Download Welcome to this lesson today on the thyroid and parathyroid glands

Welcome to this lesson today on the thyroid and parathyroid glands. Today we will be discussing the structure and
function of these glands. So the thyroid and parathyroid are located in the neck. And they work closely together to
manage blood calcium levels.
So if we take a look at this picture right here, we're going to identify the thyroid and parathyroid. So this here is our
thyroid gland. And the parathyroid glands, there's actually four of them that are located on the thyroid. So I'll just
kind of draw them in right here. These would be the parathyroid glands. And as I mentioned, we have four total.
So we're going to talk separately about each of these glands and the role that they play in our body in the
endocrine system. So the thyroid gland secretes thyroid hormone. And thyroid hormone is abbreviated as TH. So
this thyroid hormone plays a role in metabolism, growth, and optimal functioning of the central nervous system.
The thyroid gland also secretes a hormone called calcitonin. And calcitonin is a hormone that helps to regulate
blood calcium levels by lowering blood calcium levels if they get too high. So if blood calcium levels get too high,
the osteoblasts in the bone will be signaled to store that access calcium within the bone.
And then the parathyroid gland secretes parathyroid hormone, also abbreviated as PTH. And so parathyroid
hormone also plays a role in regulating blood calcium levels. So what parathyroid hormone does is helps to raise
blood calcium levels if the blood calcium levels get too low. So it will signal osteoclasts to release calcium from the
bone.
So these two hormones actually play a role in bone remodeling. And this process helps to maintain homeostasis
of blood calcium levels. So the thyroid gland and the parathyroid gland play a large role in maintaining
homeostasis of blood calcium levels, either by lowering blood calcium levels or raising blood calcium levels with
the help of osteoblasts and osteoclasts.
So we're going to take a look at some disorders here that can occur with the thyroid and parathyroid. So a simple
goiter is one type of disorder that can affect the thyroid gland. So in order for the production of thyroid hormone,
iodine is necessary.
So if a person does not get enough iodine in their diet, what happens is that lobes of the thyroid will enlarge and
swell up. So again, simple goiters are the swelling or enlargement of lobes of the thyroid caused by a diet deficient
in iodine. Generally in the US this is not much of a problem now, since you can buy iodized salts. So that's where
we get a good majority of our iodine.
Hyperthyroid is a condition in which there is excess thyroid hormone in the blood, which can lead to a high heart
rate, elevated blood pressure, and sweating. So Graves' disease is actually a disease that causes
hyperthyroidism. So in effect, Graves' disease is an autoimmune disease that basically in a nutshell stimulates
overproduction of thyroid hormone. And then that overproduction of thyroid hormone leads to this condition of a
hyperthyroid.
And then hypothyroid is low blood thyroid levels. So hyper- is high. And hypothyroid is low thyroid hormone levels.
So with these low thyroid hormone levels, as we mentioned thyroid hormone controls metabolism, growth, and
CNS functioning. So basically if thyroid hormone levels are low, it can lead to things like weight gain. A person
might feel sluggish. And they might be intolerant to very, very cold or very high temperatures. So these two
disorders are disorders that are caused by fluxes in thyroid levels, thyroid hormone levels within the blood.
So this lesson has been an overview on the structure and function of the thyroid and parathyroid.