Transcript Gut Tube and Digestion

Kidneys and Urination
Kidney
Location and
blood supply
Internal anatomy
Microscopic
anatomy and
function
Ureter
Bladder and
urethra
Location of kidney
Retroperotoneal at midabdomen
T12-L3
NAV enters at hilus
Renal aa. off aorta
Renal vv to IVC
Nerves all autonomics-renal plexus
Ureter--exits at hilus
“Ad”renal gland superior
to kidney--unrelated in
function
Own blood supply
Endocrine gland
Internal anatomy of kidney
NAV branch out from hilus
Collecting ducts unite and urine
leaves through ureter at hilus
Cortex is outer/superficial
tissue
Light, granular
Functioning nephrons here
Medulla is inner/deep tissue
Darker
Pyramid-cone shape
Collecting tubules unite into ducts
into ureter
Internal anatomy of kidney--details
Lobe of kidney is medullary
pyramid plus cortex around it
Cortex contains urineconcentrating nephrons
Medullary pyramids
Tubules receive concentrated
urine from cortex
Appear striated because
contains parallel converging
urine-collecting tubules
Flow of urine
Pg 679
Collecting tubes of medullary
pyramid minor calyx major
calyx renal pelvis ureter
Microscopic anatomy and function
Nephron or urineconcentrating unit
is in outer cortex-millions
Capillaries
surround
glomerulus (ball)
and filtrate passes
into duct
Counter-current
exchange in ducts
(Loop of Henle)
concentrates
urine)
More details at “How Stuff Works”
http://science.howstuffworks.com/kidney.htm/printable
Ureter--from kidney to bladder
LAYERS OF URETER
External connective tissue-adventitia
Middle muscular layer-muscularis
Smooth Muscle
Inner Longitudinal
Outer Circular
External longitudinal (on distal
third)
Peristaltic action moves urine to
bladder (and stones!!)
Inner lining of transitional
(stretchy) epithelium--Mucosa
Bladder
Muscular (what kind?)
sac that fills with urine
from ureters
Anterior against pubis in
pelvis (more with pelvis)
Filled with urine
expands into abdomen
Blood supply from
internal iliac arteries
Innervation is
autonomic from
hypogastric plexus
Layers of bladder wall
Outer connective tissue-adventitia
Middle muscular layer
(“detrusal” or expulsor)-inner and outer
longitudinal fibers around
middle circular fibers
Inner transitional
(stretchy) epithelium
Bladder can expand 15
times its empty volume to
hold 500 ml of urine
Trigone is triangle
between ureters/urethra-persistent sight of
infection
Urethra
Drains urine from bladder to outside
Female = short tube
Males = long tube
Prostatic, Membranous, Spongy (penile) portions
Also carries sperm
Internal Urethral Sphincter
Between bladder + urethra
Thickening of detrusor (smooth muscle)
External Urethral Sphincter
Within urogenital diaphragm
Skeletal muscle = voluntary control urination
External Urethral Orifice
Males = end of penile urethra
Females = anterior to vaginal opening, posterior to clitoris
(more later with pelvis)
Micturition = Urination
Emptying bladder
Stretch receptors in bladder respond when bladder
full
Parasympathetic signals detrusor muscle to
contract and internal urinary sphincter to open (also
inhibits sympathetic pathways that would prevent
urination)
Other brain receptors can inhibit urination by
relaxing detrusor, and keep external urinary
sphincter closed
Voluntary contraction of abdominal wall muscles
increases abdominal pressure
Voluntary relaxation of external urethral sphincter
For nice review of kidneys and urination
http://webanatomy.net/anatomy/urinary_notes.htm
See pg 692,
M&M
Ascent of the kidney in development
Kidneys from intermediate
mesoderm
Pronephric kidney in fetus shows
segmental body plan
Fish with dorsal renal tissue lateral
to vertebral column for most of
length
In human, metanephric kidney
migrates from inferior to superior
Variation in kidney shape not
uncommon (horseshoe kidney
Ureter also from intermediate
mesoderm