Transcript Nervous System - School District of La Crosse

Nervous System
 1. Function – Receives and sends out info
from and to the outside and inside your
body
 2. Two parts of the Nervous System
A. Central (CNS) – Brain and Spinal Cord
B. Peripheral (PNS) – All of the other
nerve cells
3. Neurons (Nerve Cells)
 A. Cell Body – Contains the nucleus
 B. Dendrite – Receives nerve impulse
 C. Axon – Sends the nerve impulse away
 D. Myelin – Protects the axon. Allows the
nerve impulse to move very fast
 D. Node of Ranveir – places between the
myelinated Schwann cells where action
potential takes place
Action Potential:
https://www.youtube.com/results?search_query=action+poten
tial+in+neurons
 4. Synapse – Gap in between to neurons
 5. Nerve Impulse – Signal that moves
through the Nervous System.
 A. Travels in 2 Ways

1. Electrical – As it moves through the
neuron.

2. Chemical – As it moves across a
synapse
6. The Pathway
 A. Receptor Cells – Special cells that


detect the stimulus from inside or
outside your body
1. Found everywhere in your body.
2. Some are connected to your
5 senses
 B. Sensory Neurons – Receive the
impulse from the receptor cells and pass it
on to the inter-neurons
 C. Interneurons – Neurons found in the
spinal cord and brain
 D. Motor Neurons – Carry the response
impulse away from spinal cord to an
effector
 E. Effector – A muscle or a gland that
receives the response impulse
7. Reflex Arc
 Response to a stimulus that does not
come from the brain. It comes from the
Spinal Cord
http://search.live.com/images/results.aspx?q=nerve%20impulse&FORM=BIRE#focal=efa67884cff46a
d340d0c811ff7fcdee&furl=http%3A%2F%2Fwww.mybrainmybody.com%2Fimages%2FL2_pic_Brain_
Explore.jpg
You can see in the magnified
box that the axon is a bundle
of little fibers and the myelin
is actually wrapped around it
several times liked a rolled up
carpet. Myelin serves some
incredibly important
functions. It protects the
axon. It allows an impulse to
get from one neuron to
another, and it allows that
impulse to move very, very
fast
1. Sensory Receptors structures that detect changes in external & internal environment
modified neurons or epithelial cells that have evolved
to respond to stimuli (eye, ear, nose, muscles)
Motor Neuron
Action Potential
Interneuron

Classes of Sensory Receptors
chemo-receptors: chemicals sense solutes in solvents, taste, smell
osmo-receptors: of hypothalmus which monitors blood osmotic
pressure
photo-receptors: light - eye, eyespots, infrared receptors of snakes,
etc...
thermo-receptors: radiant (heat) energ
phono-receptors: sound waves
electro-receptors: detect electric currents... electric eels, etc..
noci-receptors: pain receptors... naked dendrites of skin
(epidermis)
mechano-receptors: mechanical forces - stretching alters
membrane permeability
Link: parts of the neuron
 In turn, these pathways can be divided
according to the direction in which they conduct
stimuli:
 Afferent system by sensory neurons, which carry
impulses from a receptor to the CNS
 Efferent system by motor neurons, which carry
impulses from the CNS to an effector
 Relay system by relay neurons (also called
interneurons), which transmit impulses between
the sensory and motor neurones.