Renal Physiology 2 Flashcards by harryl martinez

requires energy to move solute against an electrochemical or a concentration gradient.
where reabsorption occurs down an electrochemical, pressure or concentration gradient.

Active Process
Passive Process

Active Process – requires energy to move solute against an electrochemical or a concentration gradient.

Passive Process – where reabsorption occurs down an electrochemical, pressure or concentration gradient.

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– coupled indirectly to an energy source (e.g. ____)
– requires the hydrolysis of a direct energy source (e.g.___)

Secondary active transport
Primary active transport
Na+/K+ ATPase
ion gradient

Primary active transport – requires the hydrolysis of a direct energy source (e.g. Na+/K+ ATPase)

o Secondary active transport – coupled indirectly to an energy source (e.g. ion gradient)

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All reabsorption processes are linked to the basolateral ____

o Na+/Cl- co-transport
o Na+/amino acid co-transport
o Na+/K+ ATPase
o Na+/glucose co-transport
o Na+/H+ counter-transport

Which of this transport are primary active and secondary active

All reabsorption processes are linked to the basolateral Na+/K+ ATPase

o Na+/Cl- co-transport (secondary active)
o Na+/amino acid co-transport (secondary active)
o Na+/K+ ATPase (primary active)
o Na+/glucose co-transport (secondary active)
o Na+/H+ counter-transport (secondary active)

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is passive because the moving Na+ ion is going to draw it in order to maintain electrical neutrality
is passive at the PCT
the concentration gradient is created mainly by active Na+ reabsorption

Cl reabsorption
H2O reabsorption

Cl reabsorption is passive because the moving Na+ ion is going to draw it in order to maintain electrical neutrality

H2O reabsorption is passive at the PCT
- the concentration gradient is created mainly by active Na+ reabsorption

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reabsorption is ____ ( ____ mOsm) - the body does not reabsorb more solute than water, nor does it reabsorb more water than solute

isoosmotic
hypoosmotic
hyperosmotic

the concentration gradient is created mainly by active Na+ reabsorption

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Glucose reabsorption is through the transporters ____

SGLT1 and SGLT2

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reabsorption is due solely to osmosis and is not subject to direct regulation
reabsorption can be regulated
E.g.: Anti-diuretic hormone (ADH)
E.g. reabsorption of water in the PCT

Facultative Reabsorption
Obligatory Reabsorption

Obligatory Reabsorption - reabsorption is due solely to osmosis and is not subject to direct regulation
- E.g. reabsorption of water in the PCT

Facultative Reabsorption – reabsorption can be regulated
E.g.: Anti-diuretic hormone (ADH)

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occurs in the vasa recta and aids the countercurrent multiplier mechanism

renal threshold
Countercurrent Exchanger
Countercurrent Multiplier Effect

Countercurrent Exchanger

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Occurs in the Loop of Henle; the overall process by which the loop of Henle, and in particular the thick ascending limb, generates the hyperosmotic medullary interstitial gradient

renal threshold
Countercurrent Exchanger
Countercurrent Multiplier Effect

Countercurrent Multiplier Effect

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Purpose: increase the osmolality of the interstitial fluid and concentrate urine

renal threshold
Countercurrent Exchanger
Countercurrent Multiplier Effect

Countercurrent Multiplier Effect

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The plasma concentration of substrate at which the transport maximum occurs is called the

renal threshold
Countercurrent Exchanger
Countercurrent Multiplier Effect

The plasma concentration of substrate at which the transport maximum occurs is called the renal threshold

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Stimulates magnesium reabsorption in the loop of Henle
Stimulus: Plasma volume expansion/ increase in ECV
Stimuli: increase in Renin secretion
Stimuli: increased plasma osmolality & decrease in effective circulating volume (ECV)
Stimuli: increase in angiotensisn II and increase in plasma [K+]

Aldosterone
Angiotensin II
Antidiuretic Hormone
Atrial Natriuretic Peptide
Parathyroid Hormone

Parathyroid Hormone
Atrial Natriuretic Peptide
Angiotensin II
Antidiuretic Hormone
Aldosterone

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Secreted by zona glomerulosa cells of adrenal cortex
Secreted by specific cells in cardiac atria

Aldosterone
Angiotensin II
Antidiuretic Hormone
Atrial Natriuretic Peptide
Parathyroid Hormone

Aldosterone

Atrial Natriuretic Peptide

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Site of action: thick ascending limb, distal tubule, & collecting duct
Site of action: distal tubule & collecting duct
Site of action: PCT
Site of action: collecting ducts

Aldosterone
Angiotensin II
Antidiuretic Hormone
Atrial Natriuretic Peptide
Parathyroid Hormone

Aldosterone
Antidiuretic Hormone
Angiotensin II
Atrial Natriuretic Peptide

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Aldosterone increases activity of

Na+ channel
K+ channel
Na+/K+ ATPase

Aldosterone increases activity of Na+ channel, K+ channel, and Na+/K+ ATPase pump

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– marked loss of sodium and accumulation of potassium due to adrenal destruction or malfunction
– increased sodium retention and potassium depletion due to adrenal tumors.

Increased Aldosterone
Decreased Aldosterone
Addison’s Disease
Conn’s syndrome

Decreased Aldosterone
Addison’s Disease – marked loss of sodium and accumulation of potassium due to adrenal destruction or malfunction

Increased Aldosterone
Conn’s syndrome – increased sodium retention and potassium depletion due to adrenal tumors.

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increase NaCl and H2O reabsorption in the PCT

Aldosterone
Angiotensin II
Antidiuretic Hormone
Atrial Natriuretic Peptide
Parathyroid Hormone

Angiotensin II

increases the water permeability of renal cells in the distal tubule and collecting duct, thus decreasing the volume and increasing the osmolarity of urine

Aldosterone
Angiotensin II
Antidiuretic Hormone
Atrial Natriuretic Peptide
Parathyroid Hormone

Antidiuretic Hormone

It inhibits the reabsorption of sodium and water, w/c results to increased urinary excretion

Aldosterone
Angiotensin II
Antidiuretic Hormone
Atrial Natriuretic Peptide
Parathyroid Hormone

Atrial Natriuretic Peptide

Increases reabsorption of calcium in distal tubules and in the loop of Henle.

Aldosterone
Angiotensin II
Antidiuretic Hormone
Atrial Natriuretic Peptide
Parathyroid Hormone

Parathyroid Hormone

Its action helps to return blood volume back to normal

Aldosterone
Angiotensin II
Antidiuretic Hormone
Atrial Natriuretic Peptide
Parathyroid Hormone

Atrial Natriuretic Peptide

Inhibits phosphate reabsorption by the proximal tubule

Aldosterone
Angiotensin II
Antidiuretic Hormone
Atrial Natriuretic Peptide
Parathyroid Hormone

Parathyroid Hormone

Stimulates aldosterone secretion

Aldosterone
Angiotensin II
Antidiuretic Hormone
Atrial Natriuretic Peptide
Parathyroid Hormone

Angiotensin II

Hormone Major stimulus Nephron site of action Effect on transport
Angiotensin II ↑Renin PT ↑NaCl and H2O reabsorption

Aldosterone ↑Angiotensin II,↑[K+]p TAL, DT/CD ↑NaCl and H2O reabsorption*

ANP ↑ECV CD ↓H2O and NaCl reabsorption

Urodilatin ↑ECV CD ↓H2O and NaCl reabsorption

Sympathetic nerves ↓ECV PT, TAL, DT/CD ↑NaCl and H2O reabsorption*

Dopamine ↑ECV PT ↓H2O and NaCl reabsorption

ADH ↑Posm, ↓ECV DT/CD ↑H2O reabsorption*

Hormone Major stimulus Nephron site of action Effect on transport
Angiotensin II ↑Renin PT ↑NaCl and H2O reabsorption
Aldosterone ↑Angiotensin II, ↑[K+]p TAL, DT/CD ↑NaCl and H2O reabsorption*
ANP ↑ECV CD ↓H2O and NaCl reabsorption
Urodilatin ↑ECV CD ↓H2O and NaCl reabsorption
Sympathetic nerves ↓ECV PT, TAL, DT/CD ↑NaCl and H2O reabsorption*
Dopamine ↑ECV PT ↓H2O and NaCl reabsorption
ADH ↑Posm, ↓ECV DT/CD ↑H2O reabsorption*

Tubular Secretion  Functions for the removal of ions, which are either metabolic wastes (e.g. H+ and urea) or excess electrolytes, and toxins from

Proximal tubule Loop of Henle Distal convoluted tubule and collecting duct reabsorbs by osmosis → water by simple diffusion → bicarbonate ions, urea reabsorbs by osmosis in the descending limb → water by active transport in the ascending limb → Na, K, Cl reabsorbs by osmosis → water secretes → hydrogen ions, urea (if ADH is present) secretes → urea secretes → hydrogen ions, ammonium ions, urea, creatinine, organic anions and cations

Proximal tubule reabsorbs by osmosis → water secretes → hydrogen ions, ammonium ions, urea, creatinine, organic anions and cations Loop of Henle reabsorbs by osmosis in the descending limb → water by active transport in the ascending limb → Na, K, Cl secretes → urea Distal convoluted tubule and collecting duct reabsorbs by osmosis → water by simple diffusion → bicarbonate ions, urea secretes → hydrogen ions, urea (if ADH is present)

The principal components of the medullary interstitial fluid are H2O K NaCl urea

NaCl | urea.

``` Resistance Vessels Adrenal Cortex Brain Posterior Pituitary Sympathetic Nervous System ``` - Release Aldosterone, Enhances Sodium reabsorption increasing water reabsorption (because water follows Na+) - Vasoconstriction (increase Total Peripheral resistance)/ Increase Renal Arterial Pressure - Stimulates norepinephrine release and inhibits reuptake to enhance Sympathetic effects (vasoconstricton) - Release Vasopressin (Increases Fluid retention, Increase Fluid Volume) - Stimulates Thirst Center, to increase fluid volume

Resistance Vessels - Vasoconstriction (increase Total Peripheral resistance)/ Increase Renal Arterial Pressure Adrenal Cortex - Release Aldosterone, Enhances Sodium reabsorption increasing water reabsorption (because water follows Na+) Posterior Pituitary - Release Vasopressin (Increases Fluid retention, Increase Fluid Volume) Brain - Stimulates Thirst Center, to increase fluid volume Sympathetic Nervous System - Stimulates norepinephrine release and inhibits reuptake to enhance Sympathetic effects (vasoconstricton)

When NaCl is elevated in the tubular fluid, renin release is inhibited stimulated

inhibited

___ located on the JG cells respond to sympathetic nerve stimulation by releasing renin Beta1-adrenoceptors Alpha1-adrenoceptors Na-K ATPase Osmoreceptors

Beta1-adrenoceptors

RAAS Pathway When renin is released into the blood → proteolytic cleavage of angiotensinogen → angiotensin I → angiotensin-converting enzyme (ACE), cleaves angiotensin I → angiotensin II (AII)

When renin is released into the blood → proteolytic cleavage of angiotensinogen → angiotensin I → angiotensin-converting enzyme (ACE), cleaves angiotensin I → angiotensin II (AII)

cells within the hypothalamus, which are sensitive to changes in osmotic pressure of the blood Beta1-adrenoceptors Alpha1-adrenoceptors Na-K ATPase Osmoreceptors

Osmoreceptors

Order ther, Formation of concentrated (hyperosmotic) urine - ADH release by posterior pituitary - Increased blood osmolality - Increased insensible water loss or decreased water intake - Increased water reabsorption - Osmoreceptor stimulation - Stimulate insertion of water channels in collecting ducts (CD)

Formation of concentrated (hyperosmotic) urine 1. Increased insensible water loss or decreased water intake 2. Increased blood osmolality 3. Osmoreceptor stimulation 4. ADH release by posterior pituitary 5. Stimulate insertion of water channels in collecting ducts (CD) 6. Increased water reabsorption

Order the, Formation of dilute (hyposmotic) urine ``` Decrease blood osmolality Decreased water reabsorption at CD Increased water intake or decrease insensible water loss No release of ADH No stimulation of osmoreceptor ```

Formation of dilute (hyposmotic) urine 1. Increased water intake or decrease insensible water loss 2. Decrease blood osmolality 3. No stimulation of osmoreceptor 4. No release of ADH 5. Decreased water reabsorption at CD

URINE VOLUME SPECIFIC GRAVITY COLOR State of Hydration: Decreased Water Intake Increased Water intake Physical Activity Exercise Rest Fluid Intake Dehydration Overhydration Ambient temperature Hot Cold

URINE VOLUME SPECIFIC GRAVITY COLOR State of Hydration: Decreased Water Intake Decreased Increased Darker yellow Increased Water intake Increased Decreased Clear-Light yellow Physical Activity Exercise Decreased Increased Darker yellow Rest Increased Decreased Clear-Light yellow Fluid Intake Dehydration Decreased Increased Darker yellow Overhydration Increased Decreased Clear-Light yellow Ambient temperature Hot Decreased Increased Darker yellow Cold Increased Decreased Clear-Light

– thus regulating the filtered load of Na+ (the amount of Na+ filtered out into the tubules) – Compensates for changes that may occur in the GFR – Reabsorption of Na+, primarily by the PCT, is adjusted to match GFR – Increase in the number of apical membrane NaCl symporter in the thick ascending limb of the loop of Henle – Inc GFR = inc Na+ reabsorption by PCT, and vice versa Glomerulotubular (G-T) balance Ability of the loop of Henle (spec. thick ascending limb) and DT to vary Na+ reabsorptive rates Autoregulation of GFR

Autoregulation of GFR – thus regulating the filtered load of Na+ (the amount of Na+ filtered out into the tubules) o Glomerulotubular (G-T) balance – Compensates for changes that may occur in the GFR – Reabsorption of Na+, primarily by the PCT, is adjusted to match GFR – Inc GFR = inc Na+ reabsorption by PCT, and vice versa o Ability of the loop of Henle (spec. thick ascending limb) and DT to vary Na+ reabsorptive rates – Increase in the number of apical membrane NaCl symporter in the thick ascending limb of the loop of Henle

Positive Na+ balance: Negative Na+ balance: Volume contraction Volume expansion

Positive Na+ balance: Volume expansion | Negative Na+ balance: Volume contraction

Regulation of Na+ excretion when minor variations in dietary NaCl intake occur  Small adjustments in collecting duct reabsorption are sufficient to balance intake with excretion  Aldosterone primarily regulates Na+ reabsorption (and thus excretion too) in the CD  Increase aldosterone, increase Na+ reabsorption by CD → decrease Na+ excretion

 GFR decrease and thus a decrease in filtered load of Na+  Increase Na+ reabsorption (decrease Na+ excretion) in the PCT  Na+ reabsorption increases in the CD  Increase NaCl reabsorption in the PCT Stimulation of ADH secretion Inhibition of ANP Increased activity of the renal sympathetic nerves Stimulation of the RAAS

Increased activity of the renal sympathetic nerves  GFR decrease and thus a decrease in filtered load of Na+ Inhibition of ANP  Increase Na+ reabsorption (decrease Na+ excretion) in the PCT Stimulation of ADH secretion  Na+ reabsorption increases in the CD Stimulation of the RAAS  Increase NaCl reabsorption in the PCT