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Urinary System

Terms in this set (20)

Functions of the Kidneys
-Maintain the chemical consistency of blood
-FIlters many liters of fluid from blood
- Send toxins, metabolic wastes, and excess water out of body (produces Urea, uric acid and creatinine)
Relationship of Kidneys and Ribs
Located retroperitoneally - Lateral (T12-L3)
Hilum - on concave surface - vessels and nerves enter and exit
Fibrous capsule surrounds the kidney
- Perirenal fat - external to renal capsule
- Renal fascia - external to perirenal fat
Renal arteries
Branch into segmental arteries - branch into interlobar arteries - arcuate arters branch from interlobar arteries
Nerve supply of kidneys
Renal plexus - network of autonomic fibers
- offshoot of the celiac plexus
-Supplied by sympathetic fibers from lowest thoracic splanchnic nerve and first lumbar splanchnis nerve
Kidney functions
Filtration - filtrate of blood leaves kidney capillaries
Reabsorption - most nutrients, water, and essential ions reclaimed
Secretion - active process of removing undesirable molecules
Nephron
Renal corpuscle - first part of nephron
Glomerulus and glomerular capsule
- Glomerulus - tuft of capillaries - fenestrated
- Glomerular capsule - parietal and visceral layer
Filtration membrane
Filter that lies between blood in the glomerulus and capsular space - 3 layers - endothelium of capillary, slits b/w foot processes, basement membrane
Basement membrane and slit diaphragm
Hold back most proteins
allow through water, ions, glucose, amino acids and urea
Renal Tubule
Filtrate proceeds to renal tubules from glomerulus
-Proximal convoluted tubule
-Nephron loop - descending, thin and thick
- Distal convoluted tubule
- Collecting ducts
Classes of Nephron
Cortical nephrons - 85%
Juxtamedullary - 15% - contribute to kidneys ability to concentrate urine
Blood Vessels Associated with Nephrons
Closely associate with 2 capillary beds
-Glomeruli
- Peritubular capillaries in cortical nephrons or vasa recta
Glomeruli
Produce filtrate that becomes urine
Fed and drained by arterioles - afferent and efferent
Generate 1 L of fluid every 8 minutes
- 99% of filtrate is resorbed by tubules
Peritubuar capillaries
Areise from the efferent arterioles
are adapted for absorption
- low pressure, porous capillaries
- all molecules secreted by nephrons into urine are from peritubular capillaries
Vasa recta
Continue from efferent arterioles of juxtamedullary nephrons
are thin walled looping vessels - descend into medulla
are part of the kidneys urine concentrating mechanism
Juxraglomerular Apparatus
-Functions in regulating blood pressure
-An area of specialed contact b/w terminal end and afferent arteriold
- Initiates renin-agiotensin mechanism
- Regulated blood flow within the glomerulus
Ureters
Carry urine from the kidneys to the urinary bladder
Oblique entry into bladder prevents backflow of urine
Urinary bladder
A collapsible muscualr sac - stores and expels urine
Full bladder - spherical - expands abdominal cavity
Empty bladder - lies entirely within pelvis
Urethra
Transitional epithelium - at proximal end
Stratified and pseudostratified columnar - mid urethra
Stratified squamous epithelium - at distal end
Urethra
femals - 3-4cm
Males - 20cm (Prostatic, membranous, spongy)
Disorders
Urinary tract infections - more common in females
Renal calculi - kidney stones
Bladder cancer - more common in men 3%
Kidney cancer
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