00:00
On this slide, you can see two
sections taken through the hard palate.
00:06
On the left-hand side under very low
magnification, you can see the hard
palate labelled. It's actually bone. And on
top of that bone, on the surface of the
bone on the oral side is the masticatory mucosa
that I'll describe in more detail in a
moment. But superior to the bone of the hard
palate, you can see two roughly even
clearer structures. And in those clear
areas, you can see two almost overlooking
pale stained structures. This is the nasal
cavity, and the two overlooking
structures are in fact parts of the
inferior concha. They are very important
because they house respiratory tract
epithelium, and also a very wide network
of blood vessels called swell bodies that
help warm, moisten and clean the air as
it passes through the nasal cavity. And I've
covered details of that in a lecture on the
respiratory system. But focus now on the
hard palate, and below, just below, you
can see some rather pale stained structures
on either side of the centre
of the hard palate. They're mucus-secreting
glands. A lot of glands secrete into
the oral cavity to moisten it and also to
help form that bolus of food I
mentioned at the very
beginning of the lecture.
01:40
On the far extreme of each end of this particular
section are teeth. There's a tooth on the left section
and a tooth on the right embedded in
alveolar bone. And if you look very
closely at this section,
you can see a bright
red component. That is the dentin of the
tooth. And central to that dentin is a
very pale region which is the pulp cavity.
You don't see the enamel there because
the enamel is a very mineralized
structure. This section has been
decalcified, and therefore, all you see
here is the organic components remaining,
and therefore, taking out the stain.
Focus now on the right-hand section and
on the masticatory mucosa. It has got a
very thick epithelium, its stratified
squamous epithelium. But if you look
closely at this section, you might see a
little bit of keratin on the surface. That
can happen in the oral cavity where
there is constant wear and tear, or
constant abrasion. It's a bit above
normal. For instance, if you wear a denture
that doesn't fit properly, it can start
to keratinize the epithelial surface
at that location. We call it para
keratinized because it doesn't go
through the full keratinization
process. But generally speaking, the oral
mucosa and the masticatory mucosa on the
surface of the hard palate is just
stratified squamous epithelium.
03:27
Notice the epithelium actually embeds into
the underlying connective tissue, and the
underlying connective tissue is very
dense collagen. So this epithelial
surface is very tightly bound to the bone.
03:41
It forms a very, almost hard surface for
the tongue to push food up against
and help to mechanically break it down.