Functions of the Urinary System
! Elimination of waste products
o Nitrogenous wastes
o Toxins
o Drugs
Functions of the Urinary System
! Regulation of aspects of homeostasis
o Water balance
o Electrolytes
o Acid-base balance in the blood
o Blood pressure
o Red blood cell production
o Activation of vitamin D
Organs of the Urinary System
! Kidneys
! Ureters
! Urinary bladder
! Urethra
Kidneys
! Location and structure
o The kidneys are situated against the dorsal body wall in a retroperitoneal
position (behind the parietal peritoneum)
o The kidneys are situated at the level of the T12 to L3 vertebrae
o The right kidney is slightly lower than the left (because of position of the liver)
Kidneys
! Location and structure (continued)
o Renal hilum
! A medial indentation where several structures enter or exit the kidney
(ureters, renal blood vessels, and nerves)
o An adrenal gland sits atop each kidney
Kidneys
! Location and structure (continued)
o Fibrous capsule encloses each kidney
o Perirenal fat capsule surrounds the kidney and cushions against blows
o Renal fascia is the outermost capsule that anchors the kidney and adrenal
© 2015 Pearson Education, Inc.
, gland to surrounding structures
Kidneys
! Location and structure (continued)
o Three regions revealed in a longitudinal section:
1. Renal cortex—outer region
2. Renal medulla—deeper region
o Renal (medullary) pyramids—triangular regions of tissue in the
medulla
o Renal columns—extensions of cortex-like material that separate
the pyramids
Kidneys
! Location and structure (continued)
o Three regions:
3. Renal pelvis—medial region that is a flat, funnel-shaped tube
o Calyces—cup-shaped extensions of the renal pelvis that enclose
the renal pyramids
o Calyces collect urine and send it to the renal pelvis, on to the
ureter, and to the urinary bladder for storage
Blood Supply
! One-quarter of the total blood supply of the body passes through the kidneys each
minute
! Renal artery provides each kidney with arterial blood supply
! Renal artery divides into segmental arteries " interlobar arteries " arcuate arteries
" cortical radiate arteries
Blood Supply
! Venous blood flow
o Cortical radiate veins " arcuate veins à interlobar veins à renal vein
o There are no segmental veins
o Renal vein returns blood to the inferior vena cava
Nephrons
! Nephrons:
o Structural and functional units of the kidneys
o Responsible for forming urine
! Each nephron consists of two main structures:
1. Renal corpuscle
2. Renal tubule
© 2015 Pearson Education, Inc.
! Elimination of waste products
o Nitrogenous wastes
o Toxins
o Drugs
Functions of the Urinary System
! Regulation of aspects of homeostasis
o Water balance
o Electrolytes
o Acid-base balance in the blood
o Blood pressure
o Red blood cell production
o Activation of vitamin D
Organs of the Urinary System
! Kidneys
! Ureters
! Urinary bladder
! Urethra
Kidneys
! Location and structure
o The kidneys are situated against the dorsal body wall in a retroperitoneal
position (behind the parietal peritoneum)
o The kidneys are situated at the level of the T12 to L3 vertebrae
o The right kidney is slightly lower than the left (because of position of the liver)
Kidneys
! Location and structure (continued)
o Renal hilum
! A medial indentation where several structures enter or exit the kidney
(ureters, renal blood vessels, and nerves)
o An adrenal gland sits atop each kidney
Kidneys
! Location and structure (continued)
o Fibrous capsule encloses each kidney
o Perirenal fat capsule surrounds the kidney and cushions against blows
o Renal fascia is the outermost capsule that anchors the kidney and adrenal
© 2015 Pearson Education, Inc.
, gland to surrounding structures
Kidneys
! Location and structure (continued)
o Three regions revealed in a longitudinal section:
1. Renal cortex—outer region
2. Renal medulla—deeper region
o Renal (medullary) pyramids—triangular regions of tissue in the
medulla
o Renal columns—extensions of cortex-like material that separate
the pyramids
Kidneys
! Location and structure (continued)
o Three regions:
3. Renal pelvis—medial region that is a flat, funnel-shaped tube
o Calyces—cup-shaped extensions of the renal pelvis that enclose
the renal pyramids
o Calyces collect urine and send it to the renal pelvis, on to the
ureter, and to the urinary bladder for storage
Blood Supply
! One-quarter of the total blood supply of the body passes through the kidneys each
minute
! Renal artery provides each kidney with arterial blood supply
! Renal artery divides into segmental arteries " interlobar arteries " arcuate arteries
" cortical radiate arteries
Blood Supply
! Venous blood flow
o Cortical radiate veins " arcuate veins à interlobar veins à renal vein
o There are no segmental veins
o Renal vein returns blood to the inferior vena cava
Nephrons
! Nephrons:
o Structural and functional units of the kidneys
o Responsible for forming urine
! Each nephron consists of two main structures:
1. Renal corpuscle
2. Renal tubule
© 2015 Pearson Education, Inc.
