Med-Surg Endocrine System, part 5: Epinephrine, Norepinephrine, Calcitonin, PTH, Insulin & Glucagon
Epinephrine, norepinephrine, calcitonin, PTH, insulin and glucagon are important hormones to know about in Medical-Surgical Nursing. Having a baseline understanding of these hormones’ functions, pathways, and origins is crucial to understanding the related diseases and disorders. There are also manufactured versions of these hormones that you will learn about in Pharmacology.
The KEY things you need to know about these hormones for your Med-Surg exams are condensed into 3 cards in our Medical-Surgical Flashcard deck.
Epinephrine and Norepinephrine
What are epinephrine and norepinephrine?
Epinephrine (adrenaline) and Norepinephrine (noradrenaline) are hormones known as catecholamines that are released in response to acute stress. When these hormone levels increase, the body prepares for the "fight or flight" response.
What controls the release of epinephrine and norepinephrine?
The sympathetic nervous system (SNS) controls the release of epinephrine and norepinephrine. When you are under acute stress, the SNS is activated, which activates nerves that are connected to the adrenal medulla, causing secretion of epinephrine/norepinephrine.
Which endocrine diseases and disorders are related to epinephrine and norepinephrine?
Pheochromocytoma, which is a tumor on the adrenal medulla, causes excess secretion of epinephrine and norepinephrine.
Epinephrine and norepinephrine as medications
The manufactured form of epinephrine and norepinephrine are used as medications for shock, and these drugs are covered in our Pharmacology Flashcards.
What is calcitonin?
Calcitonin is a hormone that decreases blood calcium levels.
Easy way to remember the function of calcitonin
Calcitonin helps tone down calcium levels in the blood!
How does calcitonin decrease blood calcium levels?
Calcitonin decreases blood calcium levels in two ways:
- Calcitonin decreases the activity of osteoclasts, cells that move calcium into the bloodstream by breaking down bone.
- Calcitonin increases excretion of calcium at the kidneys.
What controls the release of calcitonin?
When the body senses that we have too much calcium in the bloodstream, or hypercalcemia, this stimulates the release of calcitonin from the thyroid gland.
Which endocrine diseases and disorders are related to calcitonin?
One related endocrine disease is hyperparathyroidism, also known as parathyroid disease. The manufactured form of calcitonin can be given to treat hypercalcemia caused by hyperparathyroidism.
Calcitonin as a medication
Parathyroid Hormone (PTH)
What is PTH?
PTH stands for Parathyroid Hormone and it's responsible for increasing the amount of calcium in the bloodstream.
PTH basically does the opposite of what calcitonin does in the body. PTH increases calcium in the bloodstream, while calcitonin decreases it.
How does PTH increase blood calcium levels?
PTH increases blood calcium levels in three ways:
- PTH pulls calcium out of the bones and into the bloodstream by recruiting those osteoclasts we mentioned earlier.
- PTH causes the kidneys to reabsorb more calcium, and causes the kidneys to release vitamin D, which helps with calcium absorption in the body.
- PTH increases absorption of calcium in the intestines.
What controls the release of PTH?
You might remember from our endocrine glands overview that PTH is produced by the four parathyroid glands in the neck. Makes sense, right? Parathyroid glands make parathyroid hormone.
When the body senses that there's not enough calcium in the bloodstream, which is called hypocalcemia, that stimulates the release of PTH from the parathyroid glands.
Which endocrine disorders and diseases are related to PTH?
Hypoparathyroidism and hyperparathyroidism are two Endocrine diseases directly related to PTH. Decreased or insufficient secretion of PTH can lead to hypOparathyroidism. Excess secretion of PTH can lead to hypERparathyroidism.
Again, this makes sense: Parathyroid glands make parathyroid hormone, but an inappropriate amount can lead to one of the -parathyroidisms.
What is insulin?
Insulin is a hormone that decreases blood glucose levels. Insulin allows glucose to move from the bloodstream into the body's cells, where it can be used for energy. Blood glucose is colloquially known as blood sugar.
What controls the release of insulin?
When the body senses that blood glucose levels are rising, the beta cells in the pancreas (in the islets of Langerhans) release insulin to help move that glucose into the body's cells.
Which endocrine diseases and disorders are related to insulin?
You might be able to guess this one. Diabetes Mellitus is an endocrine disease caused by either insufficient production of insulin (Type 1) or insulin resistance (Type 2).
Insulin as a medication
The manufactured form of insulin helps diabetic patients control blood sugar. Four main types of insulin are covered in our Pharmacology Flashcards and in our video and article on insulin medications.
- Rapid-acting insulin (insulin lispro)
- Short-acting insulin (regular insulin)
- Intermediate-acting insulin (NPH insulin)
- Long-acting insulin (insulin glargine, Lantus insulin)
What is glucagon?
Glucagon is a hormone that increases blood glucose levels.
Glucagon basically does the opposite of what insulin does. Glucagon increases blood sugar, and insulin decreases it.
How does glucagon increase blood sugar?
Glucagon increases blood sugar in three ways.
- Glucagon kicks off a pathway called glycogenolysis in which glycogen in the liver is converted into glucose and then released into the bloodstream.
- Glucagon stimulates gluconeogenesis, which is production of new glucose. If you break down the word into its medical terminology parts, "Gluco" means relating to glucose, "neo" means new, and "genesis" means formation. Like glycogenolysis (#1), gluconeogenesis (#2) happens primarily in the liver.
- Glucagon causes adipose tissue to break down fat for use as energy.
What controls the release of glucagon?
When the body senses that blood glucose levels are low, then glucagon is released from the alpha cells in the pancreas.
Which endocrine diseases and disorders are related to glucagon?
Glucagon can be used to treat the diabetes complication hypoglycemia.
Glucagon as a medication
Check out Cathy’s easy way to remember what glucagon is for.
Understanding these hormones and how this system works is crucial to understanding the pathophysiology of the related diseases and disorders of the Endocrine System. The Medical-Surgical Nursing - Endocrine video tutorial series is intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI and NCLEX.
In this video, we are going to go over some more important hormones in the body, including epinephrine, or adrenaline is another name for epinephrine, as well as norepinephrine. We're also going to talk about calcitonin and parathyroid hormone as well as insulin and glucagon.
Let's first talk about epinephrine and norepinephrine. These two hormones are catecholamines that are released by the adrenal medulla - so that's the inside of the adrenal gland - in response to acute stress. So if you are being chased by a bear, that would be acute stress, and that would kick off your body's flight or fight response and result in the release of epinephrine and norepinephrine.
These hormones will cause a number of changes in the body, including vasoconstriction, increase of heart rate and blood pressure, bronchodilation, pupil dilation, increase blood flow to the muscles, and increase blood glucose levels.
Your body's basically preparing to run from the bear, and it wants to make sure that you're getting enough oxygen in those lungs and that the blood is circulating throughout the body and getting that oxygen and nutrients to your skeletal muscles and everywhere else. So those are the changes you can expect when epinephrine and norepinephrine are released.
Keep in mind that epinephrine has more of an effect on the heart, versus norepinephrine which has more of an effect on the blood vessels.
So in terms of what controls release of epinephrine and norepinephrine, when you have an acute stress situation, the sympathetic nervous system is activated, which activates nerves that are connected to that adrenal medulla, which allows for the secretion of epinephrine and norepinephrine.
Now let's talk about calcitonin, which is a hormone that decreases blood calcium levels. It opposes the action of parathyroid hormone, which we'll talk about next. So it decreases blood calcium levels by doing two different things.
The first thing it does is it decreases the activity of osteoclasts. So osteoclasts are cells that break down the bone and move that calcium into the bloodstream. And we don't want that, right, because we're trying to decrease levels of calcium in the bloodstream. So it opposes the action of osteoclasts.
Then the other thing that calcitonin does is it increases excretion of calcium at the kidney. So we're just getting rid of extra calcium so it doesn't build up in the bloodstream. So the way that I remember what calcitonin does is if you look at the word calcitonin, you can remember that calcitonin tones down the calcium. And that little hint is here on card 11 [of the Endocrine System section in the Medical-Surgical Flashcards].
So what stimulates release of calcitonin? When the body senses that we have too much calcium in the bloodstream, or hypercalcemia, this stimulates a release of calcitonin from the thyroid gland.
Now, let's talk about parathyroid hormone, or PTH. This basically does the opposite of what calcitonin does. So PTH wants to increase the amount of calcium in the bloodstream, and it does this by doing three different things.
The first thing it does is it pulls calcium out of the bones and into the bloodstream.
The second thing it does is it causes the kidneys to reabsorb more calcium, and it also causes the kidneys to release vitamin D, which helps with the absorption of calcium in the body.
And then the third thing it does is it increases absorption of calcium in the intestines. So it does all of these three things to bring those calcium levels up in the bloodstream.
So what controls release of PTH? When the body senses that there's not enough calcium in the bloodstream, so hypocalcemia, that stimulates the release of PTH from the parathyroid gland.
Let's talk about insulin and glucagon.
Insulin decreases blood glucose levels. Insulin allows glucose to move from the bloodstream into the body's cells, where it can be used for energy. So when the body senses that blood glucose levels are rising, insulin is released from the beta cells in the pancreas to help escort that glucose into the body's cells.
Glucagon is basically doing the opposite. It wants to increase blood glucose levels, as opposed to insulin, which wants to decrease blood glucose levels. Glucagon increases blood glucose levels in three different ways.
The first way is through glycogenolysis. So this is where we convert glycogen in the liver into glucose and then release that into the bloodstream.
The second way that glucagon increases blood glucose levels is through gluconeogenesis, so this is production of new glucose.
And then the third way that glucagon increases blood glucose levels is it causes the adipose tissue to break down fat for use as energy. So it does these three things to bring up those blood glucose levels. So when the body senses that blood glucose levels are low, then glucagon is released from the alpha cells in the pancreas.
So we got through all of those hormones, so good job in sticking with me through all those. Next, we're going to talk about that negative feedback mechanism that I mentioned in a previous video, as well as the positive feedback mechanism that is used by just a couple of the hormones in the endocrine system, so stay tuned for that information in my next video. Take care!
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