Aziel S. Amor BSN 2B
Overview of the Anatomy of the Renal System
Renal System, in humans, organ system that includes the kidneys, where urine is produced,
and the ureters, bladder, and urethra for the passage, storage, and voiding of urine.
The system contains two kidneys, which control the electrolyte composition of the blood and
eliminate dissolved waste products and excess amounts of other substances from the blood; the
latter substances are excreted in the urine, which passes from the kidneys to the bladder by way
of two thin muscular tubes called the ureters.
Kidney
These bean-shaped organs are
41 ⁄2 to 5 (11.5 to 12.5 cm) long
and 21 ⁄2 (6.5 cm) wide. Located
retroperitoneally on either side of
the lumbar vertebrae, the kidneys
lie behind the abdominal organs
and in front of the muscles
attached to the vertebral column.
The peritoneal fat layer protects
them.
The regulatory functions of kidneys:
By producing the enzyme renin (re’nin), they help regulate blood pressure,
and their hormone erythropoietin stimulates red blood cell production in bone marrow.
Kidney cells also convert vitamin D to its active form.
Several structures, including the ureters, the renal blood vessels, and nerves, enter or exit
the kidney at the renal hilum.
A transparent fibrous capsule encloses each kidney and gives a fresh kidney a glistening
appearance. A fatty mass, the perirenal fat capsule, surrounds each kidney and acts to
cushion it against blows. The renal fascia, the outermost capsule, anchors the kidney and
helps hold it in place against the muscles of the trunk wall.
Internal structure of the Kidney
Renal cortex- Outermost layer. It is made of renal corpuscles and convoluted tubes
Renal medulla- Middle layer. Made of loops of Henle and collecting tubules. Consists of
wedge-shaped pieces called renal pyramids.
Each pyramid’s tip releases urine into cup-shaped structures called calyces
(singular: calyx). The calyces collect the urine and send it to the renal pelvis.
Renal Pelvis- Innermost region, a flat, funnel-like cavity that collects urine.
Blood Supply
The kidneys continuously cleanse the blood and adjust its composition, so it is not
surprising that they have a very rich blood supply. Approximately one-quarter of the total
blood supply of the body passes through the kidneys each minute.
, Summary of the pathway of renal blood vessels.
Blood from the abdominal aorta enters the renal artery, which
branches extensively within the kidney into smaller arteries. The
smallest arteries give rise to afferent arterioles in the renal cortex.
From the afferent arterioles, blood flows into the glomeruli
(capillaries), to efferent arterioles, to peritubular capillaries, to veins
within the kidney, to the renal vein, and finally to the inferior vena
cava.
Nephrons
The structural and functional unit of the kidney. Each kidney contains approximately 1
million nephrons. It is in the nephrons, with their associated blood vessels, that urine is
formed. Each nephron has two major portions: a renal corpuscle and a renal tubule.
Renal corpuscle consists of a glomerulus surrounded by a Bowman’s capsule. The
glomerulus is a capillary network that arises from an afferent arteriole and empties into an
efferent arteriole.
Bowman’s capsule (or glomerular capsule) is the expanded end of a renal tubule; it
encloses the glomerulus. It collects the filtered fluid from the glomerulus.
Renal tubule continues from Bowman’s capsule and consists of the following parts:
proximal convoluted tubule (Reabsorbs nutrients, water, and essential ions back into the
blood.), loop of Henle (Regulates water and salt balance to concentrate urine.), and distal
convoluted tubule (Fine-tunes ion and pH balance before the fluid moves on).
Nephrons’ Role in Urine Formation
1. Filtration – Blood enters the glomerulus, and waste, water, and small molecules are
filtered into the nephron.
2. Reabsorption – Essential substances like glucose, water, and ions are reabsorbed back
into the blood.
3. Secretion – Extra waste products and ions are secreted into the nephron for removal.
4. Excretion – The remaining fluid (urine) flows into the collecting duct, then to the ureter,
and finally to the bladder.
Ureters
The ureters act as ducts to allow urine to pass from the kidneys to the bladder. They
measure about 10 to 12 (25.5 to 30.5 cm) in adults and have a diameter varying from 2 to
8 mm, with the narrowest portion being at the ureteropelvic junction. The left kidney is
higher than the right one, so the left ureter typically is slightly longer than the right one.
Essentially, the ureters are passageways that carry urine from the kidneys to the bladder.
Although it might appear that urine could simply drain to the bladder below by gravity, the
ureters do play an active role in urine transport. Smooth muscle layers in their walls
contract to propel urine into the bladder by peristalsis. Once urine has entered the
bladder, it is prevented from flowing back into the ureters by small valve like folds of
bladder mucosa that flap over the ureter openings.
Overview of the Anatomy of the Renal System
Renal System, in humans, organ system that includes the kidneys, where urine is produced,
and the ureters, bladder, and urethra for the passage, storage, and voiding of urine.
The system contains two kidneys, which control the electrolyte composition of the blood and
eliminate dissolved waste products and excess amounts of other substances from the blood; the
latter substances are excreted in the urine, which passes from the kidneys to the bladder by way
of two thin muscular tubes called the ureters.
Kidney
These bean-shaped organs are
41 ⁄2 to 5 (11.5 to 12.5 cm) long
and 21 ⁄2 (6.5 cm) wide. Located
retroperitoneally on either side of
the lumbar vertebrae, the kidneys
lie behind the abdominal organs
and in front of the muscles
attached to the vertebral column.
The peritoneal fat layer protects
them.
The regulatory functions of kidneys:
By producing the enzyme renin (re’nin), they help regulate blood pressure,
and their hormone erythropoietin stimulates red blood cell production in bone marrow.
Kidney cells also convert vitamin D to its active form.
Several structures, including the ureters, the renal blood vessels, and nerves, enter or exit
the kidney at the renal hilum.
A transparent fibrous capsule encloses each kidney and gives a fresh kidney a glistening
appearance. A fatty mass, the perirenal fat capsule, surrounds each kidney and acts to
cushion it against blows. The renal fascia, the outermost capsule, anchors the kidney and
helps hold it in place against the muscles of the trunk wall.
Internal structure of the Kidney
Renal cortex- Outermost layer. It is made of renal corpuscles and convoluted tubes
Renal medulla- Middle layer. Made of loops of Henle and collecting tubules. Consists of
wedge-shaped pieces called renal pyramids.
Each pyramid’s tip releases urine into cup-shaped structures called calyces
(singular: calyx). The calyces collect the urine and send it to the renal pelvis.
Renal Pelvis- Innermost region, a flat, funnel-like cavity that collects urine.
Blood Supply
The kidneys continuously cleanse the blood and adjust its composition, so it is not
surprising that they have a very rich blood supply. Approximately one-quarter of the total
blood supply of the body passes through the kidneys each minute.
, Summary of the pathway of renal blood vessels.
Blood from the abdominal aorta enters the renal artery, which
branches extensively within the kidney into smaller arteries. The
smallest arteries give rise to afferent arterioles in the renal cortex.
From the afferent arterioles, blood flows into the glomeruli
(capillaries), to efferent arterioles, to peritubular capillaries, to veins
within the kidney, to the renal vein, and finally to the inferior vena
cava.
Nephrons
The structural and functional unit of the kidney. Each kidney contains approximately 1
million nephrons. It is in the nephrons, with their associated blood vessels, that urine is
formed. Each nephron has two major portions: a renal corpuscle and a renal tubule.
Renal corpuscle consists of a glomerulus surrounded by a Bowman’s capsule. The
glomerulus is a capillary network that arises from an afferent arteriole and empties into an
efferent arteriole.
Bowman’s capsule (or glomerular capsule) is the expanded end of a renal tubule; it
encloses the glomerulus. It collects the filtered fluid from the glomerulus.
Renal tubule continues from Bowman’s capsule and consists of the following parts:
proximal convoluted tubule (Reabsorbs nutrients, water, and essential ions back into the
blood.), loop of Henle (Regulates water and salt balance to concentrate urine.), and distal
convoluted tubule (Fine-tunes ion and pH balance before the fluid moves on).
Nephrons’ Role in Urine Formation
1. Filtration – Blood enters the glomerulus, and waste, water, and small molecules are
filtered into the nephron.
2. Reabsorption – Essential substances like glucose, water, and ions are reabsorbed back
into the blood.
3. Secretion – Extra waste products and ions are secreted into the nephron for removal.
4. Excretion – The remaining fluid (urine) flows into the collecting duct, then to the ureter,
and finally to the bladder.
Ureters
The ureters act as ducts to allow urine to pass from the kidneys to the bladder. They
measure about 10 to 12 (25.5 to 30.5 cm) in adults and have a diameter varying from 2 to
8 mm, with the narrowest portion being at the ureteropelvic junction. The left kidney is
higher than the right one, so the left ureter typically is slightly longer than the right one.
Essentially, the ureters are passageways that carry urine from the kidneys to the bladder.
Although it might appear that urine could simply drain to the bladder below by gravity, the
ureters do play an active role in urine transport. Smooth muscle layers in their walls
contract to propel urine into the bladder by peristalsis. Once urine has entered the
bladder, it is prevented from flowing back into the ureters by small valve like folds of
bladder mucosa that flap over the ureter openings.
