A. The general function of the
urinary system is to maintain
homeostasis by balancing the
volume and chemical make up of
the blood (thus Kidney has long
term control of blood pressure)
and elimination of wastes [toxins,
nitrogenous wastes, and excess
ions]
1. Kidneys
2. Ureters
3.
Urinary
Bladder
4.
Urethra
Long paired muscular tubes that drain each
kidney and propel urine by peristalsis into
the urinary bladder.
Stretchy storage unit for urine, contracts to
empty
Urine exits body thru urethra, a narrow tube
about 1.5 inches in females and 8 inches in
males
a. Collection and
storage area for urine.
b. Collapsed when
empty.
c. Longitudinal &
circular smooth
muscle
d. Transitional epithelial
tissue
e. Internal sphincter and
external sphincter
1. Located in lower back
T12-L3, just under 12th
rib
2. 7 lobes
3. Three layers of
supportive tissue (renal
capsule, adipose
capsule, fibrous
capsule)
4. Parts of K are cortex,
medulla w/ Calyces
(pyramids), renal pelvis,
renal sinus and hilus
Need to know
(1) Juxtamedullary
(2) Cortical
Nephron
c. Bowman’s capsule,
Efferent Arteriole connects
to Peritular Capillaries
d. Filtration membrane in glomerulus
(1) Pressure within Glomerulus produces
filtrate (ions, glucose, water, amino acids)
(2) 2 highly permeable membranes due to
fenestrations, podacytes & thin basement
membranes in glomerulus
• Layer 1 is gomerular
fenestrations of glomerular
capillaries
• Layer 2 is fusion of
glomerlular & renal capsule
basement membranes
• Layer 3, the podacyte
is visceral layer of renal
capsule, has slit diaphragms
(filter) between podacytes.
Filtrate enters Bowman’s
capsular space
e. Cell types in nephron (how kidney works)
(1) PCT cubodial epithelium w/ microvilli.
Absorption from PCT to peritubular capill.
(2) Loop of henle, thin segment is simple
squamous for osmosis of H20 out and into
blood; water follows Na+ from left side loop.
(3) Collecting ducts are cuboidal/columnar w/
aquaporins inserted when ADH for [urine]
(4) DCT lumen is ridged. M/B is enfolded, for
secretion movement from blood to DCT(pH).
(5) JG cells (JGA) BP sensors in arterioles,
smooth muscle cells control diameter of As
(6) Macula densa (JGA), chemoreceptors in DCT
promote dilation or constriction of afferent
Arteriole, as Renin is released eA is
constricted, as are other BV of body = rise in
BP.
(7) Peritubular
capillaries arise
from efferent
arteriole and
surround PCT and
other tubules, but
are called vasa
recta when long
loops of henle dip
down into medulla
in juxtamedullary
nephrons. (F) is
removal of H2O
which follows Na+ =
[urine]
f. Histology of kidney
Tubules, PCT & DCT (no microvilli)
Shows collecting duct
Cortex of Kidney
Pyramids and Renal Pelvis
End of story: the Liquid that
remains in tubules , leading
to Collecting ducts = excess
water and ions, waste &
toxins is sterile
Whooda guessed?