Controlling Processes

Front

Homeostasis Noun

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[hoh-mee-oh-stay-sis]

Back

Homeostasis

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The process by which an organism maintains a stable, constant internal environment despite changes in external conditions.

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Example: This balance scale represents homeostasis, your body's ability to keep internal conditions like temperature and hydration stable and balanced for survival.

Front

Feedback Loop Noun

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[feed-bak loop]

Back

Feedback Loop

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A biological pathway where the response to a stimulus influences the original stimulus, thereby regulating a system's output.

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Example: This diagram shows a feedback loop, where a stimulus causes a change that the body detects and corrects, returning the system to its set point.

Front

Set Point Noun

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[set poynt]

Back

Set Point

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The target value or normal range for a physiological variable that the body's homeostatic mechanisms work to maintain.

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Example: This diagram shows a 'set point' as a target line. A wavy line shows a body parameter, like temperature, fluctuating normally around this set point.

Front

Stimulus Noun

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[stim-yuh-luhs]

Back

Stimulus

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A detectable change in the internal or external environment that elicits a physiological response from an organism.

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Example: The sharp spine of the cactus is an external stimulus that causes the girl to react by pulling her hand away in pain.

Front

Receptor Noun

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[ri-sep-ter]

Back

Receptor

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A specialized cell or group of nerve endings that detects a specific type of stimulus and initiates a signal.

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Example: This image shows two types of photoreceptor cells in the eye, rods and cones, which are examples of receptors that detect light.

Front

Control Center Noun

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[kon-trohl sen-ter]

Back

Control Center

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The component in a feedback system that receives sensory input and determines the appropriate response to maintain homeostasis.

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Example: This diagram shows the cell's nucleus, the organelle that acts as the control center by storing the cell's genetic instructions (DNA).

Front

Effector Noun

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[ih-fek-ter]

Back

Effector

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A muscle, gland, or organ that responds to signals from the control center to produce a specific effect.

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Example: After a nerve signal travels from the spinal cord, the muscle in the arm (the effector) contracts to pull the hand away from danger.

Front

Negative Feedback Noun

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[neg-uh-tiv feed-bak]

Back

Negative Feedback

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A regulatory mechanism where the response counteracts the initial stimulus, stabilizing the system around a set point.

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Example: A speed hump is a form of negative feedback; it provides a signal (the bump) that causes a car to reduce its speed.

Front

Positive Feedback Noun

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[poz-i-tiv feed-bak]

Back

Positive Feedback

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A regulatory mechanism that amplifies or reinforces the initial stimulus, pushing a process toward a specific endpoint.

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Example: During childbirth, contractions cause the release of a hormone that makes contractions even stronger, amplifying the effect in a positive feedback loop.

Front

Neuron Noun

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[noor-on]

Back

Neuron

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A specialized cell that transmits nerve impulses; the fundamental unit of the nervous system for communication.

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Example: This diagram shows a neuron, or nerve cell, and labels its main parts: the dendrites that receive signals, the soma (cell body), and the axon.