Communication

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  • Created by: Amira200
  • Created on: 06-06-16 15:07
Outline the need for communication systems within multicellular organisms
Respond to changes in the internal and external environment. Coordinate the activities of different organs.
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How do cells communicate with each other
A process called cell signalling
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State two systems that communicate with each other using cell signalling
Hormonal and neuronal. Hormonal sends messages in the form of hormones to different parts of the body and neuronal does the same in the form of action potentials
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Define homeostasis
The maintenance of the internal environment at a constant state despite any changes in the external environment.
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Define negative feedback
A process that brings about a reversal of any change in conditions ensuring the optimum steady state is maintained
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Define positive feedback
A process that increases any change detected by receptors. Tends to be harmful and does not lead to homeostasis
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Give an example of when positive feedback can be beneficial
Bring dilation od cervix at the end of pregnancy. As cervix begins to stretch, the pituitary gland secretes oxytocin which increases the uterine contractions which stretch the cervix even more. Once the cervix is fully dilated, the baby can be born.
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What happens to the body when body temperature falls below the optimum
Have an effect upon the structure of proteins e.g. enzymes. Rate of activity decreases and they don't function properly. If temp decreases well below optimum then enzymes may denature as there tertiary structure changes
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What are ectotherms
Organisms that relies on external sources of heat to regulate its body temperature.
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What are the advantages to being an ectotherm
Use less food in respiration.Can survive longer periods without eating so can find less food.More energy used for growth
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What are the disadvantages to being an ectotherm
Less active in cooler temperatures- greater risk of predation
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How does an ectotherm behave when too cold
Lie on warm surface. Expose body to sun. Orientate body to sun so larger SA for more heat absorption. Alter body shape to expose more SA to sun
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How do an ectotherm behave when too hot
Stay in shade or underground. Orientate body away from sun.Hide in burrow. Alter body shape. Increase breathing movements
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What are endotherms
Organism that can use internal sources of heat to maintain body temperature
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What are the advantages of endotherms
Internal temperature fairly constant whatever the external temp is. Activity possible at all times. Ability to inhabit colder parts of planet
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What are the disadvantages to endotherms
Lot of energy used to maintain body temperature. More food required. Less energy used for growth so more food needed to help in that
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Describe what happens to the sweat glands in the skin when an endotherm is too hot or cold
Hot- sweat glands secrete more sweat onto skin. Water evaporates by latent heat of vaporisation. COLD- no sweat secreted
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Describe what happens to lungs mouth and nose when endotherm is too hot or cold
HOT- increased panting to evaporate water by latent heat of vaporisation. COLD- No panting so no water evaporation
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Describe what happens to the hair on skin when endotherm is too hot or cold
HOT- hair lies flat, little insulation , more heat loss by convection&radiation. COLD- Hairs raise, erector pili muscles contract, trap a layer of insulating air, less heat loss through radiation and convection
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Describe what happens to capillaries in skin when ectotherm is too hot or cold
HOT- Vasodilation, more blood into capillaries near skin surface, more heat radiated from skin. COLD- Vasoconstriction, less blood through capillaries near skin surface, less heat radiated
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Describe what happens to liver cells when ectotherm is too hot or cold
HOT- reduced rate of metabolism less heat generated from exergonic reactions. COLD- increased rate of metabolism more heat generation by respiration
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Describe what happens to the skeletal muscles when an endotherm is too hot and too cold
HOT- No spontaneous contractions. COLD- Spontaneous contractions, muscles respire more, heat generated
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Although endotherms behave in the same way as ectotherms in order to regulate its temperature, it also behaves in another way in which has no effect on ectotherms, what is this
Endotherms can increase.decrease their activity in order to generate heat in muscles. Ectotherms don't do this as their internal temperature is controlled externally
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Other cards in this set

Card 2

Front

How do cells communicate with each other

Back

A process called cell signalling

Card 3

Front

State two systems that communicate with each other using cell signalling

Back

Preview of the front of card 3

Card 4

Front

Define homeostasis

Back

Preview of the front of card 4

Card 5

Front

Define negative feedback

Back

Preview of the front of card 5
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