Nervous System Overview

The control center of the nervous system, consisting of the brain and spinal cord.

The network of nerves outside the CNS, responsible for carrying information to and from the CNS to the rest of the body.

The part of the PNS controlling voluntary movements, like walking or typing. It connects to skeletal muscles and skin.

The part of the PNS controlling involuntary actions, like breathing or heart rate. It connects to vital organ systems like the heart and digestive system.

The 'fight or flight' response, which prepares the body for immediate action in stressful situations.

The 'rest and digest' response, which promotes relaxation and recovery.

A simple nerve pathway that creates a reflex response, bypassing the brain for faster reactions.

Specialized cells that transmit electrochemical signals throughout the nervous system.

Multipolar neurons that carry impulses from the CNS to effectors, like muscles, organs, or glands, to produce a response.

Bipolar neurons that connect sensory and motor neurons, primarily found in the CNS.

The central part of a neuron, containing the nucleus and majority of the cytoplasm.

Projections of cytoplasm that carry impulses toward the cell body.

An extension of cytoplasm that carries nerve impulses away from the cell body.

The end of the axon where impulses end and chemicals are released.

An insulated covering (fatty protein) over the axon of some nerves, preventing loss of charge.

Regularly occurring gaps between sections of the myelin sheath.

The process by which the nerve cell generates an electrical signal, involving a rapid change in the electrical potential across the cell membrane.

The minimum level of stimulation required to trigger an action potential.

A mechanism that pumps sodium ions (Na+) out and potassium ions (K+) into the neuron, maintaining a resting potential.

Chemical messengers that transmit signals across the synapse between neurons.

A neurotransmitter responsible for muscle contraction and other functions.

A neurotransmitter involved in learning, memory, and addiction.

A large part of the brain responsible for higher cognitive functions, including planning, language, and memory.

The tough outer layer of the eye, providing protection.

The clear, dome-shaped front part of the eye that focuses light.

The opening in the center of the iris that controls the amount of light entering the eye.

A flexible, transparent structure behind the pupil that focuses light onto the retina.

The colored part of the eye that controls the size of the pupil, regulating light.

The light-sensitive inner layer of the eye that contains photoreceptor cells (rods and cones) responsible for vision.

A small area in the center of the retina with the highest density of cones, responsible for sharp, central vision.

The area where the optic nerve and blood vessels exit the eyeball, lacking photoreceptor cells, creating a blind spot in our vision.

Photoreceptor cells that detect low levels of light, responsible for night vision.

Photoreceptor cells that detect different wavelengths of light, responsible for color vision and fine detail.