THERMOREGULATION AND OSMOREGULATION. Shelby Cotta and Maddy Davis Period 5, AP Biology 4/2/2015

Size: px

Start display at page:

Download "THERMOREGULATION AND OSMOREGULATION. Shelby Cotta and Maddy Davis Period 5, AP Biology 4/2/2015"

Clifford Morrison
5 years ago
Views:

1 THERMOREGULATION AND OSMOREGULATION Shelby Cotta and Maddy Davis Period 5, AP Biology 4/2/2015

Thermoregulation- 40.3 Thermoregulation is the process which allows an animal to maintain its internal temperature within a tolerable range.

2 Thermoregulation Thermoregulation is the process which allows an animal to maintain its internal temperature within a tolerable range. Biological and physical processes (like protein activity, chemical bonds, and membrane fluidity) are largely impacted by changes in body temperature, and therefore thermoregulation.

Ectothermic organisms gain most of their heat from external sources.

3 Endothermy and Ectothermy Both the internal metabolism and external environment provide heat sources for thermoregulation. Endothermic organisms are warmed mostly by heat that is generated by their own metabolism. Ectothermic organisms gain most of their heat from external sources. Endothermic animals can maintain stable body temperatures in many different environments, however, ectothermy is the most effective survival strategy due to the lower need for food, and higher tolerance for temperature fluctuation.

4 Organisms may not be solely ectothermic or endothermic, they may have qualities of both. For this reason, animals are classified as either ectothermic or endothermic based upon which mode they rely on the most. Examples of mainly endothermic Examples of mainly ectothermic birds lizards walrus snakes dogs turtles cats fish

5 Variation in Body Temperature Animal s body temperatures can either be variable or constant. An animal whose body temperature varies with it s environment is called a poikilotherm, and an animal with a relatively constant body temperature is called a homeotherm. There is no fixed relationship between the source of heat and the stability of body temperature, therefore, ectotherms are not always poikilothermic and endotherms are not always homeothermic.

Balancing Heat Loss and Heat Gain There are four physical processes by which heat is exchanged: radiation, evaporation, convection, and conduction.

6 Balancing Heat Loss and Heat Gain There are four physical processes by which heat is exchanged: radiation, evaporation, convection, and conduction. Insulation, circulatory adaptions (vasodilation and vasoconstriction) and countercurrent exchange alter the rate of heat exchange. Countercurrent exchange is the flow of adjacent fluids in the opposite direction that maximizes transfer rates of heat or solutes. (example: Blood vessels are adjacent so that warm blood can flow and heat up blood from the adjacent colder vessels.) Behavioral adaptations are also key to thermoregulation.

7 Acclimatization in Thermoregulation Many mammals and birds (endothermic animals) adjust the amount of body insulation in response to changes in environmental temperatures. Ectotherms undergo a variety of changes (enzyme production and saturated/unsaturated lipid proportions) at the cellular level to acclimatize to shifts in temperature.

Physiological Thermostats and Fever Mammals regulate their body temperature by complex negative feedback mechanisms that involve several organ systems, including the nervous, circulatory, and

8 Physiological Thermostats and Fever Mammals regulate their body temperature by complex negative feedback mechanisms that involve several organ systems, including the nervous, circulatory, and integumentary systems. The sensors for thermoregulation are concentrated in the brain region called the hypothalamus, and contain nerve cells that activate mechanisms promoting heat loss or gain.

9 Energy requirements are directly related to thermoregulation and also animal size, activity, and the environment. BMR (basal metabolic rate) is the minimum metabolic rate of endotherms that are completely at rest with an empty stomach. SMR (standard metabolic rate) is the metabolic rate of a fasting, nonstressed ectotherm. BMR is generally substantially higher than SMR.

10 Osmoregulation Osmoregulation is the regulation of solute concentrations and water balance in a cell or organism based on the movement of solutes between internal fluids and the external environment in order to maintain homeostasis

11 Osmosis and Osmolarity In order for an organism to reach homeostasis, they must balance water uptake and loss. Water enters and leaves the cell through osmosis. It occurs when two solutions separated by a selectively permeable membrane differ in osmolarity (osmotic pressure).

All osmoconformers are marine animals, and because their internal osmolarity is the same as their environment, there is no need to gain or

12 Osmotic Challenges There are two ways an organism can regulate water loss and gain, one is by being an osmoconformer, which would be isoosmotic with its surroundings. Then there are osmoregulators who who control their internal osmolarity independent of their environment. All osmoconformers are marine animals, and because their internal osmolarity is the same as their environment, there is no need to gain or lose water. However, osmoregulation enables animals to live in environments that are uninhabitable for osmoconformers, such as land or freshwater.

can always tolerate substantial changes in external osmolarity and

13 Osmotic Challenges cont... Whether an organism is an osmoconformer or osmoregulator, neither can always tolerate substantial changes in external osmolarity and are said to be stenohaline. If an organism is eurkhaline, it means that they can handle fluctuations in salinity.

Energetics of Osmoregulation When an animal maintains an osmolarity difference between its body and the external environment, there is an energy cost.

14 Energetics of Osmoregulation When an animal maintains an osmolarity difference between its body and the external environment, there is an energy cost. This is because when diffusion equalizes the concentrations in a system, osmoregulators must expand energy to maintain the osmotic gradients that cause water to move in and out. They use active transport to manipulate the solute concentrations in their body.

15 Energetics cont... The amount of energy expended depends on the difference between the animals osmolarity and its environment s, how easily it can move across the surface of the cell, and the how much work is required to to pump solutes across the membrane.

Transport Epthelia in Osmoregulation Osmotic regulation and metabolic waste disposal rely on one or more kinds of transport epitheliumone or more layers of specialized epithelial cells

16 Transport Epthelia in Osmoregulation Osmotic regulation and metabolic waste disposal rely on one or more kinds of transport epitheliumone or more layers of specialized epithelial cells that regulate solute movements. They move specific solutes in controlled amounts in specific directions and aer typically arranged into complex tubular networks with extensive surface areas.

1.) An ectotherm gains heat from energy generated within themselves, true or false? 2.) Which of these is an example of an ectothermic animal? A) bird B) polar bear C) lizard D) wolf 3.

17 1.) An ectotherm gains heat from energy generated within themselves, true or false? 2.) Which of these is an example of an ectothermic animal? A) bird B) polar bear C) lizard D) wolf 3.) The sensors for thermoregulation are concentrated in the brain region called the 4.) Osmoregulators control their internal osmolarity independent of their environment, true or false? 5.) Which of these is an example of an organism said to be eurkhaline? A) salmon B) shark C) sea anemone D) barnacle 6.) Layers of specialized epithelial cells that regulate solute movements are called

18 Quiz Answers 1. False 2. C 3. hypothalamus 4. True 5. D 6. transport epithelium

Basic Principles of Animal Form and Function Anatomy/Physiology Animal form and function are correlated at all levels of organization

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Basic Principles of Animal Form and Function Anatomy/Physiology Form and function are related Animal form and function are correlated at all levels of organization Evolution