ADH effects on blood pressure Renal system physiology NCLEXRN Khan Academy
We left off the story of antidiuretic hormone when it was just secreted into the blood vessels of the posterior pituitary. So it was just synthesized, just made. It’s a little hormone. And ADH was on its way to different parts of the body. So let’s just pick up the story right there.
And figure out where does it go next. So this little molecule is, we said, a small peptide hormone made up of amino acids. And so I’m just going to draw it here. And this little hormone is going to go off to do a couple of important things. So we know at the end of the day, it really wants to increase blood pressure.
So one of the places it visits is all of the vessels of the body, all the arterial vessels of the body. And specifically, it targets smooth muscle. So this hormone is going to go and get this smooth muscle to constrict. And we know that when smooth muscles constrict, the blood vessels are actually going to tighten down,.
And we call that vasoconstriction. So the blood vessels are going to get tight and small, and that’s going to increase resistance. And increased resistance is going to relate to blood pressure. And we’ll talk about how we know that. There’s that formula. I’m going to write it over here delta P equals flow.
Q is flow times resistance, is R. And you can actually change that around to say arterial pressure minus venous pressure equals and we know the flow is actually stroke volume times heart rate, and it’s all multiplied by resistance. So if you look at this, and if we assume for the moment that the venous pressure is going.
To be basically unchanged, then anything that increases the resistance over here is going to increase our pressure over here. So that’s why, in this case, if ADH is able to cause constriction of the blood vessels and increase resistance, our pressure would go up as well. So that’s actually one of the things that it does. And the other thing that it does is.
It’s going to act on the kidney. So it’s going to have an effect on the kidney. Here’s my kidney. And specifically what it’s going to do is it’s going to cause increased reabsorption of water. So increased reabsorption of water is going to increase our stroke volume. So now you can see the other key effect it’s going to have.
Aldosterone raises blood pressure and lowers potassium NCLEXRN Khan Academy
All right, we’ve talked about renin, we’ve talked about angiotensin. Let’s talk about aldosterone now. Aldosterone is the final hormone that gets your blood pressure to go up. And so where does it come from? Aldosterone comes from a gland.
I’m going to draw it here. And the gland is actually called the adrenal gland. And this gland literally sits right on top of the kidney. And so let me draw the kidney here for you so you can kind of orient yourself to where this gland would be sitting. And, of course, you have two kidneys. And you have two adrenal glands.
You have the left and the right. And if you were to look inside of the adrenal gland, you’d notice that, actually, in the middle of the adrenal gland is an area that looks different than the outside. And we call that the medulla. The inside is the medulla. And the outer bit is the cortex. And they make different hormones.
And this cortex is actually the part of the adrenal gland that makes the aldosterone. So let me draw some cortex cells here for you. And in the middle is a blood vessel kind of running through. I’ll draw that in just a moment. So these cortex cells are basically like any other cells. They need food, they need nutrients, they need oxygen. And so these capillaries that are running through.
Are going to provide all of that to these cortex cells. And if you were to take a microscope and, let’s say, look deep within these cells. Maybe not even with a microscope, but let’s say you were able to look deep within these cells, you’d notice that there is cholesterol in these cells. So there’s cholesterol sitting inside of the cells. Actually, not visible, but it is there.
And the cholesterol, I’ve always wondered, what is the point of cholesterol? It always seems like it’s a bad thing. This cholesterol is actually really useful to these cells because it helps them make the hormone aldosterone. Actually, aldosterone comes from cholesterol. And if you put the molecules next to each other, you’ll see how similar they are.
They actually look really, really similar. So these cells are the ones making aldosterone. But, of course, you can’t just make aldosterone willynilly, you have to wait for the right moment, right? So when does that cell know to make aldosterone? What are the triggers? Well, there are a couple triggers. One would be if you see, or if those cells encounter.