Transcript Powerpoint Presentation: Osmoregulation

OSMOREGULATION
CONTROL OF WATER BALANCE
© 2008 Paul Billiet ODWS
Fluid compartments and
exchange surfaces
EXTERNAL ENVIRONMENT
Exchange surfaces
Lungs
Intestines
Skin
Kidneys
Capillary
networks
BLOOD PLASMA (5%)
TISSUE FLUID (15%)
CYTOPLASM
(40%)
Plasma
membranes
NB Percentages shown = % Body Mass
© 2008 Paul Billiet ODWS
BODY FLUID BALANCE
INPUT ......……....… AND …......…….. OUTPUT
Drinking
COLON
BODY
LUNGS
Breath
SKIN
Sweat
KIDNEYS
Urine
•
A mammal cannot stop breathing because it would suffocate
•
A mammal cannot stop sweating because it would over heat
•
It can reduce water loss by the kidneys
•
It can add water to the body by drinking
© 2008 Paul Billiet ODWS
Dehydration
NEGATIVE
FEEDBACK
Dehydration
Blood
concentration
rises
© 2008 Paul Billiet ODWS
Thirst
reflex
Hypothalamus
Kidney
Osmoreceptors ADH
Concentration of
circulating blood
Drinking,
water
absorbed by
the colon
Less urine +
concentrated
urine
Blood
concentration
falls
Hyperhydration
NEGATIVE
FEEDBACK
Concentration of
circulating blood
Drinking
Blood
concentration
falls
Hypothalamus
Osmoreceptors
Kidney
More urine
+ diluted
urine
Blood
concentration
rises
Note: for a terrestrial animal this is a less likely situation and it is easy to lose
water
Dehydration is more likely so the control system has evolved to saving or
getting water
© 2008 Paul Billiet ODWS