30.4 Excretory System
Structures in the Excretory System.
Functions of the Excretory System
Control of the Excretory System
Excretion
• This is the process your body uses
to excrete metabolic wastes and
maintain homeostasis.
• An example of metabolic waste is
ammonia.
Structures in the
Excretory System
•Skin
•Lungs
•Liver
•Kidney
Skin
• Excess water, salts
and small amounts
of toxins (urea) are
released in sweat.
• This occurs in small
amounts that may
not be noticeable.
The Lungs
• Carbon
dioxide is
exhaled from
the lungs
along with
water vapor
The Liver
• The liver converts dangerous
nitrogenous wastes into less
dangerous, less toxic, substances.
• For example: Ammonia into urea.
The Kidney
The Kidney
•The major organ
involved in excretion
•Filters metabolic
wastes from the blood
•Produces urine
Functions of the Kidney
• Filtration
• Reabsorption
• Urine Excretion
Filtration
• Passing a liquid or
gas through a filter to
remove wastes or
impurities.
• Example (location)
• Glomerulus: a dense
network of capillaries
encased in the
Bowman’s Capsule
Reabsorption
• The filtrate is
moved through the
tubules, and down
the loop of Henle.
• As the filtrate
moves through the
loop, salts and
water are moved
out of the tubule
and back into the
veins and arteries.
Urine Excretion
• Once reabsorption is
complete, the filtrate
passes into the
collecting duct. The
urine then moves
down the ureter, into
the bladder, and out
the urethra.
Kidney Control
• ADH, Anti-diuretic hormone or vasopressin,
controls how much water can pass out of the
tubule and back into the body.
Kidney Stones
• Form when different
substances
crystallize in your
kidneys.
• Most kidney stones
are formed from
calcium
• High fat and salt
diets in people over
40 lead to kidney
stones
Diabetes and the Kidneys
Classwork
• Imagine you just ate a bowl of
chicken noodle soup, follow the
soup through the digestive
system and then through the
excretory system.