ppt

1. Urinary System
CONCEPTS
Identify and describe
the components of the
urinary system and
their function
Describe the
(histological)
organization of the
nephron
Identify the blood vessels that supply blood to the nephrons
Describe the blood flow through and around the nephron

2. Functions of Urinary System
(Kidneys):
● Regulate fluid balance (fluid
volume) of the body
● Excrete organic waste
products and conserve
nutrients, etc
Stabilize pH
Regulate ion concentrations in
the blood

3. Kidney
Location
Lateral to vertebral
column high on body
wall, under floating
ribs
in retro-peritoneal
position

4. Surface
Anatomy
Size of bar of soap
Bean shaped
Hilus – indentation
Three layers
● Renal fascia – fibrous tunic
● Adipose capsule – protects kidney
● Renal capsule – anchors kidney to body
wall, continuous with peritoneum

5. Sectional Anatomy
Cortex: outer layer, light
reddish brow, granular
appearance (due to many
capillaries)
Medulla: darker striped
appearance (due to
tubules) Subdivided into
distinct renal pyramids,
terminating with a papilla.
Separated by renal
columns from the cortex.

6. Urine collection:
Ducts within each renal
papilla release urine
into minor calyx
major calyx
renal pelvis
ureter

7. Renal Circulation
Segmental arteries
Interlobar arteries
Arcuate arteries
Interlobular arteries
Afferent arterioles
Glomerulus
Efferent arterioles
Peritubular
capillaries
Renal
Artery
Renal Vein
Segmental veins
Interlobar veins
Arcuate veins
Interlobular veins
Venules

8. Functional unit:
h
:
Nephron
(>mio/kidney)
● Renal corpuscle:
» Glomerulus
» Bowman’s capsule
● Tubular passageways wit
associated blood vessels
» PCT
» LOH
» DCT
» CD

9. Filtration: Passage across Three
Barriers
Capillary endothelium
Fenestrated
What gets through?
Basement membrane
Glomerular epithelium (= visceral
layer of Bowman’s capsule)
slit pores between pedicels of podocyte

10. Two Types of Nephrons
● Cortical nephrons
(85%) shorter, mostly
in cortex of kidney,
produce "standard"
urine
● Juxtamedullary
nephrons (15%), "juxta-
next-to" the medulla -
responsive to ADH, can
concentrate urine

11. Juxtaglomerular Apparatus
Macula densa
+
Juxtaglomerular
cells (smooth muscle
fibers from afferent
arteriole)
= Juxtaglomerular
Apparatus
= Endocrine
system
structure (renin
and EPO)

12. Urine Transport, Storage,
and Elimination
●Trace drop of urine
from kidneys to
outside world
●Lining of these parts?
●Nephroptosis (=
floating kidneys)
●Nephrolithiasis

13. Transitional Epithelium
empty bladder
full bladder
from renal pelvis to
neck of urethra.

14. Nephrolithiasis
Occurs when
urine
becomes too
concentrated
and
substances
crystalize.
Symptoms
arise when
stones begin
to move down
ureter causing
intense pain. Kidney stones may form in the pelvis or
calyces of the kidney or in the ureter.

15. Anatomy of Urinary
Bladder
● Retroperitoneal, behind pubis
● Internal folds - rugae - permit expansion (max.
holding capacity ~ 1L)
● Trigone - area at base delineated by openings of
ureters and urethra - without muscle
● Internal urethral sphincter - involuntary sphincter
Histology
1. transitional epithelium
2. detrusor muscle – smooth muscle

16. Urethra
sphincters – voluntary at
External urethral
pelvic floor
Female - short – from base of bladder to
vestibule
Male
1. prostatic urethra – from base of bladder
through prostate gland
2. membranous urethra – between prostate
gland & base of penis
3. penile (spongy) urethra – traverses penis to
orifice

17. UTIs (esp. E.coli)
Male versus Female

18. ●Kidneys may
sustain 90%
loss of
nephrons and
still not show
apparent
symptoms!!!
●2-4 % of
population only
have 1 kidney!
POINTS TO NOTED