3'8 HUMAN URINARY SYSTEM

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3.8 HUMAN URINARY SYSTEM?

• Removes wastes to maintain homeostasis
• Converts nitrogenous wastes into urea to be
  excreted
• human urinary system
• kidney
• ureter
• urinary bladder
• urethra
• blood vessels

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• A. kidneys
• The major organ for processing waste products of
  metabolism
• The entire blood volume is filtered here every 5
  minutes to remove the nitrogen wastes 180 L/day
• contain 1 million nephrons each
• regulate the water content of the blood and,
  therefore, blood volume.

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• A closer look at how the kidney worksbased on
• the function of one nephron..times a million
• a. One end of the nephron has a cuplike part
  that fits over a cluster of capillaries (called
  glomerular capsule) that carry blood from the
  body. This is where the blood filtering process
  starts.

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Cortex
Nephron
renal artery
renal vein
ureter
To the bladder
medulla
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• b. The tubule is a long tube that filtrate from
  the blood travels through.
• long coils for increased
• surface area for
• reabsorption of materials into
• the circulatory system.
• c. The other end of the nephron opens into a
  duct which collects urine to go to the bladder

Bowmans Capsule
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• d. 3 functions of the nephron
• - filtration - fluid part of blood
• is forced through the nephron (filtrate)
• plasma,salts, ions, glucose, amino acids
• - reabsorption as filtrate passes thru
• the nephron cells absorbs water, salt,
• glucose, aas (gets 85) back into
• cappilaries
• secretion of materials back into the
• filtrate before entering the collecting tubule
• and urine sent to ureter and bladder. Final
• step in trying to maintain homeostasis

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• B. Ureter
• tubes that carries urine away from the
• kidneys
• C. Urinary bladder
• a holding tank for
• urine
• D. Urethra
• Males a tube leading from the bladder for urine
  to go out (also carries sperm in males more
  about this later)

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male
female
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• Other important information..
• Hormones regulate the excretion of certain
  substances by the nephron
• For example
• - antidiuretic hormone (ADH) is secreted
  
• into the blood by the pituitary gland
  to
• regulate water volume in blood
• if a person is dehydrated.
• 1. water volume in blood drops
• 2. blood pressure drops
• .

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• 3. Collecting ducts become more
• permeable to water and so it is
  
• reabsorbed
• This is an example of feedback regulation
• substances inhibit their own formation.
• Helps maintain balance and stability
• in this casewater.

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• summary of kidney functions
• removal of nitrogenous wastes from blood as urea
• regulation of water-salt balance
• regulation of blood pressure
• conservation of blood glucose
• excretion of excess salt, within limits