THE URINARY SYSTEM
FUNCTIONS OF THE URINARY SYSTEM
➔ Excretion
➔ Regulation of blood volume and pressure
➔ Regulation of blood solute concentration
➔ Regulation of extracellular fluid pH
➔ Stimulation of red blood cell synthesis
➔ Activation of vitamin D
ORGANS OF THE URINARY SYSTEM
Kidneys
Ureters
Urinary bladder
Urethra
LOCATION OF THE KIDNEYS
✔ Against the dorsal body wall
✔ At the level of the T12 to L3 vertebrae
✔ The right kidney is slightly lower than the left
KIDNEY FEATURES
Are retroperitoneal and are located on each side of the vertebral column.
They are bean-shaped, and each measures about 11cm long, 5cm wide, and 3cm thick.
RENAL HILUM
✔ A medial indentation where several structures enter or exit the kidney (ureters, renal blood
vessels, and nerves)
An ADRENAL GLAND sits atop each kidney
➔ COVERINGS OF THE KIDNEYS
FIBROUS CAPSULE
◦ Surrounds each kidney
PERIRENAL FAT CAPSULE
◦ Surrounds the kidney and cushions against blows
RENAL FASCIA
◦ Outermost capsule that helps hold the kidney in place against the muscles of the trunk
wall
➔ REGIONS OF THE KIDNEY
RENAL CORTEX—outer region
RENAL MEDULLA—inside the cortex
RENAL PELVIS—inner collecting tube
➔ KIDNEY STRUCTURES
❄ RENAL or MEDULLARY PYRAMIDS—triangular regions of tissue in the medulla
❄ RENAL COLUMNS—extensions of cortex-like material inward that separate the pyramids
❄ CALYCES—cup-shaped structures that funnel urine towards the renal pelvis
➔ BLOOD SUPPLY
◦ One-quarter of the total blood supply of the body passes through the kidneys each minute.
, NEPHRON ANATOMY AND PHYSIOLOGY
➔ The structural and functional units of the kidneys
➔ Responsible for forming urine
➔ Main structures of the nephrons:
☞ Glomerulus
☞ Renal tubule
NEPHRON ANATOMY
➔ Glomerulus
Knot of capillaries
Capillaries are covered with podocytes from the renal tubule
Glomerulus sits within a glomerular (Bowman’s) capsule (the first part of the renal tubule)
➔ Renal tubule extends from glomerular capsule and ends at the collecting duct
1. Glomerular (Bowman’s) capsule
2. Proximal convoluted tubule (PCT)
3. Loop of Henle
4. Distal convoluted tubule (DCT)
TYPES OF NEPHRONS
➔ CORTICAL NEPHRONS
✰ Located entirely in the cortex
✰ Includes most nephrons
➔ JUXTAMEDULLARY NEPHRONS
✰ Found at the boundary of the cortex and medulla
NEPHRON ANATOMY
Nephrons are associated with two capillary beds
Glomerulus
Peritubular capillary bed
➔ GLOMERULUS
❏ Fed and drained by arterioles
▪ Afferent arteriole—arises from a cortical radiate artery and feeds the glomerulus
▪ Efferent arteriole—receives blood that has passed through the glomerulus
▪ After the efferent arteriole, it gives rise to a plexus of capillaries called =
PERITUBULAR CAPILLARIES (specialized = vasa recta)
❏ Specialized for filtration
➔ PERITUBULAR CAPILLARY BEDS
❏ Arise from efferent arteriole of the glomerulus
❏ Normal, low pressure capillaries
❏ Adapted for absorption instead of filtration
❏ Cling close to the renal tubule to reabsorb (reclaim) some substances from collecting tubes
FUNCTIONS OF THE URINARY SYSTEM
➔ Excretion
➔ Regulation of blood volume and pressure
➔ Regulation of blood solute concentration
➔ Regulation of extracellular fluid pH
➔ Stimulation of red blood cell synthesis
➔ Activation of vitamin D
ORGANS OF THE URINARY SYSTEM
Kidneys
Ureters
Urinary bladder
Urethra
LOCATION OF THE KIDNEYS
✔ Against the dorsal body wall
✔ At the level of the T12 to L3 vertebrae
✔ The right kidney is slightly lower than the left
KIDNEY FEATURES
Are retroperitoneal and are located on each side of the vertebral column.
They are bean-shaped, and each measures about 11cm long, 5cm wide, and 3cm thick.
RENAL HILUM
✔ A medial indentation where several structures enter or exit the kidney (ureters, renal blood
vessels, and nerves)
An ADRENAL GLAND sits atop each kidney
➔ COVERINGS OF THE KIDNEYS
FIBROUS CAPSULE
◦ Surrounds each kidney
PERIRENAL FAT CAPSULE
◦ Surrounds the kidney and cushions against blows
RENAL FASCIA
◦ Outermost capsule that helps hold the kidney in place against the muscles of the trunk
wall
➔ REGIONS OF THE KIDNEY
RENAL CORTEX—outer region
RENAL MEDULLA—inside the cortex
RENAL PELVIS—inner collecting tube
➔ KIDNEY STRUCTURES
❄ RENAL or MEDULLARY PYRAMIDS—triangular regions of tissue in the medulla
❄ RENAL COLUMNS—extensions of cortex-like material inward that separate the pyramids
❄ CALYCES—cup-shaped structures that funnel urine towards the renal pelvis
➔ BLOOD SUPPLY
◦ One-quarter of the total blood supply of the body passes through the kidneys each minute.
, NEPHRON ANATOMY AND PHYSIOLOGY
➔ The structural and functional units of the kidneys
➔ Responsible for forming urine
➔ Main structures of the nephrons:
☞ Glomerulus
☞ Renal tubule
NEPHRON ANATOMY
➔ Glomerulus
Knot of capillaries
Capillaries are covered with podocytes from the renal tubule
Glomerulus sits within a glomerular (Bowman’s) capsule (the first part of the renal tubule)
➔ Renal tubule extends from glomerular capsule and ends at the collecting duct
1. Glomerular (Bowman’s) capsule
2. Proximal convoluted tubule (PCT)
3. Loop of Henle
4. Distal convoluted tubule (DCT)
TYPES OF NEPHRONS
➔ CORTICAL NEPHRONS
✰ Located entirely in the cortex
✰ Includes most nephrons
➔ JUXTAMEDULLARY NEPHRONS
✰ Found at the boundary of the cortex and medulla
NEPHRON ANATOMY
Nephrons are associated with two capillary beds
Glomerulus
Peritubular capillary bed
➔ GLOMERULUS
❏ Fed and drained by arterioles
▪ Afferent arteriole—arises from a cortical radiate artery and feeds the glomerulus
▪ Efferent arteriole—receives blood that has passed through the glomerulus
▪ After the efferent arteriole, it gives rise to a plexus of capillaries called =
PERITUBULAR CAPILLARIES (specialized = vasa recta)
❏ Specialized for filtration
➔ PERITUBULAR CAPILLARY BEDS
❏ Arise from efferent arteriole of the glomerulus
❏ Normal, low pressure capillaries
❏ Adapted for absorption instead of filtration
❏ Cling close to the renal tubule to reabsorb (reclaim) some substances from collecting tubes
