Physiology-McCormick Flashcards
Which cations and anions predominate IC?
K: IC=140, EC=4-4.2
Mg: IC=20
Phosphate: IC=11
Diarrhea/hemorrhage, water deprivation/dehydration, and diuretics/adrenal insufficiency have what effect on volume in a darrow-yanet?
Volume contraction
Infusion of isotonic NaCl, high NaCl intake, and SIADH have what effect on volume in a darrow yanet diagram?
Volume expansion
Distribution of fluid between the ECF and ICF is determined primarily by:
Ion distribution (Na) ATPase activity
Distribution of ECF between the plasma (vascular space) and interstitial (tissue) compartments is determined by:
Balance of hydrostatic vs oncotic pressures
Intravascular pressure in capillaries vs plasma protein and solute concentration
___ is swollen cells due to increased ICF volume..does NOT respond to diurectics
Non-pitting edema
___ is increased interstitial volume…nephrotic syndrome, CHF, pregnancy, cirrhosis
Pitting edema
Can respond to diuretics
These cells are within the afferent arteriole and cause renin secretion
Granular cells
___ are from the sacral micturition center S2-S4 (pelvic nerve) and stimulate detrusor muscle and inhibits contraction of internal urethral sphincter
Parasympathetic fibers (cholinergic-Ach)
___ inhibits detrusor constriction, constricts internal urethral sphincter
Sympathetic fibers (adrenergic-NE)
Hypogastric n.
__ are voluntary and constrict the external urethral sphincter
Somatic motor neurons
Pudendal n.
Which cations and anions predominate in the EC?
Na: plasma=142, interstitial=139, IC=14
Cl: Plasma and interstitial=108, IC=4
HCO3: plasma=24, interstitial=28.3, IC=10
Ca: EC=1.3, IC=0
What is the equation for GFR?
GFR=Kf x Puf
Kf-ultrafiltration coefficient
Puf-Capillary ultrafiltration pressure
How do you calculate the ultrafiltration pressure?
Puf=Pgc - (Pbc + piGC)
Pgc-glomerular capillary pressure
Pbc-bowmans capsule pressure
piGC-oncotic pressure in bowmans capsule
This is the net filtration pressure and bowmans capsule oncotic pressure is zero so not needed in calculation
Contraction of __ cells shortens capillary loops, lowers Kf, and, thus lowers GFR
Mesangial
Describe what happens to the following when you have afferent arteriole constriction:
- Greater pressure ___ upstream of glomerular capillaries
- Pgc will ___, which lowers GFR
- Renal blood flow ___ due to increased resistance
Drop
Drop
Drop
Describe what happens to the following when you have efferent arteriole constriction:
- Pooling of blood in the ___
- ___ Pgc will increase GFR
- Renal blood flow will ___
Glomerular capillaries
Increased
Decrease
Describe what happens to Pgc, RBF, and GFR when you have increased systemic arterial pressure:
They all increase
Describe what happens to Pgc, RBF, and GFR when you constrict the afferent arteriole
They all go down
Describe what happens to Pgc, RBF, and GFR when you have moderate efferent arteriolar constriction
Increased Pgc
Decreased RBF
Increased GFR
What is the equation for Clearance?
Cx= Ux x V / Px
Cx-Clearance of x
Ux-Concentration of x in urine
V-Urine volume
Px-Concentration of X in plasma
As creatinine goes up, what happens to GFR?
Goes down
Pcreatinine is inversely proportional to GFR–> useful for long-term monitoring of renal function
What is the equation for filtration fraction?
FF=GFR/RPF
Normally, approximately 20%
In renal artery stenosis, what happens to FF?
Increased–> decrease the denominator
FF=GFR/RPF
What is the equation for filtered load?
Filtered load of x=GFR x Px
If excretion is less than filtration, net __ occured
If excretion is greater than filtration, net __ occurred
Reabsorption
Secretion
The PCT reabsorbs most of filtered ___
Several organic anions and cations (drugs, drug metabolites, creatinine, urate) are secreted in the ___
Water, Na, K, Cl, bicard, Ca, P. Reabsorbs all of filtered glucose
PCT
Proximal tubular __ reabsorption provides the driving force for reabsorption of water, other solutes.
Na
Where is the Na/K ATPase?
Basolateral membrane
Where does Na cotransport with glucose, AA’s, phosphate, and Na countertransport with H+ occur?
PCT
Where does Na/K/2Cl occur?
Thick ascending limb
Where does Na/Cl cotransport occur?
Early DCT
__ are a new class of oral antihyperglycemic agents which lower the Tmax for glucose excretion
SLGT-2
Side effects include UTIs and increase in the osmolarity in the tubule system due to excess glucose can lead to dehyrdration due to osmotic diuresis
___ inhibits proximal tubular phosphate reabsorption
PTH
This effect of PTH increases the amount of P excreted at any given plasma P concentration
Overdose of an organic acid (acetylsalicylate or aspirin) may be treated by ___ of urine through HCO3 administration which promotes urinary excretion by trapping the acid in tubular lumen
Alkalinization
This portion is freely permeable to water and impermeable to Na and Cl
Desc limb of henle
This portion is always impermeable to water
Asc limb of henle
This portion of the ascending limb does NaCl reabsorption
Thin
This part of the asc limb of henle has an active Na/K/2Cl cotransporter
Thick segment
__ is the major site of physiological control of salt and water balance
Late DCT and CD
__ stimulate Na reabsorption, K secretion, and H secretion in the late DCT and CD
Aldosterone
Aldosterone acts primarily on these cells in CD
Principal cells
What conditions can drive K out of the ICF and into ECF?
Hypokalemia and Acidemia
What conditions can push K from the ECF into the ICF?
Hyperkalemia
B-adrenergic agonists (epi)
INSULIN
__ is freely filtered into bowmans capsule, 67% reabsorbed in PCT, 20% reabsorbed in thick AL of henle, and physiological control is exerted in the CD
K
__ cells either reabsorb or secrete K, depending on body’s K balance
Principal
___ stimulates K secretion in CD to maintain electroneutrality when Na is reabsorbed
Aldosterone
In a low-sodium diet, you get less __ delivery to the late distal tubule, the collecting duct will have less K secretion and excretion which can cause ___
Na
Hyperkalemia
HyperK can be treated by increasing downstream delivery of Na to distal tubules/CDs
How does Mg paracelluarly diffuse in the thick AL?
K leak channels create a positive charge in the tubule which sets up a gradient to paracellularly transport
___ increases water and urea permeability of late DCT and CD
ADH
Describe water permeability of CD in a well-hydrated pt:
Water remains in tubular lumen; dilute urine is excreted
LOW ADH
Describe water permeability in a dehydrated pt:
CD is highly water-permeable, water is reabsorbed, low volume of concentrated urine is excreted
HIGH ADH
___ promotes urea reabsorption from inner medullary CD by increasing expression of urea transporters
ADH
Describe the urine volume and concentration in dehydration and SIADH?
Low volume, highly concentrated
High ADH
Describe the urine volume and concentration in diabetes insipidus and volume expansion
High volume of dilute urine is excreted
Low ADH
__ increases Na and water excretion by increasing GFR, inhibiting Na reabsorption in medullary CD, suppressing renin secretion, suppressing aldosterone secretion, it is a systemic vasodilator, and suppresses AVP secretion
ANP
How do you calculate Free Water clearance?
CH2O=V - Cosm
If Uosm is less than Posm, CH2O is positive and pure water is ___
Cleared from the body
If Uosm > Posm, CH2O is negative, pure water is ___
Retained
How do you calculate Fractional Excretion of Na?
UNa x PCr / PNa x UCr
What does a FENa below 1% suggest?
What does a FENa above 2% suggest?
Below 1%-prerenal and AGN-Na avidly reabsorbed
Greater than 2%-ATN, renal-Tubular damage disrupts normal Na reabsorption
In acidemia, increased H has what effect on Ca?
Increased free plasma [Ca]
H displaces Ca from plasma proteins
Acidemic pts tend to have hyperkalemia
Acidosis has what effect on EC potassium?
Hyperkalemia
How do you calculate anion gap?
What is the normal range for anion gap?
Cations - anions
Na - (Cl + HCO3)
Normal range= 8-11 mEq/L
What are causes of high anion gap acidosis?
Methanol Uremia DKA Propylene glycol Isoniazid Lactic acidosis Ethylene glycol Salicylates
MUDPILES
