Download The Nervous System

Drew Grinsteinner
Jacob McGoogan
Functions of the System
 Movement
 The control room for all muscle contractions
 Senses
 Taste
 Touch
 The nervous system allows us to observe and
react to changes in our environment
Functions of the System
Movement
Central Nervous System (CNS)
All intentional movements, feelings, thoughts and processes
Peripheral Nervous System (PNS)
All actions of the body that do not deal with the CNS. These
are all essentially reactions.
Sounds Familiar….. Reactions are a feedback mechanism!
Functions of the System
 Intentional movement (CNS)
 These movements originate as nerve impulses from the brain
 The impulses travel down the spinal chord and reach a particular
muscle fiber
 The neurons that transmit this impulse are called motor neurons
Functions of the System
 Reactions (PNS)
 Reactions are movements that do not deal with the CNS, but instead,
the Peripheral Nervous System
 Sensory Neurons transmit an impulse to interneurons located in the
spinal chord
 These impulses are then transferred to motor neurons connected to the
muscle fiber it stimulates
Functions of the System
 The Feedback Mechanism
 Stimulus- A sudden force put onto the body that a sensory neuron
picks up
 Receptor- The sensory neuron that transmits a nerve impulse to the
spinal chord. The impulse hits an interneuron and is sent back through
a motor neuron pathway
 Effector- The nerve impulse hits the motor neuron which then
stimulates the muscle to contract briefly, causing a twitch
Structure of the Neuron
 Nerve cells= Neurons
 These cells are structural and functional units of the
nervous system that are specialized to react to physical
and chemical changes in the surrounding
environment
 These cells send nerve impulses which are in the form of
electrochemical changes
Structure of the Neuron
 Neurons have…
The main rounded area which is the cell body
 Off of the cell body are 2 types of attachments,
dendrites and an axon
Dendrites are the attachment that receive impulses
Axons are the attachment that send impulses
Structure of the Neuron Cont.
 All along the axon, Schwann Cells or Neurolemmocytes
envelope the axon
 The purpose of a Schwann Cell is to produce myelin
 Myelinated Nerve cells appear white and whole groups of cells are
referred to as white matter
 Unmyelinated cells do not appear white and are viewed in a group
as grey matter
Structure of the Neuron

http://www.enchantedlearning.com/subject
s/anatomy/brain/Neuron.shtml
Synapses
 The junction between any two communicating
neurons is called a synapses.
 The impulses that are sent travel between many
neurons in a series of complex nerve pathways.
 The neuron carrying the impulse into the synapse is the
sender or the pre-synaptic neuron
 The Neuron receiving the impulse in a synapse is the
receiver or the post-synaptic neuron
Axon end of synapses (PreSynaptic)
 The distal end of the axon have either 1 or more
extensions called synaptic knobs, which are
absent in dendrites
 When a nerve impulse reaches a synaptic knob, the
synaptic vesicles in the knob release
neurotransmitters
 Neurotransmitters diffuse across the axon’s
and bind with specific receptors in
neuron
membrane
the post-synaptic
Dendrite end of the synapse (postsynaptic)
 The post-synaptic neurotransmitter receptors receive the
electro-chemical signals
 The unused portion of the neurotransmitters get
recycled by diffusing back in to the vesicles
located in the axon
 This process is then repeated until the nerve impulse
reaches its destination. Ex: Muscle Fibers,
Interneurons, or the Brain
Synaptic Transmission
http://mycozynook.com/28_06aNeuronCommuni
cat-L.jpg
Central Nervous System(CNS)
 The Central nervous system is composed primarily of
the Brain and Spinal cord
 Disruptions of the central nervous system can cause
side effects ranging from paralysis to death.
 So be careful
The Brain
The Brain
 There
are 5 lobes of the brain which
include:
 Frontal lobe
 Occipital lobe
 Parietal lobe
 Temporal lobe
 Insula lobe (inside the brain)
The Brain
 The
cerebellum is used to send signals to
voluntary muscle control
 The
brain stem is used to send those
signals outside the brain.
The Spinal Cord
The Spinal Cord
 The
spinal cord is made up of 31 segments
each with a pair of spinal nerves
 Also
part of the CNS
The Spinal Cord
 The
spinal cord unlike the peripheral
neurons can send messages to the nerves
itself causing reflexes.
Peripheral Nervous System(PNS)
The peripheral nervous system is the nerves and nervous tissue outside of
the central nervous system
Damage to these nerves are not as fatal and life changing unlike the central
nervous system
The system is split in two categories the Autonomic and Somatic nerves.
Autonomic Vs. Somatic
Autonomic Nervous
System
Somatic Nervous
System
0 The part of the PNS
0 The part of the PNS
that functions
independently
0 Runs in two parts
Sympathetic and
Parasympathetic
that functions
dependently
0 Responsible for
Senses and Cranial
Nerves
HUMAN SENSES AND CRANIAL NERVES
HUMAN SENSES AND CRANIAL NERVES
Optic
Oculomotor
•
Sensory
•
Primarily Motor
•
Transmits the senses of vision
•
Transmit impulses that raise eyelids,
move eyes, focus lenses, and adjust
light entering eye
HUMAN SENSES AND CRANIAL NERVES
Trochlear
Trigeminal
•
Primarily Motor
•
Mixed
•
Transmit messages to move the eyes
•
Transmit messages to the mouth and
tear glands
HUMAN SENSES AND CRANIAL NERVES
Abducens
Vestibulocochlear
•
Primarily Motor
•
Sensory
•
Transmit messages to move the eyes
•
Transmit impulses to aid hearing and
equilibrium
HUMAN SENSES AND CRANIAL NERVES
Glossopharyngeal
Vagus
•
Mixed
•
Mixed
•
Transmit impulses to throat and saliva
glands as well as swallowing
•
Transmit impulses to assist speech
and swallowing
HUMAN SENSES AND CRANIAL NERVES
Accessory
Hypoglossal
•
Primarily Motor
•
Primarily Motor
•
Cranial Branch
•
Transmit impulses to the tongue
Transmit impulses to the soft plate,
pharynx, and larynx.
•
Spinal Branch
Transmit impulses to the neck and back
HUMAN SENSES AND CRANIAL NERVES
Taste Vs. Smell
Olfactory cells (sense of smell)
Facial (sense of taste)
The to senses are connected via limbic system which is responsible for emotions and
memories
Which means when you eat something you like it does not really taste good it is your body
remembering it tasting good and displaying emotion accordingly.
AUTONOMIC NERVOUS
SYSTEM(SYMPATHETIC)
 Preganglionic Fibers originate in the gray matter of the spinal cord
 The axons leave through ventral roots traveling a short distance
 They leave the spinal nerves and enter a member of the paravertebral
ganglia
 After this the postganglionic fiber returns to the spinal cord
Autonomic Nervous
System(Parasympathetic)
 The preganglionic fibers of the parasympathetic
division arise from the brain stem and the spinal cord
 From there they go to various viscera the relatively
short postganglionic fibers go to specific muscles or
glands
DISEASES AND DISORDERS
Headaches
Brain Tissue has no pain sensitive nerve cell therefore when
somebody has a headache it is actually caused by blood vessels in the
brain where other nerves in the brain transmit as pain.
Migraines are just a more extreme case of the same concept.
DISEASES AND DISORDERS
Multiple Sclerosis
The immune system in this genetic disorder attacks the myelin in the
nerve cell as a alien disease and starts to eat away at the myelin. As the
myelin breaks down nerve impulses are disrupted causing many
people with the disorder to lose balance and coordination.
DISEASES AND DISORDERS
Epilepsy
1 in every 100 to 200 people have this condition where the brain
temporally lose all control to process incoming and control skeletal
muscle. The visible symptoms of this is seizures and loss of
consciousness for the time the episode begins the symptoms can be
treated through medication.
Now lets play telephone to help learn these concepts