Overview of the Nervous System and Its Functions

central nervous system

integrates and processes all incoming sensory information and outgoing motor commands

peripheral nervous system

All nerves that go from the brain to the rest of the body (subdivided into the somatic and autonomic systems)

ganglion

a collection of neuron cell bodies located outside the central nervous system

sympathetic nervous system

mobilizes energy in stress or activity (fight or flight)

parasympathetic nervous system

conserves energy and promotes routine maintenance (rest or digest)

sensory fibers

relay sensory information to the brain (in somatic)

motor fibers

have impulses from the brain to the skeletal muscular system (in somatic)

autonomic nervous system

regulates the body to maintain homeostasis: heart + respiratory rate

somatic nervous system

Conscious control of skeletal muscles

motor Neurons

Transmit signals from the brain to the muscle to make it contract. Part of the somatic nervous system.

electrical signals

What type of signals does the nervous system send?

brain, spinal chord

What are the main organs of the nervous system?

chemical synapses

use chemical signaling molecules as messengers

electrical synapses

use ions as messengers

axon

Long extension of the cell body of a neuron; transmits nerve impulses to other cells.

axon terminal

Branches at the end of an axon of a neuron; points where the neuron communicates with other cells.

cell body

Central part of a neuron; contains the nucleus and other cell organelles.

central nervous system (CNS)

One of two main divisions of the nervous system that includes the brain and spinal cord.

dendrite

Extension of the cell body of a neuron; receives nerve impulses from other neurons.

glial cell

A cell that provides support for a neuron.

interneuron

Neuron that carries nerve impulses back and forth between sensory and motor neurons.

myelin

A lipid produced by a Schwann cell; forms the myelin sheath.

myelin sheath

Lipid layer around the axon of a neuron; allows nerve impulses to travel more rapidly down the axon.

nerve impulse

Electrical signal transmitted by the nervous system.

peripheral nervous system (PNS)

One of two major divisions of the nervous system; consists of all the nervous tissue that lies outside the central nervous system.

Schwann cell

A type of glial cell responsible for producing myelin.

sensory neuron

Neuron that carries nerve impulses from tissue and organs to the spinal cord and brain.

endocrine system

System of glands that secrete hormones into the bloodstream.

nervous system

Body system that sends electrical messages throughout the body; controls all other body systems.

organ system

Groups of organs that work together to perform a specific task.

neurotransmitter

Chemical that carries a nerve impulse from one nerve to another at a synapse.

resting potential

Difference in electrical charge across the plasma membrane of a neuron that is not actively transmitting a nerve impulse.

sodium-potassium pump

Active transport protein; exchanges sodium ions for potassium ions across the plasma membrane of animal cells.

synapse

Junction where an axon terminal meets another cell.

synaptic cleft

Space between the axon terminals of one cell and the receptors of the next cell.

action potential

Reversal of electrical charge across the membrane of a resting neuron that travels down the axon of the neuron as a nerve impulse.

brain

Central nervous system organ inside the skull; the control center of the nervous system.

brain stem

Lowest part of the brain that connects the brain with the spinal cord; controls unconscious functions such as heart rate and breathing.

cerebellum

Part of the brain below the cerebrum; coordinates body movements.

cerebrum

Largest part of the brain; controls conscious functions such as reasoning and sight.

spinal cord

Thin, tubular bundle of nervous tissue that extends from the brainstem down the back to the pelvis; connects the brain with the peripheral nervous system.

vertebrae

(singular, vertebra): Repeating bony units that make up the vertebral column of vertebrates.

autonomic nervous system (ANS)

Division of the peripheral nervous system; controls involuntary activities not under conscious control, such as heart rate and digestion.

motor division

Division of the peripheral nervous system; carries nerve impulses from the central nervous system to muscles and glands throughout the body.

nerve

One of many cable-like bundles of axons that make up the peripheral nervous system.

parasympathetic division

The subdivision of the autonomic nervous system; controls involuntary activities that are not emergencies.

reflex arc

The path taken by a reflex.

sensory division

Division of the peripheral nervous system; carries sensory information from the body to the central nervous system.

somatic nervous system (SNS)

Division of the peripheral nervous system; controls voluntary, conscious activities and reflexes.

sympathetic division

The subdivision of the autonomic nervous system that deals with emergencies.