Thyroid and Adrenal Gland (Nursing)

00:01 Let's continue our discussion of the endocrine system by looking at some endocrine organs outside of the brain.

00:08 We'll start by looking at the thyroid gland.

00:12 The thyroid gland is located in the neck, but it's located inferior to the larynx.

00:19 And I make that distinction right away.

00:22 Because there is a cartilage in the larynx called the thyroid cartilage.

00:26 It's very common to forget over time that the thyroid gland doesn't sit on top of the thyroid cartilage, it actually sits further down, sitting over the trachea.

00:38 The thyroid gland itself has a right lobe, a left lobe, and a portion that connects it called the Isthmus.

00:50 The thyroid gland is going to secrete thyroid hormones.

00:55 And I say hormones because it comes in two varieties depending on how much iodine is in that hormone either T3 or T4.

01:04 But regardless, it carries out basically stimulatory functions of metabolism.

01:11 So these thyroid hormones will stimulate protein synthesis.

01:16 It will help with the maturation of the nervous system during development.

01:20 It will increase the rate of cellular respiration.

01:24 It will elevate the overall basal metabolic rate.

01:28 So again, it has an overall stimulating effect on metabolism.

01:34 Here we see it from a posterior view.

01:38 And on the posterior surface of the thyroid, we can see the parathyroid glands which are going to have a very different function than the thyroid gland, and we'll be more related to calcium.

01:52 The thyroid gland is also the site of a lot of pathologies.

01:57 There's a lot of hyperthyroidism and hypothyroidism that are going to be very self explanatory in a lot of ways.

02:06 Hyperthyroidism is essentially too much thyroid activity, whereas hypothyroidism is going to be too little thyroid activity.

02:16 And because we know what thyroid hormones do, we can kind of guess the symptoms that will result from hyper versus hypothyroidism.

02:25 Hyperthyroidism is going to produce a lot of activity and stimulation so sleep will be decreased, whereas hypothyroidism result in more lethargy and more sleep.

02:36 It's also going to affect heat intolerance.

02:41 Because the body is going to be very metabolically active with hyperthyroidism, body's going to be very intolerant to heat, whereas the opposite will be true with hypothyroidism.

02:50 With the lower metabolic rate, people will feel more cold.

02:56 Pulse rate will be elevated in hyperthyroidism, because metabolism has been stimulated and it will be slower with hypothyroidism.

03:04 Same thing with GI systems.

03:07 So there will be frequent bowel movements, there will be a lot of weight loss, whether it's even planned or not, because of this stimulation of the metabolic system.

03:21 Hypothyroidism, on the other hand, would be the exact opposite, things will slow down dolmens will decrease, constipation will result, and weight will be put on because metabolism is slowed.

03:35 And there will also be psychological effects as a result of this stimulation, as you might suspect stimulation is going to create a lot more nervousness and anxiety whereas a lack of stimulation will really lead to more apathy or depression.

03:54 The next organs we're going to look at are the suprarenal or adrenal glands.

03:59 And as the name implies, they're going to sit adjacent to the kidneys.

04:05 Here we see the right kidney with the right super renal or adrenal gland, sitting somewhat along the superior aspect of the kidney.

04:14 And same on the left side.

04:18 Here's a cross section through the kidney and adrenal gland.

04:22 And we again see this word cortex and medulla.

04:27 And they mean the same thing they have in other organs where cortex refers to the outer portion.

04:33 Medulla refers to the inner portion.

04:38 And if we were to look at this in sort of a micro and atomic way, we would see that the adrenal gland has a thin little capsule, and then the cortex has various zones.

04:50 So the outermost zone is called the zona glomerulosa.

04:54 And that's going to secrete mineralocorticoids, things like aldosterone which the hormone that will have an effect on the kidneys.

05:05 The next layer down the zona fasciculata produces glucocorticoids.

05:11 And that's going to be something classically would be cortisol.

05:16 And that's going to be your classic glucocorticoid.

05:20 The deepest layer of the cortex is going to be the zona reticularis.

05:24 And that's going to secrete androgens, mostly something called dehydroepiandrosterone, which is something that can be further modified by other parts of the body once it reaches the bloodstream.

05:37 The cortex looks very different from the medulla here and cross section in part because they come from two different embryologic origins.

05:45 So the medulla is going to be very different from the surrounding cortex.

05:50 We mentioned that the pituitary has a lot of effects on the cortex through something called adrenocorticotropic hormone or ACTH.

05:59 Therefore, these various zones of the cortex are stimulated hormonally by the pituitary.

06:06 The medulla is different, because the medulla is actually stimulated by the autonomic nervous system.

06:12 So it's actually sort of modified nervous cells in the medulla.

06:17 And in response to the autonomic nervous system, the medulla is going to secrete stress hormones, like epinephrine and norepinephrine.