AP Bio - Feedback Loops & Communication

Autocrine signaling

A cell releases a signal that affects itself

Juxtacrine signaling

Cell-to-cell communication requiring direct physical contact

Paracrine signaling

Local signaling where a cell affects nearby cells

Endocrine signaling

Long-distance signaling using hormones in the bloodstream

Reception

Target cell detects a signaling molecule when it binds to a receptor

Transduction

Series of molecular steps converting the signal into a cellular response

Response

The final action the cell performs in response to a signal

Ligand

A signaling molecule that binds to a specific receptor

Local regulator

A signaling molecule that acts over a short distance

Hormone

A long-distance signaling molecule carried in the bloodstream

Protein kinase

Enzyme that adds phosphate groups to proteins

Protein phosphatase

Enzyme that removes phosphate groups from proteins

Target cell

A cell that has receptors for a signaling molecule

Ion channel

Membrane protein that allows specific ions to pass through

Apoptosis

Programmed cell death

Homeostasis

Maintenance of stable internal conditions

Negative feedback

Mechanism that reverses a change to return to a set point

Positive feedback

Mechanism that amplifies a change

Set point

The ideal internal value the body maintains

Stimulus

A change that triggers a homeostatic response

Sensor

Structure that detects the stimulus

Control Center

Processes the signal and sends instructions

Effector

Structure that carries out the response

Vasoconstriction

Narrowing of blood vessels to conserve heat

Vasodilation

Widening of blood vessels to release heat

Ligand-gated ion channel

Receptor that opens/closes an ion channel when a ligand binds

Surface receptor particles

Polar ionic and hydrophilic molecules need surface receptors

Intracellular receptor particles

Nonpolar and hydrophobic molecules use intracellular receptors

Shivering

Muscle contractions that generate heat

Sweating

Evaporation of sweat that cools the body

Vasodilation (thermoregulation)

Increases blood flow to skin to release heat

Vasoconstriction (thermoregulation)

Decreases blood flow to skin to conserve heat