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19 Cards in this Set
- Front
- Back
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Stimulus |
Any change in the environment that causes a response |
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Response |
A change in behaviour or physiology as a result of a change in the environment |
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Examples in internal environments |
1. Tissue fluid - metabolic activities produce toxic products that build up changing this environment |
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Examples of external environments |
1. Air 2. Water 3. Soil 4. Predation 5. Temperautre |
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Why is coordination important? |
To ensure different parts of the body can work together effectively |
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A good communication system will... |
1. Cover the whole body 2. Enable cells to communicate 3. Rapid and specific communication 4. Short and long term responses |
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Define: Cell signalling |
Process by which cells communicate with eachother |
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Two types of C.S: |
1. Neuronal - network of interconnected neurones, enable rapid responses 2. Hormonal - cells in an endocrine release hormone directly into the blood which is carried round the body and only recognised by target cells - allows longer term responses |
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Homeostasis |
Maintaining a constant internal environment despite external changes |
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Negative feedback |
The reversal of a change in the internal environment to return to a optimum steady rate (stimulus -> receptor -> communication pathway -> effector -> response) |
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Positive feedback |
Amplifies a change detected by receptors further from the normal level - not homeostasis E.G. Hypothermia |
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Ectotherms |
Rely on an external heat source to maintain their body temperature Change their behavior/physiology to increase their heat absorption or loss Some have physiological or anatomical adaptations |
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Advantages of being a cool Ectotherm |
- Use less energy for respiration, more available for growth - Need to find less food |
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Disadvantages of being a lame Ectotherm |
- Less active in cooler temperatures, greater risk of predation - Stores of energy required to survive winter |
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ENDOTHERMs |
- use internal sources of heat, such as heat generated by metabolism in the liver, to maintain their body temperature (exergonic reactions) |
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Adv. Endotherms |
Fairly constant temperature despite external conditions, can remain active in cooler external temperatures Can live in cold areas of the planet |
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Dis Adv. Endotherms |
More energy to remain warm, less energy for growth More food needed to meet energy demand |
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Why thermoregulation is important? |
Temp effects bonds in 3o structures of proteins Enzymes must maintain shape to be effective |
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Control of body temperatures in endotherms |
-Thermoregulatory centre of hypothalamus - Thermoreceptors to detect change in blood - Peripheral temperature receptors in skin |
