Proximal Convoluted Tubule: Part 1

[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

[Djalitana]

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

[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]

@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!!!

[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?

[khushba]

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

[rkhedk]

thanx a ton!!

[jd1iraq]

man, u r AWESOME ...

[LoserMcBeaver]

What i dont get is...

When you have higher blood pressure doesnt that mean the afferent should widen instead of constriction?

Because contriction only leads to more pressure and speed of the blood?

PLease someone help me I have a major exam on this :9

[Mayalives]

@LoserMcBeaver. No restriction of the afferent arteriole will cause less flow.

[innelfrr]

thank you !

you help me done my home work ~ =]

[rezaeijavan]

It was amazinggggggggggg

[Catchetat]

300l of blood per day?

[enycedoll]

@Catchetat

yes, 180 is turned into filtrate

[enycedoll]

Never mind, i figured it out. the arteriole constricts or dilates to maintain a steady GFR. if blood pressure is high, the arteriole will constrict and if it's low, the arteriole will dilate.

[Catchetat]

@enycedoll @enycedoll True but i don't quite understand. If blood pressur eis low then the renal perfusion in the JG cells of the afferent arteriole will be low. It produces renin which is a potent vasoconstrictor, which is opposite to what u said about vasodilation. Can someone explain please? THanks.

[enycedoll]

@Catchetat

the afferent arteriole is not only under the control of renin. It's myogenic...it dialates and constricts based on the pressure in the glomerulus. The point is to maintain a specific GFR. If it's too high, the afferent arteriole has to constrict to limit the amount of blood entering the glomerulus and if gfr is too low, it dialates to allow more blood to enter so it can get back the normal gfr.

[rkhedk]

@Catchetat actully..when the GFR is low JG cells secrete reninacts on angiotensin present in d systemic blood converts it into angiotensin 1 a converting enzyme convers angiotensin1 into angiotensin 2 which is a powerful vasopress/ vasoconstrictor that causes EFFERENT ARTERIOLAR CONSTRICTON which increases the glomerular pressure inc net filteration pressure and eventually increases GFR.

[enycedoll]

wait, i'm a little confused...if the blood pressure is high in afferent arteriole, shouldn't it dilate? wouldn't constriction of the arteriole put more pressure on the walls?

[nerdycrush]

Thanks a bunch!

[YeaOrNot]

thank you :)

[tightKnit]

This video is right on time. I have an exam next week on the urinary system and being able to watch all of your videos is priceless for those of us, who are visual learners.