Kidney Function 1

Question 1

Describe where the kidneys are found

Answer 1

Each side of vertebral column T12-L3

At back of abdominal cavity

Outside peritoneum

Question 2

What substances are excreted by the kidneys? (6)

Answer 2

Urea

Uric acid

Creatinine

Hormone metabolites

Foreign chemicals

Hb breakdown products

Question 3

Why is urine yellow?

Answer 3

Presence of Hb breakdown products

Question 4

What does the kidney regulate?

Answer 4

Blood volume

Water balance

pH

Question 5

What hormones can act on the kidney? (5)

Answer 5

ADH

Aldosterone

Natriuretic peptides

PTH

FGF 23

Question 6

What hormones can be produced by the kidney? (5)

Answer 6

Renin

Vitamin D3/cholecalcitriol (active)

Erythropoietin

Prostaglandins

a-Klotho

Question 7

How many nephrons are there in a kidney?

Answer 7

> 1 million

Question 8

How much of the blood passing through the glomerulus is filtered into Bowman’s space?

Answer 8

20%

Question 9

What is the fluid in Bowman’s capsule called?

Answer 9

Ultrafiltrate

Question 10

What is the maximum diameter of the fenestrations in the glomerular endothelium?

Answer 10

15nm

Question 11

What proteins are important in filtration slits?

Answer 11

Nephrin

Podocin

Question 12

What are the two types of nephron and where are they found?

Answer 12

Cortical nephrons - outer 2/3 of cortex

Juxtamedullary nephrons - inner 1/3 of cortex

Question 13

What percentage of nephrons are cortical?

Answer 13

85%

Question 14

What is the main difference between cortical and juxtamedullary nephrons?

Answer 14

Cortical nephrons have shorter loops of Henle

Question 15

Which type of nephron produces more concentrated urine?

Answer 15

Juxtamedullary

Question 16

Where are juxtaglomerular cells found?

Answer 16

In wall of afferent arteriole

Adjacent to glomerulus

Question 17

What are the functions of extraglomerular mesangial cells? (3)

Answer 17

Generate extracellular matrix

Contract as have smooth muscle properties

Phagocytic

Question 18

What arteriole do peritubular capillaries branch off?

Answer 18

Efferent

Question 19

What is the name given to the peritubular capillaries in the loop of Henle region?

Answer 19

Vasa recta

Question 20

Where are renal corpuscles found?

Answer 20

Renal cortex

Question 21

How can you calculate the amount of a substance excreted in the urine?

Answer 21

Amount excreted = amount filtered + amount secreted - amount reabsorbed

Question 22

Is glomerular filtration active or passive?

Answer 22

Passive

Question 23

What is tubular secretion?

Answer 23

Secretion of solutes from peritubular capillaries into tubules

Question 24

What is tubular reabsorption?

Answer 24

Movement of materials from filtrate into peritubular capillaries

Question 25

What substance is filtered and secreted but not reabsorbed in the nephron?

Answer 25

Para-aminohippuric acid

Question 26

What substances are filtered and partly reabsorbed in the nephron?

Answer 26

Water Most electrolytes Urea

Question 27

What substances are usually filtered and completely reabsorbed in the nephron? (4)

Answer 27

Glucose Amino acids Vitamins Bicarbonate

Question 28

What substance is completely removed from the blood by metabolism in the tubule epithelium?

Answer 28

Glutamine

Question 29

What molecular size is completely freely filtered at the renal corpuscle?

Answer 29

7kD or less

Question 30

What molecular size is not able to be freely filtered at the renal corpuscle?

Answer 30

69kD

Question 31

What type of molecular charge is most easily filtered at the renal corpuscle?

Answer 31

Positive

Question 32

What type of molecular charge is least easily filtered at the renal corpuscle?

Answer 32

Negative

Question 33

What type of drugs does albumin bind?

Answer 33

Acidic

Question 34

What type of drugs does α1-acidglycoprotein bind?

Answer 34

Basic

Question 35

Are protein-bound substances freely filtered at the renal corpuscle?

Answer 35

No

Question 36

What can infection or damage to the glomerulus or high blood pressure result in? (3)

Answer 36

Proteinuria Haemoglobinuria Haematuria

Question 37

What is the glomerular filtration rate (meaning)?

Answer 37

Volume of fluid filtered from the glomeruli in ml per minute

Question 38

What three factors affect GFR?

Answer 38

Starling forces Hydraulic permeability Surface area

Question 39

What are the two Starling forces?

Answer 39

Hydrostatic pressure (45mmHg out) Colloid/oncotic osmotic pressure (29mmHg in)

Question 40

What is the approximate net glomerular filtration pressure?

Answer 40

(45 - 29 =) 16mmHg out of capillaries

Question 41

How does constricting the afferent arteriole affect GFR?

Answer 41

Decreased hydrostatic pressure so decreased GFR

Question 42

How does dilating the efferent arteriole affect GFR?

Answer 42

Decreased hydrostatic pressure so decreased GFR

Question 43

How does constricting the efferent arteriole affect GFR?

Answer 43

Increased hydrostatic pressure so increased GFR

Question 44

How does dilating the afferent arteriole affect GFR?

Answer 44

Increase hydrostatic pressure so increased GFR

Question 45

How can the surface area for glomerular filtration be reduced?

Answer 45

Sympathetic stimulation of smooth muscle in glomerular mesangial cells causes contraction

Question 46

How much ultrafiltrate is formed per day?

Answer 46

180L

Question 47

What is the approximate urine output per day?

Answer 47

1.5L

Question 48

Describe the wall of the proximal tubule.

Answer 48

Simple columnar cells with microvilli and mitochondria

Question 49

What transporters are involved in the reabsorption of glucose in the proximal tubule?

Answer 49

SGLT (Na-dependent) - luminal GLUT facilitated transporter Na/K-ATPase

Question 50

What is the maximum rate that glucose can be reabsorbed?

Answer 50

380mg/min

Question 51

What is the renal threshold of glucose?

Answer 51

200mg/100ml or 200mg% 11mM

Question 52

What causes cystinuria?

Answer 52

Mutations in proximal tubule basic amino acid transporters Cystine cannot be reabsorbed

Question 53

How many amino acid transporters are there and how many of these are Na-dependent?

Answer 53

At least 8 6 are Na-dependent

Question 54

How is the vast majority of filtered protein reabsorbed?

Answer 54

In PCT by endocytosis and degraded into amino acids (eg. insulin and GH)

Question 55

In the PCT, which substances require Na-coupled transporters for reabsorption?

Answer 55

Glucose Amino acids Phosphate Sulphate

Question 56

In the PCT, which substances are reabsorbed passively?

Answer 56

Urea Potassium Calcium

Question 57

What endogenous organic acids are secreted in the PCT?

Answer 57

Bile salts Fatty acids Prostaglandins

Question 58

What organic acid drugs are secreted in the PCT?

Answer 58

Furosemide Penicillin Acetazolamide

Question 59

What diagnostic agent is secreted in the PCT?

Answer 59

Para-aminohippuric acid

Question 60

Describe the process by which organic acids (anions) are secreted in the PCT.

Answer 60

1. Dicarboxylate accumulates in cells by metabolism and Na-coupled transport (encouraged by Na/K-ATPase) 2. OA- enters cell in exchange for dicarboxylate via the organic anion transporter/OAT (BL membrane) 3. OA- enters tubule lumen via ATP-dependent transporters (MRP2/4, ABCG2/BCRP)

Question 61

What endogenous organic bases are secreted in the PCT?

Answer 61

Choline Creatinine Dopamine Guanidine Histamine Serotonin

Question 62

What organic base drugs are secreted in the PCT?

Answer 62

Atropine Cimetidine Morphine

Question 63

Describe how organic bases (cations) are secreted in the PCT.

Answer 63

1. Enter cell via facilitated organic cation transporters (OCT2) 2. Enter tubule lumen via multidrug and toxin extrusion proteins (MATEs) in exchange for protons

Question 64

Which multidrug and toxin extrusion protein is specific to the kidneys?

Answer 64

MATE2-K