3. TheExcretorySystem
•
Your body does not use all the food that you
take in.
•
The unused food parts are waste products.
•
These wastes are processed by the
excretory system.
•
The excretory system collects and
eliminates wastes from the body and
regulates the level of fluid in the body.
5. FunctionsoftheExcretorySystem
•
When the trash cans in your home are full of
waste, you must take the trash outside. The
waste in your body also must be removed.
•
Waste that is not removed, or eliminated,
from your body can become toxic, or
poisonous, and damage your organs.
Collection and Elimination
6. FunctionsoftheExcretorySystem
•
The excretory system also regulates the
level of fluids in the body.
•
Recall that water is an essential nutrient for
your body. Some of the water in your body is
lost when waste is eliminated.
Regulation of LIquids
8. TypesofExcretion
•
Your body excretes, or eliminates, different
substances from different body systems.
•
The excretory system is made of four body
systems.
9. TypesofExcretion
Digestive System
collects and removes
undigested solids from
the foods you eat
Urinary System
processes, transports,
collects, & removes
liquid wastes from body
Respriatory System
removes carbon dioxide &
water vapor from the body
secretes excess salt and
water from the body
through sweat glands
Integementary System
15. Kidneys
•
The bean-shaped organ that filters, or
removes, wastes from blood is the kidney.
•
You have two kidneys, one on each side of
your body.
•
They are near the back
wall of your abdomen,
above your waist, and
below your rib cage.
17. •
Each kidney is about
the size of your fist.
•
Kidneys are dark red
in color because of the
large amount of blood
that passes through
them.
Kidneys
18. •
The kidneys have several functions.
•
Here we focus on the role of the kidneys in
the urinary system. But the kidneys have
other important functions.
•
They produce hormones that stimulate the
production of red blood cells.
•
They also control blood pressure and help
control calcium levels in the body.
Kidney Function
Kidneys
19. Kidneys
•
The kidneys contain blood vessels and
nephrons.
•
Nephrons are networks of capillaries and
small tubes, or tubules, where filtration of
blood occurs.
•
Each kidney contains about one million
nephrons.
Nephrons
21. •
Blood contains waste products, salts, and
sometimes toxins from cells that need to be
removed from the body.
•
As blood passes through the kidneys, they
filter these products from the blood.
•
When blood is filtered, a fluid called urine is
produced.
•
The kidneys filter the blood and produce
urine in two stages.
Urine
Kidneys
22. •
Blood is constantly circulating and filtering
through the kidneys.
•
In one day, the kidneys filter about 180 L of
blood plasma, or the liquid part of blood. That
is enough liquid to fill ninety 2-L bottles.
•
You have about 3 L of blood plasma in your
body. This means that your kidneys filter
your entire blood supply about 60 times each
day.
First Filtration
Kidneys
23. •
The first filtration
occurs in the
nephrons.
•
There, groups of
capillaries filter
water, sugar,
salts, and wastes
out of the blood.
First Filtration
Kidneys
26. •
What would happen if all of the liquid from
the first filtration were excreted?
•
Your body would quickly dehydrate, and
important nutrients would be lost.
•
To regain some of this water, the kidneys
filter the liquid collected in the first filtration
again.
Second Filtration
Kidneys
28. •
During the second filtration, up to 99
percent of the water and nutrients from
the first filtration are separated out and
reabsorbed into the blood.
•
The remaining liquid and waste products
form urine.
•
On average, an adult excretes about 1.5 L
of urine per day.
Second Filtration
Kidneys
31. •
Urine leaves each
kidney through a tube
called the ureter.
•
Each of your kidneys
has a ureter.
•
Both ureters drain
into your bladder.
TheUreters,BladderandUrethra
32. •
The bladder is a
muscular sac that
holds urine until the
urine is excreted.
•
Your bladder
expands and
contracts like a
balloon when it fills
or empties.
TheUreters,BladderandUrethra
33. •
An adult bladder can
hold about 0.5 L of
urine.
TheUreters,BladderandUrethra
34. •
Urine leaves the
bladder through a tube
called the urethra.
•
The urethra contains
circular muscles
called sphincters that
control the release of
urine.
TheUreters,BladderandUrethra
35. •
The nephrons are damaged and the ability
of the kidneys to filter blood is reduced.
•
In the beginning stages, there might not be
symptoms.
•
Possible causes: diabetes, high blood
pressure, poisons, trauma
UrinaryDisorders
Kidney Disease
36. •
Infections usually occur in the bladder or
urethra but can be in the kidneys and
ureters.
•
Symptoms might include burning during
urination, small and frequent urination,
and blood in urine.
•
Possible causes: bacteria in the urinary
system
UrinaryDisorders
Urinary Tract InFection
37. •
Kidney stones are solid substances that
form in the kidneys.
•
The most common type is made of calcium.
•
Stones that pass through the urinary
system can be very painful.
•
Possible causes: calcium buildup in the
kidneys
UrinaryDisorders
Kidney Stones
38. •
Urine is released from the bladder
involuntarily.
•
These problems occur in women more
often than in men.
•
Possible causes: urinary tract infections,
muscle weakness, prostate enlargement
UrinaryDisorders
Bladder Control Problems
39. •
The excretory system filters wastes from
the blood.
•
The blood is part of the circulatory
system. A buildup of wastes in the
circulatory system would be toxic to your
body.
TheExcretorySystemandHomeostasis
40. •
Homeostasis is also maintained by the
removal of wastes from the digestive
system.
•
Wastes would damage your body if the
excretory system did not remove them
from the digestive system.
TheExcretorySystemandHomeostasis
41. •
The excretory system also interacts with
the nervous system.
•
The hypothalamus is an area of the brain
that helps to maintain homeostasis.
TheExcretorySystemandHomeostasis
42. •
One function of the hypothalamus is to
control the secretion of some hormones.
•
One hormone causes the tubules of the
kidneys to absorb more water from the
blood.
•
This helps the body control fluid levels.
Water is kept in the blood instead of being
excreted in the urine.
TheExcretorySystemandHomeostasis
