Introduction to Nephrology

Question 1

essential functions of the kidney

Answer 1

• maintains optimal extracellular environment
• excretes waste products (urea, creatinine, UA, others)
• balanced excretion of water and electrolytes
• hormone production
• clearance of medications

Question 2

where are glomeruli located?

Answer 2

cortex

Question 3

where are tubules located?

Answer 3

both cortex and medulla

Question 4

basic unit of the kidney

Answer 4

nephron

Question 5

how many nephrons in adult kidney?

Answer 5

1 to 1.3 million

Question 6

where is the ultrafiltrate of plasma formed?

Answer 6

glomerulus

Question 7

where is the ultrafiltrate further modified?

Answer 7

tubules

Question 8

what is reabsorption?

Answer 8

REMOVAL of a substance from the ultrafiltrate

Question 9

what is secretion?

Answer 9

ADDITION of a substance from the ultrafiltrate

Question 10

gross components of kidney from out to in

Answer 10

cortex –> inner and outer medulla –> calyces –> pelvis –> and ureter

Question 11

how are the tubules divided?

Answer 11

• proximal tubule
• loop of Henle
• distal convoluted tubule
• connecting segment
• initial collecting tubule
• cortical and medullary collecting tubule

Question 12

after modification of the glomerular ultrafiltrate by the tubules, how urine sequentially drained?

Answer 12

calyces –> renal pelvis –> ureter –> bladder

Question 13

what percentage of cardiac output is sent to the kidneys?

Answer 13

• 20% (1/5 of CO!!!)

- 1 liter/min of BLOOD and 600 mL/min of plasma

Question 14

circulation of blood to the kidneys

Answer 14

renal artery –> interlobar arteries –> arcuate arteries –> interlobULar arteries –> afferent arteriole into glomerulus

Question 15

renal circulatory anatomy allows precise modulation of

Answer 15

salt and water balance

Question 16

the glomerular capillary loop is comprised of what?

Answer 16

• endothelial cell
• glomerular basement membrane (GBM)
• podocyte

Question 17

the glomerular capillary loop is structurally supported by which cells?

Answer 17

mesangial cells

Question 18

how does the glomerular capillary wall restrict solute movement?

Answer 18

size and charge

Question 19

what are the cell types that make up the mesangium?

Answer 19

• mesangial cells

- macrophages and monocytes

Question 20

major determinant of ultrafiltrate formation from glomerular capillary wall into Bowman space

Answer 20

Starling forces

Question 21

GFR =

Answer 21

(capillary porosity x surface area) x (pressure of GC - pressure of BS - oncotic pressure of plasma)

Question 22

GFR rises and falls in proportion to changes in what?

Answer 22

renal plasma flow rate (RPF)

Question 23

capillary hydrostatic pressure is influenced by which variables?

Answer 23

• aortic (renal artery) pressure

- afferent and efferent arteriolar resistances

Question 24

afferent and efferent arteriolar resistances are controlled by what?

Answer 24

• myogenic control
• tubuloglomerular feedback (TGF) from macula densa
• vasodilatory/vasocontrictor hormones (A2, NE, PGs, endothelin, ANP, and NO)

Question 25

which arteriole regulates the RPF and GFR in parallel?

Answer 25

Afferent arteriole

Question 26

which arteriole regulates the RPF and GFR inversely?

Answer 26

Efferent arteriole

Question 27

how does body keep RPF and GFR at a constant level?

Answer 27

autoregulation and tubuloglomerular feedback (TGF)

Question 28

between what MAPs is autoregulation able to maintain a constant GFR?

Answer 28

40 to 70 mmHg

Question 29

macula densa response to increased NaCl delivery

Answer 29

MD sends signals to afferent arteriole to cause vasoconstriction to decrease GFR and bring it back to normal

Question 30

macula densa response to decreased NaCl delivery

Answer 30

MD sends signals to afferent arteriole to cause vasodilatation to increase GFR