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The Kidney
Majid Ali, M.D.
An air filter functions well if
it filters clean air. A water filter functions well
if it filters clean water. The kidney is a filter
and it stays healthy as long as it filters clean
blood. So kidney disease is a problem of the
circulating blood. The progression of genetic kidney
diseases—though these often do not begin with the
problems of the blood—also is determined by the
state of the circulatinmg blood. The circulating
blood has two guardian angels: the spirit (sun) and
the bowel (soil). That simply stated, is my Sun-Soil
Model of Kidney Health.
The human kidneys are bean-shaped
organs, each embedded in retroperitoneal perinephric
fat, lying on the side of the vertebral column and
aorta, below the adrenal glands and above the pelvic
brim. The kidneys receive their blood flow from the
aorta through renal arteries. Renal veins carry the
venous blood to the inferior vena cava. Each adult
kidney weighs about 150 grams and measures
approximately 10 cm. x 7.5 cm x 5.5 cm. Bisection of
the kidney shows an outer red-brown region called
the cortex and an inner pale-gray zone called the
medulla. The cortex ranges from 1.2 cm to 1.5 cm
thickness. The surface of the cortex is delineated
from the surrounding adipose tissue by a thin renal
capsule that can be readily striped from the kidney.
The medulla contains conical structures (pyramids)
with tips (papillae) that point to and drain into a
system of funnel-shaped collecting structures called
the calyceal system.
The functional unit of the kidney
is called the nephron. Each kidney contains
approximately one million of nephrons, each of which
contains a glomerulus, proximal convoluted tubule,
ascending and descending loops of Henle, and distal
renal tubules. The glomerulus is located in the
renal cortex and is composed of a spherical mass of
tangled capillaries (glomerular tuft) that are fed
by an arteriole called the efferent arteriole and
drain into another designated as the afferent
arteriole. During development, the glomerular tuft
invaginates an expanded extremity of the renal
tubules—presses into and takes on an envelop from
it—to form Bowman's capsule. Thus, the glomerulus
establishes a link between the vascular system
(represented by the glomerulus) and the excretory
system (renal tubule) of the body.
The convoluted tubules are also
located in the cortex while the ascending and
descending loops are situated in the medulla.
Kidney Function
The kidneys serve the Oxygen King
of the body in many ways. Following are their major
functions:
1. Maintenance of the
composition, osmolality, and the volume of
extracellular function;
2. Removal of useless
metabolites, such as creatinine, urea, and
uric acid;
3. Conservation of useful
metabolites, such as glucose, amino acids,
and proteins (total daily amino acid loss is
about 700 mg);
4. Production of
hormones, such as renin, erythropoietin, and
1,25 (OH)2 vitamin D; and
5. Detoxification and
clearance of certain xenobiotics, including
drugs.
Under physiologic conditions, the
kidneys maintain serum osmolality within narow
limits despite wide variations in the fluid intake.
During periods of low fluid intake and dehydration:
1. Increased osmolality
stimulates thirst, which increases fluid
intake;
2. Increased osmolality
affects osmoreceptors which stimulate the
release of antidiuretic hormone (ADH) which,
in turn, reduces water loss through the
kidneys; and
3. Reduced circulating
blood volume also increases secretion of ADH
through its effect on baroreceptors
(pressure-sensitive receptors).
States of water excess increase
plasma volume, renal blood flow, and glomerular
filtration rate (GFR). All those changes suppress
renin production—and, of necessity—the entire
renin-angiotensinogen-angiotensin system. That leads
to reduced production of aldosterone and decreased
reabsorption of sodium. The sodium loss is
accompanied by water loss that, in turn, corrects
the state of excess water.
Angiotensinogen—a glycoprotein of
more than 400 amino acids—is produced in the liver
and converted into angiotensin I in the kidney by
renin. Next, angiotensin I is converted into
angiotensin II —the most potent known
vasoconstrictor—under the enzymatic influence of
angiotensin-converting enzyme (ACE). This is the
rationale for the clinical use of ACE-inhibitor
drugs. It is noteworthy that ACE is also involved
with the growth dynamics and different alleles of
its gene have been associated with different levels
of performance among competition athletes.
Aldosterone is the main
mineralocorticoid in the body. It increases the
activity of Na+/K + ATPase
which, in turn, causes sodium retention and
increases potassium excretion. In addition to acting
on the kidney, aldosterone also exerts similar
effects on the salivary glands, sweat glands, and
gastrointestinal tract.
Anoxia (lack of oxygen) causes
both oxidosis and acidosis, and so provides an
essential link between the most important regulatory
pathways of the body—the oxygen homeostasis.
Cellular dehydration is both oxidizing and
acidifying, thus providing another interface between
the great homeostatic system of the body.
Kidney Health
Course Part One
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Kidney Health Course
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Urinary System
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Kidney Health Course
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Kidney Anatomy
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The Corrosive Urine State
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The
Oxygen Model of Kidney Failure
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Normalizing Blood Creatinine Level
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Reversing
Kidney Failure
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I Don't
want Dialysis
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Can I Get Off
Dialysis?
Kidney Health
Course Part Two
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No Healthy Heart Without Healthy Kidneys
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Oxygen' Three-Legged
Throne
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The Oxygen Model of Disease
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Oxygen
Kaleidoscope
Kidney Health
Course Part Three
I offer my video seminars and DVDs on entitled
Reversing Kidney Failure and "Saying NO to Dialysis
to further assist people who wish to take this
course. These materials can be obtained from
www.aliacademy.org
*
Prostate Anatomy
*
Prostate Health
*
What
Is PSA?
*
What is Prostatitis?
* The Pelvic Pain Syndrome
*
BPH
The dysox model of
renal insufficieny and
improved renal function with
oxystatic therapies.
Townsend Letter for Doctors
and
Patients.2005;267:101-108.
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