Nervous System

Anatomy/Physiology Fall 2025

Neurology

Study of the nervous system

Electrical signals in nervous system are measured in

Milivolts

Central Nervous System (CNS)

Brain + Spinal Cord

Peripheral Nervous System (PNS)

Nerve Fibers extending to other parts of the body (12 cranial nerves + 31 spinal nerves)

Divisions of the Peripheral Nervous System (PNS)

Afferent and Efferent

Afferent Division

Carries info from receptors into CNS (the 6 senses)

Efferent Division

Transmits instructions from CNS to effector organs

Sympathetic NS

Fight/Flight

Parasympathetic NS

Rest/Digest

Which aspects of the NS are autonomic (ANS)?

Parasympathetic ANS and Sympathetic ANS

Somatic Nervous System

Voluntary; motor neurons that supply skeletal muscle

Autonomic Nervous system

Innervate smooth muscle, cardiac muscle, glands, and other non-motor organs. 

Neuron

Nerve Cell; structural + Functional Unit of NS

Nucleus (of CNS)

“Dump” of normal cell bodies inside CNS (NOT THE ORGANELLE)

Ganglion

“dump” of neuronal cell bodies outside CNS in PNS

Nerve

Bundle of axons outside CNS

Tract

Bundles of axons within CNS

Neuroglia

Connective tissues inside CNS

Dendrites

Receive electrical/chemical signals from other neurons to be transmitted into cell body.

Axon

Responsible for info leaving cell body

Axon terminals

Release of info; where neurochemical mediators are stored

What happens after info is received from dendrites?

It flows into the trigger zone → initiates actional potential → cell body makes chemical that is stored in axonal ending → neurochemical is secreted via exocytosis

How many dendrites does a neuron have?

Usually more than 1

Neuroplasm

Nerve cytoplasm

Axoplasm

Axon Cytoplasm

Neurolemma

Nerve Cell Membrane

Nissl Bodies

Cytoplasmic Granules; serves as Rough ER in neuron (important for Protein Synthesis)

Schwann Cell

Wraps around nerve cell to protect axon region