Nephrons and Diuretic Sites of Action (Nursing)

by Rhonda Lawes, PhD, RN

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    00:00 Now, let's take a look deep into the kidney.

    00:03 First of all, reorient yourself.

    00:05 You've got the medulla, which is in the middle, and then you've got the cortex.

    00:10 Now we kind of blew that out.

    00:12 If you see that we - looks like we've got one kind of pyramid shaped there.

    00:15 I want you to remember, each kidney has 1 million nephrons.

    00:20 So they're pretty densely packed in there.

    00:23 But we blew that up and just showed you a couple of the nephrons to kind of give you the idea.

    00:28 So look at that drawing.

    00:29 Can you find the glomerulus? Do you see Bowman's capsule? And then do you see both of the tubules? Okay, great.

    00:38 That's where they're located.

    00:40 So we're looking at just a couple of the million nephrons in each kidney.

    00:45 We kind of blew that up just to remind you and to give you a refresher, you've got the glomerulus which is a tangle of capillaries, surrounded by the Bowman's capsule, and then you have the tubules.

    00:55 The three main parts of the nephron.

    00:58 Now we stretching this out even farther.

    01:01 Look at that middle line across.

    01:03 You see on the top is the cortex below is the medulla and the nephron is stretched from the cortex through to the medulla.

    01:11 So just to give you an idea of where you are in the kidney.

    01:14 Now this to me is fascinating.

    01:17 I know we might not be a pharmacology nerd, but look at what was discovered.

    01:21 We know exactly where the sites of action are for diuretics on the nephron.

    01:27 So why are we talking about diuretics with kidneys? Because this is one of the biggest areas of trouble for a patient with kidney failure or kidney problems.

    01:36 They can't get rid of that waste, they can't get rid of that volume.

    01:40 So we use diuretics, medications that will increase how much of the fluid is excreted from the body.

    01:46 Now there they are the PCT and the DCT.

    01:50 You've got them right there.

    01:51 The Proximal Convoluted Tubule and the Distal Convoluted Tubule.

    01:55 Now here, first up, about 65% to 70% of the sodium is reabsorbed there.

    02:02 See the next one? Sodium potassium, you've got about 25% of it absorbed there.

    02:08 5% of the sodium chloride is absorbed there, and 1% to 5% of the sodium potassium is reabsorbed there.

    02:16 Okay, so notice the majority of that gets absorbed at the beginning.

    02:20 So you've got 65% to 70%.

    02:23 Look at, follow it around all the way to the end.

    02:27 And you see we're down to 1% to 5%.

    02:30 So progressively, it gets lower.

    02:32 You start at 65 to 70, trace it around, you go to 25, then your at five and then follow it all the way out to the end where you're at one to five.

    02:42 Now this tells us kind of lets us know how strong or how potent a diuretic is going to be depending on where exactly it works in the nephron.

    02:52 Now, I've put the names up there for you.

    02:54 The 65% to 70% are the Carbonic Anhydrase Inhibitors.

    02:58 We call those CAIs because that's a mouthful.

    03:02 Next are the loop diuretics.

    03:04 Now you're probably more familiar with those Lasix or furosemide.

    03:09 Now, these are the strongest ones we use for people in renal failure.

    03:13 We used to CAIs for people with eye problems, but we're looking at loop diuretics that's predominantly what you'll see prescribed for people with kidney disease, or need to pull off extra fluid.

    03:24 Next, are the thiazides.

    03:26 Now, both of these groups have diuretics.

    03:28 Loop diuretics and thiazides.

    03:30 We'll really go after a patient's potassium.

    03:33 So keep that in mind.

    03:35 Loop diuretics will cause the most significant drop in potassium, but thiazide diuretics will also cause a drop in potassium.

    03:42 Now finally, we end up with potassium sparing diuretics.

    03:46 Toot-toot.

    03:47 They're at the end of the line.

    03:49 And that's why they're not very intense.

    03:52 We get our biggest impact with most patients with things like the loop diuretics.

    03:57 The potassium sparing diuretics are used on special occasions Or to help patients who are losing too much potassium in treatment.

    04:04 That's why they're called potassium sparing diuretics.

    About the Lecture

    The lecture Nephrons and Diuretic Sites of Action (Nursing) by Rhonda Lawes, PhD, RN is from the course Review: Anatomy and Physiology of the Renal and Urinary System (Nursing).

    Included Quiz Questions

    1. Proximal tubule
    2. Loop of Henle
    3. Distal tubule
    4. Glomerulus
    1. Loop diuretic
    2. Carbonic anhydrase inhibitor
    3. Thiazide medication
    4. K-sparing medication

    Author of lecture Nephrons and Diuretic Sites of Action (Nursing)

     Rhonda Lawes, PhD, RN

    Rhonda Lawes, PhD, RN

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