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 12 Outline (Ch. 44)

• I. Homeostasis
• II. Water Balance
• III. Animal Excretory Systems
• Human Urinary System
• Bladder
• Kidneys
• Water Control
• Preparation for next lecture

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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
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
(a) Osmoregulation in a saltwater 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 metanephridia
Collect body waste
Remaining waste excreted
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Vertebrate Urinary System
Most urinary waste nitrogenous from digesting
protein
Desert kangaroo rat excretes very concentrated
urine
Blood filtered by kidneys
Fish excrete ammonia
Land vertebrates convert to urea add to urine
To reduce water-loss, desert animals (reptiles,
snakes, birds) excrete uric acid
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Which excretory system produces the most
concentrated excretion product?

1. protonephridia
2. malpighian tubules
3. metanephridia
4. kidneys

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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 When you SHOULD go
The infamous candiru When NOT TO go
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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
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Human Urinary System - Kidneys
Reabsorption
In proximal tubule, most water and nutrients are
reabsorbed into blood.
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Human Urinary System - Kidneys

• Loop of Henle
• increasing osmolarity from cortex to the medulla
• due to active transport of Na, Cl at
  ascending loop
• reabsorption of water from descending loop and
  collecting duct

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Human Urinary System - Kidneys
Secretion
In distal tubule, additional wastes actively
secreted into the tubule from the blood
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Human Urinary System - Kidneys
Concentration
At collecting duct, additional water leaves, thus
urine more concentrated than blood.
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Human Urinary System - Kidneys
Two-solute model NaCl and Urea are moved into
the kidney medulla The filtrate in the nephron
passes into this area three times
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If a drug blocked Na/Cl- cotransporters, what
effect would this have on urine volume?

1. Increase volume, water would be retained
2. Decrease volume, water would be retained
3. Decrease volume, water would be excreted
4. Increase volume, water would be excreted

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Water Balance
Body detects dehydration. Signal from
hypothalamus to posterior pituitary.
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What effect would blocking ADH have?

1. Lots of dilute urine produced
2. Lots of concentrated urine produced
3. Minimal dilute urine produced
4. Minimal concentrated urine produced

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Water Balance
Urine Waste and remaining water from nephron

• 95 water / 5 solutes (ions, urea)

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Things To Do After Lecture 12

• Reading and Preparation
• Re-read todays lecture, highlight all vocabulary
  you do not understand, and look up terms.
• Ch. 44 Self-Quiz 1, 3, 4, 6(correct answers in
  back of book)
• Read chapter 44, focus on material covered in
  lecture (terms, concepts, and figures!)
• Skim next lecture.

• HOMEWORK (NOT COLLECTED but things to think
  about for studying)
• Compare and contrast the four different types of
  excretory systems.
• Diagram the nephron, labeling regions and
  describing uptake/excretion at each region.
• Explain the parts of the human urinary system.
• Discuss the role of ADH location of secretion
  and effect.