F2144 Communication, Homeostasis & Energy definitions

Created by: Becky0295
Created on: 21-03-13 19:25

Negative Feedback

A process in which any change in a parameter brings about the reversal of that change so the parameter is kept fairly constant.

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Positive feedback

A process in which any change in a parameter brings about an increase in that change.

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Homeostasis

The maintenance of a constant internal environment despite external changes.

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Endocrine gland

A gland that secretes hormones directly into the blood plasma.

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Exocrine gland

A gland that secretes substances into a duct.

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Hormone

A molecule released into the blood plasma that acts as a chemical messenger.

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Target tissue

Cells that have receptors embedded in the plasma membrane that are complementary in shape to specific hormone molecules. Only these cells will respond to that specific hormone.

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First messenger

A hormone that acts as a message in the blood plasma.

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Second messenger

A chemical inside the cell released in response to a hormone binding to the cell surface membrane. (cAMP)

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Excretion

The removal of metabolic waste (waste from the reactions inside cells) from the body.

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Autotroph

Organism that makes its own organic food (eg. CHO) using simple inorganic molecules (eg. CO2)

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Heterotroph

Organism that gains its nutrients from complex organic molecules. They are then digested to simpler, soluble molecules which are respired to release energy or used to synthesise other organic molecules it needs.

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Photosynthetic pigment

Chemicals that absorb light energy.

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Other cards in this set

Card 2

Front

A process in which any change in a parameter brings about an increase in that change.

Back

Positive feedback

Card 3

Front

The maintenance of a constant internal environment despite external changes.

Back

Card 4

Front

A gland that secretes hormones directly into the blood plasma.

Back

Card 5

Front

A gland that secretes substances into a duct.

Back

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F2144 Communication, Homeostasis & Energy definitions