Name:
Period:
Anatomy & physiology
Part 1: The Nervous System
Three Functions of the Nervous System:
Sensory Input:
Gathers _____________________________________ (receives information)
____________________________________________________:
Processes and interprets information
Motor Output:
Causes a response to _______________________________________ or glands
Organization of the Nervous System:
Structural Classification:
Central Nervous System (CNS): ________________________________________& spinal cord
_____________________________________________________ Nervous System (PNS): spinal & cranial
nerves
Sensory Division (a.k.a. Afferent): nerves carrying info to the ______________________________from the
_____________________________________________________
_______________________________________________ Division (a.k.a. Efferent): nerves carrying info from
the CNS to the muscles or glands
This includes:
Somatic Nervous System: _____________________________________________ control (skeletal
muscles)
Autonomic Nervous System (ANS): involuntary control
(________________________________________ &
_________________________________________). This includes: sympathetic & parasympathetic.
Functional Classification:
Supporting Cells of the Nervous System:
1. Microglial cells: support neurons & carry out _______________________________________________
2. Oligodendrocytes: form ______________________________________________ within the brain; occur in
rows along nerve fibers
3. _______________________________________________________: found between neurons & bv’s;
support, regulate [nutrients] & [ions], & form scar tissue following a CNS injury.
4. Ependymal cells: membrane like structure that ________________________________________________
parts of the brain (choroid plexuses) & forms inner linings of brain (ventricles) & spinal cord (central canal).
Neurons: Nerve Cells
______________________________________________ vary in size, shape & function
Name:
Period:
Mature neurons do NOT _____________________________________________
All neurons have:

A ______________________________________________body is the main component of a neuron. It
contains cytoplasm, a cell membrane, a nucleus, & organelles.

The ER of a cell body is called the chromatophilic substance or
__________________________________________________ (perform protein synthesis).
Neuron Anatomy:

Dendrites and axons are nerve fibers that attach to the cell body (most neurons have these).

_____________________________________ (usually more than 1 on a cell body) are the
communication means of one neuron to the next. They receive messages. These are short branched
fibers.

Axons take impulses _________________________________________ from the cell body. They are
usually one fiber with side branches.

Large axons have a covering sheath called a
________________________________________________sheath (a membrane of lipoprotein).

The myelin sheath is composed of ________________________________________________
(neuroglial cells).

The gaps between the myelin sheaths are called nodes of
_____________________________________________________________.

In the CNS, __________________________________________ matter are the fibers that are
myelinated while _______________________________________matter are the fibers that are
unmyelinated.
Terminology:

Nuclei: clusters of cell bodies in the ________________________________

____________________________________: small clusters of cell bodies in the PNS (outside the CNS)

Tracts (or nerve tracts): bundles of _______________________________________ fibers running
through the CNS

Nerves: fibers running through the ___________________________________

White Matter: _________________________________________________ fibers

Gray Matter: __________________________________________________ fibers
Types of Neurons: Structural Classification:
1. ________________________________________________ neurons: 2 nerve fibers, one at each end (1
axon & 1 dendrite). Found in the nose, eyes, & ears.
Name:
Period:
2. ________________________________________________ neurons: 1 nerve fiber from the cell body that
has 2 branches (1 branch acts as a dendrite & the other branch acts as an axon).
3. ________________________________________________ neurons: many nerve fibers, 1 axon and many
dendrites. Found in the brain & spinal cord.
Types of Neurons: Functional Classification:
1. Sensory neurons: carry impulses from ________________________________________________ body
parts to brain & spinal cord (from PNS to CNS). Most are
_______________________________________________, some bipolar.
2. ________________________________________________________: carry impulses between neurons.
Multipolar neurons.
3. Motor neurons: carry impulses from the brain & spinal cord to the
_______________________________________________ (muscles & glands outside of the NS) to carry out a
response. __________________________________________________.
Nerve Impulses:

An unmyelinated nerve fiber carries an impulse
______________________________________________ than a myelinated nerve fiber.

Nerve impulses range in speed according to their diameter
(_____________________________________________________________________). Ex: skeletal
muscle travels ~120 meters/second

Nerve impulses respond in an
___________________________________________________________________________ response.

More stimuli= __________________________________________impulses (per second), not stronger
intensity of impulses.
Nerve Impulses:

A ____________________________________________is a junction between 2 communicating
neurons. The neurons are NOT connected.

A synaptic cleft is the __________________________________ between these 2 neurons.

A nerve impulse must jump this gap.

A ____________________________________________________ is a chemical that enables the
impulse to jump the synaptic cleft.
Reflexes:
•
These are rapid, _______________________________________________ responses
•
A reflex _________________________________________ is the simplest nerve pathway that
contains only a few neurons.
Name:
•
Period:
The _________________________________________________ reflex is a protective reflex (pulling
your finger away from a hot pot) b/c it limits tissue damage. In addition to this reflex, interneurons
also trigger a response to _________________________________________.
•
__________________________________________________reflexes include skeletal muscles (pulling
your hand away from a hot stove).
•
Autonomic reflexes include ___________________________________________ and cardiac muscles
as well as glands (_________________________________________________ dilating, mouth
‘watering’)
•
The knee-jerk reflex is a nerve pathway involving only 2
_____________________________________________ (1 sensory & 1 motor).