urinary system

• urinary system is the major excretory system of the bod
• Excretion- Nearly 21% of the blood pumped out of the heart

  each minute is routed to the kidneys.
• Kidneys dispose of waste products in urine:

  § Nitrogenous wastes

  § Toxins

  § Drugs

  § Excess ions
• Kidneys’ regulatory functions include:

  § Production of renin to maintain blood pressure

  § Production of erythropoietin to stimulate red blood cell production

  § Conversion of vitamin D to its active form
• the maintenance of Glomerular Filtration Rate (GFR) is due to the process of autoregulation
• Kidneys dispose of waste products in urine

  § Nitrogenous wastes

  § Toxins

  § Drugs

  § Excess ions
• Kidneys’ regulatory functions include:

  § Production of renin to maintain blood pressure

  § Production of erythropoietin to stimulate red blood cell production

  § Conversion of vitamin D to its active form
• The kidneys are situated at the level of the T12 to L3 vertebrae
• The kidneys are situated against the dorsal body wall in a

  retroperitoneal position (behind the parietal peritoneum)
• Renal capsule- the outer layer of connective tissue that surrounds each kidney
• Perirenal fat capsule- surrounds the outside of the capsule which cushion and protects the kidney
• Renal fascia is the most superficial layer that anchors the kidney and adrenal gland to surrounding structures
• Renal hilum

  A medial indentation where several structures enter or exit the

  kidney (ureters, renal blood vessels, and nerves)
• Renal sinus- adipose and connective tissue-filled cavity of the kidney
• Renal cortex —outer region
• Renal medulla —deeper region
• Renal (medullary) pyramids —triangular regions of tissue in the

  medulla
• Renal columns —extensions of cortexlike material that separate

  the pyramids
• Renal pelvis— medial region that is a flat, funnel-shaped tube
• Calyces form cup-shaped “drains” that enclose the renal pyramids
• Calyces collect urine and send it to the renal pelvis, on to the

  ureter, and to the urinary bladder for storage
• One-quarter of the total blood supply of the body passes through

  the kidneys each minute
• Renal artery provides each kidney with arterial blood supply
• Renal artery

  segmental arteries

  → interlobar arteries

  → arcuate arteries

  → cortical radiate arteries
• Cortical radiate veins → arcuate veins → interlobar veins →

  renal vein
• Renal vein returns blood to the inferior vena cava
• nephrons- structural and functional unit of the kidney
• Each kidney contains over a million nephrons
• Each nephron consists of two main structures

  § Renal corpuscle

  § Renal tubule
• renal corpuscle- filters the blood
• renal corpuscle- consist of glomerulus and glomerular(bowman's) capsule
• Glomerulus, a knot of capillaries made of podocytes
• Podocytes make up the inner (visceral) layer of the

  glomerular capsule
• podocytes-Foot processes cling to the glomerulus; Filtration slits ideal for filtration
• Glomerular (Bowman’s) capsule is a cup-shaped

  structure that surrounds the glomerulus
• Glomerular (Bowman’s) capsule first part of the renal tubule
• renal tubule- Extends from glomerular capsule and ends when it

  empties into the collecting duct
• the subdivisions of the renal tubule are:

  § Proximal convoluted tubule (PCT)

  § Nephron loop (loop of Henle)

  § Distal convoluted tubule (DCT)

  collecting duct
• filtrate- fluid filtered from the glomerulus
• Cortical nephrons

  § Located entirely in the cortex

  § Include most nephrons