urinary system

• 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
• • Organs of the Urinary System: Kidneys, Ureters, Bladder, Urethra
• urinary system

  A) Hepatic Vein (cut)

  B) inferior vena cava

  C) adrenal gland

  D) aorta

  E) iliac crest

  F) rectum

  G) uterus

  H) urinary bladder

  I) urethra

  J) renal artery

  K) renal hilum

  L) renal vein

  M) kidney

  N) ureter

  
• Location and structure:

  • The kidneys are situated against the dorsal body wall in a retroperitoneal position (behind the parietal peritoneum)
  • The kidneys are situated at the level of the T12 to L3 vertebrae
  • The right kidney is slightly lower than the left (because of position of the liver)
• Kidney structure

  • An adult kidney is about 12 cm (5 in) long and 6 cm (2.5 in) wide
  • Renal hilum
  • A medial indentation where several structures enter or exit the kidney (ureters, renal blood vessels, and nerves)
  • An adrenal gland sits atop each kidney
• Kidney structure

  • Three protective layers enclose the kidney
  • Fibrous capsule encloses each kidney
  • Perirenal fat capsule surrounds the kidney and cushions against blows
  • Renal fascia is the most superficial layer that anchors the kidney and adrenal gland to surrounding structures
• Three regions revealed in a longitudinal section

  1. Renal cortex—outer region

  2. Renal medulla—deeper 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, funnelshaped 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
• kidney anatomy

  A) Renal cortex

  B) renal column

  C) major calyx

  D) minor calyx

  E) renal pyramid

  
• Blood supply

  • 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 divides into segmental arteries → interlobar arteries → arcuate arteries → cortical radiate arteries
• Kidneys

  Venous blood flow

  • Cortical radiate veins → arcuate veins → interlobar veins → renal vein
  • There are no segmental veins
  • Renal vein returns blood to the inferior vena cava
• Internal Kidney Anatomy

  A) Renal Cortex

  B) Renal Column

  C) Minor Calyx

  D) Renal Pyramid

  E) Fibrous Capsule

  F) Cortical Radiate Vien

  G) Cortical Radiate Artery

  H) Arcuate Vein

  I) Arcuate Artery

  J) Interlobar Vein

  K) Interlobar Artery

  L) Segmental Arteries

  M) Renal Vein

  N) Renal Artery

  O) Renal Pelvis

  P) Major Calyx

  Q) Ureter

  
• Nephrons

  Structural and functional units of the kidneys

  Each kidney contains over a million nephrons

  Each nephron consists of two main structure: Renal corpuscle and Renal tubule
• Nephrons

  Renal corpuscle consists of:

  • Glomerulus, a knot of capillaries made of podocytes
  • Podocytes make up the inner (visceral) layer of the glomerular capsule
  • Foot processes cling to the glomerulus
  • Filtration slits create a porous membrane—ideal for filtration 2. Glomerular (Bowman’s) capsule is a cup-shaped structure that surrounds the glomerulus  First part of the renal tubule
• Internal Anatomy of Kidney

  A) Aorta

  B) Renal Artery

  C) Segmental Artery

  D) Interlobar Artery

  E) Arcuate Artery

  F) Cortical Radiate Artery

  G) Afferent Arteriole

  H) Glomerulus (capilliaries)

  I) Efferent Arteriole

  J) Peritubular Capillaries

  K) Cortical Radiate Vein

  L) Arcuate Vein

  M) Interlobar Veim

  N) Renal Vein

  O) Inferior Vena Cava

  
• Structure of the Nephron

  A) Renal Cortex

  B) Renal Medulla

  C) Renal Pelvis

  D) Renal Cortex

  E) Ureter

  F) Renal Medulla

  G) Cortical Nephron

  H) Fibrous Capsule

  I) Collecting Duct

  J) Proximal Convoluted Tubule

  K) Glomerulus

  L) Distal Convoluted Tubule

  M) Nephron Loop

  N) Juxtamedullary Nephron

  
• Cortical nephrons

  • Located entirely in the cortex
  • Include most nephrons
  • Juxtamedullary nephrons
  • Found at the cortex-medulla junction
  • Nephron loop dips deep into the medulla
  • Collecting ducts collect urine from both types of nephrons, through the renal pyramids, to the calyces, and then to the renal pelvis
• Structure of the Nephron

  A) PCT

  B) Glomerular Capsular Space

  C) Glomerular Capillary Covered by Podocytes

  D) Efferent Arteriole

  E) Afferent Arteriole

  
• Two capillary beds associated with each nephron

  1. Glomerulus
  2. Peritubular capillary bed
• Structure of the Nephron

  A) Filtration Slits

  B) Podocyte Cell Body

  C) Foot Processes

  
• Glomerulus

  • Fed and drained by arterioles

  Afferent arteriole—arises from a cortical radiate artery and feeds the glomerulus

  Efferent arteriole—receives blood that has passed through the glomerulus

  • Specialized for filtration
  • High pressure forces fluid and solutes out of blood and into the glomerular capsule
• Structure of the Nephron

  A) Peritubular Capillaries

  B) Proximal Convoluted Tubule (PCT)

  C) Glomerular Capillaries

  D) Glomerular (Bowman's) Capsule

  E) Efferent Arteriole

  F) Afferent Arteriole

  G) Arcuate Artery

  H) Cortical Radiate Artery

  I) Arcuate Vein

  J) Cortical Radiate Vein

  K) Collecting Duct

  L) Nephron Loop

  M) Cells of the Juxtaglomerular Apparatus

  N) Distal Convoluted Tubule (DCT)

  
• Nephrons

  • Peritubular capillary beds
  • Arise from the efferent arteriole of the glomerulus
  • Low-pressure, porous capillaries
  • Adapted for absorption instead of filtration
  • Cling close to the renal tubule to receive solutes and water from tubule cells
  • Drain into the interlobar veins
• Urine formation is the result of three processes 1. Glomerular filtration 2. Tubular reabsorption 3. Tubular secretion
• The kidney depicted schematically as a single large, uncoiled nephron.

  A) Cortical Radiate Artery

  B) Afferent Arteriole

  C) Glomerular Capillaries

  D) Efferent Arteriole

  E) Glomerular Capsule

  F) Peritubular Capillary

  G) To Cortical Radiate Vein

  H) Urine

  I) Rest of Renal Tubule Containing Filtrate

  
• Three major renal processes:

  1. Glomerular filtration: Water and solutes smaller than proteins are forced through the capillary walls and pores of the glomerular capsule into the renal tubule.
  2. Tubular reabsorption: Water, glucose, amino acids, and needed ions are transported out of the filtrate into the tubule cells and then enter the capillary blood.
  3. Tubular secretion: H 1 , K1 , creatinine, and drugs are removed from the peritubular blood and secreted by the tubule cells into the filtrate.
• Glomerular filtration The glomerulus is a filter  Filtration is a nonselective passive process  Water and solutes smaller than proteins are forced through glomerular capillary walls  Proteins and blood cells are normally too large to pass through the filtration membrane  Once in the capsule, fluid is called filtrate  Filtrate leaves via the renal tubule
• Basic structure of the female urinary bladder and urethra

  A) Urinary Bladder

  B) Ureter

  C) Ureteral Orifice

  D) External Urethral Sphincter

  E) Urogenital Diaphragm

  F) Trigone

  G) Internal Urethral Orifice

  H) Internal Urethral Sphincter

  I) Urethra

  
• Glomerular filtration

  The glomerulus is a filter

  • Filtration is a nonselective passive process
  • Water and solutes smaller than proteins are forced through glomerular capillary walls
  • Proteins and blood cells are normally too large to pass through the filtration membrane
  • Once in the capsule, fluid is called filtrate
  • Filtrate leaves via the renal tubule