How does the kidney work?
What controls the rate and
concentration of urine?
Review nephron in kidney
Steps in urine formation and
concentration
Glomerular filtration
Reabsorption
Tubular secretion
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Kidney Function and Nephrons - Basic Human Anatomy - Lecture Slides, Slides of Anatomy
Human Anatomy course teaches a student the structural nature and significance of each of the major organ systems, and how each system carries out its unique role in the living organism. Key points in this lecture are:Kidney Function and Nephrons, Glomerular Filtration, Reabsorption, Tubular Secretion, Urine Formation, Nephron is Functional Unit of Kidney, Filtration at Glomerulus, Glomerular Filtration Rate, Tubular Secretion, Signs of Kidney Problems
Typology: Slides
2012/2013
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How does the kidney work?
What controls the rate and
concentration of urine?
Review nephron in kidney
Steps in urine formation and
concentration
Glomerular filtration Reabsorption Tubular secretion
Nephron is functional unit of kidney
Over 1 million nephrons in human kidney Glomerulus is filtration site in cortex Tubules form loop of Henle, extending a few centimeters into medulla Reabsorption and secretion in tubules
Filtration at Glomerulus Filtration membrane formed by podocyte cells lets all of plasma components of blood filter out of glomerular capillaries and into proximal convoluted tubule
What happens to filtrate to make urine?
Filtrate contains all non-protein and non-cellular parts of blood Water Dissolved ions Dissolved glucose Amino acids Nitrogenous wastes (nitrites, urea) No proteins No cells Production of urine and thus control of blood chemistry involves three processes Control over glomerular filtration rate (how fast is blood plasma filtering out of blood into tubules of kidney Subsequent movement of fluid and dissolved substances out of filtrate and back into blood by reabsorption Tubular secretion or further removal of certain substances from blood
What controls glomerular filtration rate?
Locally, glomerular filtration depends on Blood pressure in glomerular capillaries “Osmotic pressure” or amount of dissolved substances in blood versus amount of dissolved substances in surrounding glomerular tissues Local changes in kidney arterial pressure (by smooth muscles in walls of vessels vaso-dilating) is main control of glomerular filtration rate
But many external factors can also control
glomerular filtration rate
How would caffeine affect glomerular filtration rate?
Reabsorption creates concentration gradient
- Reabsorption of sodium creates concentration gradient
- Other substances, like glucose are also reabsorbed or pass back into blood across tubule membranes.
- Urea, uric acid and creatinine, all nitrigenous waste productrs of the body’s metabolism, remain in filtrate
Changes in permeability of collecting duct
produce concentrated or non-concentrated urine
Final composition of urine
depends on
Glomerular filtration rate gives initial volume Amount of reabsorption of water will affect final urine volume Amount of reabsorption of sodium will affect final salinity or concentration of urine Tubular secretion may add certain other substances to urine