PRIN Review Flashcards
How can you calculate plasma volume?
(Blood Volume) x (1 - hematocrit)
How is ECFV measured?
Using inulin and Na+*
These remain in ECF compartment.
How is plasma volume measured?
Albumin* or Evans blue dye.
These remain in the vasculature.
How is TBW measured?
D2O and antipyrine.
These distribute to all body compartments.
What is the difference btwn mmol and mEq?
mEq reflects charges:
mEq = (mmol) x (valence charge)
What is the difference btwn mol and osmol?
osmole reflects number of osmotically active particles.
1 mol NaCl = 2 osmoles
What is osmotic pressure?
The pressure required to stop water from diffusing across a semi-permeable membrane.
Proportional to the number of osmotic particles dissolved.
What are the major cations and anions in ECF?
Na+
Cl-
HCO3-
What are the major cations and anions in the ICF?
K+
proteins
amino acids
organic phosphates
What is the range of normal osmolality for ECF & ICF?
280-300 mosmol/kg H2O
What is an effective osmol?
particle that cannot diffuse across a membrane
What is the difference btwn osmolality and tonicity?
Tonicity measures effective osmoles whereas osmolality measures everything even if it can diffuse across the membrane.
What is the normal [Na+] in plasma?
135-145 mmol/L
What is Starling’s Law?
Fluid Flux = (Kf) x [ (Pc - Pi) - (pi c - pi i) ]
Between the ICF and ECF,
- what travels freely?
- what requires transport proteins?
Water and urea diffuse freely.
Glucose and electrolytes require transport proteins.
Between the ISF and plasma,
- what travels freely?
- what requires transport proteins?
Water and solutes (urea, electrolytes, glc) diffuse freely.
Proteins (albumin) require transport proteins
What are the regulatory functions of the kidneys?
Maintains and regulates:
- [electrolytes]
- pH
- ECFV
- CO
What are the endocrine functions of the kidneys?
Produce and secrete hormones:
- Erythropoietin (from renal peritubular cells)
- Vitamin D (from proximal tubular epithelial cells: helps Ca++ & PO4— metabolism)
- RAAS (prorenin–>renin in JG cells)
- Vasodilators: Kinins & PGs
What is the excretory function of the kidneys?
What are the main waste products?
Concentration and dilution of urine, then voiding/micturition.
Waste products:
- Urea (from protein metab)
- Uric acid (from purine metab)
- Creatinine (from muscle metab)
What spinal level are the kidneys located at?
T12 - L3
List 4 methods used to estimate GFR.
- Clearance of inulin or creatinine
- Serum/Plasma [creatinine]
- Cockcroft-Gault equation
- Starling’s Forces
What is the function of mesangial cells?
Provide support for the capillary network.
Help regulate GFR (by contracting/relaxing).
What are the 3 layers in the filtration barrier?
- Glomerular capillary endothelium (fenestrated)
- Glomerular basement membrane (collagen & proteoglycans)
- Bowman’s Capsule epithelium (podocytes)
When does GFR = Clearance?
When referring to a substance that is:
- freely filtered
- not reabsorbed
- not secreted
- not produced by kidneys
ex. Creatinine or Inulin
What is the filtered load?
(Plasma [X]) x (GFR)
Why is GFR estimated from creatinine rather than inulin?
Inulin is an exogenous substance so it needs to be introduced into the body which is more invasive.
What is a normal value of plasma [creatinine]?
40-120 micro-mol/L
What is the Cockcroft-Gault equation for estimating GFR?
Creatinine Clearance = { (140 - years of age) x (kg body weight) x (0.85**if female) }
/
{ (72) x (mg/dL Plasma [creatinine]) }
What is the equation for blood flow?
Blood flow = (change in Pressure) / (change in Resistance)
Flow = P / R
What cells compose the Juxtaglomerular Apparatus (JGA)?
- Extraglomerular Mesangial Cells
- Macula Densa (tubule epithelium)
- Juxtaglomerular Cells (afferent arteriole wall - secrete renin)
How does aldosterone act on the kidney?
Increases reabsorption of Na+ in the DCT & CD.
How does ADH/Arginine Vasopressin act on the kidney?
Increases water reabsorption in the CD
Increases Na+ reabsorption in the TAL
