3A The central and peripheral nervous systems

Central nervous system (CNS)

The brain and the spinal cord; processes and coordinates responses to sensory stimuli.

Brain

A complex structure that receives and processes sensory stimuli from the body and coordinates responses, including movements, emotions, and conscious thought, such as breathing, temperature regulation and hunger.

Spinal cord

A dense bundle of nerves that carries sensory information from the body to the brain and motor information from the brain to the body.

Spinal reflex

An involuntary and unconscious survivial (usually harmful) response to a stimulus involving the spinal cord, which occurs without input from the brain

Sensory receptor

A sensory nerve ending that produces an afferent or sensory impulse when stimulated

Sensory neuron

A nerve cell that carries sensory signals throughout the nervous system

Interneuron

A nerve cell in the spinal cord that connects motor and sensory neurons by relaying information between the two.

Motor neuron

A nerve cell that transmits motor impulses from the spinal cord to the skeletal and smooth muscles.

Peripheral nervous system

All the nerves outside of the central nervous system that carry messages between the central nervous system and muscles, organs and glands throughout the body

Somantic nervous system

A subdivision of the peripheral nervous system connects sensory receptors to the CNS and the CNS to the skeletal muscles. It also carries sensory information to the CNS and motor information to the body.

Autonomic nervous system

A subdivision of the peripheral nervous system, it connects the CNS to internal organs and glands, controlling the body’s internal environment in an autonomous or self-regulated manner. It consists of the sympathetic, parasympathetic and enteric nervous system.

Sympathetic nervous system

A subdivision of the autonomic nervous system that increases our arousal, readying the body for a quick response. Dominates when we are under threat, increases arousal, and prepares the body to respond.

Parasympathetic nervous system

A subdivision of the autonomic nervous system that controls the body's internal environment in an autonomous or self-regulated manner. Dominates during normal everyday activities and returns the body to homeostasis.

Unconscious response

Any response of our nervous system that does not require awareness

An example of this is eating food and the body unconsciously digests it.

Conscious response

Any response of the nervous system that require awareness

An example of this is deciding to pick up your drink bottle and drink water because you’re thirsty

Enteric nervous system

Directly connected to the CNS, which controls the nervous system.