An albatross can drink salt water

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An albatross can drink salt water how can they
do this without getting sick?!
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Thought Questions
If you eat a lot of salt, what happens to your
urine?
If you do not drink enough water, what happens to
your urine?
If you drink excess water, what happens to your
urine?
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Lecture 15 Outline (Ch. 44)

• I. Homeostasis
• II. Water Balance
• III. Animal Excretory Systems
• Human Urinary System
• Bladder
• Kidneys
• Water Control
• Lecture Concepts

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Urinary System
aka Excretory System
Maintains homeostasis of body fluids via water
balance
Osmolarity, (solute concentration of solution),
determines movement of water across selectively
permeable membranes
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Water Balance
Excrete salt ions from gills
Uptake water, ions in food
Osmotic water gain from gills, body surface
Uptake salt ions by gills
Gain water, salt ions from food
Osmotic water loss from gills, body surface
Excrete salt ions little water in scanty urine
from kidneys
Gain water, salt ions from seawater
Excretion of large amounts of dilute urine
(a) Osmoregulation in a saltwater fish
(b) Osmoregulation in a freshwater fish
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Water Balance
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Animal Excretory Systems
Simplest system
Flatworms use protonephridia
Wastes stored in excretory pore, drawn out by
water environment
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Animal Excretory Systems
Insects use malpighian tubules
Actively pump waste, extra salt and water into
tubules
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Animal Excretory Systems
Worms use nephridia
Collect body waste
Remaining waste excreted
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Vertebrate Urinary System
Most urinary waste nitrogenous from digesting
protein
Blood filtered by kidneys
Fish excrete ammonia
Land vertebrates convert to urea add to urine
To reduce water-loss, desert animals (reptiles,
snakes, birds, and the Kangaroo Rat) excrete uric
acid
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Human Urinary System

• 1) Kidneys
• Blood w wastes brought by renal artery to
  kidney
• Filtered blood carried away by renal vein
• 2) Ureters

• Transport urine away
• from kidney

• 3) Bladder
• Stores urine
• Max capacity 1 L

4) Urethra

• Transport urine from
• bladder to outside body

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Human Urinary System
Micturition (urination)
Gotta pee?
Stretch stimulates contractions
Sphincters control release
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Human Urinary System - Bladder
Ureter
Bladder
Urogenital diaphragm
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Human Urinary System - Bladder
Stretch (200 ml)
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Urinary Disasters
Tycho Brahe GO when you need to
The infamous candiru DONT GO when in water?
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Human Urinary System - Kidneys
Urine forms in the nephron, 1 million/kidney
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Human Urinary System - Kidneys
Each nephron is a filter Glomerulus- network of
capillaries Bowmans capsule- cup around
glomerulus Collecting duct- carries fluid from
nephron
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Human Urinary System - Kidneys
Filtration
Water, nutrients, and wastes - filtered
from glomerulus into Bowmans capsule
1. FILTRATION
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Human Urinary System - Kidneys
Reabsorption
In proximal tubule, most water and nutrients are
reabsorbed into blood.
2. TUBULAR REABSORPTION
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Human Urinary System - Kidneys
Secretion
In distal tubule, additional wastes actively
secreted into the tubule from the blood
3. TUBULAR SECRETION
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Human Urinary System - Kidneys
Concentration
At collecting duct, additional water leaves, thus
urine more concentrated than blood.
4. CONCENTRATION
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Human Urinary System - Kidneys
Fluid travels a loop in the nephron
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Water Balance
Body detects dehydration. Signal from
hypothalamus to posterior pituitary.
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Water Balance
Urine Waste and remaining water from nephron

• 95 water / 5 solutes (ions, urea)

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Water Balance
Homeostatic Functions of Kidney
(1) Eliminate waste (2) Balance salts (3)
Filter toxins
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Lecture 15 concepts

• Why do water-dwelling animals (fish) have a
  challenge that land animals do not?
• Describe animal systems besides the kidney for
  filtering out waste.
• Know the relative locations of kidneys,
  ureters, bladder, urethra.
• What is a nephron? How many are in a kidney?
• Describe the process of filtration in a nephron
  using correct terminology. How is ADH involved?
• List any new terminology and definitions.