Transcript 12.1 Kidneys and Waste Excretion

12.1 Kidneys and
Waste Excretion
Unit D – Human Systems
Learning Objectives Covered in this
Lesson
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Identify and describe roles of the principal
structures in the excretory system.
Describe the role of the kidney in excreting
wastes and expelling them into the
environment.
Identify major structures of the nephron.
Anatomy of Urinary System
 renal
artery carries oxygenated
blood to the kidney
 renal veins carry deoxygenated
blood from the kidney back
toward the heart.
 Waste
material filtered from the
blood by the kidney enters
ureters.
 Ureters are tubes that carry urine
from the kidney to the bladder.
urinary bladder holds urine until it fills to
the point that it stretches, opening a
sphincter muscle.
 Urine moves through sphincter into the
urethra,
 Urethra is a tube that carries urine from
the bladder to the exterior of the body.
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Role of Kidneys
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Removing waste materials from blood (urea
and uric acid)
Balance blood pH
Maintain water balance in blood
Eating too much protein?
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Modern human diet contains more protein
than necessary to maintain body tissue
cells.
The excess protein in our diet has its
Amino groups removed from its amino
acids (building blocks of proteins) in the
liver.
Deamination
 The
removal of amino groups
from amino acids producing
ammonia gas.
 Ammonia is toxic and must be
converted to a less toxic form,
Urea.
 Uric
acid, another nitrogen
containing waste product,
produced from the breakdown of
nucleic acids.
Balancing Blood pH
and release H+ and
HCO3- ions in order to keep blood
pH neutral.
 Secrete
Maintaining water balance
 Reabsorbs
and secretes water to
ensure your body has enough
water.
Nephron
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Small “functional units” of the kidney.
Approximately 1 million nephrons make up
one kidney.
Is a series of capillaries and tubes that
filter and clean blood.
Blood Supply to the Nephron
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Renal arteries branch off into afferent
arterioles that supply the nephrons with
blood.
Afferent arterioles branch into a smaller
knot of capillaries called the glomerulus.
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The blood leaves the nephron by way of
the efferent arterioles, which are carried to
the peritubular capillaries, that are wrapped
around the tubes of the nephron.
The peritubular capillaries connect to the
renal vein and take blood back to the heart.
Parts of the Nephron
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Glomerulus is surrounded by a funnel
called the Bowman’s capsule. This is where
wastes leave the blood stream and is
filtered.
Bowman’s capsule is attached to the
proximal tubule, which is where nutrients
are reabsorbed back into the bloodstream.
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The Loop of Henle connects the proximal
tubule to the next section of the nephron,
the distal tubule.
The distal tubule is the site of secretion of
waste products out of the blood, and
passes urine to the collecting ducts.
Many collecting ducts join together and
pass urine to the ureter.
Student Tasks for Lesson
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Label “Urinary Structures” diagram (Pg
379).
Label diagram of a Nephron, outlining the
major function of each part.
Complete #1-3 on page 380.
Complete #1-2 on page 386.