ILE U4 D1 Flashcards
Adults are _% water
50-60%
Children are _% water
75%
The elderly is _% water
45%
Blood plasma has high concentrations of
Na, Cl, Bicarb, protein
The IF has high concentrations of
Na, Cl, bicarb, lower level of protein
ICF has high levels of
K, phos, mag, and protein
How does H2O move across cell membranes?
Passively, largely through osmosis and facilitated diffusion
H2O movement depends on
The concentration of the environment
Passive movement occurs __ the concentration gradient
down (high -> low)
Channels offer ___ and ___
insulated and larger passageways for molecules to cross
Ligand gating
Channel opens in response to (ligand) binding
Voltage gating
Channel opens in response to change in membrane potential
Posttranslational modification
Channel gates in response to modification (like phosphorylation)
_K:_Na in K:Na pump?
2K:3Na
Isotonic solution
same concentration inside membrane as outside membrane
Hypertonic solution
Higher concentration outside membrane than inside membrane
Hypotonic solution
Solution outside membrane has lower concentration than inside membrane
Capillary wall is made up of
Thin membrane of endothelial cells
How do substances go through capillary walls ?
- Junctions between endothelial cells
- vesicular transport
- Diffusion
- Filtration
The rate of filtration at any point depends of forces called
Starling forces
J[v]
Net fluid flux
K[f]
Filtration coefficient
P[c]
Capillary pressure
P[I]
interstitial pressure
sigma
reflection coefficient
pi[c]
capillary oncotic pressure
pi[I]
interstitial oncotic pressure
Colloids
large molecules that are not freely permeable to the membrane
Colloids are more present in ____ than in interstitium
vascular fluid
Most prominent vascular colloid
albumin
hypoproteinemia
Low levels of vascular colloids
What does hypoproteinemia cause?
edema
What can changes in sodium concentration cause?
edema
Osmolality mostly measures
extracellular sodium concentration
hyponatremia causes cellular
edema
hypernatremia causes cellular
dehydration
Tonicity
term used to describe the in-vivo osmolality of a fluid; the manner in which the infused fluid will effect transcellular fluid flux.
T/F; the kidney can generate new nephrons
F
Strongest diuretic
Loop
Loop diuretic ADRs
OHH DAANG
- ototoxicity (ears)
- hypokalemia
- hypomagnesemia
- Dehydration
- Allergy
- Alkalosis
- Nephritis
- Gout
Loops lose/gain Ca
lose
Loop diuretic mechanism
Inhibit Na/K/Cl transport system of THICK ASCENDING LoH
What inhibits loops?
NSAIDs
When do you use loop diuretics?
edematous states, hypertension, hypercalcemia
Ethacrynic acid drug type
loop diuretic
ethacrynic MoA
similar to other loops (furosemide) but MORE ototoxicity
Thiazide diuretics MoA
Inhibits NaCl reabsorption in early DISTAL CONVOLUTED TUBULE, dilates capacity of nephron, decreased Ca excretion
When would you use a thiazide?
Hypertension, hypercalciuria, osteoporosis, diabetes insipidus
Thiazide ADRs
HyperGLUC
- Hyperglycemia
- Hyperlipidemia
- Hyperuricemia
- Hypercalcemia
K sparing diuretics MoA
Inhibit Na channel in cortical collecting duct either directly or by interfering with aldosterone
K sparing diuretics that directly inhibit Na channel in cortical collecting duct
triamterene and amiloride
K sparing diuretics that interfere with aldosterone
Spirinolactone and eplerenone
Diuretic’s efficacy in edema therapy depends on
Amount of filtered Na normally reabsorbed at its site of action, distal to its site of action, adequate drug delivery to site of action, amount of Na that reaches site of action
When are diuretics appropriate?
When reduced water and sodium intake are ineffective
All diuretics act by reducing Na uptake in the
renal tubules; just differ in place within the tubules
FeNa
Fractional excretion of Na
Which are more powerful;
Loop>/
Loop > K-sparing/thiazides
The effectiveness of thiazides and loop diuretics is dependent on
Drug concentrations in tubular lumen
How do thiazides and loop diuretics reach the tubular lumen?
active transport via proximal tubular cells
Spirinolactone gains access to ____ via _____ in the ____
Spirinolactone gains access to mineralocorticoid receptors in the cortical collecting duct through diffusion from the systemic circulation
natriuresis
excretion of Na in urine
To achieve natriuresis, what must occur?
threshold of loop or thiazide diuretic concentration (“ceiling dose”)
Ceiling dose for furosemide
40 mg IV
If a patient has chronic kidney disease, is their ceiling dose reduced or increased?
reduced, because renal absorption is reduced according to decrease in GFR
Primary driving force for GFR
hydrostatic pressure gradient across the glomerular capillary wall
Myogenic reflex
Acute changes in renal perfusion pressure evoke reflex constriction or dilatation of the afferent arteriole in response to increased or decreased pressure
TGF
changes the rate of filtration and tubular flow by reflex vasoconstriction or dilatation of the afferent arteriole. TGF is mediated by specialized cells in the thick ascending limb of the loop of Henle called the macula densa(sense solute concentrations and tubular flow rate)
Angiotensin II
When reduced renal blood flow, renin is released from GRANULAR cells within the wall of the AFFERENT ARTERIOLE near the MACULA DENSA in a region called the JUXTAGLOMERULAR APPARATUS. ATII evokes vasoconstriction of the EFFERENT ARTERIOLE, and the resulting increased glomerular hydrostatic pressure elevates GFR to normal levels
mGFR
Measured GFR; used to determine kidney damage
ideal filtration marker is defined as
a solute that is freely filtered at the glomerulus, nontoxic, neither secreted nor reabsorbed by the kidney tubules, and not changed during its excretion by the kidney
Inulin
fructose polysaccharide with molecular wgt– 5.2 kD
Freely filtered through glomerulus - gold standard for measuring GFR, but test is invasive
Methods to measure GFR:
- CrCl
- Cockcroft-Gault
- Modification of diet in renal disease (MDRD)
- Chronic kidney disease epidemiology collaboration
All based on creatinine
Normal range for CrCl
Adults 0.6-1.2mg/dL
CrCl equation
[(140-(age)) x lean body weight (kg) ] / (serumCr x 72)
^ x 0.85 if woman
With kidney disease, CrCl should be adjusted to
BSA (body surface area)
Using the Cockcroft-Gault equation with creatinine values measured by most laboratories in the United States today will result in a
10-40% overestimate
BUN
Blood urea nitrogen - concentration of nitrogen (in urea) in serum (NOT RBCs)
Normal BUN
8 –23 mg dL
Elevated BUN indicates
Higher production (high protein diet), less tubular reabsorption,
Azotemia
clinical condition of elevated BUN (READ TABLE 11-1 in Chapter 11 of the Handbook of Laboratory Values to see causes of azotemia according to broad classification of pre-renal, intra-renal, or post-renal azotemia).
BUN/serum creatinine ration (normal)
10-15:1. Greater than 20:1 in renal disease
