Urinary System

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Urinary System

• Anatomy and Physiology

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Functions of Urinary System

• Regulate the volume, composition, and pH of body
  fluids
• Remove or add substances to the blood
• Form urine

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Organs of the Urinary System

• Two kidneys
• Two ureters
• Bladder
• urethra

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Kidneys

• Reddish brown bean shaped on the posterior wall
  of the abdomen
• Inner region is the medulla outer region is the
  cortex
• Nephrons are the working units

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Ureters

• Tubes which drain the urine from the kidneys to
  the bladder
• Peristalsis moves the urine from the kidney to
  the bladder
• Can become inflamed in a urinary tract infection

ureter
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Bladder

• Hollow muscular organ
• Stores urine
• At the neck is the internal urethral sphincter
  muscle
• Can become inflamed in a urinary tract infection

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Urethra

• Tube that takes the urine from the bladder to the
  outside
• Can become inflamed in a urinary tract infection
• Delivers both urine and semen in males

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Urethra
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Regulating substances and forming urine

• The nephrons of the kidneys filter the blood
• This means they remove substances from the blood
• The removed substances are called filtrate
• If these substances stay in the tubes of the
  urinary structures, they will be part of the
  urine and excreted

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Regulating substances and forming urine

• The nephrons filter out some things we still need
• Part of the nephrons job, then, is to put these
  wanted substances back into the blood
• Putting them back into the blood is called
  reabsorption
• This happens as the filtrate moves through the
  nephron structure

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Nephron
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Nephron
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One million nephrons in each kidney
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Glomerulus
Glomerulus This is the filter.
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Reabsorption

• Different substances are reabsorbed back into the
  bloodstream at specific locations along the
  nephron tubules.
• Some areas of the wall are more permeable to
  certain substances

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Secretion

• Sometimes, to adjust the blood and the filtrate
  for homeostasis, certain substances are added
  back into the tubule
• This is called secretion

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Dilute versus Concentrated

• Dilute urine contains lots of water, and not many
  dissolved particles. Light color
• Concentrated urine contains very little water,
  and lots of dissolved particles. Dark in color.
  Dehydrated!
• Kidneys make adjustments to the blood, which
  results in the composition of urine