M1 Renal Physiology Flashcards
Very general kidney functions:
Excretion of metabolic waste products and foreign chemicals
Regulation of water and electrolyte balances
Regulation of body fluid osmolality and electrolyte concentrations
Regulation of arterial pressure
Regulation of acid-base balance
Secretion, metabolism, and excretion of hormones
Gluconeogenesis
`What is the central physiologic role of the kidneys?
control the volume and composition of the body fluids
What is total body water?
60% of total body weight
How much to total body water is ICF and ECF?
2/3 is ICF
1/3 is ECF
What is the barrier between the ICF and ECF?
cell membrane
What are the major ions of the ECF?
Na+ and Cl- and HCO3-
What are the major ions of the ICF?
K+ and PO4- and protein
What is the concentration of osmotically active particles in total solution and is expressed in terms of mOsm/liter of water?
Osmolarity
What is the average osmolarity of the ECF and ICF?
osmolarity of the ECF and ICF averages 280-300 mOsm/liter - identical in nearly all body fluids
What is expressed in terms of mOsm/kg of solvent?
Osmolality
In relatively dilute solutions, such as those found in the body, how do osmolality and osmolarity relate to each other?
osmolality ≈ osmolarity
What are the 4 kidney processes that determine composition of the urine?
- filtration
- reabsorption
- secretion
- excretion
What is the glomerular filtrate?
ultrafiltrate of plasma containing the same concentration of most salts and organic substances found in plasma
What physical forces cause filtration by glomerular capillaries?
starling forces:
glomerular hydrostatic pressure
glomerular colloid osmotic pressure
bowman’s capsule pressure
What is the equation for GFR?
GFR = Kf x [ (PGC +πBS) - (πGC + PBS)]
Kf = Ultrafiltration Coefficient- the product of the hydraulic permeability (Lp)and the surface area (SA) of the glomerular capillary membranes PGC= Glomerular Capillary Hydrostatic Pressure πGC= Glomerular Capillary Oncotic Pressure PBS= Bowman’s Space Hydrostatic Pressure πBS= Bowman's Space Oncotic Pressure
Over what range of BP can autoregulation help regulate kidney blood flow best?
80-160 mmHg