Download URINARY SYSTEM

URINARY SYSTEM
Urology is the branch of medicine
that deals with the urinary system
and the male reproductive tract
Function
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Regulates volume, composition, and pH of
body fluids
Excretes metabolic wastes
Regulates blood pressure, RBC production,
activates calcitriol (vitamin D), and perform
gluconeogenesis
Major structures
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Located retroperitoneally on each side of the
vertebral column between T12-L3
Left kidney lower than right one
Connective tissue layers: renal capsule,
adipose capsule and renal fascia
Ureters
Bladder
Urethra
Internal Anatomy
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Cortex
Medulla
Renal pyramids
Renal columns
Renal pelvis
Calyces
Blood Supply
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Renal artery
Segmental artery
Interlobar artery
Arccuate artery
Interlobular arteries
Afferent artery
Glomerular capillaries
Efferent arteries
Peritubular/vasa recta
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Interlobular veins
Arcuate veins
Interlobar veins
Segmental veins
Renal vein
NEPHRON
FUNCTIONAL UNIT OF THE
KIDNEY
Nephron
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Renal corpuscle
glomerulus
 Bowman’s capsule
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Renal tubule
proximal convoluted
tubule
 Loop of Henle
 distal convoluted tubule
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Types of Nephrons
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Cortical nephron - contained almost entirely
in the cortex
Juxtamedullary nephron - go deep into the
renal medulla; able to produce more
concentrated urine
Glomerulus - Bowman’s capsule
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Glomerulus = network of capillaries arising
from an afferent arteriole that empties into an
efferent arteriole
Bowman’s capsule is a double layer structure
that receives the filtrate
Consists of parietal and visceral layer
Endothelial - Capsular
Membrane
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Glomerular endothelium - fenestrated
Podocytes “foot cells” - intertwining
processes cling to basement membrane of
glomerulus
Renal Physiology
Filtration
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Glomerular filtration forces plasma and
wastes products out of capillaries and into
the Bowman’s capsule
Net filtration pressure is primarily controlled
by glomerular blood hydrostatic pressure
Glomerular filtration rate is the amount of
filtrate formed in both kidneys per minute
125 ml/min (180 L/day!!!)
Reabsorption
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Tubular reabsorption is the movement of
water and other substances back into the
blood such as glucose, amino acids, sodium,
potassium, and other ions
99% of filtrate reabsorbed
Occurs mainly in proximal tubule
Both active and passive transport used
Transport maximum
Secretion
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Occurs mainly in the DCT
Acid-base balance and water adjustment
Tubular secretion involves the movement of
substances out of the blood into the tubules
K+ ions, urea, uric acid, drugs
Composition of Urine
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Color = clear to yellow; varies on
concentration and diet
Odor = develops ammonia odor
pH = 6.0 (varies 4.5-8.0)
Specific gravity = 1.001-1.035
Chemical composition = 95% water, 5%
solutes (urea, Na+, K+, PO4, SO4,creatinine,
uric acid)
Diuretics
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Enhance urinary output
Common diuretics include: Caffeine, Alchol
Usually inhibit sodium ion reabsorption
Urine Elimination
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Ureters
Bladder
 Transitional epithelium
 Trigone
 Detrusor muscle
 Can hold 500-1,000 ml
Urethra
 internal & external sphincters
Micturition = Urination = Voiding
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200 ml = urge to void
Voiding reflex relaxes internal sphincter
If suppressed, 200-300 ml more will
accumulate before reflex returns
Incontinence - inability to control voiding
Urinary retention - inability to void