Lecture Notes: Chapter 1 – Homeostasis, Gradients, and Thermoregulation

Vocabulary flashcards covering key concepts from the notes on homeostasis, gradients, and thermoregulation.

Homeostasis

The body's ability to detect changes, activate opposing mechanisms, and maintain relatively stable internal conditions; achieved through dynamic equilibrium near a set point via regulatory processes (e.g., negative feedback).

Negative feedback

A control mechanism that reverses a detected change to restore normal conditions; involves receptor, integrating center, and effector; produces dynamic equilibrium around a set point.

Positive feedback

A self-amplifying cycle that increases the initial change in the same direction; common in rapid events (e.g., childbirth, blood clotting, protein digestion, nerve signal generation); can be dangerous if unchecked (e.g., runaway fever).

Receptor

A structure that senses a change in the body (e.g., baroreceptors monitoring blood pressure).

Integrating center

Control center that processes sensory information, makes a decision, and directs a response (e.g., cardiac center in the brain).

Effector

The cell or organ that carries out the final corrective action to restore homeostasis (e.g., the heart).

Set point

The normal value around which a variable is regulated.

Homeostatic imbalance

Disturbances in homeostasis that can lead to disease or death if not corrected.

Gradient

A difference in chemical concentration, charge, temperature, or pressure between two points; matter and energy tend to flow down gradients.

Flow down gradients

Movement of matter and energy down gradients—from higher to lower potential; moving against a gradient requires energy (up gradient).

Concentration gradient

Difference in the concentration of a chemical between two points; substances tend to move down this gradient.

Electrical gradient

Difference in electrical charge across a region; ions flow down this electrical gradient.

Thermal gradient

Difference in temperature between two points; heat flows down this thermal gradient.

Thermoregulation

Process of maintaining core body temperature within a narrow range using homeostatic mechanisms (e.g., vasodilation and sweating when warm; vasoconstriction and shivering when cold).

Vasodilation

Widening of blood vessels, especially near the skin, to dissipate heat.

Vasoconstriction

Narrowing of blood vessels to conserve heat.

Shivering

Involuntary muscle contractions that generate heat in response to cold.

Sweating

Production of sweat to evaporate and dissipate heat.

Claude Bernard

French physiologist who noted the constancy of internal conditions despite changing external conditions.

Walter Cannon

Physiologist who coined the term homeostasis.

Baroreceptors

Receptors that detect changes in blood pressure and help regulate blood pressure by signaling the cardiac center.

Dynamic equilibrium

A steady state where conditions remain within a narrow range around a set point, despite fluctuations.