Neural and
Hormonal
Systems
Neurons: The Building Blocks of
the Nervous System
 Nervous
system – the body’s
electrochemical system
 Brain, spinal cord and nerves are formed
by NEURONS
 Neurons have 3 tasks:

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1. receive information
2. carry information
3. pass information
Structure of a Neuron
 Dendrite
– branchy extensions that
receive messages from other cells
 Soma – cell body; contains nucleus and
keeps cell healthy
 Axon – passes messages away from cell
body to other neurons, muscles, glands
 Myelin Sheath – covers axon of neurons
 Axon Terminals – points of departure; onto
next neurons dendrites
Neural Communication
 The
Neural Impulse – What are the steps
taken when a neuron “fires”?

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1. action potential – brief, electrical charge
that travels down the axon
2. refractory period – “recharging” phase of
a neuron; cannot fire just yet
3. resting potential – neuron is capable and
ready to generate another action potential
How is neural impulse like
flushing a toilet?
1.
2.
3.
What is the action
potential?
What is the refractory
period?
What is the resting
period?
JUST LIKE A NEURON!!!!
Communication Between
Neurons


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Neurons communicate with each without
actually touching one another!
Synapse – fluid-filled gap between axon
terminal of one neuron and dendrite of
another
Neurotransmitter – chemical messengers that
travel across synapse from one neuron to the
next
Reuptake – sending neuron reabsorbs excess
neurotransmitter molecules
Other key terms:
 Excitatory
effect – neurotransmitter that
likely generates an action potential
 Inhibitory effect – neurotransmitter that
likely does not generate an action
potential
 Sensory nerves – carry info to central
nervous system
 Motor nerves – carry info from central
nervous system to muscles and glands
Structure of the Nervous System
Nervous System
Central Nervous
System (Brain and
Spinal Cord)
Peripheral
Somatic (controls
voluntary
movement of
skeletal muscles)
Autonomic
(controls actions
of internal organs
and glands)
Sympathetic
(arousing)
Parasympathetic
(calming)
Endocrine System
 Endocrine
system – set of glands that
produce hormones, chemical messengers
that circulate in the blood stream

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Hormone – chemical messengers
Pituitary gland – “master gland” in brain;
controls the other glands
Thyroid gland – regulates energy levels
Adrenal glands – help to arouse body in
times of stress