Transcript Excretory System - Mr. Eeds Biology

Excretory System
Excretory System: Poison
Protection
• If you knew there was poison hidden in
your house, you would surely do
everything possible to find and remove
that poison. If you didn't, you and your
family would slowly die. How would you
find it? How would you remove it? You
would probably figure out a system of
searching and removing. That would be an
excretory system.
Functions of the Excretory System
• Remove toxic nitrogen wastes
(urea) from the body
• Helps maintain homeostasis by
eliminating or conserving water
and salts
• In humans, the organs used for
excretion are the kidneys
Kidneys
• Kidneys are located near the
lower back on either side of
the spinal column
• Blood enters the kidneys
through the renal artery and
exits through the renal vein
• The kidneys remove wastes from
the blood and produce liquid
waste called urine
• Kidneys maintain blood pH and
regulate the water content of the
blood
Blood Purification
• The mechanism of blood
purification involves two
distinct processes:
–Filtration
–Reabsorption
Filtration
• Nephrons are the sites of filtration
• Takes place in the glomerulus (small
network of capillaries encased in the
upper end of the nephron by a hollow,
cup shaped structure called Bowman’s
Capsule)
• The filtrate contains water, urea,
glucose, salts amino acids & some
vitamins
Reabsorption
• The process in which liquid is taken
back into a vessel
• Materials including amino acids, fats
& glucose are removed from the
filtrate by active transport &
reabsorbed into the capillaries (water
is returned by osmosis)
• The clean blood returns through
the renal vein and into circulation
• Urine is collected in the urinary
bladder
• Urine is released from the bladder
through a tube called the urethra
Parts of the Excretory System
• The wastes follow this path:
•
Kidneys  Ureter  Bladder  Urethra
–The ureter and urethra are transport
tubes
–The bladder is a collection point
The Excretory System
Artery
Vein
Kidney
Ureter
Urinary
Bladder
Urethra
• Kidney failure can cause toxic
chemicals to build up to lethal levels
in the blood
• Dialysis machines can perform the
function of the kidneys
• Kidney transplants have become
routine transplant surgeries
• The kidneys were the first organs to
be successfully transplanted in 1954
Interesting Facts
• Your blood passes through the kidneys
300 times a day.
• The nephrons clean all your blood in 45
minutes.
• Every day the nephrons send about six
cups of urine to the bladder.
Here is a graph on dialysis and
transplant survival from 1985-1994:
• Kidney disease causes the build up of
wastes in your system. Some cases of
kidney disease can be treated with
medication. But if the disease is more
severe, then the patient might be put on a
dialysis machine. Blood is pumped
through a dialysis machine that filters the
waste from the blood and returns the clean
blood. Some patients have to spend near
60 hours/month on a dialysis machine.