Download excretory system

Reminder…
• Regulation within animal systems requires
maintaining homeostasis- the ability of the
body or a cell to seek and maintain a stable
internal environment when dealing with
external changes
• There are several organ systems that work
together to maintain an organism’s internal
environment, despite changes that occur in its
external environment.
Excretory System
• How did the nervous system maintain
homeostasis?
• The excretory system helps regulate the
concentration of water and other
components of body fluids.
The Excretory System Maintains Homeostasis In 3 Steps:
1. Filtration- Filters substances from the blood
2. Reabsorption- Regulate the chemical composition
of body fluids by retaining the proper amounts of
water, salts, and nutrients
3. Secretion- Elimination of wastes in the form of
urine
Evolutionary Trends in Excretion
Complex
Simple
Animal
Aquatic
Worms and
Taxon
Invertebrates
Mollusks
Release
Wastes
By…
diffusion to remove
waste across their cell
membranes directly into
the water
Use of nephridia- tiny
pores along the body
excrete waste
Insects
Using malpighian
tubules to collect and
excrete wastes
Vertebrates
Use of kidneys,
ureters, and a
bladder to collect
and excrete waste
Picture of
system
Examples
Sponges, jellyfish,
Earthworm, clam,
Grasshopper, ants,
planaria
octopus
bees
mammals, birds,
reptiles, fish,
amphibians
1. Kidneys: pair of organs that
removes wastes
*Note: renal=kidney
 receive blood via the renal
artery
 Contain millions of filtering
units called nephrons that
remove wastes (excess salt
and urea) from the blood
and produce urine.
 Every 45 minutes kidneys
filter all the blood in your
body
 Filtered blood leaves kidneys
and returns to circulation
carrying nutrients, salts, and
water via the renal vein
 Excess water and toxic waste in
the form of urine leave the
kidney via the ureter
 Sometimes excess salts or
minerals in the urine crystallize
and form kidney stones. When
kidney stones block the
ureters, they cause great pain.
2. Ureters—tubes that
carry urine from
kidneys to urinary
bladder
3. Bladder—muscular
sac where urine is
stored temporarily
before being
excreted
4. Urethra—tube that carries urine from bladder
to the outside
Levels of Organization
Nephrons
Kidneys, Bladder, Ureter, Urethra
Excretory
Interaction with other systems for Regulation
Lungs of the respiratory
system remove CO2 from
blood.
The circulatory system
brings wastes to the lungs,
kidneys, and skin for
excretion.
Skin of the integumentary
system excretes water,
urea, salts, and other
wastes through sweat.