The Urinary System

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The Urinary System

• Waste Removal System

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The Urinary System

• The major function of the urinary system is to
  remove metabolic waste from blood and direct them
  out of the blood.
• The major organs of the urinary system are the
  kidneys, ureters, urinary bladder and urethera.

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Urinary Organs
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Urinary Organs

• The kidneys are located high on the posterior
  abdominal wall.
• The right kidney lies just below the left.

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Urinary Organs

• The structure of the kidney is divided into the
• Renal capsule, tough outer shell of the kidney
• Renal cortex, outer portion of the kidney
• Renal medulla, inner portion of the kidney
• Renal pyramids, cone shaped masses of tissue in
  renal medulla

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Urinary Organs

• Kidney structure (cont.)
• Ureter, the tube leading away from the kidneys
• Renal pelvis, superior end of the ureter which is
  expanded to form a funnel shape
• Major calyces, division of renal pelvis
• Minor calyces, division of major calyces

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Urinary Organs

• The function of the kidneys is to remove
  metabolic waste from the blood.
• They also regulate RBC formation with the hormone
  erythropoietin.
• They regulate blood pressure with the hormone
  renin.
• They regulate blood volume with the hormone ADH.
• They also control blood composition and blood pH.

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Urinary Organs

• The functional unit of the kidney is called the
  nephron.
• A nephron is made up of a renal corpuscle and a
  renal tubule

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Urinary Organs

• A renal corpuscle is a glomerulus within a
  Bowmans capsule.
• The glomerulus is the filtration unit.
• The Bowmans capsule sac of tissue surrounding
  the glomerulus.

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Urinary Organs

• The renal tubule is tube made up of the loop of
  Henle.
• The loop of Henle is a tube in which water and
  solute flow to regulate blood levels.

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Urinary Organs

• There are three major steps in the process of
  urine formation
• 1.) Glomerular filtration
• 2.) Tubular reabsorption
• 3.) Tubular secretion

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Urinary Organs

• Glomerular filtration is when water and dissolved
  particles are filtered out of the blood into the
  Bowmans capsules.
• This filtration is due to the force of
  hydrostatic pressure.
• Hydrostatic pressure is the pressure felt by the
  fluid because of the weight of the fluid above
  it.
• The magnitude of the hydrostatic pressure is
  determined by the bodies blood pressure and blood
  volume.

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Urinary Organs

• Tubular reabsorption is the process by which
  substances are transported from the glomerular
  filtrate to blood in the peritubular caps.
• Most of this reabsorption takes place by active
  transport.
• The reabsorbed substances include glucose, amino
  acids, water, ions and other minor substances.

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Urinary Organs

• Tubular secretion is the process by which
  substances are transported from the blood in the
  peritubular caps.
• This process maintains ion concentrations in the
  blood.

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Urinary Organs

• The hormone anti-diuretic hormone (ADH) promotes
  the reabsorption of water.
• This negative feedback loop is responsible for
  preventing dehydration.

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Urinary Organs

• The wastes that make up urine are
• Urea, which is formed during amino acid
  metabolism
• Uric acid, which is formed during nucleotide
  metabolism

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Urinary Organs

• Urine is composed of 95 water and 5 other
  components including
• Urea
• Uric acid
• Trace amino acids
• Electrolytes

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Urinary Organs

• The ureters are small tubes that carry urine from
  each kidney to the urinary bladder for storage.
• They are 25 39cm in length.
• They are made up of three layers
• 1.) Mucosa layer, inner
• 2.) Muscularis layer, middle layer of smooth
  muscle
• 3.) Serosa layer, outer

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Urinary Organs

• The urinary bladder is located in the pelvic
  cavity.
• It is a hollow, distensible and muscular organ.
• It is made up of three layers of smooth muscle.
• It functions in the storage of urine.

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Urinary Organs

• The urethra is a tube that carries urine from the
  urinary bladder to the outside.
• Length depends on sex, females have a urethra
  approximately 4cm long where as males on average
  have a 20cm long urethra.
• Micturition is the process of expelling urine
  from the urinary bladder.

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Life Span Changes

• As a person ages the kidneys become grainy and
  scarred.
• Reabsorption can significantly decrease causing
  frequent urination.
• The elasticity of the urinary organs decreases
  also causing frequent urination.

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Common Urinary Disorders

• Kidney stones are concentrations of calcium salts
  and uric acid.
• They form small stones which can block the
  ureters.
• If the ureters are blocked pressure can backup
  into the kidney causing swelling and severe pain.

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Common Urinary Disorders

• Proteinuria is excess levels of protein in the
  urine.
• Proteinuria was at one time considered a sure
  sign of kidney damage.
• It has since been discovered that somewhat high
  protein levels among healthy active young adults
  is normal.

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Common Urinary Disorders

• Urinary tract infections (UTI) are an
  inflammatory process occurring in the kidney,
  ureter, bladder, or adjacent structures that
  occurs when microorganisms (usually Escherichia
  coli) enter through the urethra.
• The infection causes inflammation and in turn
  discomfort.
• They are usually quickly and easily treated by
  the use of a broad spectrum antibiotic.