Renal Physiology 2 Flashcards
- 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.
– 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)
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)
- 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
reabsorption is ____ ( ____ mOsm) - the body does not reabsorb more solute than water, nor does it reabsorb more water than solute
isoosmotic
hypoosmotic
hyperosmotic
100 200 300 400 500
the concentration gradient is created mainly by active Na+ reabsorption
Glucose reabsorption is through the transporters ____
SGLT1 and SGLT2
- 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)
occurs in the vasa recta and aids the countercurrent multiplier mechanism
renal threshold
Countercurrent Exchanger
Countercurrent Multiplier Effect
Countercurrent Exchanger
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
Purpose: increase the osmolality of the interstitial fluid and concentrate urine
renal threshold
Countercurrent Exchanger
Countercurrent Multiplier Effect
Countercurrent Multiplier Effect
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
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
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
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
Aldosterone increases activity of
Na+ channel
K+ channel
Na+/K+ ATPase
Aldosterone increases activity of Na+ channel, K+ channel, and Na+/K+ ATPase pump
– 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.
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
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
- Increased insensible water loss or decreased water intake
- Increased blood osmolality
- Osmoreceptor stimulation
- ADH release by posterior pituitary
- Stimulate insertion of water channels in collecting ducts (CD)
- 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
- Increased water intake or decrease insensible water loss
- Decrease blood osmolality
- No stimulation of osmoreceptor
- No release of ADH
- 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
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
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
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
