The Nervous System

Human Brain

The command center for the nervous system, enabling thoughts, memory, movement, and emotions.

Movement Theory

Some researchers suggest the brain evolved primarily to facilitate movement.

Sea Squirt

An organism that illustrates the concept of movement; it absorbs its brain after settling down and no longer needing to move.

Nervous System

Composed of the brain, spinal cord, and nerves; controls thoughts, movement, and automatic responses.

Neurons

Specialized cells that send messages throughout the nervous system.

Peripheral Nervous System

The network of nerves branching from the brain and spinal cord, facilitating communication between the CNS and body parts.

Subdivided into Afferent and Efferent Neurons.

Afferent Neurons

Sensory neurons that carry nerve impulses from sensory stimuli to the CNS and brain.

Efferent Neurons

Motor neurons that transmit commands from the CNS to the muscles.

Somatic Nervous System

Relays sensory information to the CNS and controls voluntary muscle movements.

Automatic Nervous System

Regulates glands and organs involuntarily, maintaining homeostasis.

Homeostasis

A self-regulating process that maintains stability in an organism while adjusting to conditions for survival.

Sympathetic Nervous System

Activates the 'fight or flight' response during stress or danger.

Parasympathetic Nervous System

Dominates during 'rest and digest' conditions, conserving energy and regulating functions like digestion.