Transcript nervous system 2012 - Junction Hill C

The nervous system gathers and interprets
information about the body’s internal and
external environments and response to that
information
The nervous system keeps your organs
working properly and allows you to
speak, smell, taste, hear, see, move,
think, and experience emotions.
SHHHH,
don’t tell him
it smells
Your nervous system controls and
coordinates many things that happen in
your body. It acts as a central command
post, collecting and process information and
making sure appropriate information gets
sent to all parts of the body.
The nervous system is
divided into two
subdivisions:
 The central
nervous system
(CNS)
 Peripheral
nervous system
The Central
Nervous
system (CNS)
includes your
brain and
spinal cord.
It processes
all incoming
and outgoing
messages
The peripheral
nervous system
(PNS) consists of
communication
pathways, or
nerves, that
connect all areas
of your body to
your CNS.
A. Central nervous system
B. Peripheral nervous system
B1. Somatic nervous system
B2. Autonomic nervous system
Neurons transfer messages
throughout your body in the form
of fast-moving electrical energy
Electrical
messages
that pass
along the
neurons are
called
impulses.
Impulses
may travel
as fast as
150 m/s or
as slow as
0.2 m/s
The neuron is the
functional unit of the
nervous system. Humans
have about 100 billion
neurons in their brain
alone! While variable in
size and shape, all
neurons have three
parts. Dendrites receive
information from
another cell and
transmit the message to
the cell body. The cell
body contains the
nucleus. The axon
conducts messages
away from the cell body.
Dendrites are short, branched extensions that
receive information from other cells.
A neuron may have many dendrites, allowing it
to receive impulses from thousands of other cells
From the cell body, information is transmitted
to other cells by a fiber called an axon. Axons
can be very short or quite long.
You have some really long axons that extend
almost 1 meter from your lower back to your
toes
The end of an
axon often has
branches that
allow
information to
pass to yet more
cells.
The tip of each
branch is called
an axon terminal
Sensory neurons
typically have a long
dendrite and short
axon, and carry
messages from
sensory
receptors to the
CNS
Sensory neurons have
specialized dendrites
called receptors that
detect changes inside
and outside the body.
Examples of Sensory Neurons
Receptors in your eyes
detect the light around you
Receptors in your stomach
let your brain know when
your stomach is full or
empty
Motor neurons have
a long axon and
short dendrites
and
transmit messages
from the central
nervous
system to the
muscles
(or to glands).
Motor neurons cause the muscles
around your eyes to move when
the sensory neurons in your eyes
detect bright light. This movement
makes you squint, which reduces
the amount of light entering the eye
Motor neurons also send
messages to your gland,
such as sweat glands.
These messages tell the
sweat glands to release
sweat
The CNS is connected to the
rest of your body by nerves.
A nerve is a bundle of
axons
Most nerves contain the
axons of both sensory and
motor neurons.