Excretory System of Mammals
Excretory system of vertebrates including mammals, is formed of one pair of
kidneys, one pair of ureter, a urinary bladder and a urethra.
1. Kidneys:
These are the primary
or major excretory
organs of man and
other vertebrates.
These are one pair,
large sized, bean
shaped, dark red,
slightly flattened
structures present in
upper part of
abdominal cavity
between the levels of
last thoracic and third
lumbar vertebra along
dorsal body wall, one
on either side of
vertebral column.
Concavity of kidney, called hilum or hilus renalis is always inward
directed.
These are asymmetrical in position, right kidney is slightly posterior in
position and is probably pushed by well-developed liver.
These are extra-coelomic, retroperitoneal and metanephros in position.
Internally each kidney is formed of about one million uriniferous tubules or
renal tubules or nephrons held together by connective tissue and
surrounded by a tough white fibrous capsule which further surrounded by a
shock absorbing layers of fat called renal fat, followed by a fibrous
membrane called renal fascia.
Nephrons are convoluted in outer part of kidney, called renal cortex, while
run straight in central part of kidney, called renal medulla.
, The medulla consists of multiple pyramidal tissue masses, called the renal
pyramids.
In between the pyramids are spaces called renal columns of Bertini through
which the blood vessels pass.
The tips of the pyramids, called renal papillae, point toward the renal pelvis.
There are, on average, eight renal pyramids in each kidney.
The renal pyramids along with the adjoining cortical region are called
the lobes of the kidney.
The renal pelvis leads to the ureter on the outside of the kidney.
On the inside of the kidney, the renal pelvis branches out into two or three
extensions called the major calyces, which further branch into the minor
calyces.
Functions of Kidneys:
Remove waste products from the body.
Remove drugs from the body.
Balance the body's fluids.
Release hormones that regulate blood pressure.
Produce an active form of vitamin D that promotes strong, healthy bones.
Excretory system of vertebrates including mammals, is formed of one pair of
kidneys, one pair of ureter, a urinary bladder and a urethra.
1. Kidneys:
These are the primary
or major excretory
organs of man and
other vertebrates.
These are one pair,
large sized, bean
shaped, dark red,
slightly flattened
structures present in
upper part of
abdominal cavity
between the levels of
last thoracic and third
lumbar vertebra along
dorsal body wall, one
on either side of
vertebral column.
Concavity of kidney, called hilum or hilus renalis is always inward
directed.
These are asymmetrical in position, right kidney is slightly posterior in
position and is probably pushed by well-developed liver.
These are extra-coelomic, retroperitoneal and metanephros in position.
Internally each kidney is formed of about one million uriniferous tubules or
renal tubules or nephrons held together by connective tissue and
surrounded by a tough white fibrous capsule which further surrounded by a
shock absorbing layers of fat called renal fat, followed by a fibrous
membrane called renal fascia.
Nephrons are convoluted in outer part of kidney, called renal cortex, while
run straight in central part of kidney, called renal medulla.
, The medulla consists of multiple pyramidal tissue masses, called the renal
pyramids.
In between the pyramids are spaces called renal columns of Bertini through
which the blood vessels pass.
The tips of the pyramids, called renal papillae, point toward the renal pelvis.
There are, on average, eight renal pyramids in each kidney.
The renal pyramids along with the adjoining cortical region are called
the lobes of the kidney.
The renal pelvis leads to the ureter on the outside of the kidney.
On the inside of the kidney, the renal pelvis branches out into two or three
extensions called the major calyces, which further branch into the minor
calyces.
Functions of Kidneys:
Remove waste products from the body.
Remove drugs from the body.
Balance the body's fluids.
Release hormones that regulate blood pressure.
Produce an active form of vitamin D that promotes strong, healthy bones.
