Download Human Excretory System The human excretory system functions to

Human Excretory System
The human excretory system functions to remove waste from the human body. This system consists of
specialized structures and capillary networks that assist in the excretory process. The human excretory system
includes the kidney and its functional unit, the nephron. The excretory activity of the kidney is modulated by
specialized hormones that regulate the amount of absorption within the nephron.
Kidneys
They are bean-shaped organs located on either side of the backbone at about the level of the stomach and liver.
Blood enters the kidneys through renal arteries and leaves through renal veins. Tubes called ureters carry
waste products from the kidneys to the urinary bladder for storage or for release.
The product of the kidneys
is urine, a watery solution of
waste products, salts, organic
compounds, and two important
nitrogen compounds: uric acid
and urea. Uric acid results
from nucleic acid
decomposition,
and urea results from amino
acid breakdown in the liver.
Both of these nitrogen
products can be poisonous to
the body and must be removed
in the urine.
Nephron
The functional and structural
unit of the kidney is
the nephron. The nephron
produces urine and is the
primary unit of homeostasis in the body. It is essentially a long tubule with a series of associated blood vessels.
The upper end of the tubule is an enlarged cuplike structure called the Bowman's capsule. Within the
Bowman's capsule is a coiled ball of capillaries known as glomerulus. Blood from the renal artery enters the
glomerulus. The force of the blood pressure induces blood plasma to pass through the walls of the glomerulus,
pass through the walls of the Bowman's capsule, and flow into the proximal tubule. Red blood cells and large
proteins remain in the blood.
Salts, glucose, amino acids, and other useful compounds flow back through tubular cells into the blood by
active transport. Once more, salts, water, and other useful materials flow back into the bloodstream.
Homeostasis is achieved by this process: A selected amount of hydrogen, ammonium, sodium, chloride, and
other ions maintain the delicate salt balance in the body.
The waste product made by the kidneys then begins to be moved towards the bladder. This waste fluid is
referred to as urine. Urea, uric acid, salts, and other metabolic waste products are the main components of urine.
The urine flows through the ureters toward the urinary bladder. When the bladder is full, the urine flows
through the urethra to the exterior.
Fetal Pig Excretory System
Figure B
Figure A
Figure A pictures the ureter which transports waste
between the kidney and bladder.
Figure B highlights the anatomy of the excretory
system with respect to the reproductive organs of a
female pig.
Figure C shows the renal artery and vein. The renal
artery brings blood into the kidney which filters out
urea and uric acid to produce urine. The renal vein
carries the filtered blood out of the kidney and back into
the circulatory system.
Figure C