Transcript The Nervous System

The Nervous System
A Brief Overview!
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What you will understand at
the end of this lecture:
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Functions of the nervous system
Divisions of the nervous system
Parts of the nervous system
Nerve cell (neuron) structure
How a message travels throughout your
body
Nervous System Functions
 Communication!
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Receive info
Process info
Respond to info
Maintain homeostasis
 Homeostasis: the process of maintaining the
balance inside your body, regardless of your
external environment (ex. Maintaining a normal
temperature)
Nervous System Functions
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Thinking
Feeling
Moving
Tasting
Seeing
Hearing
Talking
Smelling
Touching
Function #1: Receiving Info
 Nervous System receives info from
INSIDE and OUTSIDE your body
 Helps you be AWARE of your
surroundings
 Keeps internal body conditions in check
(normal) ex. Blood sugar level, heart
rate, temperature
Function #2: Responding to
Info
 STIMULUS: signal that triggers nervous
system to react
 Ex. Mosquito buzzing, phone ringing, ball flying
toward your face
 NS responds to stimulus
 RESPONSE: what your nervous system tells
your body to do to react to the stimulus
 Ex. You hit mosquito, you answer phone, you
catch the ball
Divisions of the Nervous
System
 Central Nervous
System
 Peripheral Nervous
System
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Central Nervous System
 Brain and spinal
cord
 Brain: controls
body’s functions
 Spinal cord:
connects brain to
nerves of peripheral
nervous system to
relay messages
Peripheral Nervous System
Divided into Somatic and Autonomic Nervous system
 Somatic Nervous
System
 Controls VOLUTARY
actions
 Autonomic Nervous
system
 Controls tasks you
do not think about
 Breathing, heart rate,
body temp.
 Divided into
sympathetic and
parasympathetic
systems
Peripheral Nervous System
http://www.montana.edu/wwwai/imsd/rezmeth/anatomy.htm
Peripheral Nervous System
Calming
Energy
Conservation
Fight
or
flight
http://www.drstandley.com/images/nervous5.bmp
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Nervous System Organization
Organization
 Cells --> tissues --> organs --> organ
systems
 Nerve cell --> nerves --> brain -->
central nervous system (brain and
spinal cord)
 Nerve - bundle of nerve cells held
together by connective tissue
Neuron Structure
 Specifically designed to carry messages
 Main parts: Dendrites, cell body, axon,
axon tip
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Neuron Structure
 Dendrites: receives incoming stimulus, sends
message to cell body
 Cell body: contains organelles, passes
message to axon
 Axon: carries message (impulse) awas from
the cell body towards the next neuron’s
dendrites
 Axon tip: end of axon, message reaches here
and jumps to next neuron’s dendrites
Neuron to Neuron: Passing
the message along
http://www.ascd.org/ASCD/images/publications/books/sprenger1999_fig1.2.gif
Neuron to Neuron: Passing
the message along
http://psych.hanover.edu/krantz/neurotut.html
Neuron Types
 Sensory neuron: senses stimulus,
changes it into an impulse
 Interneuron: passes impulse from
neuron to neuron
 Motor neuron: sends impulse to muscle
or gland or part of body that needs to
respond to stimulus
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Neurons (SEM picture)
Nerve Impulse (Message)
 Travels from dendrites --> cell body -->
axon --> axon tips --> jumps synapse
(space between 2 neurons) -->
dendrites --> cell body --> axon --> axon
tips
 Impulses can travel 120 m/s
 Impulses travel across synapse either
as an electrical signal or a chemical
signal
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