Intro to Nerves

Functions of the Nervous

System

• The nervous system

collects information about
the body’s environment,
processes that
information, and responds
to it.

• Controls the functions of

and communicates with all
other body systems.

Divisions of the nervous system

1. Central nervous system (CNS)

– Brain
– Spinal cord

2. Peripheral nervous system-
consists of all the nerves outside

the CNS

Neurons are the functional unit

of the nervous system

• Neurons - specialized cells that gather

information about your environment, interpret
the information and react to it.

Parts of a neuron

• Dendrite- carry signals (impulses) toward cell body
• Cell body – contains the nucleus of the neuron and other

organelles

• Axon- carries nerve impulses away from the cell body to

other neurons

• myelin sheath- insulates neuron

SYNAPSE &
Neurotransmitters

Synapse: A space between 2 neurons

⦿ neurons communicate between each

other using chemicals called
neurotransmitters.

⦿ Neurotransmitters: are chemical

messages used to communicate between
neurons.

⦿ Ex. Serotonin

Neurotransmitters are released by exocytosis.
The neurotransmitter diffuses across the
synapse to receptors on the other neuron

http://www.mind.ilstu.edu/flash/synapse_1.swf

http://www.mind.ilstu.edu/flash/sy
napse_1.swf

Neurotransmitters – carry

signals from one neuron to the

next.

2 main kinds of neurons

• 1. sensory neuron

• 2. motor

• 1. sensory neuron –
picks up information from sense organs and

carries it to brain or spinal cord.

2. motor neuron- carry impulses away from the

brain to a muscle or gland.

sensory neuron

motor neuron

Spinal Reflex Arc-

a no brainer

• A reflex arc is a nerve pathway that consists of a

sensory neuron, an interneuron (in spinal cord),
and a motor neuron.

• Brain is NOT involved

Reflexes do NOT involve the brain
They are designed for a quick reaction, to help keep you safe.

reflex arc- no brain involved