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A/P > Lecture 11/15: Renal Physiology Cont'd > Flashcards

Lecture 11/15: Renal Physiology Cont'd Flashcards

Final

1
Q

What does it mean when creatinine clearance is reduced?

A

Renal function is reduced

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2
Q

How does chronic HTN above MAP of 150 effect the kidney?

A

AA will try to constrict but only to an extent –> increased RBF –> increased pressure in GC –> increase GFR –> increases UO

The GC is most effected by this

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3
Q

What are the 2 things in the kidney effected by HTN?

A

GC: Primary; prolonged high pressure = scarring; effects podocytes efficiency; widens fenestrations

AA: prolonged constriction = stiffening & prevents dilation when needed (BP drops)

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4
Q

T/F: increasing GFR will increase Reabsorption rate

A

F

You will reabsorb the same amount which is 124 ml/min

You will EXCRETE MORE

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5
Q

What happens to Reabsorption when GFR is decreased? why?

A

Reabsorption is increased

-fluids moving slowing thru the nephron
-more time in nephron = more time for reabsorption

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6
Q

What happens in the kidney when BP is decreased?

A

AA dilates –> GFR decreases –> reabsorption increases –> UO decreases

**MD senses… juxta releases renin –> constricts EA

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7
Q

Most vasoconstrictors, except ANG II, constricts ______ more than _______

A

AA

EA

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8
Q

T/F: ANG II constricts the AA & EA both equally

A

F

Constricts both, but constricts EA more

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9
Q

Prostaglandins preferentially dilate the ______ more

A

AA

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10
Q

NSAIDs preferentially vasoconstrict the ______ more. How?

A

AA

By inhibiting prostaglandins

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11
Q

T/F: There is reabsorption happening at every segment of the nephron

A

T

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12
Q

How much is reabsorbed at the PCT?

A

2/3

65%

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13
Q

Where is the MD located?

A

TAL

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14
Q

How does the MD work? Explain for low & high GFR

A

Acts as a sensor that counts Na+ & Cl- molecules as they pass by

Can detect a higher/lower number of Na/Cl and gauges GFR

Low: More ions are reabsorbed –> less ions make it to MD –> MD dectects that GFR is low –> juxta cells release renin –> ANG II increases –> EA constrict –> Pressure in GC increases –> GFR increases

High: normal ions are reabsorbed –> more ions make it to MD –> MD dectects that GFR is high –> juxta cells decrease release renin –> ANG II decreased –> EA relax –> Pressure in GC decreases –> GFR decreases

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15
Q

In addition to constricting to EA & AA, what other effects do ANG II have?

A

Increases Na reabsorption in PCT

This increases water reabsorption –> increase fluid volume –> increases BP

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16
Q

Describe the pathology if you had an increase in reabsorption of Na+ in the nephron. What could cause this? What is the Tx for this?

A

GFR could be normal, you’re just reabsorbing more more Na+

Less Na+ molecules at MD –> MD thinks GFR is low –> Juxta cells release Renin –> increase ANG II –> EA constricts –> Pressure in GC increases –> GFR increases (even tho it was fine)

This is bad. Creates high pressure at the GC which can destroy the GC –> destroys the nephron.

Causes: THE DIABETES!!!!
-Excess sugar intake causes the excess Na intake as well via the SGLT transporters in the PCT

Tx: ACE inhibitors (-prils)
ARBs (-sartan)

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17
Q

All of _____ & _______ should be filtered and reabsorbed at the proximal tubule if WNL

A

Glucose

Amino acids

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18
Q

What is the concentration of Na+ in the tubular cells?

A

14

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19
Q

What is the charge inside of the tubular cell?

A

-70 mV

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20
Q

Describe the amino acid transporter

A

1 Amino acid & 1 Na+
Cotransporter

-Located in PCT
-Apical side

21
Q

What happens if you constant consume a high amount of amino acids?

A

Kidneys could be destroyed

Na+ reabsorption is increased with amino acids –> GFR is normal but Na+ at MD decreased –> Juxta releases Renin/ANGII

This causes pressure in the GC to increase which increases GFR more than needed

This is the same pathology as Diabetes

22
Q

What is the main pathology in uncontrolled glucose (DM)?

A

Hyperfiltration of the GC

This causes damage to the GC which can ultimately destroy the Nephron putting strain on other nephrons –> this shortens the lifespan of the other nephrons

23
Q

What food items are high in amino acids?

A

Steak
pre-workout
protein shakes

24
Q

T/F: Glucose & amino acids can be absorbed in many places in the nephron

A

F

25
Q

What happens if Glucose is not reabsorbed in the PCT?

A

It will not be reabsorbed anywhere else. It will be excreted

26
Q

What is the tubular lumen?

A

The inside of the tubular structure (nephron)

27
Q

The ______ side of the tubular cell touches the nephron & the _______ side of the cell touches the renal ISF

A

Apical

Basolateral

28
Q

Describe the SGLT transporters

A

SGLT2: S1 Segment-Early PCT
-1Na/1Glucose
-High efficiency/low affinity
-GLUT2

SGLT1: S2/S3 Segments-Later in PCT
-2Na/1Glucose
-High affinity/low efficiency
-GLUT1
-Requires more energy (extra Na+ bc more dilute fluid & harder to pull out glucose)
-S3 segment has very few pumps

-Located in PCT
-Apical side

-Secondary Active transport
-dependent on Na+ electrochemical gradient (Na+ = 14 & -70mV inside cell)

29
Q

Describe the GLUT transporter

A

Transfers glucose out of PCT brought in from SGLT transporters

-Located in PCT
-Basolateral side

-No energy required
-Gradient created by SGLT transporters by increasing glucose in tubular cell

GLUT2 = SGLT2
GLUT1 = SGLT1

30
Q

What should the glucose concentration be at the end of the PCT?

A

0

31
Q

T/F: Glucose concentration in the tubule should be the same as plasma glucose concentration

A

T

32
Q

What are the 3 segments of the Proximal tubule?

A

S1: early part of PCT

S2: later part

S3: Last part

33
Q

What portion of glucose is absorbed in each section of the Proximal tubule?

A

S1 = 90%
S2 - 10%

34
Q

What is filtered load?

A

Amount of solute thats been filtered

Plasma concentration x GFR

35
Q

What is the threshold for glucose? What does this mean?

A

Threshold: Between 101-199 mg/dL

This is where glucose will start showing up in the urine

SGLT1 transporters will start to miss excess glucose

36
Q

What happens when you glucose transporters become saturated?

A

This is called Transport Maximum

For every extra glucose that is filtered, that extra glucose will show up in the urine

pathology: Reabsorption pumps become saturated bc they cannot do conformational changed fast enough.

37
Q

What is glucose transport max? What does this mean?

A

300 mg/dL

Any higher sugar than this:
-The excretion line will become line
-1 extra glucose filtered = 1 extra glucose excreted

38
Q

What does the MD primarily monitor? Why is this important?

A

Na+

More sensitive to changes due to high glucose (diabetes) and amino acids

39
Q

What is the rate limiting step in ANG II?

A

Renin

It’s the rate limiting step in formation of ANG II bc its the rate limiting step to formation of ANG I

40
Q

What is the process to get to ANG II?

A

Angiotensinogen (produced in the liver) + renin = ANG I + Angiotensin Converting Enzyme-ACE (produced in the lungs) = ANG II

41
Q

What is a side effect of ACE inhibitors?

A

Bad cough/chest congestion

Inhibits ACE which is an enzyme produced in the lungs

42
Q

When GFR is low, and what does the MD cells DIRECTLY do?

A

Releases Nitric oxide –> relaxes AA –> Increases RBF –> Increases GC pressure –> Increase GFR

43
Q

When GFR is low, what are the 3 arms that are effected?

A
  1. Juxta with Renin/ANG II –> EA constricts
  2. MD with NO –> Dilates AA
  3. ANG II –> Na/Water reabsorption at PCT
44
Q

MD release ______ on the ________ causing vasodilation

A

Nitric Oxide

AA

45
Q

T/F: ANGII constricts both the AA & EA

A

T

Just constricts the EA more

46
Q

What does ANGII do?

A
  1. Constricts EA to increase GFR
  2. Increase Na/Water reabsorption at PCT to increase blood volume
47
Q

What adverse effects do we expect to see with excess glucose in the urine? What type of medications can cause this? What are these medications used for?

A

Excess glucose in downstream anatomy = breading ground for infection
-Ex) urethra: UTI

Also excess glucose build up can trigger an immune reaction (Glycocaylx damage)

Medication: SGLT inhibitors & GLP agonist
-Both are for DM but are commonly used for weight loss

48
Q

What was very rare/expensive 2000 years ago & was used as a perservative?

A

Salt

49
Q

Why was salt expensive 2000 years ago?

A

It was difficult to extract

A/P (33 decks)

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