The major stimulus for release of parathyroid hormone is a. hormonal, b. humoral, c. neural.

Video transcript

Hi, everybody. Welcome back. Here's our next question. The major stimulus for the release of parathyroid hormone P T H is typically humoral specifically a decrease in blood calcium levels. When blood calcium level drops below a certain threshold, the parathyroid glands release P T H which acts on the bones, kidneys and intestines to increase calcium levels in the blood. What are the other stimuli that can induce the release of P T H A hormonal stimuli? Low levels of vitamin D B. Neural stimuli such as stress or pain, C decrease in blood glucose. D both A and B or E, both B and C. So we're talking about different types of stimuli that cause hormones to be released. Our question major mentions the major stimulus for P T H release being moral. We can recall that a humoral response is a response to a change in extracellular fluids. In this case, blood calcium levels dropping our other two stimuli that are mentioned as answer possibilities are choice. A hormonal stimuli. The example being given is low levels of vitamin D. Well, this might seem a little strange because if we're thinking about low levels of vitamin D in the blood. We might think that's a humoral response. But we need to recall that vitamin D is actually a hormone. It has the name vitamin because it's essential to the body's function. But it is a hormone. And so response to low levels of vitamin D would be a hormonal stimuli. And this is indeed the case because vitamin D is essential for uh home the homos stasis of calcium levels because it's necessary for the absorption of calcium from the intestines. So a low level of vitamin D, low vitamin D means that there will be less calcium absorbed and therefore lower levels of calcium in the blood. So you'd want to release P T H to stimulate more uptake of calcium from the kidneys, bones and intestines. So choice A is the correct answer. But we know we have those options of choice D, both A and B. So we're gonna put a little dot here and we're gonna go ahead and eliminate choice E which is both B and C because we know that A is correct. So let's move on to choice B. Joyce B says neural stimuli such as stress or pain. So that would be if hormones are released in response to neural signals, neural happenings, neural messages and P T H is released in response to stress or pain. This is a minor effect compared to actual levels of calcium in the blood. Um levels of vitamin D which makes sense um And it's just not very well understood, but it does act as a stimulus for the release of P P H. So it is a correct answer. I'm gonna put a dot There. And so we know our answer must be choice D both A and B now, just to be thorough, we'll look at choice C to understand why that is not going to be our answer. Even though by process of elimination, we know it can't be our answer. Android a decrease in blood glucose, but P T H is not involved in regulating blood glucose. So there wouldn't be any reason for it to be a stimulus for the release of P T H. Choice C is incorrect. And our answer here for the other stimuli that can induce the release of P T H is choice of D both A and B. See you in the next video.