Final Exam Lecture 5

Question 1

What exactly does the Macula Densa do?

Answer 1

Looks at Quantity of Na+ and Cl- that goes by it in a certain amount of time

Question 2

How is Creatinine concentration as we get further into the PT?

Answer 2

It is increased, as we filter more H2O

Question 3

What 2 substances have a VERY LOW to 0 CL?

Answer 3

Glucose and Amino Acids

Question 4

True or False: SGLT Tx of Glucose and Na+ is Primary Active Tx?

Answer 4

False; 2nd Active Transport relying on the Na+ CG

Question 5

What transporter sends glucose into the renal interstitium?

Answer 5

GLUT

Question 6

What is Hyperfiltration?
*What Pt population is this seen in a lot

Answer 6

The MD hyperfiltrates Na+ as it sees the #’s are lower, despite what the cause may be
*This happens a lot in diabetic Pts

Question 7

What is the Amino Acid and Na+ ratio in the transporters located in the cell?

Answer 7

1:1

Question 8

What is the tubular side of the cell called?

Answer 8

Apical Side

Question 9

What is the Interstitital Side of the Cell called?

Answer 9

Basolateral Side

Question 10

Where is the S1 segment of the PT?
*What 2 transporters are located here: Ratio and %
*Describe efficiency and affinity

Answer 10

Early proximal tubule
*SGLT 2 Transporters [90%]; 1:1
*GLUT-2
*High efficient but low affinity

Question 11

Where is the S2,3 segment of the PT?
*What 2 transporters are located here: Ratio and %
*Describe efficiency and affinity
*Why this Na+ to glucose ratio?

Answer 11

Late Proximal Tubule
*SGLT1 [10%]; very few in S3: 2 Na+ to 1 Glucose
*GLUT-1
*Lower efficiency but high affinity
*2 Na+ b/c harder to pump out glucose in a lower concentrated environment

Question 12

What is the glucose threshold to not seeing glucose in the urine?

Answer 12

200 mg/dL

Question 13

What is the Transport Maximum of Glucose?
*How does the graph look after the transport maximum
*What does this mean

Answer 13

300 mg/dL
*1:1 linear line for concentration and excretion in urine
*After 300 mg/dL, every glucose molecule in the blood will show up in the urine

Question 14

What is Filtered Load?
*What 2 things is it dependent on

Answer 14

How much stuff has been filtered
*Plasma Concentration and GFR

Question 15

What is the normal Filtered Load of Glucose?
*Math

Answer 15

GFR = 1.25 dL/min x 100 mg/dL = 125 mg/min of glucose to be filtered

Question 16

What cells release Renin?
*What does this activate and where do they work?

Answer 16

JG cells
*Activates Angiotensin 2, which constricts the Efferent Arteriole

Question 17

When Angiotensin 2 is released, what exactly does it do?

Answer 17

Constricts EA and increases NaCl reabsorption to increase BP and GFR

Question 18

What compensatory mechanism do the kidneys do in response to decreased arterial pressure?

Answer 18

Decreased renal blood flow, decreased GFR = constriction of EA and dilation of AA

Question 19

How do vessels look in chronic HTN and DM

Answer 19

Stiff and Calcified

Question 20

In Chronic HTN and DM, what happens to AR in the kidneys?
*PCap of GC?
*Podocytes, Fenestrations, Slit Pores?
*Dysfunction of what vessel is mostly effected?

Answer 20

AR is less effective as the vessels are stiff and calcified, so cannot dilate or constrict as well
*PCap of GC will be >60, which will lead to GC destruction
*Podoyctes damaged, Fenestrations and Slit pores widen and scar
*Dysfunction in the AA

Question 21

What is most damaged in the kidney from Chronic HTN, which leads to renal failure and other long-term kidney injuries?

Answer 21

Glomerular Capillary Beds, as the PCap is constantly higher than normal

Question 22

If the Macula Densa recognizes a filtration deficiency, what happens?

Answer 22

Renin is released from JG cells to activate Angiotensin 2 and constrict the EA

Question 23

If the Macula Densa recognizes a filtration increase, what happens?

Answer 23

Less renin will be released to slow down activation of Angiotensin 2 and dilate the EA

Question 24

In the kidneys, where do drugs normal effect in terms of AA vs EA?

Answer 24

Mostly AA

Question 25

Out of AA and EA, where does Angiotensin 2 mostly effect?

Answer 25

EA

Question 26

What would the GFR be if we had a MAP of 200 in severe HTN?
*Math
*New NFP and old

Answer 26

40 mmHg [NFP] x 12.5 [Kf] = 500 ml/min
*New NFP would be about 40 mmHg, when normal is 10 mmHg