Physiology 9

Question 1

What does GFR show us about the kidney?

Answer 1

It shows us how well the nephrons of the kidney are functioning.

Question 2

What is the normal GFR per minute?

Answer 2

125mls/min.

Question 3

what is the normal decline in GFR with ageing?

Answer 3

After 30, GFR declines at 1ml/min per year.

Question 4

how much less is women GFR in comparison to men?

Answer 4

10% less

Question 5

What does it mean that the kidneys have a high reserve capacity?

Answer 5

you can loose a lot of nephrons before GFR is affected, and your GFR has to recuse greatly before osmolarity is affected.

Question 6

What was the first way of measuring GFR?

Answer 6

By measuring inulin clearance? Because it is filtered, but NOT reabsorbed or secreted.

Question 7

What is the new way to measure GFR?

Answer 7

Creatinine clearance - creatinine is a breakdown product of the muscles creatine.

Question 8

What will the clearance be in comparison to inulin if something is reabsorbed?

Answer 8

Less, because some of the plasma which has been cleared will be stuck with the reabsorbed substance.

Question 9

What will the clearance be in comparison to inulin if something is secreted?

Answer 9

Higher, because theres more filtered product so less of the plasma has been filtered

Question 10

What will happen to drugs if GFR declines?

Answer 10

drugs might not be excreted as efficiently, we might have to reduce the drug dose in order to prevent drug toxicity from occurring.

Question 11

What does a decline in GFR suggest?

Answer 11

a decline in nephron function

Question 12

is the creatinine and GFR relationship linear or curved?

Answer 12

It is curved, this means that a reduction in GFR won’t always be displayed by creatinine clearance levels.
Eg - GFR needs to drop by 50% to see a reduction in creatinine clearance.

Question 13

What is eGFR?

Answer 13

this is the estimated GFR - this uses equations and measures creatinine clearance more accurately, taking into account the curved relationship.

Question 14

What causes an increase in creatinine?

Answer 14

Increased muscle mass - increased creatine turnover

Creatine supplementation

Question 15

What causes a decrease in creatinine?

Answer 15

Vegetarian - they don’t get much creatinine from food.

Question 16

what should normal glucose clearance be?

Answer 16

0 - all glucose should be reabsorbed (unless theres too much)

Question 17

What should normal urea clearance be?

Answer 17

50%

Question 18

What is the importance of PAH? parraamino-hippuric acid?

Answer 18

Over 90% of PAH is filtered with each round of GFR - therefore by measuring PAH clearance, you know roughly the amount of plasma that is filtered in one round of Glomerular filtration.

Question 19

What does parasympathetic nerves do regarding micturition?

Answer 19

They cause an increase in micturition, they increase detrusor muscle contraction.

Question 20

What does the sympathetic nerves do regarding micturition?

Answer 20

causes constriction of the internal urethral sphincter, inhibits bladder detrusor muscle contraction.

Question 21

what do somatic motoneurons do regarding micturition?

Answer 21

They cause relaxation and contraction of the external urethral sphincter (even against strong urges to pee)

Question 22

What is the trigone?

Answer 22

The 1 urethral opening

the 2 vesicoureteric openings

Question 23

What is the main muscle of the bladder?

Answer 23

The detrusor muscle

Question 24

how does the female urethra empty after micturition?

Answer 24

by gravity

Question 25

How does the male urethra empty after micturition?

Answer 25

via the bulbocavernosus muscles.

Question 26

When do higher brain centres NOT have an effect on micturition?

Answer 26

in babies or paraplegic patients.

Question 27

At what volume does the increase to void increase?

Answer 27

400-500mls

Question 28

Explain the steps in the micturition reflex?

Answer 28

increase in urine in the bladder (400-500)

• causes an increase in parasympathetic nerves (increasing bladder muscle contractions)
• inhibition of the sympathetic nerves (relaxation of internal urethral sphincter)
• motoneurons - controlled by higher brain centres - you can relax or contract the external urethral sphincter depending on whether you want to micturate.
• parasympathetic activity inhibits the sympathetic activity and contraction of external urethral sphincter (it gets easier to pee and harder to fight it off).