Urinary System
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Transcript of Urinary System
Urinary SystemUrinary SystemCOCEPTS
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
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
Kidney Kidney LocationLocation
Lateral to vertebral column high on body wall, under floating ribs in retro-peritoneal position
Surface Anatomy
Size of bar of soap Bean shapedHilus – indentation
Three layers Renal fascia – fibrous tunic Adipose capsule – protects kidney Renal capsule – anchors kidney to body wall,
continuous with peritoneum
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.
Urine collection: Ducts within each renal
papilla release urine
into minor calyx
major calyx
renal pelvis
ureter
Renal CirculationRenal Circulation
Segmental arteries
Interlobar arteries
Arcuate arteries
Interlobular arteries
Afferent arterioles
Glomerulus
Efferent arterioles
Peritubular capillaries
Segmental veins
Interlobar veins
Arcuate veins
Interlobular veins
Venules
Renal Artery Renal Vein
Functional unit: Nephron
Renal corpuscle:» Glomerulus
» Bowman’s capsule
Tubular passageways with associated blood vessels:» PCT
» LOH
» DCT
» CD
(>mio/kidney)
Filtration: Passage across Three Barriers
Capillary endotheliumFenestrated
What gets through?
Basement membrane
Glomerular epithelium (= visceral layer of Bowman’s capsule)slit pores between pedicels of podocyte
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
Juxtaglomerular Apparatus
Macula densa
+Juxtaglomerular cells
(smooth muscle fibers from afferent arteriole)
= Juxtaglomerular Apparatus
= Endocrine system structure (renin and EPO)
Urine Transport, Storage, and Urine Transport, Storage, and EliminationElimination
Trace drop of urine from kidneys to outside world
Lining of these parts?
Nephroptosis (= floating kidneys)
Nephrolithiasis
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.
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
Histology1. transitional epithelium2. detrusor muscle – smooth muscle
Urethra
External urethral sphincters – voluntary at pelvic floor
Female - short – from base of bladder to vestibule
Male1. prostatic urethra – from base of bladder through
prostate gland2. membranous urethra – between prostate gland &
base of penis3. penile (spongy) urethra – traverses penis to orifice
UTIs (esp. E.coli)
Male versus Female
Kidneys may sustain 90% loss of nephrons and still not show apparent symptoms!!!
2-4 % of population only have 1 kidney!
POINTS TO NOTED