CNS PNS

Central nervous system (CNS)

contains gray and white matter and covered by bone and meninges

Brain

Spinal cord

Peripheral nervous system (PNS)

All the neural tissue outside CNS

Composed of nerves, ganglia, and nerve plexuses

Afferent division

Nerve cell that transmits action potentials from an effector organ to the CNS

Efferent division

Nerve cell that transmits action potentials from the CNS to an effector organ, such as a muscle or gland

Somatic nervous system

Nerve that innervates skeletal muscle; conveys impulses causing muscle contraction

Autonomic nervous system

Nerve that innervates and controls the actions of the visceral organs (skin smooth muscle, cardiac muscle, and glands)

Sympathetic

Preganglionic neurons in the thoracic and lumbar segments of the spinal cord. “Fight or flight” system

Parasympathetic

Preganglionic neurons in the brain and sacral segments. “Rest and digest” system

Neurons

For information transfer, processing, and storage

Cell body

Composed of nucleus, mitochondria, RER, other organelles

Dendrites

Signal reception (inward) respond to specific stimuli and conduct impulses to the cell body.

Axon

Signal propagation (outward that conducts impulses away from the cell body.

Continuous propagation

Involves entire membrane surface

Proceeds in series of small steps (slower)

Occurs in unmyelinated axons

Saltatory propagation

Involves patches of membrane exposed at nodes

Proceeds in series of large steps (faster)

Occurs in myelinated axons

synapse

the functional connection between the axon terminal of a presynaptic neuron and a dendrite of a postsynaptic neuron

Synaptic cleft

tiny gap separating the presynaptic and postsynaptic membranes

Axon terminal

is the distal portion of the presynaptic neuron at the end of the axon

Synaptic vesicles

contain a neurotransmitter chemical, the most common of which is acetylcholine

Neurotransmitter receptors

receivers of the neurotransmitters

Cholinergic synapses

Release neurotransmitter acetylcholine

Enzyme in synaptic cleft (acetylcholinesterase) breaks it down

Adrenergic synapses

Release neurotransmitter norepinephrine

Dopaminergic synapses

Release neurotransmitter dopamine

Meninges

Layers that surround and protect the brain and spinal cord

Dura mater

Tough, fibrous outer layer

Epidural space above dura of spinal cord

Arachnoid

Subarchnoid space

Cerebrospinal fluid

Pia mater

Thin inner layer

Sensory neurons

Deliver information to CNS

Motor neurons

carry instructions from the CNS to other tissues, organs or organ system.

Interneurons

as the name implies, connect other neurons. They are responsible for the distribution of sensory information and coordination of motor activity.

also play role all higher function such as memory, planning and learning

Somatic Motor Neuron

innervate skeletal muscles

Visceral motor Neuron

innervate all other effectors, including cardiac muscles, smooth muscles, glands, and adipose