Renal and Acid-Base Physiology Flashcards
What happens to the ECF volume in burn patients?
Decreases
What happens to the ECF osmolarity in patients with SIADH?
Decreases
During increased sweating, what happens to the ECF volume and ECF osmolarity, respectively?
Decreases; Increases
What is the formula for estimating plasma osmolarity?
2 x Na + Gluc/18 + BUN/2.8
What type of nephron has shorter loops of Henle and peritubular capillaries?
Cortical Nephron
What cell secretes erythropoietin?
Interstitial cells in the peritubular capillary bed
What is the effect of PGE2 and
PGI2 on the RBF and GFR?
Increases
What substance, at low doses,
causes dilation of arteries but
causes constriction at higher
doses?
Dopamine
What are the 3 charge and
filtration barriers of the glomerulus?
Capillary ENDOTHELIUM
Basement Membrane
Podocytes
What are these modified smooth muscles capable of phagocytosis and keep the basement membrane free of debris?
INTRAglomerular Mesangial Cells
What is another name for the
EXTRAglomerular Mesangial cells?
Lacis Cells
Where are the JG cells found?
Walls of afferent arterioles
Function: secrete renin
What cell monitors Na+ concentration in the lumen of
distal tubule?
Macula Densa
The descending and ascending limb of the Loop of Henle is permeable only to which substances, respectively:
Descending: Permeable to water
Ascending: Permeable to solutes
Where is the Na-K-2Cl symport found?
Thick Ascending Limb of LH
What is the function of the principal cells in the late distal tubule?
Reabsorb Na+; Secrete K+
Intercalated Cell: Reabsorb K+; Secrete H+
Where is the site of action of
Aldosterone?
Distal Tubule
Where is the site of action of ADH?
Collecting Duct
This refers to when graded osmolarity in the renal medulla is CREATED:
Countercurrent Multiplier
With Loop of Henle
This refers to when graded osmolarity in the renal medulla is PRESERVED:
Countercurrent Exchanger
With Vasa Recta
What is the formula for Filtered Load?
GFR x plasma
What is the formula for the Reabsorption Rate?
Filtered Load – Excretion Rate
Excretion R = V x urine
What is the renal threshold of
glucose?
plasma glucose 200mg/dL
Substances start to appear in the urine
Some nephrons exhibit saturation
What is the renal transport
maximum of glucose?
plasma glucose >375mg/dL
All excess substances appear in the urine
All nephrons exhibit saturation
This refers to the volume of
plasma cleared of a substance
per unit of time:
Clearance
UV / P
Which substance has the highest clearance?
PAH
Reason: Filtered and Secreted, not
reabsorbed
What substance is used to estimate renal blood flow and renal plasma flow?
PAH
Reason: Filtered and Secreted, not
reabsorbed
What is the formula of the renal blood flow?
RBF = RPF / 1-Hct
What is the normal value of GFR?
125mL/min or 180L/day
Determined by Starling Forces at the level of the glomerular capillary (glomerulus)
Which starling force is increased by vasodilation of afferent arteriole or moderate vasoconstriction of efferent arteriole?
Glomerular Capillary Hydrostatic Pressure
Which starling force is increased by ureteral obstruction?
Bowman Space Hydrostatic Pressure
What is the normal value of the BS oncotic pressure?
0 – no protein is normally filtered
What is the formula for the
Filtration Fraction
GFR / RPF
What happens to the GFR, RPF, and FF during efferent arteriole constriction?
Increase – decrease – increase
What is the effect of prostaglandins on the afferent arterioles?
DILATES afferent arterioles
PDA – Prostaglandin Dilates Afferent
ACE – Angiotensin II Constricts Efferent
What are the substances released if the BP is LOW?
Angiotensin II
Vasoconstricts the efferent arteriole
Nitric Oxide
Vasodilates the afferent arteriole
What is the function of adenosine in tubuloglomerular feedback?
Adenosine vasoconstricts afferent arteriole to decrease GFR back to
normal
What are the 4 common factors that cause K+ influx (Hypokalemia)?
Insulin
Beta-adrenergic agonists
Alkalosis
Hypoosmolarity
What is known as the breakdown product of protein catabolism?
Urea
Synonym: Carbamide
Where in the tubules is urea
impermeable?
DT, Cortical Collecting Ducts and Outer Medullary Collecting Ducts
What substance increases urea
recycling and the development
of osmotic gradient?
ADH
In the inner medullary collecting ducts ↑ ADH secretion → ↑ Water AND Urea reabsorption → Low Urine Flow Rate
What is the effect of Thiazides
and Loop Diuretics on Ca++
reabsorption, respectively?
Increases; Decreases
Where in the tubular system is 66% of filtered water reabsorbed?
PCT
Where in the tubular system is 66% of filtered Na+ and K+ reabsorbed?
PCT
Where is the majority of phosphate reabsorbed?
PCT
reabsorbs 85% of filtered Phosphate via Na-PO4 cotransport;
other parts to do not reabsorb PO4
The remaining 15% is excreted in the urine
Where is the majority of magnesium reabsorbed?
65% TAL of LH
25% PCT
What is the immediate effect
of water deprivation on plasma osmolarity?
Increases
What is the effect of water intake on urine osmolarity?
Decreases
What is the Free Water Clearance if ADH is present?
Negative
If (-) ADH: Free Water excreted and CH2O is positive
If (+) ADH: Free Water is NOT excreted (water is reabsorbed) and CH20 is negative
What are the three renal regulations of acid-base balance?
Secretion of excess
Reabsorption of filtered HCO3-
if warranted
Production of New HCO3- if
warranted
What pH is compatible with
life?
pH = 6.8-8.0
What happens to calcium and
potassium when hydrogen
increases?
Hypercalcemia
Hyperkalemia
What is the compensation of
metabolic acidosis?
Hyperventilation
What is the compensation of
respiratory alkalosis?
Decrease H+ excretion
Decrease HCO3-reabsorption
Why is chloride high in
NAGMA (normal-anion gap
metabolic acidosis)?
to maintain electroneutrality
Also called Hyperchloremic Metabolic Acidosis with Normal Anion Gap
How do we compute for the
Anion Gap?
(Na+) – [(HCO3-) + (Cl-)]
Anion Gap (AG) used to help diagnose cause of metabolic acidosis
Normal: 8-16 mEq
What are the causes of NAGMA?
HARD-UP: NAGMA
Hyperalimentation
Acetazolamide
RTA,
Diarrhea
Ureteroenteric fistula
Pancreaticoduodenal Fistula
What are the causes of HAGMA (high-anion gap metabolic acidosis)?
MUDPILES: HAGMA
Methanol
Uremia
DKA
Paraldehyde
Propylene Glycol
Iron Isoniazid
Idiopathic Acidosis
Lactic Acidosis (in Sepsis, Shock),
Ethylene Glycol
Ethanol
Salicylic Acid
What is the expected acid-base
balance of a patient with
profuse vomiting?
Hypochloremic Metabolic Alkalosis
Loss of gastric HCL
What is the expected acid-base
balance of a patient having diarrhea?
Metabolic Acidosis
Loss of HCO3-
In which acid-base disorder is
hyperventilation used as a
compensatory mechanism?
Metabolic Acidosis
Body Fluid Markers
TBW: Titrated water, D20, antipyrine
ECF: Sulfate, inulin, mannitol
Plasma: Radioactive Iodinated Serum Albumin (RISA), Evans Blue
Indirect measurements:
ICF: TBW - ECF
Interstitial: ECF - Plasma
ISOOSMOTIC VOLUME EXPANSION
Examples
ECF volume
ICF volume
ECF osmolarity
ICF osmolarity
ISOOSMOTIC VOLUME EXPANSION
Example(s): Infusion of Isotonic NaCl (0.9%)
ECF volume: increased
ICF volume: no change
ECF osmolarity: no change
ICF osmolarity: no change
ISOOSMOTIC VOLUME CONTRACTION
Examples
ECF volume
ICF volume
ECF osmolarity
ICF osmolarity
ISOOSMOTIC VOLUME CONTRACTION
Examples: Diarrhea, burns
ECF volume: Decreased
ICF volume: no change
ECF osmolarity: no change
ICF osmolarity: no change
*bya nagtatae lang ng isotonic NaCl
HYPEROSMOTIC VOLUME EXPANSION
Examples:
ECF volume:
ICF volume:
ECF osmolarity:
ICF osmolarity: Increased
HYPEROSMOTIC VOLUME EXPANSION
Examples: Ingestion of sea water
ECF volume: Increased
ICF volume: Decreased
ECF osmolarity: Increased
ICF osmolarity: Increased
HYPEROSMOTIC VOLUME CONTRACTION
Examples:
ECF volume:
ICF volume:
ECF osmolarity:
ICF osmolarity:
HYPEROSMOTIC VOLUME CONTRACTION
Examples: Sweating, diabetes insipidus, fever
ECF volume: Decreased
ICF volume: Decreased
ECF osmolarity: Increased
ICF osmolarity: Increased
HYPOOSMOTIC VOLUME EXPANSION
Examples:
ECF volume:
ICF volume:
ECF osmolarity:
ICF osmolarity:
HYPOOSMOTIC VOLUME EXPANSION
Examples: SIADH
ECF volume: Increased
ICF volume: Increased
ECF osmolarity: Decreased
ICF osmolarity: Decreased
HYPOOSMOTIC VOLUME CONTRACTION
Examples:
ECF volume:
ICF volume:
ECF osmolarity:
ICF osmolarity:
HYPOOSMOTIC VOLUME CONTRACTION
Examples: Adrenal insufficiency
ECF volume: Decreased
ICF volume: Increased
ECF osmolarity: Decreased
ICF osmolarity: Decreased
Where is EPO produced?
In the INTERSTITIAL CELLS of the PERITUBULAR CAPILLARIES
What is the main charge barrier of the Glomerulus?
Basal lamina/Basement membrane
(Negatively charged to repel proteins like albumin)
What does the capillary endothelium secrete?
NO
Endothelin-1
Diluting segment of loop pf henle
TAL of LH
Parts of nephron termed as countercurrent multiplier and countercurrent exchanger
TAL of LH; Vasa recta
SGLT-2 is found in?
Early PCT
Relative clearances of substances
PAHK! CIUNGA
PAH > K > Creatinine > Inulin > Urea > Na > Glucose, Amino acids, HCO3, and Cl
Weak Acids
1.___________ - lipid soluble form
2.___________ - water soluble form
In acidic urine, the 3.__________ predominates, 4. causing __________ back diffusion, 5.______________ the excretion of weak acids
In alkalinic urine, the 6.__________ predominates, causing 7.__________ back diffusion, 8..______________ the excretion of weak acids
- HA form
- A form
- HA form
- More (back diffusion)
- Decreasing (excretion of weak acids)
- A form
- Less (back diffusion)
- Increasing (excretion of weak acids)
Weak Bases
1.___________ - lipid soluble form
2.___________ - water soluble form
In acidic urine, the 3.__________ predominates, 4. causing __________ back diffusion, 5.______________ the excretion of weak bases
In alkalinic urine, the 6.__________ predominates, causing 7.__________ back diffusion, 8..______________ the excretion of weak bases
- B form
- BH form
- BH form
- Less (back diffusion)
- Increasing (excretion of weak bases)
- B form
- More (back diffusion)
- Decreasing (excretion of weak bases)
Vasoconstriction of afferent arterioles
Modified Starling force:
Effect on GFR:
Effect on RPF:
Effect on FF:
Vasoconstriction of afferent arterioles
Modified Starling force: dec. GCH
Effect on GFR: Decreased
Effect on RPF: Decreased
Effect on FF: No change (dec GFR/dec RPF)
Vasoconstriction of efferent arterioles
Modified Starling force:
Effect on GFR:
Effect on RPF:
Effect on FF:
Vasoconstriction of efferent arterioles
Modified Starling force: inc GCH
Effect on GFR: Increased
Effect on RPF: Decreased
Effect on FF: Increased (inc GFR/dec RPF)
Increased Plasma protein
Modified Starling force:
Effect on GFR:
Effect on RPF:
Effect on FF:
Increased Plasma protein
Modified Starling force: inc GCO
Effect on GFR: Decreased
Effect on RPF: No change
Effect on FF: Decreased (dec GFR)
Ureteral obstruction
Modified Starling force:
Effect on GFR:
Effect on RPF:
Effect on FF:
Ureteral obstruction
Modified Starling force: inc BSH
Effect on GFR: Decreased
Effect on RPF: No change
Effect on FF: Decreased
Autoregulation of Renal blood flow is to maintain GFR. At what BP that this occur?
BP = 80-200 mmHg
Increased secretion of _______________ are mediated by macula densa when there is decreased BP
Angiotension II - VASOCONTRICT EFFERENT arteriole
NO - VASODILATE AFFERENT arteriole
Increased secretion of _______________ is mediated by macula densa when there is increased BP
Adenosine - VASOCONSTRICTS afferent arteriole
*adenosine is generally a vasodilator. Only in kidneys is it a vasoconstrictor
Used to estimate RBF and RPF
PAH
*filtered, secreted, BUT NOT REABSORBED
Used to measure GFR
Inulin, creatinine
*Filtered, NOT SECRETED, NOT REABSORBED
Causes of Hyperkalemia (K efflux)
Insulin deficiency
Beta-adrenergic antagonists
Acidosis
Hyperosmolarity
Inhibitors of Na-K-ATPase pump
Exercise
Cell lysis
Causes of Hypokalemia (K influx)
Insulin
Beta-adrenergic agonist
Alkalosis
Hypoosmolarity
Causes of INCREASED Distal Tubule Secretion of K
HHALLT
High K intake
Hyperaldosteronism
Alkalosis
Loop diuretics
Luminal ions
Thiazide diuretics
Causes of DECREASED Distal Tubule Secretion of K
KHAL
K-sparing diuretics
Hypoaldosteronism
Acidosis
Low K diet
Adverse effect of Spironolactone
Hyperkalemia
Gynecomastia
Increases the maximum osmolarity of renal interstitium
Urea
Increases maximum urine osmolarity
Urea
____________reabsorbs_____% of filtered urea via _______________
____________secretes urea via ____________
______________,_______________,_____________ are ______________ to urea
PCT; 50%; simple diffusion
Thin descending limb of LH; simple diffusion
DCT, cortical collecting duct, and medullary collecting duct; impermeable 
PCT and LH reabsorb _______% of filtered Ca, while DT and CD reabsorb ______% of filtered Ca
90%; 8%
Binds with calcium in intestines, stimulated by Vit D
Calbindin
_______% of plasma Ca is filtered
60%
These increase Ca reabsorption
PTH
Thiazide diuretics
This decreases Ca reabsorption
Loop diuretics
PCT reabsorbs _____% of filtered phosphate and the remaining _____% is ______________
85%; 15%; excreted in the urine (acts as urinary buffer for excess acids H+)
Inhibits reabsorption of phosphate through adenylate cyclase and cAMP inhibition of Na-PO4 cotransport
PTH
In the TAL of LH, what 2 electrolytes compete with each other for reabsorption? Such as the increase of one will decrease the other?
Ca and Mg
CONDITIONS INVOLVING ADH
Primary Polydipsia
Serum ADH:
Serum Osm:
Urine Osm:
Urine flow rate/Urine volume:
CH2O:
Primary Polydipsia
Serum ADH: ↓
Serum Osm: ↓
Urine Osm: ↓ (hypoosmotic)
Urine flow rate/Urine volume: ↑
CH2O: (+)
CONDITIONS INVOLVING ADH
Central DI
Serum ADH:
Serum Osm:
Urine Osm:
Urine flow rate/Urine volume:
CH2O:
Central DI
Serum ADH: ↓
Serum Osm: ↑
Urine Osm: ↓ (hypoosmotic)
Urine flow rate/Urine volume: ↑
CH2O: (+)
CONDITIONS INVOLVING ADH
Peripheral DI
Serum ADH:
Serum Osm:
Urine Osm:
Urine flow rate/Urine volume:
CH2O:
Peripheral DI
Serum ADH: ↑
Serum Osm: ↑
Urine Osm: ↓ (hypoosmotic)
Urine flow rate/Urine volume: ↑
CH2O: (+)
CONDITIONS INVOLVING ADH
Water deprivation
Serum ADH:
Serum Osm:
Urine Osm:
Urine flow rate/Urine volume:
CH2O:
Water deprivation
Serum ADH: ↑
Serum Osm: ↑ to NORMAL
Urine Osm: ↑ (hyperosmotic)
Urine flow rate/Urine volume: ↓
CH2O: (-)
CONDITIONS INVOLVING ADH
SIADH
Serum ADH:
Serum Osm:
Urine Osm:
Urine flow rate/Urine volume:
CH2O:
SIADH
Serum ADH: ↑↑↑
Serum Osm: ↓
Urine Osm: ↑ (hyperosmotic)
Urine flow rate/Urine volume: ↓
CH2O: (-)
ACID-BASE ABNORMALITIES
Respiratory Acidosis
pH:
H:
PCO2:
HCO3:
Compensation:
Respiratory Acidosis
pH: ↓
H: ↑
PCO2: ↑↑
HCO3: ↑
Compensation: ↑H+ secretion, ↑ HCO3 reabsorption
ACID-BASE ABNORMALITIES
Respiratory Alkalosis
pH:
H:
PCO2:
HCO3:
Compensation:
Respiratory Alkalosis
pH: ↑
H: ↓
PCO2: ↓↓
HCO3: ↓
Compensation: ↓ H+ secretion, ↓ HCO3 reabsorption
ACID-BASE ABNORMALITIES
Metabolic Acidosis
pH:
H:
PCO2:
HCO3:
Compensation:
Metabolic Acidosis
pH: ↓
H: ↑
PCO2: ↓
HCO3: ↓↓
Compensation: Hyperventilation
ACID-BASE ABNORMALITIES
Metabolic Alkalosis
pH:
H:
PCO2:
HCO3:
Compensation:
Metabolic Alkalosis
pH: ↑
H: ↓
PCO2: ↑
HCO3: ↑↑
Compensation: Hypoventilation
