FOCUS ON THE KIDNEYS
• Filter wastes: Every day, kidneys process about 200
quarts of blood to filter out about 2 quarts of waste
products and extra water
• Regulate composition of electrolytes: The
kidneys measure out chemicals like sodium, phosphorus,
and potassium and release them back to the blood to
return to the body. In this way, the kidneys regulate the
body’s level of these substances.
• Maintain pH: filter H+ ions
• Secrete hormones:
-erythropoietin: stimulates the bone marrow to make red
-calcitriol: helps maintain calcium for bones
• Regulates blood pressure- by secreting the enzyme
How the kidneys work
2. Blood enters the
functional unit of
the kidney called
One kidney contains
about one million
• 3 Filtration of the
blood takes place
in the renal
is made of a
glomerulus and a
(The kidney filters 7.5 L
of water per hour and
in the same time
excretes .08 L of
The filtrate goes into the glomerular capsule and
includes water, amino acids, small proteins, vitamins,
glucose, and nitrogenous wastes. Cells and large
proteins are left in the arteriole.
4. Tubular reabsorption
The blood reabsorbs
needed substances from
the proximal convoluted
-small proteins, amino acids
-ions: Na, Cl, Ca, K
The glomeruli and
make up long and
tubes which, if
run for 50 miles.
are added to the
by way of
the ureter to
About 65g/hour of
NaCl is filetered,
while as little as
2 g/hour might
8. When the bladder
is full, the urine
passes out of the
body through the
1. Diabetic Kidney Disease
If glucose stays in the blood instead of
breaking down, it can act like a poison,
damaging the nephrons.
2. High Blood Pressure
-can damage the small blood vessels in
the kidneys so they can’t filter wastes.
3. Glomerular Diseases
-attack the tiny blood vessels,
glomeruli, within the kidney.
The first sign of a glomerular disease is
often too much protein in the urine.
Another common sign is blood in the urine.
Glomerular diseases can slowly destroy
4. Inherited and Congenital Kidney
Example: Polycystic kidney disease
(PKD), for example, is a genetic disorder
in which many cysts grow in the kidneys.
5. Trauma, such as a direct and forceful
blow to the kidneys, can lead to kidney
6. Ingestions of poisons.
What happens when kidneys fail
1. The body fills with extra water and waste
products (uremia). Hands or feet may swell.
A person will feel tired and weak because the
body needs clean blood to function properly.
2. Untreated uremia may lead to seizures or
coma and will ultimately result in death.
3. A person whose kidneys stop working
completely will need to undergo dialysis or
Preview to transplant