Chronic Kidney Disease 1

Question 1

What is a nephron?

Answer 1

basic functional unit of the kidney

Question 2

What is the glomerulus?

Answer 2

cluster of tiny capillaries that receives blood from the afferent arteriole

Question 3

What filters the blood after the glomerulus?

Answer 3

Bowman’s capsule

Question 4

what is glomerular filtration rate? what is its importance?

Answer 4

volume of blood filtered by the glomerulus each minute

used for staging CKD and drug dosing

Question 5

what is a normal GFR range?

Answer 5

100-125ml/min

Question 6

what is the afferent arteriole?

Answer 6

arteriole though which blood enters the glomerulus

Question 7

how can various medications affect the afferent arteriole?

Answer 7

can cause acute kidney injury by inhibiting vasodilation of afferent arteriole

Question 8

what is the efferent arteriole?

Answer 8

arteriole through which blood leaves the glomerulus

Question 9

how can various medications affect the efferent arteriole?

Answer 9

can cause AKI by inhibiting vasoconstriction of efferent arteriole

Question 10

what is the proximal convoluted tubule?

Answer 10

receives fluid from Bowman’s capsule and reabsorbs ~80% of glomerular ultrafiltrate back into bloodstream

Question 11

what is reabsorption?

Answer 11

movement out of the tubule into the capillary where it may be retained in the body (urine to blood)

Question 12

what is usually reabsorbed by the kidneys?

Answer 12

nutrients (Glc, AAs)

electrolytes (Na, Ca, HCO3, PO4, K, Cl)

Question 13

what is fanconi syndrome?

Answer 13

disorder of proximal tubule reabsorption, leading to rickets, metabolic acidosis, hypokalemia, and hypophosphatemia

Question 14

what is secretion?

Answer 14

movement into the tubule, so that the substance may be eliminated (blood to urine)

Question 15

what is usually secreted by the kidneys?

Answer 15

creatinine
uric acid
certain drugs

Question 16

What is the loop of Henle?

Answer 16

receives fluid from the proximal tubule

Question 17

what is the function of the loop of Henle?

Answer 17

reabsorption of water (descending), Na, Cl, and Mg (ascending)

Question 18

what is the distal convoluted tubule?

Answer 18

receives fluid from the loop of henle

Question 19

what is the function of the the distal tubule?

Answer 19

reabsorption of Na and water

secretion of K, H, and phosphorus

Question 20

what is the collecting duct?

Answer 20

receives fluid from distal tubule

Question 21

what is the function of the collecting duct?

Answer 21

reabsorption of Na
secretion of K
acid base balance (excretion of acids)

Question 22

what hormone affects H2O permeability in the collecting duct? What happens to the urine when you increase/decrease levels of this hormone?

Answer 22

Anti-diuretic hormone (ADH) aka vasopressin

incr. ADH = concentrated urine
decr. ADH = dilute urine

Question 23

what are 5 functions of the kidneys?

Answer 23

1) filter urea
2) electrolyte control
3) acid-base balance
4) blood pressure control
5) hormone production

Question 24

what is urea?

Answer 24

a waste product of protein metabolism

Question 25

why is measuring urea levels important? what are the clinical utilities?

Answer 25

general indicator of renal function: urea:sCr ratio > 70 means dehydration urea increases before sCr in patients with AKI

Question 26

what are normal urea levels?

Answer 26

2.5-8mmol/L

Question 27

what role do kidneys play in acid-base balance?

Answer 27

maintain the pH of arterial blood between 7.35-7.45 through aci-base regulation

Question 28

what do the kidneys do in the case of acidosis?

Answer 28

reabsorb all filtered HCO3 into the extracellular and produce extra HCO3 to bring [H+] back to normal

Question 29

what do the kidneys do in the case of alkalosis?

Answer 29

kidneys don't reabsorb HCO3, so it gets secreted, bringing [H+] back to normal

Question 30

how are the kidneys involved in blood pressure control?

Answer 30

Renin-angiotensin-aldosterone system (RAAS) decrease in BP leads to renin release. angiotensin 1 is activated? and converted to angiotensin 2 via angiotensin converting enzyme this causes vasoconstriction, aldosterone secretion (water and Na retention) and thirst stimulated to increase BP

Question 31

how are the kidneys involved in hormone production?

Answer 31

produce erythropoietin and secrete EPO when there is low oxygen in the blood

Question 32

what is erythropoietin?

Answer 32

stimulates RBC production in bone marrow

Question 33

``` what happens to the following electrolytes in the case of CKD: Na/water K Phosphorus Mg ```

Answer 33

Na/water - edema/swelling (not able to decrease reabsorption by tubules) K - hyperkalemia (not able to incr. excretion from distal tubule) P - hyperphosphatemia (not able to decr. reabsorption in proximal tubule and incr. excretion from distal tubule) Mg - hypermagnesemia (not able to decrease reabsorption in loop of Henle)

Question 34

what are the 4 types of renal failure? which is the most common cause of AKI?

Answer 34

pseudo renal failure pre renal failure - most common cause intrinsic AKI post renal failure

Question 35

what is pseudo renal failure?

Answer 35

falsely elevated sCr due to inhibition of renal tubular secretion of sCr

Question 36

what is pre-renal AKI?

Answer 36

decreased blood flow to kidney

Question 37

what are 3 potential causes of pre-renal failure?

Answer 37

intravascular volume depletion decrease in ineffective blood volume (advanced liver disease, meds) decreased pressure in glomerulus (afferent arteriole vasoconstriction, efferent arteriole vasodilation)

Question 38

what is intrinsic AKI?

Answer 38

structural damage to kidney, effecting the glomerulus or the tubules

Question 39

what are 3 different kinds of intrinsic AKI? which is the most common?

Answer 39

Acute tubular necrosis (ATN) - most common acute interstitial nephritis glomerulonephritis

Question 40

what is acute tubular necrosis?

Answer 40

ischemia in kidney producing cell damage to tubules, typically caused by meds

Question 41

what is acute interstitial nephritis?

Answer 41

inflammatory disorder of renal interstitium, typically caused by different meds

Question 42

what is glomerulonephritis?

Answer 42

results from the stimulation of the immune system leading to inflammation of the glomerulus, caused by different bacteria and viruses

Question 43

what is post-renal failure?

Answer 43

obstruction of urine flow

Question 44

what are possible causes of post-renal failure?

Answer 44

kidney stones bladder tumour/obstruction urethral stricture/tumour crystal deposition in renal tubules (caused by meds)

Question 45

what is creatinine?

Answer 45

a byproduct of muscle metabolism that is freely filtered by the glomerulus and used as a marker for GFR

Question 46

what is the creatinine clearance equation?

Answer 46

CrCl (mL/min/72kg) =( (140-age)(88.4)x(0.85 if female))/sCr

Question 47

what is a normal sCr range?

Answer 47

80-120 umol/L