Urine Formation Flashcards
3 processes of urine formation
Glomerular filtration
Tubular reabsorption
Tubular secretion
Normal urine formed in a day
1 to 1.5 L
Reabsorbed substances from tubules
Glucose,amino acids,water,electrolytes
Glomerular filtration
Plasma filtered into bowmans capsule except plasma proteins
Filtered fluid-glomerular filtrate
3layers glomerular filtration pass through
Endothelium of glomerular membrane
Basement membrane
Epithelium of visceral layer of bowmans capsule
Filtration called ultra Filtration. /composition of glomerular filtrate similar to plasma except plasma proteins.Comment.
Plasma proteins-larger size-not pass through slit pores in endothelium of capillaries
GFR
Total quantity of filtrate formed in all nephrons of both kidneys in a given unit of time
Variation of pressures in glomerulus
Favor filtration:
1,pressure inside glomerular capillary -60 mm Hg
Oppose filtration:
1,Colloidal Osmotic in glomeruli by plasma proteins -25mm Hg
2,Hydrostatic in bowmans -15mm Hg
Only pressure which promote filtration
Pressure in glomerular capillary (highest capillary pressure)
Define colloidal osmotic and Hydrostatic pressure
Colloidal Osmotic-increased conc of proteins in glomerulus during filtration
Hydrostatic-pressure exerted by the filtrate on bowmans capsule
Factor affecting GFR
Tubuloglomerular
Glomerular capillary
Colloidal Osmotic pressure
Hydrostatic in bowmans
Constriction of afferent arteriole
Constriction of efferent arteriole
Surface area of capillary membrane
Permeability of capillary
Tubular reabsorption called selective .Explain
Tubular cells of kidney selectively reabsorps the substances present in the glomerular filtrate
Mechanism of reabsorption
Active
-against electrochemical gradient
-liberation of energy
-energy from ATP
-eg na,k,ca
Passive
-along electrochemical gradient
-no need of energy
-eg,water
Site of reabsorption
PCT-
Site of reabsorption
PCT -na,glucose, h20
Loop of henle-na,cl
DCT-na,Ca, h20
