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REGULATION
Two Types of Regulation
 Nervous:
 Accomplished
by nervous
system
 Sends message
as impulses
 Messages is
short-lived and
happens rapidly
 Chemical:
 Accomplished by
endocrine system
 Sends chemical
messengers called
hormones
 Message is
widespread and
happens slowly
Nervous System
 Stimulus: internal or external change that occurs in an
organism
 Response: organisms reaction to a stimulus
 Impulse: electrochemical message carried by nerve cell
 Receptor: structure that detects stimuli
 Effector: muscle or gland that responds or reacts to the
command of nervous system
Structure of the Nervous
System
Neurons:
Specialized cells
that help gather
information, interpret
it and react to it.
Using Electrochemical
messages
Structure of the Nervous
System
Nerve:
A bundle of neurons
Parts of the Neuron
Main Parts of the Neuron
Dendrites: Receive impulses from
other Neurons and conducts it to
cell body
Cell Body: The nucleus and
other organelles are found here
Axon: Carries the nerve impulse
away from the cell body to other
neurons and muscles
Terminal Branch: End of axon; area
where neurotransmitters are secreted
Parts of the Neuron
Main Parts of the Neuron
Myelin Sheath: Insulation that
increases the speed at which
the impulse can travel
Schwann Cells: Surrounds the
axon; produces the myelin sheath
Node Of Ranvier: Gap between
neighboring Schwann cells
Synapse
Synapse: Small space between two
successive Neurons
Synapse and Neurotransmitters
Synapse:
Is the small gap
between the axon and the
dendrite of neighboring
nerve cells.
Neurotransmitter:
Chemical that is released from a
neurons axon and binds with
receptors of another neuron’s
dendrites
Ex: Acetylcholine
Synapse
Synapse
Neurotransmitter
Synapse
Neurotransmitters - are chemicals used to
transmit an impulse from the axon of one neuron to
the dendrites of the next neuron
Neurotransmitters
 Excitatory neurotransmitters
 will excite a neuron, causing an action
potential ( Norepinephrine, Acytylcholine)
 Inhibitory neurotransmitters
 will depress (inhibit or slow) a neuron,
suppressing an action potential that might
otherwise go forward (Serotonin)
The Synapse
3 Types of Neurons
Sensory neurons:
Transmit impulses from the skin
and sense organs (Receptors)
to the central nervous system
(Brain and Spinal Cord).
Interneurons:
Interpret and relay nerve
impulses between sensory
and motor neuron.
(ONLY found In the Brain &
Spinal Cord)
Motor Neurons
Transmit impulses from the
CNS to the muscles or glands
(Effectors)
Reflex & Reflex Arc
1. Reflex is a quick automatic involuntary
response to a stimulus.
2. Reflex arc is the pathway that an impulse
travels.
a.
b.
c.
Impulse is the message carried by the neuron.
The transmission of the impulse is very quick.
Composed of Sensory neuron, interneuron, and
motor neuron. Notice the Brain is NOT involved
Sensory Neuron
Stimulated by
sensory receptors
Interneuron
Spinal cord
Motor Neuron
Muscle or Gland
Reflex Arc
4.
RECEPTOR 
SENSORY NEURON 
INTERNEURON 
MOTOR NEURON 
5.
EFFECTOR (MUSCLE OR GLAND)
1.
2.
3.
Nerve Impulses
 Nerve Impulse: A series of electrochemical changes
in a nerve cell membrane
 Resting Potential
 The distribution of Na+ and K+ inside and outside
the neuron causing a negative charge for the
neuron.
 Unequal distribution of these ions is maintained by
active transport
Nerve Impulses
Threshold
- Is the minimum level of stimulus that activates the
neuron.
- Any stimuli weaker than the threshold WILL NOT
produce an impulse.
Nerve Impulses
Action Potential
- Begins when a neuron is stimulated by another
neuron or by its environment.
- Na+ gates on the axon open up and let Na+ flow in.
-The inside of the neuron gains an positive charge
and the outside gains a negative charge.
-This is known as action potential.
Nerve Impulses
Impulse Graph
Action Potential
Action Potential
 Action Potential Animation
The Nervous System
Consists of two major divisions:
•The Central Nervous System
•The Peripheral Nervous System
The Central Nervous System
1. The Brain
2. The Spinal Cord
Which is mostly Interneurons
Brains
The Brain…
The Brain
Is responsible for controlling
and coordinating most of the
activities of humans
Cerebrum is the center of
voluntary activities,
memory and learning
Cerebellum coordinates
motor activities and
helps in maintaining
balance
The Brain
Medulla Oblongata controls
involuntary activities such as
breathing, heartbeat,
blood pressure and peristalsis.
The Brain
Medulla Oblongata controls
involuntary activities such as
breathing, heartbeat,
blood pressure and peristalsis.
Pons: Communicates between
Cerebrum and Cerebellum
The Brain
Medulla Oblongata controls
involuntary activities such as
breathing, heartbeat,
blood pressure and peristalsis.
Pons: Communicates between
Cerebrum and Cerebellum
Hypothalamus: Maintains
homeostasis ( Temp. Thirst,
Appetite, and water balance)
Spinal Cord
•Coordinates between the brain and the other
body structures
•Reflexes are processed in spinal cord
Spinal Cord
•Protected by the Spinal Column – Bony structure
The Peripheral Nervous System
It consists of sensory neurons and
motor neurons that carry
information to and from the CNS
The Peripheral Nervous System
Somatic nervous system:
Relays information to and from the skin and
skeletal muscles. Most of the time voluntary
except for a “Reflex”
Autonomic nervous system:
Relays information to internal organs and
is involuntary
Sympathetic Nervous System
Parasympathetic Nervous System
 The autonomic division of the PNS
has 2 major divisions
 Sympathetic nerves
 Increases the activity of the organ
 Ex) accelerator nerve - speeding the heart
beat
 Parasympathetic nerves
 Decreases the activity of an organ
 Ex) the vagus nerve slowing the heart beat
Nervous System Disorders
Cerebral Palsy :
A congenital disease characterized by
a disturbance of motor functions.
Usually normal intelligence
In certain cases there is no identifiable
cause, other etiologies include
problems in intrauterine development
(e.g. exposure to radiation, infection),
asphyxia before birth, hypoxia of the
brain, and birth trauma during labor
and delivery.
Meningitis:
Is swelling and irritation (inflammation) of
the membranes covering the brain and
spinal cord.
This inflammation causes changes in the
cerebrospinal fluid (CSF) that surrounds the
brain and spinal cord.
Meningitis:
Caused by Bacterial or Viral Infection in the Spinal Fluid
Symptoms:
Headache, Stiff Neck, fever
Vomiting, light sensitivity
Treatment:
Antibiotics, anti-virals and
now a vaccine to help prevent
Polio
Is a viral disease that can affect nerves and can
lead to partial or full paralysis.
Preventable by vaccine
The first was developed by Jonas Salk and tested
in 1952.
Stroke:
Is an interruption of the blood supply to any part of
the brain. Caused by blood clot of brain or
hemorrhage.
Most symptoms are muscle weakness or paralysis
depending on which part of brain was affected.
 One’s own
immune system
attacks the myelin
sheath on their
nerve cells.
 Vision problems,
depression, muscle
weakness and
paralysis may
occur
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