Lecture 10 – urinary system
Function
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Regulates plasma ion concentrations (na, K, cl)
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Regulates blood volume and blood pressure
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Helps to stabilize blood ph
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Prevents the loss of valuable nutrients
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Eliminates organic matter/waste (urea)
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Synthesizes calcitriol (active form of vitamin D) – helps absorb calcium in
intestine
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Prevents dehydration
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Aids the live with some if its functions (detoxifying poisons)
The kidneys
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The right kidney
Covered by the live, hepatic flexure and duodenum
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The left kidney
Covered by the spleen, stomach, pancreas, splenic flexure and jejunum
Positioned higher than the right kidney
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Both capped with the suprarenal glands
Th nephron
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Basic structural and functional unit of the kidney
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Renal tubule: long tubular passageway
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Main functions:
Reabsorbs useful organic material from the filtrate
Urine processing
Reabsorbs more than 80% of the water from the filtrate
Prevents dehydration
Secretes waste into the filtrate that was missed in an earlier process
Urine processing
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2 types of nephrons:
Cortical nephrons
85% of the nephrons ate cortical
Located in cortex
Have a relatively short nephron loop
Juxtamedullary nephrons
15% of the nephrons are juxtamedullary
Capsule is located near the border of the cortex and the medulla
The renal corpuscle
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~200um in diameter,
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Produces a protein free solution: glomerular filtrate
Glomerular capsule
