Urinary System
The Kidney Structure & Function
- Urinary system is the primary regulator of fluid volume and ion concentration
- Composition and volume of body fluids must remain constant
- Stabilize osmolality, secrete excesses, reabsorb when source is scarce
- Selective excretion: important
products retained, waste removed
- Contribute to the acid balance by
removing H+ and bicarbonate
- Produce glucose by gluconeogenesis
- Produce erythropoietin to stimulate
the formation of erythrocytes
- Produce calcitriol = active form of vit
D
- Produce renin, an enzyme that
regulates the formation of
angiotensin II (regulates blood
pressure, triggers vasoconstriction)
- Kidneys are located on the upper
abdominal wall
- Arteries, veins and ureters enter
through the renal hilus
- Gets blood almost straight from aorta
- Composed of an outer cortex and an inner medulla
- Basic functional unit = nephron
, The Nephron
- Glomerulus
- Blood comes in contact with Glomerulus =
receives blood supply enters from afferent
arteriole, filtration occurs, in cortex
- Enclosed in Bowman's capsule; a layer of
epithelial cells. Protein free fluid is filtered
and accumulates in bowman's space then
enters proximal tubule
- Blood supply composed of 3 capillary beds:
- Glomerular capillaries
- Peritubular capillaries
- Vasa recta (follows loop of henle)
- Capillaries connect to the efferent arteriole
that will feed peritubular capillaries
- Proximal tubule
- where reabsorption takes place, goes into
efferent arteriole
- Highly convoluted in cortex
- Loop of Henle
- concentration of urine, absorption water
- Hairpin structure in the medulla, composed
of descending thin limb, ascending thin limb, thick ascending limb
- Distal tubule
- site of secretion and reabsorption, heart of the nephron that's regulated by hormones
- Highly convoluted, in cortex
- Initial part of distal tubule passes bw the afferent and efferent arteriole of its own
glomerulus using epithelial cells called macula densa
- Adjacent smooth muscle cells = juxtaglomerular cells, produce and secrete renin
- Helps restore blood pressure if drop is detected
- Collecting duct
- Receive distal tubules from multiple nephrons
- where final dilution of urine is controlled
- Bring urine to renal pelvis
The Basic Renal Processes
- Glomerular filtration
- Filtration of plasma from glomerular capillaries into
bowman's space
- Production of a protein free filtrate of plasma
- Glomerulus has a complex network of capillaries
and specialized structure designed to retain cells and
medium and high molecular weight proteins
The Kidney Structure & Function
- Urinary system is the primary regulator of fluid volume and ion concentration
- Composition and volume of body fluids must remain constant
- Stabilize osmolality, secrete excesses, reabsorb when source is scarce
- Selective excretion: important
products retained, waste removed
- Contribute to the acid balance by
removing H+ and bicarbonate
- Produce glucose by gluconeogenesis
- Produce erythropoietin to stimulate
the formation of erythrocytes
- Produce calcitriol = active form of vit
D
- Produce renin, an enzyme that
regulates the formation of
angiotensin II (regulates blood
pressure, triggers vasoconstriction)
- Kidneys are located on the upper
abdominal wall
- Arteries, veins and ureters enter
through the renal hilus
- Gets blood almost straight from aorta
- Composed of an outer cortex and an inner medulla
- Basic functional unit = nephron
, The Nephron
- Glomerulus
- Blood comes in contact with Glomerulus =
receives blood supply enters from afferent
arteriole, filtration occurs, in cortex
- Enclosed in Bowman's capsule; a layer of
epithelial cells. Protein free fluid is filtered
and accumulates in bowman's space then
enters proximal tubule
- Blood supply composed of 3 capillary beds:
- Glomerular capillaries
- Peritubular capillaries
- Vasa recta (follows loop of henle)
- Capillaries connect to the efferent arteriole
that will feed peritubular capillaries
- Proximal tubule
- where reabsorption takes place, goes into
efferent arteriole
- Highly convoluted in cortex
- Loop of Henle
- concentration of urine, absorption water
- Hairpin structure in the medulla, composed
of descending thin limb, ascending thin limb, thick ascending limb
- Distal tubule
- site of secretion and reabsorption, heart of the nephron that's regulated by hormones
- Highly convoluted, in cortex
- Initial part of distal tubule passes bw the afferent and efferent arteriole of its own
glomerulus using epithelial cells called macula densa
- Adjacent smooth muscle cells = juxtaglomerular cells, produce and secrete renin
- Helps restore blood pressure if drop is detected
- Collecting duct
- Receive distal tubules from multiple nephrons
- where final dilution of urine is controlled
- Bring urine to renal pelvis
The Basic Renal Processes
- Glomerular filtration
- Filtration of plasma from glomerular capillaries into
bowman's space
- Production of a protein free filtrate of plasma
- Glomerulus has a complex network of capillaries
and specialized structure designed to retain cells and
medium and high molecular weight proteins
