Lecture 7 Final Flashcards by Eric Barretto

How many % of water and electrolytes are reabsorbed in the PCT?

65%

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How much water gets reabsorbed in the thin descending limb?

20%; approximately 85% of the 2/3, remaining 15% is reabsorbed in the DCT and collecting duct.

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In the TAL how many ions are reabsorbed (NKCL2)?

25%

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The remaining 15% of reabsorption is decided in the…

DCT/collecting duct via principal cells.

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What regulates the water reabsorption in the DCT/collecting duct?

ADH

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The PTH moves the Ca++ from the lumen to the cell and then?

It is reabsorbed to the interstitium via Na/Ca exchanger (3:1) with the primary force of the N/K pump.

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Explain how the speed of Ca reabsorption in the DCT is sped up.

With the N/K pump keeping it low + charge inside the cell, the Na/Ca exchanger wants to come in even faster. Na influx and Ca into the interstitium!

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How else can you speed up the Ca++ reabsorption process in the DCT?

By using Thiazides, it’ll block the NCl channel from coming back in the DCT. Keeping it low + charged, causing N/CaE to move faster d/t Ca+ influx from the lumen.

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How does thiazide diuretics help treat osteoporosis?

It helps the kidneys reabsorb more Ca++.

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What should you be careful in taking while on thiazide diuretics?

K supplements bc the kidneys ends up holding onto more K while on thiazide diuretics.

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What other therapeutic effects can thiazide diuretics do?

Helps prevent future kidney stones bc reabsorbing Ca reduces the amount in the urine.

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What is aldosterone also a type of, other than a cholesterol? What does it act on?

It is a mineralocorticoid; acts on principal cells to retain Na and h2o while excreting more K+. It also speeds up the Na/K pump promoting the secretion (reabsorb) of Na through the ENac, K channels to efflux faster.

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increased aldosterone leads to more ____ channels in the DCT

Na+ (ENaC = endothelial Na channels)

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What are the types of K channels mediated by aldosterone?

(1st) ROMK = Renal Outer Medullary K+ channel. It’s sequestered so if not needed it just hangs out in the cell and moves to cell walls when needed.

(2nd) BK = Big K+ channels come into the cell wall if there’s a huge amount of K+ needed to be excreted.

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Which cells are the main cells used for K+ maintenance in the DCT/collecting tubules?

Intercalated cells

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Which meds work on the ENac of the DCT?

Amiloride and Triamterene and it also indirectly slows down the K secretion.

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How does Spironolactone work in the DCT?

It is an aldosterone receptor antagonist, it’ll slow down the Na/K pump > slows ENac > slows K+ secretion

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If you have more Na in the PCT, there is ___ in the DCT, which indirectly ______ secretion of _____.

even more Na+; increase; K+

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What can you do to balance the amount of Na being reabsorbed (PCT) and K+ secreted in the DCT?

Give loop diuretics with K sparing diuretics.
(ex. HCTZ with Triamterene)

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Where does aldosterone come from?

Adrenal Cortex:
Zona glomerulosa

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Where does cortisol and androgens come from?

Zona Fasciculata and Zona reticularis

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What is released from the adrenal gland?

Cortisol, glucocorticoids, estrogen (zona fasciculi)

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Structure of adrenal gland from the outside - in.

Zona glomerulosa, zona fasciculata, Zona reticularis, medulla (catecholamines)

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What is released in the adrenal medulla?

Epi/Norepi (4:1)

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What is aldosterone sensitive to?

- The more K+ levels, the more aldosterone is released via zona glomerulosa. - Low K+, lower aldosterone released.

What's the process of aldosterone release?

The RAAA (renin angiotensin aldosterone axis) > Ang II > aldosterone

What enzyme works on aldosterone?

Aldosterone synthase

ACTH secreting lung tumor leads to...

increase cortisol (glucocorticoid) > HTN

How does cortisol balance glucose?

It is a glucocorticoid released under stress to help the body "figure things out" per Schmidt

What prevents the cortisol from interacting with the aldosterone inside the principal cell?

There's a specific enzyme "11B HSD type II" that eats (dehydrogenase) all of the cortisol (steroid) inside the principal cell. (11 Beta Hydroxy steroid dehydrogenase Type II)

What happens when you have ACTH tumor?

Increase cortisol production > (Cushing's syndrome) > enzyme 11B HSD type II overwhelmed > HTN > low K+

What is the inhibitor for 11B HSD type II?

Licorice; also used for tobacco taste cause HTN > low K+ (smoking leads to HTN)

Aldosterone OD is similar to?

ACTH and Licorice exposure. (HTN, low K+)

Which cells works more on the acid/base balance in the renal system?

Intercalated cells

Are there specific intercalated cells for acids and bases?

Type A - Acids Type B - Bicarb

What channels does Type A intercalated cells work with?

H+ atp-ase pump H+/K+ atp-ase pump

Type B channel?

It is just a bicarb channel, no atp

What are intercalated cells and principal cells sensitive to?

Vasopressin, ADH, water

Vasopressin works on specific receptors in the late DCT/collecting tubule such as,

VP2. VP1 is located in the periphery blood vessels

Describe the process of Vasopressin in the kidneys

Vasopressin (AVP) > binds to VP2 > increase cAMP > activates Protein kinase A > phosphorylate AQP2 (aquaporins) lumen side; AQP3/4 interstitial side > moves to cell walls > water influx

What disease cancels the protein kinase A in the late DCT/CT?

Diabetes Insipidus

T/F: We always have ADH floating around to control UOP.

True

Problem with secretion of ADH or response of the kidney to ADH is called?

If it's a problem at the kidney to release ADH is called?

Nephrogenic DI (ex. Lithium induced)

If it's a problem with the release of ADH (brain), this is called?

Central DI

The DCT can also be known as?

the diluting segment

What effects does alcohol have on the renal system?

Less ADH released from the brain; impairs the kidneys response to ADH

Risks for head injury?

Hypothalamus Central DI

ADH can be controlled by...

(Primary) **Osmolarity**, BP, blood volume

What are osmoreceptors for?

In charge of balancing the osmolarity of the blood via vasopressin/ADH

What are baroreceptors for?

Works on the pressures in the CV system

What is the nuclei in front of the thalamus?

Supraoptic neuron = in charge of 5/6 of ADH released

What is the nuclei on the side of the 3rd ventricle?

Paraventricular Neuron = in charge of 1/6 of ADH released

Where does ADH go after released from the nuclei?

Posterior pituitary gland and into the blood vessels

What's another name for the posterior lobe of the pituitary gland? Anterior lobe?

- **Neurohypophysis** - **Adenohypophysis**

what would happen if... RBC is in Isotonic solution? Hypotonic? Hypertonic?

- No change d/t equal balance. - RBC swells - RBC shrinks

APs and its relation to intracellular fluid levels

Swelling of cells - decrease APs Shrunken cells - increased APs

In the descending loop of Henle, solutes are

highly concentrated (1200) d/t water permeability as it goes down the medulla

In the ascending loop osmolarity

decreases as the dilution part of the tubule is here

In the late DCT/CT dilution is solely based on...

ADH

T/F: Vasopressin is in control of reabsorbing water and urea as well

True

Does urea have special transporters in the DCT/CT?

Yes, UT-A1, UT-A3

What is the main thing that makes the interstitium highly concentrated?

Urea, and it allows us to hang on to water via osmosis.

If we needed to hang onto more water what does our body use to retain more water in the CT?

AQPs and UTs

What is our primary controller of plasma osmolarity?

ADH

What does caffeine do to ADH?

Lowers ADH

Reasons for decrease thirst

Low plasma osmolarity high blood volume htn low ang II gastric distention

Reasons that increase thirst

high plasma osmolarity low blood volume low bp high ang II dry mouth

causes of decrease ADH

low plasma osmolarity high bp/volume drugs: alcohol haldol clonidine

causes of increase ADH

high plasma osmolarity low bp/volume nausea/vomiting drugs: Morphine nicotine

When is the only time that our body struggles with controlling K levels?

Renal failure

Physiology: drink 1L distilled water

osmolarity is reduced > lowers ADH > increase UOP > urine osmolarity decrease after all the 1L fluid is excreted > urine osmolarity increases

Normal urine osmolarity

600 mOsm