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CPR Test 2 > Renal Physiology 3 > Flashcards

Renal Physiology 3 Flashcards

1
Q

what is the basic unit of the kidney and what is its function

A

Nephron is the basic unit of the kidney and its function is to separate water ions and small molecules from the blood, filter out wastes and toxins and facilitates the concentration of urine

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2
Q

what is the Glomerulus and the Bowmans capsule

A

Glomerulus is a tuft of glomerular capillaries which are covered by epithelial cells and are encased in bowmans capsule

large amounts of fluid are filtered from the blood

fluid filtered from the glomerular capillaries flows into bowmans capsule and then into the proximal tubule

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3
Q

Actively reabsorbed and passively reabsorbed contents of the Proximal tubule as well as some of the enzymes found here

A 
Actively rebsorbed:
-85% sodium bicarbonage
-65% sodium chloride
65% potassium
100% glucose and amino acids

Passively reabsorbed:
-water

Na/K ATPase maintains low intracellar Na concentrations sending out into the blood

Carbonic anhydrase will catalyze the formation of carbonic acid from CO2 and H20

Acid and base secretory systems secrete drugs into the lumen from the blood

Na/H (NHE3)
-Na in cell and H+ out into lumen

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4
Q

Parts of the Loop of henle and what they reabsorb and their corresponding transporters

A

THin descending loop: water reabsorption

Thin ascending loop: relatively impermeable to water and other ions/solutes

THick ascending limb:

  • impermeable to water
  • 25% sodium reabsorption
  • Na/K/2Cl cotransporter (NKCC2) establishes the ion concentration gradient in the interstitum
  • increase in K+ concentration in the cells causes back diffusion of K+ into the tubular lumen, allowing a lumen positive electrical potential to drive reabsorption of cations (Mg, Ca) via the paracellular pathway

result is the tubular fluid is concentrated in the descending limb and diluted in the ascending limb

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5
Q

Distal convoluted tubule, what it reabsorbs and its corresponding transporters

A
  • 10% NaCl reabsorbed
  • relatively impermeable to water
  • Na/Cl cotransporter (NCC) actively transports NaCl out of lumen
  • Ca is passively reabsorbed by calcium channels (regulated by PTH)

Result: tubular field is diluted

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6
Q

Collecting tube: Epithelial sodium channel

A

ENaC:

  • responsible for 2-5% of Na reabsorption
  • creates electrical gradient that facilitates K secretion down the concentration gradient
  • The most important site of K secretion by the kidney
  • site at which all dirutetic induced changes in K+ balance occur = more Na delivered to collecting tubule the more K secretion
  • Proton pumps increase urine acidity
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7
Q

Collecting tubule: Aldosterone effect

A

Increases the expression of ENaC and basolateral Na/K ATPase which increases Na reabsorption and K secretion leading to water retention and increase in blood volume and BP

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8
Q

Collecting ductL ANtidiuretic hormone (vasopressin) effect

A
  • Controls permeability of the collecting tubule to water by regulating the expression levels of aquaporin-2 (AQP2) water channels
  • No ADH means the collecting duct is impermeable to water
  • ADH levels are controlled by serum osmolality and volume status
  • Alcohol decreases ADH release and increases urine production

REsult: tubular fluid is concentrated

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9
Q

what location is the urine the most dilute, medium, and least

A

In the Cortex: 300
-most dilute

In the Outer medulla: 400-600
-medium

Inner medulla: 900-1200
-most concentrated

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10
Q

Function, Water permeability and Primary transporter in apical membrane and Diuretic: Proximal convoluted tubule

A

Function: REabsorption of 65% of filtered Na/K/Ca/Mg, 85% of bicarbonate and nearly 100% of glucose and amino acids
Isoomotic for water

Water permeabillity: Very high

Apical transporter: Na/H (NHE3) carbonic anhydrase

Diuretic: Carbonic anyhydrase inhibitor

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11
Q

Function, Water permeability and Primary transporter in apical membrane and Diuretic Proximal tubule straight segments

A

Function: Secretion and reabsorption of organic acids and bases, including uric acid and most diuretics

Water permeabillity: Very high

Apical transporter: acid, uric acid and base transporters

Diuretic: None

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12
Q

Function, Water permeability and Primary transporter in apical membrane and Diuretic Thin descending limb of loop of henle

A

Function: Passive reabsorption of water

Water permeabillity: high

Apical transporter: Aquaporins

Diuretic: None

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13
Q

Function, Water permeability and Primary transporter in apical membrane and Diuretic Thick ascending limb of loop of henle

A

Function: active reabsorption of 15-25% of filtered Na/K/Cl and secondary reabsorption of Ca and Mg

Water permeabillity: Very low

Apical transporter: Na/K/2Cl (NKCC2)

Diuretic: Loop diuretics

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14
Q

Function, Water permeability and Primary transporter in apical membrane and Diuretic Distal convoluted tubule

A

Function: Active reabsorption of 4-8% of filtered Na and Cl and Ca reabsorption under the parathyroid hormone control

Water permeabillity: Very low

Apical transporter: Na/Cl (NCC)

Diuretic: THiazides

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15
Q

Function, Water permeability and Primary transporter in apical membrane and Diuretic Cortical collecting tubule

A

Function: Na reabsorption (2-5%) coupled to K and H secretion

Water permeabillity: Variable, controlled by vasopressin

Apical transporter: Na channels (ENaC), K channels, H transporter, aquaporins

Diuretic: K+ sparring diuretic

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16
Q

Function, Water permeability and Primary transporter in apical membrane and Diuretic Medullary collecting duct

A

Function: Water reabsorption under vasopressin control

Water permeabillity: Variable, controlled by vasopressin

Apical transporter: Aquaporins

Diuretic: Vasopressin antagonist

17
Q

Diuretics and their functions

A

A diuretic is an agent that increases urine volume, while a natriuretic causes an increase in renal sodium excretion

Diuretics increase the rate of urine flow and sodium excretion

Used to adjust the volume and or composition of body fluids in a variety of clinical situations including
-Edematous state: heart failure, kidney disease and renal failure, liver disease (cirrhosis)

-Nonedematous states: Hypertension, nephrolithiasis (kidney stones), hypercalcemia, and diabetes insipidus

18
Q

What are some diuretic targets

A

Specific membrane transport protiens

  • Sodium/potassium/chloride cotransporter (loop diuretics)
  • Sodium/chloride cotransporter (thiazide diuretics)
  • Sodium channels (potassium-sparring diuretics)

Enzymes
-Carbonic anhdrase (carbonic anhydrase inhibitors)

Hormone receptors
-mineralocorticoid receptor (potassium-sparing diuretics)

19
Q

Carbonic Anhydrase Inhibitors

A

MOA: inhibits the membbrane bound and cytoplasmic forms of carbonic anhydrase

Results:

  • decrease H+ formation inside the PCT
  • decrease in Na+/H+ antiport (NHE3)
  • Increase Na and HCO3- in lumen
  • Increase in Diuresis

Urine pH is increased and pH is decreased

20
Q

Loop Diuretics

A

MOA: Inhibit the luminal Na/K/2Cl cotransporter (NKCC2) in the TAL of the loop of henle

Results:

  • decrease intracellular Na, K, Cl in TAL
  • decrease in back diffusion of K and positive potential
  • decrease in reabsorption of Ca and Mg
  • Increase in diuresis

Ion transport is virtually nonexistent
among the most efficacious diuretics available

21
Q

Thiazide Diuretics

A

MOA: cause inhibition of the Na/Cl cotransporter (NCC) and block NaCl reabsorption in the DCT

Results:

  • Increase luminal Na and Cl in DCT
  • Increase diuresis
Enhance the reabsorption of Ca in both the DCT and PCT
Largest class of diuretic agents
22
Q

K+ sparring Diuretics, 2 kinds

A

in the collecting tubule

  • most important site of K secretion
  • site at which all diuretic induced changes in K balance occur (more Na delivered to collecting tubule leads to more K secretion)

Aldosterone (mineralcorticoid) receptor (MR) antagonist

  • decreased expression of ENaC increasing Na excretion and increasing diuresis
  • K excretion is decreased
  • urine pH is increased and body pH is decreased

Na Channel ENaC inhibitor

  • decreased activity of ENaC increasing Na excretion and increasing diuresis
  • K excretion is decreased
  • urine pH is increased and body pH is decreased
23
Q

Urinary electrolytes levels, NaCl, NaHCO3, K, Body pH: Carbonic anydrase inhibitors

A

NaCl: increase

NaHCO3: big increase

K: increase

Body pH: decrease

24
Q

Urinary electrolytes levels, NaCl, NaHCO3, K, Body pH: Loop agents

A

NaCl: big increase

NaHCO3: no change

K: increase

Body pH: increase

25
Q

Urinary electrolytes levels, NaCl, NaHCO3, K, Body pH: THiazides

A

NaCl: increase

NaHCO3: increase

K: increase

Body pH: increase

26
Q

Urinary electrolytes levels, NaCl, NaHCO3, K, Body pH: Loop agents plus thiazides

A

NaCl: big increase

NaHCO3: increase

K: increase

Body pH: increase

27
Q

Urinary electrolytes levels, NaCl, NaHCO3, K, Body pH: K+ sparring agents

A

NaCl: increase

NaHCO3:slight increase

K: decrease

Body pH: decrease

28
Q

what are factors affecting sodium reabsorption and secretion along the nephron

A

Na is secreted or reabsorbed in the late DT and cortical Collecting duct according to body needs

reabsorption: Na deciciency, low diet, hyponatremia, or Na loss through severe diarrhea
- Angiotensin II
- Aldosterone

SecretionL

  • Increased ECF Na concentration
  • Increased tubular flow rate
29
Q

what are the factors affecting potassium reabsorbtion and secretion along the nephron

A

K is secreted or reabsorbed in the late DT and cortical collecting duct to the nees of the body

Most important factors that stimulate reabsorption:

  • k deficiency, low K diet, hypokalemia
  • K loss through diarrhea

Most important factors that stimulate potassium secretion

  • increased ECF K
  • aldosterone
  • increased tubular flow
  • Na delivery to cortical Collecting duct

CPR Test 2 (25 decks)

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