HOW DOES A KIDNEY
FILTER BLOOD?
Done By: Rowell Tan (1O2)
THE KIDNEYS ARE…
 a pair of vital organs that perform many functions to
keep the blood clean and chemically balanced
 organs which remove waste from the normal
breakdown of active tissues and food
HOW DOES IT WORK???
 In kidneys, there are many
tiny units called nephrons.
 In the nephron…..
1. a glomerulus (capillary)
intertwining with
a urine-collecting tube
called a tubule.
2. The glomerulus acts as a filtering unit, and keeps
normal proteins and cells in the bloodstream, allowing
extra fluid and wastes to pass through to the urinary
system via a chemical exchange.
THE PROCESS
1. The tubules receive a combination of waste
materials and chemicals the body can still use.
2. The kidneys measure out chemicals like sodium,
phosphorus, and potassium and release them back
to the blood back to the body.
3. The kidneys regulate the body's level of these
substances which is necessary for life.
erythropoietin
renin
homeostasis
calcitriol
NEPHRON
 comprises of…
a) Glomerulus- filtration occurs
here!
b) Bowman's capsule- surrounds
glomerulus, collects filtrate
c) Proximal convoluted tubule
d) Loop of Henle
e) Distal convoluted tubule
f) Collecting duct- adjusts
volume & concentration of
urine
FILTRATION
 takes place in the glomerulus
 about 20% of the plasma gets filtered into the
nephron
FILTRATION
 Filtration is driven by the hydrostatic pressure of the
blood, and causes water and small molecules to be
filtered, while blood cells and large molecules like
proteins do not pass through the filter.
large
 Reabsorption and secretion require a
amount of energy which results in the kidney being
one of the most metabolically active organs in the
body.
BLOOD CLEANING
Processes
 Glomerular Filtration
 Tubular Reabsorption
 Tubular Secretion
Fact:
The kidney is
as important
as the heart.
GLOMERULAR FILTRATION
 Blood enters the kidney via the renal artery,
eventually forming many afferent arterioles. The
diameter of the afferent(incoming)arteriole is
greater than the diameter of the efferent arteriole(by
which the blood leaves). The pressure of the blood
inside the glomerulus is increased due to the
difference in diameter of the incoming and out -going
arterioles. Most of the water, salts, glucose and urea
are filtered whereas blood and plasma are not.
TUBULAR REABSORPTION
 99% of the glomerular filtrate is reabsorbed into the
blood via Osmosis, Diffusion and Active Transport.
 Firstly, it is reabsorbed into the proximal convoluted
tube, which absorb sodium ions to facilitate passage
through its membrane. Water is also reabsorbed by
osmosis.
 Next, they go into the Loop of Henle.
The different permeability properties of the two
limbs of the Loop of Henle, together with their
counterflow arrangement to generate a high
solute concentrations in the tissue fluid.
TUBULAR REABSORPTION
 Lastly, the blood will go to the distal convoluted tube
which reacts to anti-diuretic hormone. The more
there is, the more water will be reabsorbed.
TUBULAR SECRETION
 Substances are added to the fluid in this process,
such as potassium ions, hydrogen ions, ammonium
ions, creatinine, urea and some hormones and drugs,
which helps to keep blood pH at its normal level.
FINALLY….
 Urine formed via the three processes trickles into the
kidney pelvis. At this final stage only approx. 1% of
the originally filtered volume.
MORE INFO!
1. The kidneys have a higher blood flow than even the
brain, liver or heart.
2.The kidneys reabsorb and redistribute 99% of the
blood volume and only 0.1% of the blood filtered
becomes urine.
3.Kidney stones are an accumulation of mineral salts
and mostly combined with calcium which can lodge
anywhere along the course of the urinary tract.
4.Refined carbohydrates and sugar help the body
make kidney stones.
MORE INFO!
5. Sugar will stimulate the pancreas to release insulin.
This causes extra calcium to be excreted in the urine,
which creates, kidney stones.
6. An excess of milk or antacids may cause kidney
stones.
7. Each kidney is about 4 ½ inches long.
8. Each kidney weighs approximately 4 to 6 ounces.
9. The kidneys of a newborn baby are about 3X larger
in proportion to body weight as in the adult.
10. The volume of urine excreted daily varies from
1000 to 2000 ml (averaging 1500 ml). 1000 ml
(millileters) = 1 liter.
KIDNEY STONES!
 Drink more water.
 SEE THE DOCTOR!!
Your doctor may ask you to eat
more of some foods and to cut
back on other foods.
calcium
struvite
uric acid
cystine
THANK YOU SO MUCH!!
 Thanks for
looking at my
ACE.
*Pls remember to
mark it!
BIBLIOGRAPHY
 National Kidney and Urologic Diseases Information
Clearinghouse (NKUDIC)
http://kidney.niddk.nih.gov/kudiseases/pubs/yourkidneys/# inf
o
 Kid’s Health
http://kidshealth.org/kid/htbw/kidneys.html #
 HowStuffWorks?
http://science.howstuf fworks.com/environmental/life/human biology/kidney2.htm
 Filtration: The Kidneys
http://www.rpi.edu/dept/chem-eng/BiotechEnviron/Projects00/memfilt/kidneys.htm
BIBLIOGRAPHY
 Blood Cleaning by the Kidneys
http://www.ivy rose.co.uk/HumanBody/Urinary/Urinary_System_Kidneys_Actio
ns.php
 Fun Facts about Kidneys
http://www.drstandley.com/facts_kidneys.shtml