Download Excretory System - The Northwest School

Excretory System
Kidney
Things that are excreted:
Large intestine/rectum/anus
Feces - digestive system waste
Lungs
CO2 and Water
Skin - sweat glands
Salts and water
Kidneys
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Houston, we have a problem
Our diets are very rich in protein
We don’t use all of the amino acids that are put
into our blood after the digestion of proteins
Our liver is left to deal with these amino acids
Amino Acid Structure
The C’s, O’s and some of the
H’s are turned into glucose
and stored by the liver
The N and 3 H’s become
ammonia - YIKES!
Ammonia
Ammonia (NH3) is quite toxic to cells
We clean with ammonia, because ammonia can
break down cell membranes (think: bacteria
cells)
To the Rescue
The liver takes two of these
ammonia molecules along with
CO2 and sticks them together
to make a substance called
UREA
Kidneys’ Job
It is the kidneys’ job to deal with this urea
Excrete it with water as Urine
Urinary System
kidney anatomy
Blood flows to the kidneys from
the heart
Artery off of aorta to
kidneys
Breaks up into
capillaries inside of
kidney
Blood returns to the body from
the renal vein
Venules in kidney collect
into renal vein
Kidney
Nephron
Inside the kidney there are 1,000s
of nephrons - these do the job of
filtering the blood
Inside the nephron
Each nephron has a capillary that
associates with it
This capillary enters the capsule
of the nephron
The capillary forms a “knot” =
glomerulus
The “knot” creates lots of
pressure
This pressure forces urea
and water into the nephron
tube = Urine
•The capillary leaves the capsule
and becomes a venule
•The venule collects with other
venules into the renal vein
•The renal vein leaves the kidney
and travels back to the heart
Urine
Urine travels through the
kidney nephron tubule
The tubule connects to the
ureter
Ureter drains into the bladder
Sphincter muscle at the base
of the bladder
Urine leaves the bladder
through the urethra
Kidney Animations
Click on the links below to watch kidney
animations:
http://highered.mcgrawhill.com/sites/9834092339/student_view0/c
hapter50/basic_renal_processes.html
http://www.kidneypatientguide.org.uk/HKW
anim.php