so when we're talking about the endocrine system you have to start at the very beginning because
that's a very good place to start so we start with the pituitary gland and the pituitary gland
is your master gland it controls almost all the other endocrine systems not all of them but most
of them so it is it's in your skull it's at the base of your skull and we'll go over its anatomy
but it's controlled by the hypothalamus which is it sits right below so here's our pituitary
here and here is our brain here is your optic chiasm and here is your hypothalamus so the
hypothalamus secretes factors that then control the anterior pituitary and we'll go into some
of those details the pituitary has an anterior lobe and a posterior lobe the pituitary gland
both the anterior and posterior lobes are as you can see from the illustration regulate
lots of different parts of the body they control growth water balance your metabolic rate sexual
maturity responses to stress in the environment and that's just to name a few of the things that
the pituitary gland has an influence over so the pituitary gland is an extension of kind of
your brain it sits up in the top of the base of the skull can at the bottom of the brain top of
the skull so here is okay let's to get oriented here's your hard palate here here's your nose
there's your frontal sinus there's your sphenoid sinus and here is a bony landmark that we call the
sella turcica or turkish saddle and it's kind of a bony prominence and right in the middle is your
pituitary gland just above it is your hypothalamus right here and because I can't help it I have to
review some narrow anatomy here's your brainstem in here here's your thalamus here here's that
lateral ventricle so in the illustration it shows the sella turcica this nice this bony
landmark and here is our pituitary nestled within it and the hypothalamus sitting above it as the
illustration shows which I can't show in the in the image because it's too low of magnification
is how vascular the pituitary gland is and you know it's important because it's sitting in this
bony cavity that really protects it just a side note if you are ever dissecting brains if you
ever have that opportunity to and you're removing a brain from a skull whether it be human or rodent
or any other any other animal model you and you remove the brain the pituitary will almost always
stay in the sella turcica it is so tightly bound in there that you'll pull out the brain and that
the pituitary never comes with it it's always stays in the skull it's connected to the brain
by what's called the pituitary stalk which is here and that is a very important structure
through which hormones are going to migrate it's highly vascular the pituitary is really really
close to the hypothalamus and that's it's so close and for a reason it's non transplantable
so when we talk about the endocrine system it's hormones are secreted into the vasculature they
float around the entire body and get to their targets they're not in hugely high levels but
high enough so that if something is secreted in my thorax it can get all the way to my pelvis no
problem the pituitary is very very very dependent on the hypothalamus the hypothalamus doesn't
secrete huge amounts of peptides that control the pituitary so all of the all of the secretory
neurons that live here in the hypothalamus are secreted in relatively low amounts and so
they have to get to here and here the anterior and posterior lobes and because they're in low
concentrations the pituitary must be very close to the source of the factors that regulate it if
I took my thyroid gland for example and stuck it down under my kidney capsule it would work
just fine it would get the information it needs from the pituitary and we'll talk about the ins
and outs of this as this MOOC progresses and it would still secrete thyroid hormone which
would go everywhere if I put my pituitary gland underneath my kidney capsule it's not going to
work because these factors aren't such low concentration that by the time they got all
the way to my kidney capsule area via the blood supply they just would be so dilute that they
wouldn't have any effect so the pituitary and the hypothalamus are very closely linked very
closely related and the pituitary can't function unless it's really close to the source of the
factors that regulate it and those are made in the hypothalamus in the next section we're
going to talk about the posterior pituitary gland and then we'll talk about the anterior pituitary