Osmoregulation and Temperature Regulation in Animals, Slides of Animal Anatomy and Physiology

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Homeostasis

Dr. G. Nugroho Susanto, M. Sc. Department of Biology Faculty of Mathematics and Natural Sciences University of Lampung

Homeostasis

 Homeostasis refers to maintaining internal stability within an organism and returning to a particular stable state after a fluctuation.  Homeostasis refers to maintaining internal stability within an organism and returning to a particular stable state after a fluctuation.

Homeostasis

 Systems within an organism function in an integrated way to maintain a constant internal environment around a setpoint.  Small deviations in pH, temperature, osmotic pressure, glucose levels, & oxygen levels activate physiological mechanisms to return that variable to its setpoint.  Negative feedback  Systems within an organism function in an integrated way to maintain a constant internal environment around a setpoint.  Small deviations in pH, temperature, osmotic pressure, glucose levels, & oxygen levels activate physiological mechanisms to return that variable to its setpoint.  Negative feedback

Osmoregulation & Excretion

 Osmoregulation regulates solute concentrations and balances the gain and loss of water.  Excretion gets rid of metabolic wastes.  Osmoregulation regulates solute concentrations and balances the gain and loss of water.  Excretion gets rid of metabolic wastes.

Osmosis

 Osmosis is the movement of water across a selectively permeable membrane.  If two solutions that are separated by a membrane differ in their osmolarity, water will cross the membrane to bring the osmolarity into balance (equal solute concentrations on both sides).  Osmosis is the movement of water across a selectively permeable membrane.  If two solutions that are separated by a membrane differ in their osmolarity, water will cross the membrane to bring the osmolarity into balance (equal solute concentrations on both sides).

Osmotic Challenges

 Osmoconformers , which are only marine animals, are isoosmotic with their surroundings and do not regulate their osmolarity.  Osmoregulators expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment.  Osmoconformers , which are only marine animals, are isoosmotic with their surroundings and do not regulate their osmolarity.  Osmoregulators expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment.

Osmotic Regulation

 Conditions along the coasts and in estuaries are often more variable than the open ocean.  Animals must be able to handle large, often abrupt changes in salinity.  Euryhaline animals can survive a wide range of salinity changes by using osmotic regulation.  Hyperosmotic regulator (body fluids saltier than water)  Shore crab.  Conditions along the coasts and in estuaries are often more variable than the open ocean.  Animals must be able to handle large, often abrupt changes in salinity.  Euryhaline animals can survive a wide range of salinity changes by using osmotic regulation.  Hyperosmotic regulator (body fluids saltier than water)  Shore crab.

Osmotic Regulation

 The problem of dilution is solved by pumping out the excess water as dilute urine.  The problem of salt loss is compensated for by salt secreting cells in the gills the actively remove ions from the water and move them into the blood.  Requires energy.  The problem of dilution is solved by pumping out the excess water as dilute urine.  The problem of salt loss is compensated for by salt secreting cells in the gills the actively remove ions from the water and move them into the blood.  Requires energy.

Osmotic Regulation - Freshwater

 Freshwater fishes have skin covered with scales and mucous to keep excess water out.  Water that enters the body is pumped out by the kidney as very dilute urine.  Salt absorbing cells in the gills transport salt ions into the blood.  Freshwater fishes have skin covered with scales and mucous to keep excess water out.  Water that enters the body is pumped out by the kidney as very dilute urine.  Salt absorbing cells in the gills transport salt ions into the blood.

Osmotic Regulation - Freshwater

 Invertebrates and amphibians also solve these problems in a similar way.  Amphibians actively absorb salt from the water through their skin.  Invertebrates and amphibians also solve these problems in a similar way.  Amphibians actively absorb salt from the water through their skin.

Osmotic Regulation – Marine

 Sharks and rays retain urea (a metabolic waste usually excreted in the urine) in their tissues and blood.  This makes osmolarity of the shark’s blood equal to that of seawater, so water balance is not a problem.  Sharks and rays retain urea (a metabolic waste usually excreted in the urine) in their tissues and blood.  This makes osmolarity of the shark’s blood equal to that of seawater, so water balance is not a problem.

Osmotic Regulation – Terrestrial

 Terrestrial animals lose water by evaporation from respiratory and body surfaces, excretion (urine), and elimination (feces).  Water is replaced by drinking water, water in food, and retaining metabolic water.  Terrestrial animals lose water by evaporation from respiratory and body surfaces, excretion (urine), and elimination (feces).  Water is replaced by drinking water, water in food, and retaining metabolic water.

Osmotic Regulation – Terrestrial

 Terrestrial animals must convert ammonia to uric acid.  Semi-solid urine – little water loss.  In birds & reptiles, the wastes of developing embryos are stored as harmless solid crystals.  Terrestrial animals must convert ammonia to uric acid.  Semi-solid urine – little water loss.  In birds & reptiles, the wastes of developing embryos are stored as harmless solid crystals.

Osmotic Regulation – Terrestrial

 Marine birds and turtles have a salt gland capable of excreting highly concentrated salt solution.  Marine birds and turtles have a salt gland capable of excreting highly concentrated salt solution.