Proximal Convoluted Tubule: Part 1

Part 1 of three videos discussing the sodium-dependent reabsorption of filtrate at the proximal convoluted tubule in the kidney. Glomerular filtration rate, as well as the effects of too high a GFR and too low of a GFR, are briefly discussed. Compensatory mechanisms to regulate GFR are briefly reviewed though it would be beneficial to watch the video titled glomerular filtration rate prior to this video. This video then discusses the affect of hypernatremia and hyponatremia on the ability of the PCT to reabsorb nutrients as well as wastes like urea from the filtrate and back into the blood; hypernatremia will decrease reabsorption while hyponatremia increases reabsorption. Lastly, the consequence of too high of protein or glucose in ones diet, and how it causes hyponatremia (and increased reabsorption), is described. This video is intended for freshman/sophomore pre-nursing students.

A scan of this diagram can be obtained at
http://www.kirkwood.edu/pdf/uploaded/695/pct.pdf

Category:

Education

Tags:

• proximal
• convoluted
• tubule
• hypernatremia
• hyponatremia
• absorption
• glomerular
• filtration
• rate
• PCT
• GFR
• kidney
• nephron
• protein
• failure

[pirateXhunterXzoro]

The MD receptors tell the JG cells to inhibit renin if there is too much Na. But if you inhibit renin, wouldn't that also inhibit angiotensin II and decrease blood pressure, causing more Na to flow through?

Please help, thank you.

[hennagerdj]

@pirateXhunterXzoro Reducing blood pressure would reduce GFR; this means the filtrate would flow through slower so that there is more time to pick up the proper amount of Na. What the MD cell is sensing is that GFR is too high (so there is not enough time to pick up Na). In that case, you want to inhibit renin, bring down blood pressure, and this brings down GFR.

[pirateXhunterXzoro]

btw, you're pronouncing renin incorrectly. You're pronouncing it like rennin, a protein-digesting enzyme.

[hennagerdj]

@pirateXhunterXzoro: I'll give you that it is more commonly pronounced as ree-nin (and it is probably more acceptable given the pronunciation of renal), but re-nin is an accepted pronunciation as well from Merriam-Webster. re·nin noun \ˈrē-nən, ˈre-\

[Redrocket14]

oh he doesnt say it. its in one of my lecture notes. and text book. i guess they shud say the peritubular capillary reabsorbs and not reabsorbtion takes plave in the pct. but i guess i understand now what they mean. thanks for ur help

[pirateXhunterXzoro]

@Redrocket14 You are correct. Reabsorb means to take back into the capillary. But I can't seem to find where he says that PCT reabsorbs the substance. Are you talking about high GFR?

[Redrocket14]

@pirateXhunterXzoro just a question since u seem to know alot. When in my notes in says that the PCT reabsorbs a substance. does that mean it passes into the capillary surrounding it? or pass from the capillary into the PCT? reabsorbtion means that the substance is passed back into the body right?? then why in the hell does it say that the PCT reabsprbs the substance?? that would mean that the substance passes into the PCT and ultimately ino the ureter and exits the body?? Please help!!!

[Djalitana]

thank you so much. your vids are very helpful and they made my book so much easier to understand.

[khushba]

both afferent and efferent arterioles are effected by angiotensin 2....but efferent is MORE sensitive to angiotensin 2.