Communication and Homeostasis

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Why do organisms need communication systems internally?
To respond to changes in external stimuli and co ordinate activities of different organs
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How do cells communicate with eachother?
Cell signalling- one cell releases chemiscal detected by another cell.
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What are 2 examples in the body where cell signalling occurs?
Neuronal and Hormonal systems
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What is negative feedback?
Reversal of a change in the internal environment to return to its optimum position
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What is positive feedback?
Increase original change.Useful during pregnancy(oxytosin)
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Define Homeostasis
Keeping internal environment constant despite changes in external changes
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What is the sequence of negative feedback?
Optimum>Change>Receptor detects>Effector informed>Effector reverses>Return to optimum
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What is an ectotherm?
Rely on external sources to heat up- don't generate own heat energy.
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What are the benefits of and adaptations of ectotherms?
Less food used in respiration. Energy can be used for growth. Eat less often... Expose body to sun(Snakes) ,Hide in burrows, alter body shape(Lizards), increase breathing movement(Locusts)
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What are the disadvantages of being an ectotherm?
Less active in cooler temperatures-need to warm up. Inactive during winter as need to warm up. Need sufficient energy to survive winter
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What is an endotherm?
Can generate own heat from metabolic processes to maintain body temperature
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What are the advantages and disadvantages of endothermy?
Fairly constant body temperture. Can live in colder places. Can be active in cool temperatures **A lot of energy used to maintain body temp when cold, More food required, less energy for growth
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How do endotherms regulate their body temperature when it's cold?
Behavioural: Move into sunlight, Orientate body towards sun, Move to generate heat. Physiological: Less sweat secreted/ panting(less evap.) Hairs raise reducing heat loss. Vasoconstriction- less radiation of heat, increased metabolism for respiration
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How do endotherms regulate their body temperature when it's cold?
Behavioural: Move into shade or burrow, Orientate away from sun, remain inactive and spread limbs to increase SA. Physiological: Secrete more sweat, Panting, Hairs lie flat, Vasodilation, Reduced metabolism, No spontaneous contractions
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What is the name of temperature change receptors in the skin?
Peripheral Receptors
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How is temperature change detected in endotherms?
Core temp rises>Thermoregulatory centre in hypothalamus detects>Nervous and hormonal system signals skin, liver and muscles> Less heat generated, more heat lost> Temperature falls. VICE VERSA NEGATIVE FEEDBACK
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Card 2

Front

How do cells communicate with eachother?

Back

Cell signalling- one cell releases chemiscal detected by another cell.

Card 3

Front

What are 2 examples in the body where cell signalling occurs?

Back

Preview of the front of card 3

Card 4

Front

What is negative feedback?

Back

Preview of the front of card 4

Card 5

Front

What is positive feedback?

Back

Preview of the front of card 5
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