72: Solute Handling Flashcards
Sodium (Na+) is a major cation of the …….. compartment and it determines …….volume
ECF
ECF volume affects:
Plasma Volume
Blood Volume
Blood Pressure
……….. maintain normal body Na+ content/balance so that Na+ intake= Na+ excretion
Kidneys
If there is a positive Na+ balance where Na+ excretion < Na+ intake ………
Na+ retained in ECF which leads to:
Volume expansion
Increase blood volume
Increase in blood pressure
If there is a negative Na+ balance where Na+ excretion > Na+ intake ……….
Na+ lost from ECF which leads to: Volume contraction
Decrease blood volume
Decrease blood pressure
67% of Na+ and K+ is reabsorbed from the ……..
Proximal Convoluted Tubule
100% of Na+ and K+ is filtrated by the……..
Glomerulus
25% of Na+ is reabsorbed from the……..
Thick ascending limb of the Loop of Henle
5% of Na+ is reabsorbed from the…….
Distal Convoluted Tubule
3% of Na+ is reabsorbed from the……
Collecting Duct
Around……% of Na+ is excreted from the body
1%
What happens to the following levels when Na+ intake decreases?
- Sympathetic Activity
- ANP (Atrial Natriuretic Peptide)
- Oncotic Pressure of the Capillary
- Renin-Angiotensin Aldosterone
- Sympathetic Activity- INCREASED
- ANP(Atrial Natriuretic Peptide)-DECREASED
- Oncotic Press. of the Capillary- INCREASED
- Renin-Angiotensin Aldosterone-INCREASED
What happens to the following levels when Na+ intake increases?
- Sympathetic Activity
- ANP (Atrial Natriuretic Peptide)
- Oncotic Pressure of the Capillary
- Renin-Angiotensin Aldosterone
- Sympathetic Activity- DECREASED
- ANP (Atrial Natriuretic Peptide)- INCREASED
- Oncotic PresS. of the Capillary-DECREASED
- Renin-Angiotensin Aldosterone-DECREASE
Atrial natriuretic peptide (ANP) is secreted by atria in response to …….. in ECF volume
Increase
Atrial natriuretic peptide (ANP) ………. GFR and ………. reabsorptive mechanisms along tubule that results in increase in Na+ and H20 excretion.
Increases GFR (dilate afferent / constrict efferent arterioles) Inhibits Reabsorptive Mechanisms
……….. Blood Pressure in Right Atrium leads to ……….. ANH (Atrial Natriuretic Hormone) that leads to an ……… Na+ and H20 excretion.
Increased Blood Pressure
Increased ANH (Atrial Natriuretic Hormone)
Increased excretion of NA+ and H20
The increase in the excretion of Na+ and H20 leads to water loss and ………… blood pressure
Decreased Blood Pressure
…………. is required for tissues that use action potentials and is found is more abundance in the ICF.
Potassium K+
98% in ICF, 2% in ECF
Small shifts across the membranes causes large changes in plasma and …… concentrations
ECF
K+ Shift into the cells=
Hypokalemia
K+ Shift Out of Cells=
Hyperkalemia
Causes of K+ Shift into Cells: Hypokalemia
- Insulin
- β2-Adrenergic agonists
- α-Adrenergic antagonists
- Alkalemia
- Hyposmolarity
How does insulin and insulin deficiency cause a K+ shift?
Insulin, b-agonists (albuterol), and a-antagonists all stimulate Na+-K+ ATPase activity.- K+ Shift INTO Cells
Insulin deficiency;,b-Antagonists (propranolol), a- agonists, all reduce Na+-K+ ATPase activity- K+ Shift OUT of Cells
Causes of K+ Shift out of Cells: Hyperkalemia
- Insulin deficiency (Type I Diabetes)
- β2-Adrenergic antagonists
- α-Adrenergic agonists
- Acidemia
- Hyperosmolarity
- Cell lysis
- Exercise
How does alkalemia and acidemia cause a K+ shift?
- Alkelemia: [H+] is decreased so H+ moves into blood/K+ exchanges into cells
- Acidemia: [H+] is increased so H+ leaves blood/ K+ exchanges into blood (Out of cells)
How does cell lysis, hyperosmolarity, and exercise cause K+ shift out of cells?
- Cell lysis (breakdown of cell membranes - burns, rhabdomyolysis, chemotherapy): Releases K+ from ICF into blood
- Hyperosmolarity in ECF: H2O shifts from ICF to ECF dragging K+
- Exercise: Depletion of ATP stores opens K+ channels in muscle cells - shifts into blood
If there is a positive K+ balance where K+ excretion < K+ intake ………
Hyperkalemia
If there is a negative K+ balance where K+ excretion > K+ intake ………
Hypokalemia
20% of K+ is reabsorbed from the……..
Thick ascending limb
K+ Reabsorption in the late distal tubule and collecting duct occurs with……
A low K+ diet
K+ secretion determines the K+ ………. in the collecting duct
K+ Excretion
With a normal or high K+ diet, K+ secretion ………. as a function of Na+ delivery to collecting duct; aldosterone/K+-sparing diuretic
Increases
Normal Serum Concentration of Phosphate:
2.5 – 4.5 mg/dL
Phosphate is a constituent of ….. and urinary buffer for H+
Bone (85%)
Phosphate is a constituent of ….. and urinary buffer for H+
Bone (85%)
90% of …….. is filtrated by the Glomerulus
Phosphate
85% of Phosphate reabsorbed in the ….
Proximal Convoluted Tubule
……. inhibits phosphate reabsorption
PTH (Parathyroid Hormone)
15% of phosphate is excreted and serves as ……….. (urinary buffer for H+)
Titratable acid
……… binds to the type 1 PTH (PTH1R) basolateral receptor in PCT cells which is coupled to adenylyl cyclase via a Gs protein
PTH (Parathyroid Hormone)
Parathyroid Hormone (PTH) inhibits Na+-phosphate cotransport and therefore inhibits……….
Inhibits Reabsorption. Leads to Phosphaturia (Phosphate in Urine) and Hypophophatemia (Low Phosphate in Blood
……….. catalyzes conversion of ATP to cAMP to activate protein kinaseA (PKA) and protein kinase C which stimulate the internalization and degradation of sodium-phosphate cotransporters
Adenylyl cyclase
30% of Magnesium reabsorbed from the ….
Proximal Convoluted Tubules
80% of …….. is filtrated by the Glomerulus
Magnesium
Normal serum concentration of Magnesium:
1.5-2.0 mg/dl
…….. is required for enzymatic reactions (Nerve, muscle, CV, GIT) & maintain PTH function
Magnesium
60% of magnesium is reabsorbed in……..
Thick Ascending Limb of Loop of Henle
…….. inhibit reabsorption and increase excretion and leads to hypomagnesemia
Loop diuretics
5% of Magnesium reabsorbed from…. and another 5% is ………..
Distal Convoluted Tubule
Excreted
Normal serum value of Calcium
8.4 – 10.2 mg/dL
60% of calcium in filtered by the ……
Glomerulus
67% of ………. is reabsorbed in the Proximal Convoluted Tubule
Calcium
25% of Calcium reabsorbed in ………..
Thick Ascending Limb
………. inhibits cotransporter and reabsorptive driving force - treats hypercalcemia
Loop diuretics (Furosemide)
8% Reabsorption of Calcium in ……………
Distal Convoluted Tubule
………. increase Ca+2 reabsorption treat idiopathic hypercalciuria (decrease excretion and Ca+2 stone formation)
Thiazide diuretics
Decreased Plasma Ca2+ leads to:
- PTH secretion: Increase
- Bone reabsorption: Increase
- Phosphate reabsorption: Decrease
- Calcium Reabsorption: Increase
- Urinary cAMP: Increase
