Renal excretory function of kidney

Question 1

How many litres go through the kidney

Answer 1

180

Question 2

How many litres are lost as urine

Answer 2

2

Question 3

Describe the structure of the glomerulus from venous inward

Answer 3

Venous
Porous endothelium
Glomerular basement membrane
Podocytes (epithelial surface)

Question 4

What gets through podocytes

Answer 4

Glucose
Water
Solutes
Low molecular weight proteins

Question 5

Where does filtration begin

Answer 5

Ultrafiltration of plasma within Bowmans Capsule

Question 6

Name the factors that determine filtrate

Answer 6

• Net filtration pressure
• Podocyte slit pores
• Size of molecule
• Charge of molecule
• Negative charge of GBM glycoproteins

Question 7

What can get through the glomerulus

Answer 7

Water
Electrolytes
Urea
Amino

Question 8

What is the cutoff of what can get through glomerulus

Answer 8

5200 daltons

Question 9

What is the molecular weight of albumin? Can it get through?

Answer 9

69,000 daltons

No

Question 10

What does albuminuria indicate

Answer 10

Problem at point of glomerulus because albumin shouldn’t be able to filter through

Question 11

Define glomerular filtration rate

Answer 11

Total amount of fluid that is filtered through the glomeruls

Question 12

What should normal GFR be

Answer 12

120ml/ min

Question 13

What substance is used to measure GFR

Answer 13

Creatinine

Question 14

Why is creatinine used to measure GFR

Answer 14

• Freely filtered by glomerulus and is not reabsorbed

Question 15

Why is measuring creatinine for GFR not accurate

Answer 15

It overestimates true renal function from 10-20% because it is actively secreted from peritubular capillaries

Question 16

Equation for creatinine clearance

Answer 16

(urine concentration * urine volume)/ plasma concentration

Question 17

Method for measuring clearance of a substance

Answer 17

• Measure concentration of creatinine in the plasma
• Collect urine for fixed period to get urine flow
• Measure concentration of creatinine in the collected urine

Question 18

What is the gold standard for measuring GFR

Answer 18

Nuclear medicine scan

Question 19

What is commonly used to measure GFR

Answer 19

Estimated GFR

mdrd equation

Question 20

What is required for MDRD equation

Answer 20

Sex
Age
Creatinine
Race

Question 21

What shape is the curve on the graph showing relationship between GFR and creatinine

Answer 21

Bell shaped

Question 22

What does the graph on the relationship between GFR and creatinine tell us

Answer 22

• Small changes in creatinine have large affect on GFR

- Large changes in creatinine have small effect on GFR

Question 23

Why do muscular individuals have high serum creatinine

Answer 23

Because creatinine is produced by the muscle

Question 24

Does eGFR over or underestimate true GFR in

a) muscular people
b) malnourished people

Answer 24

a) underestimate

b) overestimate

Question 25

What is the use of the drug trimethoprin? What is the effect on plasma creatinine?

Answer 25

UTI treatment | Inhibits creatinine secretion from the peritubular capillary cells

Question 26

Does the drug trimethoprin change GFR

Answer 26

No

Question 27

What is the function of tight junction between tubular cells

Answer 27

Limits water and solute movement between cells | Maintains polarity between apical and baso-lateral

Question 28

Where does primary active transport occur

Answer 28

Between tubular cell and interstitium

Question 29

What is primary active transport pump

Answer 29

Na+/K+ pump

Question 30

What is the sodium and potassium levels in tubular cell

Answer 30

10-20mmol/l sodium | 140mmol/l potassium

Question 31

What is the sodium and potassium levels in the interstitium?

Answer 31

``` Na= 140mmol/L Potassium= 4mmol/L ```

Question 32

Where does secondary active transport occur?

Answer 32

On the basolateral end of tubular cell

Question 33

What is pumped from tubular lumen to tubular cell in secondary active transport

Answer 33

Sodium Phosphate Glucose Amino Acids

Question 34

Describe the anatomy of the proximal tubule

Answer 34

Apical brush border contains microvilli | It is convuluted for the first two thirds and straight for the final third

Question 35

What is the function of the proximal tubule

Answer 35

Bulk of reabsorption of solutes

Question 36

What % of the following are reabsorbed at proximal tubule a) solutes b) water c) amino acids

Answer 36

a) 80 b) 65 c) 100

Question 37

How does sodium leave the loop of henle

Answer 37

Active transport

Question 38

What leaves through the ascending loop

Answer 38

Water

Question 39

How does osmolality change down the loop of henle

Answer 39

It increases

Question 40

Is the ascending limb permeable to water

Answer 40

No

Question 41

What does the distal nephron consist of

Answer 41

Distal tubule Collecting tubule Collecting duct

Question 42

What is the function of the distal nephron

Answer 42

Potassium excretion Regulation of sodium delivery Urine acidification

Question 43

How much sodium is left in filtrate when it reaches distal tubular cell

Answer 43

8%

Question 44

What inhibits the sodium potassium cell at distal tubular cells

Answer 44

Thiazide diuretics

Question 45

What determines the osmalality of urine in collecting tubule

Answer 45

ADH

Question 46

What happens in the presence of ADH

Answer 46

- Aquaporins become permeable to water - Passage of water from collecting tubule to interstitium down conc gradient - Production of concentrated urine

Question 47

What happens if there is a deficit of ADH secretion

Answer 47

Copious dilute urine | Diabetes insipidus

Question 48

Define renal threshold

Answer 48

Concentration of substance dissolved in blood above which kidney begin to remove it into the urine

Question 49

What happens when the renal threshold is exceeded

Answer 49

Reabsorption of substance by proximal renal tubule is incomplete and some of substance remains in the urine

Question 50

What happens at plasma levels of about 10 mmol/L

Answer 50

Glucose appears in the urine because amount of glucose exceeds reabsorption capacity of tubules (all glucose carriers are saturated)

Question 51

Define transport maximum for glucose/ Tmg

Answer 51

Constant maximal value of rate of glucose reabsorption

Question 52

Define osmotic diuresis

Answer 52

If excess solute present in tubular fluid this will atrract water and increases urine volume

Question 53

What does osmotic diuresis lead to

Answer 53

Polyuria

Question 54

Why do diabetic people often complain of increased thirst

Answer 54

Polyuria leads to increase in plasma osmolality leading to thirst sensation