Homeostasis

Homeostasis

The maintenance of a stable internal environment despite external changes.

Extracellular Fluid

Fluid or space located outside of the body's cells (e.g., blood plasma).

Intracellular Fluid

Fluid or space located entirely inside the body's cells (cytosol).

Stimulus-Response Model

The pathway: Stimulus $\rightarrow$ Receptor $\rightarrow$ Control Centre $\rightarrow$ Effector $\rightarrow$ Response.

Receptors

Cells or structures that detect changes. Types: Chemo- (chemical), Thermo- (temperature), Mechano- (pressure/movement), Photo- (light).

Transmission & Control Centre

The coordinator (usually brain or spinal cord) that processes receptor info and signals effectors.

Effector

A muscle or gland that executes the physical response directed by the control centre.

Negative Feedback

A homeostatic mechanism that reverses or counteracts the original stimulus to return the system to its set point.

Positive Feedback

A mechanism that amplifies or reinforces the original stimulus to complete a process (e.g., childbirth contractions).