 Three major areas
of ridding the
body of waste (not
including
digestive wastes)
 Exhalation
 CO2
 Sweating
 Toxic metals
 Elimination
 Urine
 Designed to help keep body in homeostasis by
removing and restoring selected amounts of solutes
and water from blood.
6
Functions
of Urinary
System
 Kidneys filter large amts of fluid from bloodstream to
eliminate
 Nitrogenous wastes
 Drugs, medications
and toxins
 excess water
 Kidneys maintain blood volume by regulating a
balance between
 salts and water
 Amt of urine produced
 Concentration of ions
 Sodium
 Chloride
 Potassium
 Calcium
 Phosphate ions
 Kidneys control
balance of hydrogen
ions
 Kidneys
produce an
enzyme RENIN
which helps
adjust filtration
pressure.
 Kidneys produce erythropoietin, a hormone that
stimulates red blood cell production.
 Kidneys convert vitamin D to calciferol, which
enhances the uptake and absorption of calcium and
other
 Kidney – paired organs
located under diaphragm;
creates urine
 Ureter – duct from each
kidney to bladder
 Bladder – hollow muscular
organ collect urine for
excretion
 Urethra – small tube leading
from bladder to outside of
body. Transports urine via
peristalsis
A lesson in Nephrology
 Renal Capsule –
outmost covering of
kidney
 Cortex – outer area
extending from
capsule to pyramids
 Medulla - inner area
containing pyramids
 Renal Pyramid –
triangular structures
inside medulla
 Papillae – tips of
pyramids
 Nephron – the
functional unit of the
kidney
 Medulla is composed
of millions of these
microscopic
collecting tubules.
 It is here that blood is
passed through
capillaries and
filtered of toxins and
excess water & ions
1. Blood vessels
2. Bowman’s capsule
 From the renal artery,
 Inside this double-
blood enters afferent
arterioles leading to
Bowman’s Capsule
layered globe is the
glomerulus, a tiny
network of capillaries.
 This is the site where
water and solute
filtration happens
 The filtered fluid flows
into the renal tubule
3. Renal Tubule
4. Loop of Henle
 Nutrients (salts,
 Tissue around the
vitamins, etc.) are
moved out of the
tubule through active
transport.
 Water follows the
nutrients by osmosis.
 Urine and other
solutes continue on
Loop of Henle is salty,
from active transport
and diffusion of
sodium chloride.
 The salty conditions
allow water to diffuse
out of the loop.
5. Distal tubule
6. Collecting Duct
 Active transport is
 More water leaves the
used to move more
nutrients out of the
concentrated urine.
 Some ions, drugs, and
toxins are actively
pumped into the
tubule
tube by osmosis, since
the tube is
surrounded by salty
tissue.
 Some urea leaves by
diffusion, and may be
cycled through the
system.
 Urine is a fluid that is composed of about 95% water. It
also contains
 Urea (converted from ammonia)
 Uric acid
 Amino acids (few)
 Electrolytes
 The average person makes between .6 and 2.5 liters a
day!
 Each collecting tubule leads ultimately through the
calyces and to a ureter.
 The ureter channels urine to the bladder.
 The urine will then empty from the bladder via the
urethra.