Download Kidney Function final

In our experiment….
What happened to the glucose and the starch?
How do you know?
The membrane is analogous to the kidney tubule.
Kidney Function • Regulate the composition of your
About 1200mL of blood
is filtered thru the kidney
each minute!!!!
•
•
•
blood
– keep the concentrations of various ions
and other important substances
constant
– keep the volume of water in your body
constant
– remove wastes from your body (urea,
ammonia, drugs, toxic substances)
– keep the acid/base concentration of
your blood constant
Help regulate your blood pressure
Stimulate the making of red blood cells
Maintain your body's calcium levels
Kidney Functions
Urea from amino acid breakdown, Creatinine from creatine phosphate
breakdown during muscle contraction, uric acid from recycling RNA..
Looking a little closer….
In a normal human
adult, each kidney is
about 12 cm long and
about 5 cm thick,
weighing 150 grams
The Nephron
Aldosterone
Regulated pump
Na+ reclaimed
K+ lost
Anti-diuretic (ADH)
Hormone controls passive
water re- absorption by
altering permeability
FILTRATION
About 20% of
the fluid
brought to the
kidney
leaves the
blood in the
Glomerulus. It
must be
reabsorbed to
prevent
dehydration.
(180L/day)
At this point
approximately
1200mL of urine
is produced/day
and 90% of the
water and
nutrients that left
the blood have
been
reabsorbed.
Rids body of : urea and ammonia from amino acid breakdown, Creatinine from
creatine phosphate breakdown during muscle contraction, uric acid from recycling RNA,
and excess water.
http://home.comcast.net/~john.kimball1/BiologyPages/K/Kidney.html
Lipid-soluble substances can easily pass
through the phospholipid membrane.
Toxins and DDT are problems.
Polar or charged particles require protein
channels and move with the concentration
gradient
Most waste products undergo only partial
reabsorption, so that large amounts of the
substance remain in the tubule and are
thus removed from the body in the urine.
Useful plasma components, such as water,
nutrients, and inorganic ions, are
reabsorbed completely or nearly
completely.
http://www.chemistry.wustl.edu/~edudev/LabTutorials/Dialysis/Kidneys.html
When large quantities of aldosterone are present, sodium reabsorption into the
blood is enhanced through active transport. Water concentration in the tubule is
then low and will leave the tubule through channels.
Water exits the tubule and enters the blood through these hydrophilic (polar)
channels by passive diffusion down the concentration gradient . The permeability
of the membrane to water is subject to being altered in response to the hormone
vasopresin, also known as antidiuretic hormone (ADH). Low ADH= More excetion
The Mechanism of Dialysis
• Blood flows by one side of a semipermeable membrane,
and a dialysis solution or fluid flows by the opposite side.
Most smaller solutes can easily pass through the
membrane.
The Unhealthy Kidney
• In the diseased kidney, dialysis is a type of
renal replacement therapy, which is used to
provide an artificial means for lost kidney
function.
• Dialysis can be for acute kidney failure or
permanent kidney failure.
• The semi-permeable membrane used in dialysis
to perform the function of the nephron is the
same as the membrane you are using in your
experiment and is made of cellulose.
The Mechanics
The concentrations of undesired solutes (among them potassium,
urea, and phosphorus, but including a large number of
compounds about which little is known) are high in the blood, but
low or absent in the dialysis solution.
• www.biotopics.co.uk/human2/andial.html
• The dialysis solution is continually replenished to maintain the
concentration gradient for the removal of unwanted solutes.
The dialysis solution has levels of minerals like sodium and
chloride that are similar to their natural concentration in healthy
blood. For another solute, bicarbonate, dialysis solution level is
set at a slightly higher level than in healthy blood. This is to
encourage diffusion of bicarbonate from dialysate to the blood,
to neutralize the buildup of acidity acidosis that is often present
in these patients.
• http://www.blobs.org/science/diffusion/imgs/diffusion2.gif
Hemodialysis and peritoneal dialysis