is that thing? It's a filter. But you'd, like, throw the sand
from the beach in it, and then you'd shake it all out, and you'd find seashells
and crabs and who knows what other cool
things you'd find in there. That's what I'm thinking about. But I want
to show you a picture, someone else's picture. This is also
from the open stacks textbook. Dude, those guys are phenomenal.
But look at this thing. You can see here its blood. Here is my efferent arterial.
Here is my afferent arterial. The blood comes in, and look at how the visceral
layer of Bowman's capsule is, like, smashed
onto the capillaries themselves. The capillaries are a knot. This is just so nice
how it's shown. The parietal layer
of Bowman's capsule is-- what kind of tissue is that?
It's simple squamous epithelium. And look at the space
in-between there. That's the capsular space. That's actually an actual-- it's not a potential space. It's an actual space
where the filtrate gathers. And then look at who is this. This is proximal
convoluted tubule. So once the fluid comes out, it's going to go
into this tubule, and now it's going to be
in there to do its thing. This, I know it looks familiar, because we looked at this thing
on day two in this class, and this is day 22.
Holy crud. Time flies when
you're having fun. So 20 classes ago we actually
looked at this slide, and we looked at the parietal
layer of Bowman's capsule as our example of simple
squamous epithelium. This is so fun.
All right. So I think--
did I label everything? Capsular space.
Oh, I didn't. I wanted to tell you
that the visceral layer of Bowman's capsule, the cells that make up
that visceral layer, they're called podocytes. And I think of pod,
foot, toes, and these are like little toes
that are sticking out here. So these are podocytes.
And then what else? That's it. Okay. Now we get to look
at three parts, the histology of three
parts of our kidney, because we can actually
tell nephron parts when looking
in at our kidney slide. So, let's get started on that.