lecture 3 (renal)

Question 1

how is GFR calculated?

Answer 1

• inulin is injected into body
• checked for kidney function by flow through body

Question 2

what is EGFR?

Answer 2

• estimated GFR
• based on blood test, sex, age and body type
• shows how well kidneys are working

Question 3

what hormones does the kidney make?

Answer 3

• renin
• erythropoietin

Question 4

what are the 6 components of a nephron?

Answer 4

• glomerulus
• bowman capsule
• proximal convoluted tubule
• loop of henle
• distal convoluted tubule

Question 5

what is the proximal tubule responsible for?

Answer 5

• large scale reabsorption of filtered water and solutes, ions, glucose, amino acids

Question 6

how is the fluid reabsoprbed?

Answer 6

• in isotonic matter
• osmolality of fluid entering proximal tubule has same osmolality as fluid leaving proximal tubule

Question 7

what is the function of angiotensin II?

Answer 7

• increases reabsorption of sodium and water in proximal tubule

Question 8

what do specific transporters do?

Answer 8

• recover vital solutes that are filtered by the glomerulus

Question 9

what is the loop of henle?

Answer 9

• drives dilution and concentration of urine

Question 10

what transporters are found in the loop of henle?

Answer 10

• Na-K2Cl transporters in ascending limb

Question 11

what is the purpose of the NaK2Cl transporter?

Answer 11

• pump solutes from tubule into medullary interstitum

Question 12

what is reabsorbed in the loop of henle?

Answer 12

• Ca2+
• Mg2+

Question 13

what is the medullary interstitium?

Answer 13

• salty brine created by loop of henle
• essential for formation of concentrated urine

Question 14

what is the function of the distal (convoluted) tubule?

Answer 14

• reasorbs sodium
• dilutes urine

Question 15

what is the collecting tubule responsible for?

Answer 15

• maintaining acid-base and potassium balance
• regulates concentration of urine

Question 16

what are the two primary types of cell in collecting tubule?

Answer 16

• principle cells
• intercalated cells

Question 17

what do principle cells do?

Answer 17

• secrete potassium
• reabsorb sodium

Question 18

what do intercalated cells do?

Answer 18

• secrete hydrogen

Question 19

what enhances sodium reabsorption and secretion of K+ and H+?

Answer 19

• aldosterone

Question 20

how does the collecting tubule regulate the concentration of urine?

Answer 20

• under influence of ADH

Question 21

what does ADH allow?

Answer 21

• the collecting tubule to become permeable to water
• production of concentrated urine

Question 22

what does absence of ADH cause?

Answer 22

• dilute tubular fluid from distal convoluted tubule to be excreted unchanged

Question 23

what occurs in bicarb reabsorption of the proximal tubule?

Answer 23

• bicarbonate combines with proton by enzyme carbonic anhydrase
• becomes co2 and water
• co2 diffuses into cells

Question 24

how is glucose reabsorbed into the proximal tubule?

Answer 24

• glucose is freely filtered
• SGLT2 receptors allow the reabsorption, high affinity transporter, combines sodium and glucose into cell
• SGLT1 couples glucose to Na2+

Question 25

what does inhibitor of SGLT do?

Answer 25

- lower blood sugar - used in treatment of diabetes - remove sugars through urine

Question 26

why does this occur?

Answer 26

- glucose is a diuretic - causes lower blood pressure

Question 27

what does increased glucose in tubules cause?

Answer 27

- increased chance of UTIs/water infections - kidney infections - thrush

Question 28

what occurs in amino acid reabsorption in proximal tubule?

Answer 28

- won't be filtered, need to be reabsorbed - SLC7A8 and SLC3A2

Question 29

what is the function of the thick ascending limb?

Answer 29

- actively reabsorbs sodium chloride - impermeable to water - increases osmolality of interstitial fluid

Question 30

what does the distal convoluted tubule do?

Answer 30

- allows management of magnesium?

Question 31

what is found beyond the collecting duct?

Answer 31

- renal pelvis - ureter - bladder - urethra

Question 32

what is the function of the collecting duct?

Answer 32

- ability to control concentration of final urine

Question 33

what can intercalated cells be?

Answer 33

- alpha (mediates H+ secretion) or beta (bicarbonate section) - change dependent on diet

Question 34

what does the principle cell do?

Answer 34

- handle sodium - ENaC channel (sodium enters, potassium leaves cell)

Question 35

what occurs in high levels of sodium?

Answer 35

- ENaC gets unregulated - swaps sodium for potassium or hydrogen ion

Question 36

how are water molecules transported?

Answer 36

- via aquaporins (water channels)

Question 37

what controls aquaporins?

Answer 37

- regulated by ADH - tell whether to loose water or retain - occurs minute by minute to allow water retention

Question 38

what occurs if control of aquaporins is lost?

Answer 38

- diabetes insipidus - X linked (younger boys) - bed wetting - severe dehydration