Overview of Renal Structure and Function - Wall

Question 1

What is the major extracellular cation?

Answer 1

Sodium

Question 2

What does total body Na determine?

Answer 2

Size of total body water

Question 3

What is the major intracellular cation?

Answer 3

Potassium

Question 4

What are the major extracellular anions?

Answer 4

Chloride

Bicarbonate

Question 5

What is bicarbonate’s role in ECF?

Answer 5

Major ECFV buffer

Key factor in acid-base balance

Question 6

What are the kidney’s endocrine functions?

Answer 6

Erythropoietin
1-alpha hydroxylase produce calcitriol
Renin

Question 7

What are the kidney’s paracrine/autocrine functions?

Answer 7

Bradykinin (vasodilatory, natriuretic)
Prostaglandin (mostly vasodilatory)
Nitric oxide (vasodilatory)
Endothelin (potent vasoconstrictor)

Question 8

What does angiotensin II do?

Answer 8

Vasoconstrict

Question 9

What does aldosterone do?

Answer 9

Promote Na reabsorption

Question 10

Name two accessory functions of the kidney.

Answer 10

Small peptide catabolism (ie insulin)

Gluconeogenesis during fasting (25-33%)

Question 11

Define neutral, positive, and negative balance.

Answer 11

Neutral - Intake + Production = Excretion
Positive - Intake + Production > Excretion
Negative - Intake + Production < Excretion

Question 12

What is the best index of kidney function?

Answer 12

GFR

Question 13

What vertebral segments do the kidneys span?

Answer 13

T12 to L3

Question 14

What percent of total blood flow to the kidney does the cortex receive?

Answer 14

90%

Question 15

What does the hilum contain?

Answer 15

Renal artery, vein, nerves, pelvis, ureter, and lymphatics

Question 16

What does the medulla contain?

Answer 16

Loops of Henle
Collecting ducts
Vasa recta

Question 17

What are sites of potential obstruction within the ureter?

Answer 17

Pelvic ureteral junction
Crossover of pelvic brim
Urinary trigone

Question 18

What is the most common spot for urethral obstruction in males?

Answer 18

Prostatic urethra

Question 19

Which type of nephrons have a higher pressure in the glomerular capillaries?

Answer 19

Juxtamedullary > Cortical

Question 20

Are nephrons working at full capacity under normal conditions?

Answer 20

Cortical - No (basis for reserve capacity)

Juxtamedullary - Yes

Question 21

What layers are between the mesangium and circulation?

Answer 21

Endothelial cells (with large fenestrations)

Question 22

Is urine volume a good index of kidney function?

Answer 22

No (urine flow rate / volume is not autoregulated)

Question 23

What does clearance represent?

Answer 23

Volume of plasma cleared of the substance

Question 24

What is the equation for clearance?

Answer 24

Cx = U * V / P

Question 25

What is the equation for clearance ratio?

Answer 25

Cx / GFR

Question 26

What does a clearance ratio 1 imply?

Answer 26

< 1 - filtered and reabsorbed = 1 - filtered > 1 - filtered and secreted

Question 27

What is the clearance of PAH equivalent to?

Answer 27

Renal Plasma Flow

Question 28

What is a normal filtration fraction?

Answer 28

~20% of RPF becomes glomerular filtrate

Question 29

What does decreased cardiac output or volume depletion result in?

Answer 29

RAS - increased FF

Question 30

What can the autoregulatory response in a hypovolemic state be disturbed by?

Answer 30

Decreased AT II production ACE-inhibitors, AT receptor blockers, renin inhibitors Prevent production of vasodilatory prostaglandins (NSAIDS)

Question 31

Describe the proximal and distal tubule in terms of resistance and capacity.

Answer 31

Proximal tubule - High capacity, Low resistance | Distal tubule - Low capacity, high resistance

Question 32

What is the major difference between carriers and channels?

Answer 32

Channels are not saturable

Question 33

What is the tonicity of the bulk reabsorption in the PCT?

Answer 33

Isotonically

Question 34

How much of the filtered load is reabsorbed by the PCT?

Answer 34

50-55%

Question 35

What is the tonicity of fluid that enters the LOH?

Answer 35

Isotonic

Question 36

What is reabsorbed in the thin descending limb?

Answer 36

Passive water and urea

Question 37

What is reabsorbed in the thin ascending limb?

Answer 37

Passive sodium / chloride

Question 38

What is reabsorbed in the thick ascending limb?

Answer 38

Active NaCl | Ca, Mg

Question 39

What is reabsorbed in the DCT?

Answer 39

NaCl | Calcium