Control of the Internal Environment and Homeostasis

Vocabulary flashcards covering key terms related to homeostasis, steady state, biological control systems, cell signaling mechanisms, and cellular stress responses.

Homeostasis

The maintenance of a constant and normal internal environment during unstressed, resting conditions.

Steady State

A balance between the demands placed on the body and the body's response to those demands, characterized by unchanging and constant physiological variables.

Biological Control System

A series of interconnected components that maintain a chemical or physical parameter of the body near a constant value.

Sensor

A component of a control system that detects changes in internal conditions and sends data to the control center.

Control Center

A component of a control system that assesses input from the sensor and directs the response of the effector.

Effector

A component of a control system that responds to a stimulus to return internal conditions to normal.

Negative Feedback

The primary method for maintaining homeostasis where the body's response reduces or reverses the original stimulus to restore normal values.

Positive Feedback

A control mechanism in which the biological response increases the original stimulus in the same direction.

Adaptation

A change in the structure or function of a cell or organ system that results in an improved ability to maintain homeostasis.

Acclimation

The adaptation of existing homeostatic systems to environmental stresses, such as hot environments or high altitude.

Cell Signaling

Communication between cells using chemical messengers to coordinate cellular activities and maintain homeostasis.

Intracrine Signaling

A cell signaling mechanism in which a chemical messenger produced inside the cell causes a specific response within that same cell.

Juxtacrine Signaling

A cell signaling mechanism in which the cytoplasm of one cell communicates with another cell through a small junction connecting their membranes.

Autocrine Signaling

A cell signaling mechanism where a cell releases a chemical messenger into the extracellular fluid that acts upon the cell producing the signal.

Paracrine Signaling

A cell signaling mechanism where a cell produces and releases a chemical messenger that acts on nearby target cells.

Endocrine Signaling

A cell signaling mechanism where a cell releases hormones into the blood to be carried to target cells throughout the body.

Cellular Stress Response

A protective mechanism initiated when homeostasis is disturbed, causing cells to synthesize stress proteins.

Stress Proteins

Proteins (such as heat shock proteins) synthesized by cells when homeostasis is disrupted to help restore cellular balance.