URINARY SYSTEM
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Transcript URINARY SYSTEM
URINARY SYSTEM
Urology is the branch of medicine
that deals with the urinary system
and the male reproductive tract
Function
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
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
Cortex
Medulla
Renal pyramids
Renal columns
Renal pelvis
Calyces
Blood Supply
Renal artery
Segmental artery
Interlobar artery
Arccuate artery
Interlobular arteries
Afferent artery
Glomerular capillaries
Efferent arteries
Peritubular/vasa recta
Interlobular veins
Arcuate veins
Interlobar veins
Segmental veins
Renal vein
NEPHRON
FUNCTIONAL UNIT OF THE
KIDNEY
Nephron
Renal corpuscle
glomerulus
Bowman’s capsule
Renal tubule
proximal convoluted
tubule
Loop of Henle
distal convoluted tubule
Types of Nephrons
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
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
Glomerular endothelium - fenestrated
Podocytes “foot cells” - intertwining
processes cling to basement membrane of
glomerulus
Renal Physiology
Filtration
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
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
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
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
Enhance urinary output
Common diuretics include: Caffeine, Alchol
Usually inhibit sodium ion reabsorption
Urine Elimination
Ureters
Bladder
Transitional epithelium
Trigone
Detrusor muscle
Can hold 500-1,000 ml
Urethra
internal & external sphincters
Micturition = Urination = Voiding
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