Renal 7 Renal handling of Ca, Phosphate, and K

Question 1

Small changes in plasma [k] profoundly affect memnrane potentials of excitable cells

Answer 1

Renal 7 Renal handling of Potassium

Question 2

increase in plasma [k] causing increased excitability

Answer 2

Renal 7 Renal handling of Potassium

Question 3

decrease in plasma [k] causing decreased excitability

Answer 3

Renal 7 Renal handling of Potassium

Question 4

increase in K excretion

Answer 4

Renal 7 Renal handling of Potassium

Question 5

810 mEq/day (huge difference compared to the 26100 mEq of sodium that is filtered each day)

Answer 5

Renal 7 Renal handling of Potassium

Question 6

67% of filtered K is reabsorbed in the early Proximal Tubule. There is a small variable amount of secretion in the distal part of the proximal tubule (whatever it takes to maintain balance)

Answer 6

Renal 7 Renal handling of Potassium

Question 7

20% of the filtered load of K is reabsprobed. Reabsorbed with Na and Cl in the thick ascending limb (Na-K-2C co transporter) Luminal [K] is low and most of the K diffuses back to the tubular lumen (recycled) to maintain transporter activity. Little “net” K reabsorption

Answer 7

Renal 7 Renal handling of Potassium

Question 8

Na-K-2Cl co transporter. K gets reabsorbed with Na and Cl

Answer 8

Renal 7 Renal handling of Potassium

Question 9

BOTH REABSORPTION AND SECRETION OF K CAN OCCUR IN THE CORTICAL COLLECTING DUCts. Principlal cells secrete K Intercalated cells reabsorb K. Normally a net secretion of K (pricipal cells predominate) Reabsorption occurs only when the kidneys are conserving K

Answer 9

Renal 7 Renal handling of Potassium

Question 10

Secrete k

Answer 10

Renal 7 Renal handling of Potassium

Question 11

Reabsorb K

Answer 11

Renal 7 Renal handling of Potassium

Question 12

required that the daily urinary secretion equal the daily dietary intake

Answer 12

Renal 7 Renal handling of Potassium

Question 13

K excretion is controlled by adjusting the rate of tubular K Secretion (NOT K reabsorption)

Answer 13

Renal 7 Renal handling of Potassium

Question 14

Exretion of potassium is greater than the excretion of sodium. 6% (k) compared to 0.6% (na)

Answer 14

Renal 7 Renal handling of Potassium

Question 15

at high K intakes secretion must predominate over reabsorption in the distal nephron to maintain balance. K balance can be maintained on a dietary intake as high as 100 mEq/day (123% of the flitered load must be exreted or more than 23% of what was filtered must be excreted)

Answer 15

Renal 7 Renal handling of Potassium

Question 16

Tubiular K is reabsorbed by K-H ATPase (ACTIVE- K is reabsorbed and H is actively secreted and a bicarbonate is rabsorbed)

Answer 16

Renal 7 Renal handling of Potassium

Question 17

ACTIVE K influx (Na-K-ATPase) - if plasma K increases K uptake increases because Na-K-ATPase pump is not normally saturated. PASSIVE K efflux - Na uptake effectively depolarizes the luminal membrane greating a lumen negative potential allowing K to leave the prinicpal cell and move into the tubulur lumen

Answer 17

Renal 7 Renal handling of Potassium

Question 18

Extra K will drive the pump. Na-K-ATPase increases the cellular load of K and keeps plasma levels low

Answer 18

Renal 7 Renal handling of Potassium

Question 19

1.) enhanced Na-K-ATPase pump activity 2.) Insulin release (promotes K uptake in skeletal muscle, heart and liver) 3.) Epinephrine release from adrenal medulla to promote K uptake in muscles and liver 4.) Aldosterone release from adrenal cortex (increases plasma K excretion by principal cells) 5.) Enhance K-H echange (passive) in muscle, red cells, and liver

Answer 19

Renal 7 Renal handling of Potassium

Question 20

[K] in the tubular cells (Na-K ATPase loads K into tubular cells)

Answer 20

Renal 7 Renal handling of Potassium

Question 21

a rapid buffer for changes in plasma [K] at the expense of acid-base status (occurs in skeletal muscle, bone, liver, RBCs, and kidney tubular cells) . If we have hyperkalemia it will result in acidosis (as plasma potassium rises pH decreases)

Answer 21

Renal 7 Renal handling of Potassium

Question 22

increased plasma causes K to be pulled into the cell and move H into the interstitium. Hyperkalemia increases K secretion and causes acidosis

Answer 22

Renal 7 Renal handling of Potassium

Question 23

Decreased K in the interstitium results in K being pulled out of the cell and H moving into the cell. Hypokalemia reduces K secretion amd causes alkalosis

Answer 23

Renal 7 Renal handling of Potassium

Question 24

H enters the cell in exchange for K - Acidosis results in reduced K secretion and causes Hyperkalemia

Answer 24

Renal 7 Renal handling of Potassium

Question 25

H leaves the cell in exchange for K. Alkalosis results in increased K secretion and causes hypokalemia

Answer 25

Renal 7 Renal handling of Potassium

Question 26

passive exchange of potassium and hydrogen ions - minimize the change in K that could be lethal

Answer 26

Renal 7 Renal handling of Potassium

Question 27

Hyperkalemia

Answer 27

Renal 7 Renal handling of Potassium

Question 28

Aldosterone stimulates the Na-K-ATPase in collecting tubules - results in cellular uptake of and increased luminal membrane permeability to K. K SECRETION SECONDARY TO INCREASED NA UPTAKE

Answer 28

Renal 7 Renal handling of Potassium

Question 29

Increased Na delivery - increased Na reabsorption and K secretion leading to K excretion and Hypkalemia

Answer 29

Renal 7 Renal handling of Potassium

Question 30

Decreased Na delivery- decreased Na reabsorption and decreased K secretion leading to decreased K excretion and hyperkalemia

Answer 30

Renal 7 Renal handling of Potassium

Question 31

increased yunular flow (diureses( results in a washout of luminal K that enhanced further K secretion - by washing out it changes the gradient and allows for more secretion of K) Decreased flow results in accumulation of luminal K and the develoment of limiting K gradients and redicved K secretion- cant pump against and already high luminal [K])

Answer 31

Renal 7 Renal handling of Potassium

Question 32

nonreabsorbable ions are diffusion trapped resulting in a compensativy increase in K and H secretion to maintain electrical meutrality

Answer 32

Renal 7 Renal handling of Potassium

Question 33

50% (the other 50% is bound to plasma albumin and other anions

Answer 33

Renal 7 Renal handling of Calcium and phosphate

Question 34

the balance beterrn gastrointestinal reabsorption and renal excretion

Answer 34

Renal 7 Renal handling of Calcium and phosphate

Question 35

99%

Answer 35

Renal 7 Renal handling of Calcium and phosphate

Question 36

70% of Ca reabsorption.PASSIVE- dependent on the reabsorption of NA and other solutes leading to the development of a favorable concentration gradient.

Answer 36

Renal 7 Renal handling of Calcium and phosphate

Question 37

20% of total Ca reabsorption - recycling of K in the thick ascending limb (Na-K-2Cl pump activity) creates a lumen positive postential that enhances the paracellular reabsorption of Na, Ca, and Mg. (Ca reabsorption is diminished with loop diuretics)

Answer 37

Renal 7 Renal handling of Calcium and phosphate

Question 38

in the distal tubule

Answer 38

Renal 7 Renal handling of Calcium and phosphate

Question 39

Ca reabsorption is ACTIVE and controlled by parathyroid hormone and Calcitrol (active metabilite of vitamin D) Calcitrol induces the syntheisis of Calcium binding protien that facilitates the movement of Ca into the cell. 3Na-Ca exchanger in the basal membrenae maintains low intracellular [Ca] that allows Ca to move into the cell (CaBP) from the tubular lumen

Answer 39

Renal 7 Renal handling of Calcium and phosphate

Question 40

1.) Enhances 3Na-Ca exchanger activity 2.) Increases Cl entry into the cell which aids in Ca enteryat the lumen 2.) Activates Calcitriol

Answer 40

Renal 7 Renal handling of Calcium and phosphate

Question 41

1.) Induces synthesis of calcium binding protein 2.) Increases Ca absorption in the gut

Answer 41

Renal 7 Renal handling of Calcium and phosphate

Question 42

parathyroid hormone 1.) increases resorption of bone 2.) Increases intestinal Ca reabsorption (through calcitriol) 3.) Increases Ca reabsorption in the distal tubule 4.) decreases phsophate reabsorption in the proximal tubule (increases phsophate excretion) NET EFFFECT = INCREASED CA AND NO CHANGE IN PLASMA PHOSPHATE

Answer 42

Renal 7 Renal handling of Calcium and phosphate

Question 43

2Na-HPO4 co transpoter in the proximal tubule reabsorbs 8-% of HPO4

Answer 43

Renal 7 Renal handling of Calcium and phosphate

Question 44

2Na-HPO4 cotransporter reabsorbs 80% of the FL of HPO4

Answer 44

Renal 7 Renal handling of Calcium and phosphate

Question 45

Reabsorbs 10% of fl and the remaining 10 is excreted

Answer 45

Renal 7 Renal handling of Calcium and phosphate

Question 46

it is excreted as a titratable acid that is an important H acceptor and helps to excrete the daily load of acid

Answer 46

Renal 7 Renal handling of Calcium and phosphate

Question 47

1.) Increases plasma Ca and HPO4 levels 2.) Decreases Tm for 2a-HPO4 and increases HPO4 excretion so that plasma levels are unchanged

Answer 47

Renal 7 Renal handling of Calcium and phosphate