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THE NERVOUS SYSTEM
By: Adriana Aguilar
Anel Perez
Stephanie Armenta
Brianne
THE NERVOUS SYSTEM
Main functions include:
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Regulates breathing-
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Regulates the heartbeat
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Regulates the body temperature
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Controls the body’s movements
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Helps with the digestion of food
THE NERVOUS SYSTEM
THE NEURON
It is the functional unit of the nervous system.
Neurons are found in the brain, spinal cord, and
sensory organs.
| A neuron is composed of a nucleus, dendrite,
soma and axon.
| Dendrite- receive messages from other neurons
| Soma- the body
| Nucleus- the brain
| Axon- carry messages away
| Neurotransmitters- carry messages
| Synapse- connection between two neurons
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TYPES OF NEURONS
There are three basic ways that neuron processes
leave the soma. The processes leave the soma
through various neurons. Such neurons like:
| Anaxonic neurons, Unipolar neurons, Bipolar
neurons, pseudounipolar neuron, and multipolar
neuron. Neurons can be structurally classified by
the way that the neuron is composed of either the
axon, dendrites or cell processes.
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FUNCTIONAL CLASSIFICATION OF SENSORY
NEURONS
Sensory neurons deliver information from
sensory receptors to the CNS. They collect
information concerning external and internal
environment.
| Somatic sensory monitor outside
| Visceral sensory monitor internal
| Sensory receptors include: exteroceptors,
proprioceptors, interoceptors.
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FUNCTIONAL CLASSIFICATION OF MOTOR
NEURONS
Motor neurons carry instructions from the CNS
to peripheral effectors. The axons traveling away
from motor neurons are called efferent fibers.
| You have conscious control over the activities of
the somatic motor neurons.
| You do not have conscious control over the
activities of the visceral motor neurons.
| To get from the CNS to a visceral effector the
signal must travel along one axon be relayed
across a synapse, and then travel along a second
axon to it’s final destination.
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FUNCTIONAL CLASSIFICATION OF
INTERNEURONS
Interneurons outnumber all other types of
neurons combined.
| Responsible for distribution of sensory
information and the coordination of motor
activity.
| Also responsible for part of memory, planning,
and learning of the brain.
| The more complex the response to a given
stimulus the greater number of interneurons.
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THE PATH OF A NERVE IMPULSE
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A nerve impulse begins when a stimulus is collected by he
sense organs through the sensory neurons.
Nerve impulses are electrical and/or chemical signals sent
through our bodies.
Nerve impulses travels within the neuron as an electrical
signal-an impulse travels within a neuron from the
dendrites through to the axon terminals
Nerve impulses travel between neurons as chemical
signals-Neurons are not connected to one another they are
separated by tiny gaps called a synapse. The impulses
changes to a chemical signal at the axon terminal, travels
through the synapse, and then is picked up once again as
an electrical signal by the dendrites.
Nerve impulses travel in only one direction-from the
dendrite to the axon terminal-from sensory neuron to
interneuron to motor neuron.
THE PATH OF A NERVE IMPULSE
THE CENTRAL NERVOUS SYSTEM
It is composed of the brain and spinal cord.
| The brain is composed of three major parts: the
cerebrum, cerebellum, and medulla oblongata.
| The brain consists of ventricles, the lateral, the
third, and the fourth ventricle.
| The spinal cord is the linkage and
communication site for the brain to the rest of the
body.
| The spinal cord has three major functions:
maintaining reputative, coordinating skeletal
muscle contractions, and conducting info to and
from the brain.
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THE PERIPHERAL NERVOUS SYSTEM
It contains only nerves.
| It connects the CNS to rest of the body.
| It is made up of two subdivisions: the somatic
and autonomic.
| The two main components are the sensory and
motor pathways.
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SPINAL NERVES
A series of connective tissue layers surrounding
each spinal nerve and its peripheral branches.
| It consists of three layers: the epineurium,
perineurium, and endoneurium.
| A pair of spinal nerves is known as dermatome.
| Similar to the spinal nerves are the Cranial
nerves.
| Cranial nerves are however derived from the
cells located in the brain.
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NERVE PLEXUSES
A complex interwoven network of nerves.
| There are four major plexuses: the cervical,
brachial, lumbar, and sacral.
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REFLEXES
They are rapid automatic responses to specific
stimuli.
| They preserve homeostasis.
| There are five steps in the path the reflex takes.
| They can be classified by either: their
development, the site of information processing,
the nature of the resulting motor response, the
complexity of the neural circuit involved.
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TYPES OF REFLEXES
The Spinal reflex is the most complicated
intersegmented reflex arc.
| In Monosynaptic reflexes there is little between
sensory input and motor output.
| The Polysynaptic reflexes can produce far more
complicated responses.
| Flexor reflex is a representative withdrawal
reflex.
| Cross Extensor reflex is the stretch, tendon and
withdrawal reflex.
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MEMBRANE POTENTIAL
It is the voltage difference between the interior
and exterior of a cell.
| It affects the activity of excitable cells and the
trans-membrane movement of all charged
substance.
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THE NERVOUS SYSTEMS WORKING WITH
OTHER BODY SYSTEMS.
The Nervous system works with all the other
body systems.
| For all the systems it monitors pressure, pain
and temperature it also adjusts tissue blood flow
patterns.
| Examples of systems that work with the Nervous
system are the skeletal system, the respiratory
system and the digestive system.
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INTERESTING FACTS
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A new born baby loses about half their nerve cells
before they are born.
There are about 1,350,000 neurons in the human
spinal cord.
The average adult female brain is about 100 grams
less than then the average adult male.
Only four percent of the brains cells work while the
remaining cells are kept in reserve.
If we lined up all the neurons in our body I would be
around 600 miles long.
The human brain stops growing at age 18.
The brain continues to send out electrical wave
signals until approximately 37 hours after death.
Men listen with the left side of the brain and women
use both sides of the brain.