Renal Blood Flow and Glomerular Filtration - Rao Flashcards
What are the functions of the kidneys?
ridding the body of metabolic by-products
excrete toxins and otehr foreign substances
ability to balance daily intake of salts and water
acid base balance
endocrine function (conversion of vit d to active form and synthesis of epo)
What happens when the kidneys fail? Long pathway…
renal failure edema (due to lack of fluid and salt balance) increase in work load of heart heart failure and pulmonary edema death due to acidemia and hyperkalemia
what percentage of nephrons are superficial? juxtamedullary?
85%
15%
what percentage of body mass is kidney? what percentage of CO?
less than 0.5% but receives more than 20% of cardiac output
Explain the pathway of blood flow in the kidney?
renal artery - interlobular arteries - arcuate arteries - radial arteries - afferent arterioles - glomerular capillaries - efferent arteriole - peritubular capillaries - renal vein
how is the naming of the efferent arteriole an exception?
it’s the only place in the body where blood leaves a capillary bed and remains in something called an arteriole
what is the section of blood taht is surrouding the loop of henle
vasa recta
explain the drops in the arteriovenous pressure in the renal vasculature
the first major drop is within the afferent arteriole. the second major drop is within the efferent arteriole. the third major drop occurs in the peritubular capillaries
explain the blood pressure within the glomerular capillaries
the pressure barely drops, maintaing a high level
what two pressures allow for the unique glomerular filtration
the low oncotic pressure and high capillary pressure, which forces fluid out of the glomerular capillaries and into the urinary space
what are the 3 processes of urine formation?
glomerular filtration
tubular reabsorption
tubular secretion
why is it smart to filter large amount of body fluids and solutes and then reabsorb them later when it is a huge energy use?
- allows the kidney to rapidly remove waste products from the body that depend primarily and glomerular filtration for excretion
- allows all body fluids to be filtered and processed several times each day.
what is the composition of filtrate?
similar to plasma, but without large proteins (less than 1% albumin and globulin, rarely hgb)
explain the gibbs donnan effect
the proteins in the basement membrane of the glomerulus have a negative charge (i.e. heparin sulfate). the negative charge. thus 4-5% more anions and 4-5% less cations
What is the gfr in a normal person?
130 ml/min or 180 l.day
what is the filtration fraction?
GFR/RPF (renal plasma flow)