THE URINARY SYSTEM

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THE URINARY SYSTEM
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functions of the urinary system

• removes toxins, salts nitrogenous wastes
• helps maintain normal concentrations of water
  electrolytes in body fluids
• regulates the pH volume of body fluids
• helps control RBC production blood pressure
• kidney cells convert vitamin D to its active form

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parts of the urinary system their functions

• 2 kidneys filter blood to remove wastes
• 2 ureters tubes carrying urine from the kidneys
  to the bladder
• urinary bladder a
• smooth muscle bag
• that stores urine
• urethra tube leading
• from the bladder
• out of the body

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kidneys

• about the size of a bar of soap
• consist of an inner renal medulla an outer
  renal cortex
• lie on either side of the vertebral column
  extend from T12 to L3
• lie outside of the parietal peritoneum against
  the deep muscles of the back
• enclosed in a fatty capsule that helps hold them
  in place

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kidneys

• The right kidney is slightly lower than the left
  because it is crowded by the liver
• secrete erythropoietin, a hormone that stimulates
  RBC production
• help maintain blood pressure
• by secreting an enzyme, renin
• 1 kidney contains about
• 1 million nephrons

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waste removal

• when blood enters the kidney through the renal
  artery, proteins blood cells remain in the
  blood
• water ions are
• removed by a filter
• but may be
• reabsorbed later
• waste material that is
• not reabsorbed is
• excreted in the urine

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Summary of excretory functions

• 1) filtration water, etc. is forced from the
  blood through a capillary wall into a kidney
  tubule, forming filtrate
• 2) reabsorption water valuable solutes are
  reclaimed from the filtrate and returned to the
  blood
• 3) secretion specific substances such as drugs
  are transported into the filtrate
• 4) excretion urine is passed to the bladder
  until it is expelled

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nephron the functional unit of the kidney

• nephron the filtering device of the kidney
• blood entering a nephron contains the waste
  products of body cells
• blood immediately flows into a bed of capillaries
  called the glomerulus

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nephron the functional unit of the kidney

• water, glucose, vitamins, amino acids, protein
  waste products (urea), salts, ions pass into
  the Bowmans capsule
• this liquid passes into a U-shaped tubule (the
  loop of Henle) where most of the ions, water,
  glucose, amino acids are reabsorbed into the
  bloodstream
• the liquid that remains in the tubules urine
  urea, water (95), N wastes, salt

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nephron the functional unit of the kidney

• blood leaves the kidneys
• through the renal vein
• the water ions move into out of the
  capillaries via diffusion active transport to
  maintain homeostasis (sodium levels, pH, water
  content)
• you produce about 2 liters of urine / day

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trace the path of urinary waste

• cell? blood? nephron of the kidney ? ureter?
  urinary bladder? urethra

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urination

• urination micturition expelling urine from
  the bladder
• involves muscles in wall of the bladder,
  abdominal wall, pelvic floor
• muscles in the thoracic wall, diaphragm,
  external urethral sphincter must relax

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urination

• the micturition reflex center is located in the
  spinal cord
• micturition reflex
• stretch receptors are stimulated in the bladder
  wall
• the micturition reflex center sends
  parasympathetic motor impulses to the bladder wall

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urination

• as the bladder fills, its internal pressure
  increases, forcing the internal urethral
  sphincter open
• a 2nd reflex the external urethral sphincter
  unless voluntary control maintains its
  contraction
• nerve centers in the cerebral cortex brain stem
  aid control of urination

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THE URINARY SYSTEM HOMEOSTASIS?

• the major waste products of cells are nitrogenous
  wastes (such as ammonia urea), which come from
  the breakdown of proteins
• both ammonia urea are toxic, so they must be
  removed from the blood regularly
• the kidneys regulate the sodium levels in blood
  by removing reabsorbing sodium ions

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THE URINARY SYSTEM HOMEOSTASIS?

• the kidneys regulate pH of blood by filtering out
  H ions allowing bicarbonate to be reabsorbed
  back into the blood
• Water concentration in blood is regulated by the
  brain via ADH
• diabetics have excess glucose in their blood it
  is filtered out

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renal failure kidney failure

• the inability of kidneys to filter blood
• Many causes
• Injury
• Illness (high BP, diabetes, infection)
• Prolonged use of pain relievers, alcohol, drugs

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disorders of the urinary system

• glucosuria glucose in urine
• gout elevated concentrations of uric acid in
  the plasma, causing uric acid crystals to be
  deposited in joints
• kidney stones form in the collecting ducts,
  cause pain when they pass into the ureters, made
  of uric acid, calcium oxalate, calcium phosphate,
  or magnesium phosphate

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disorders of the urinary system

• cystitis inflammation of the bladder
• ureteritis inflammation of the ureter
• oliguria scanty urine output
• polyuria excess urine output
• pyuria pus in urine
• nephrectomy surgical removal of a kidney

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disorders of the urinary system

• dialysis hemodialysis using an artificial
  kidney to separate small molecules in blood from
  larger ones - for a person with kidney failure

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Abnormal Urinary ConstituentsSubstance Condit
ion Cause

• Glucose Glycosuria Too much sugar
  in diet, diabetes
• Proteins Proteinuria pregnancy, physical
  exertion, high BP
• Pus Pyuria urinary tract infection
• RBCs Hematuria bleeding in the tract
• Bile pigment Bilirubinuria liver disease