Transcript Nervous System PPT

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Nervous System (NS)
Peripheral NS
Autonomic NS
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Somatic NS
Central NS
Brain
Spinal Cord
What is the nervous system?
Each day, you use verbal and nonverbal
communication as a signal to others. For
example, to signal a student has a question,
he/she would raise his/her hand. The teacher
would recognize this signal and direct his/her
attention to the student. Your body works in
much the same way. The nervous system is one
of your body’s personalized communication
systems. Signals are sent from one location to
another in order to control and coordinate many
bodily functions. The nervous system responds
to internal and external stimuli.
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• Are cells, which transmit electrical signals or
impulses
• Provide a pathway for messages going to and
from the brain and spinal cord
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• Characteristics:
– have a cell body, which is the largest part
– have processes
» are fiber-like extensions
» increase the distance at which signals can
be transmitted
» two types of processes:
dendrites -- carries signal to the cell body
axons -- carries signal away from cell body
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Cell body
Myelin sheath
Axon
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Dendrites
Nucleus
Axon terminals
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Transmit signals toward the body
Are short and branch extensively
Neurons may have dozens of dendrites
Are bound with axons to form a nerve
pathway
• Transmit signals away from the body
• Most neurons have only one very long
axon
• Gaps between synaptic knobs are
called synapses
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• Myelin sheath
» cover the axon for protection
» aid in delivery of impulses traveling
through the axon by insulating the nerve
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• Is the location where neurons transfer impulses
between cells
• Are gaps separating the axon terminal from dendrites of
adjacent cell
• Have terminals containing sacs filled with
neurotransmitters
– are chemicals used by neurons to transmit impulses
across a synapse to another cell
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1. Central nervous system
•
central processing system of
the nervous system -- much
like the main processing chip
of a computer
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Peripheral nervous system
• relays information received
from the central nervous
system to organs and
glands
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• Brain
• Spinal Cord
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• Is the central control unit for the body
• Is protected by the skull
– cerebrospinal fluid (CSF) occupies
space between two layers
» functions as a shock
absorber
» allows for the exchange of
nutrients and waste between
blood and nervous tissue
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• Divided into:
– cerebrum
– cerebellum
– brain stem
Did you know the average
adult human brain weighs
about 3 lbs.?
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• Connects brain and
spinal cord
• Is located beneath the
cerebellum
• Has two regions, which
act as a control system,
regulating information
between the brain and
body
– medulla oblongata
– Pons
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INJURY to this can lead
to COMA!!
• Is enclosed in the
vertebral column
• Is a continuation of the
brain stem
• Serves as the main
communication link
between the brain and
body
• Functions to:
– transmit impulses to
and from the brain
– control several reflex
actions
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Divided into two parts:
1. Motor Division
–
relays impulses from the central nervous system to
muscles and glands
2. Sensory Division
–
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relays impulses from sensory organs to the central
nervous system
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• Electroencephalogram: EEG, measures electrical
impulses in the brain
• CT/ CAT: shows cross section images of the brain
• Myelogram: picture of spinal cord after a contrast is
injected
• Cerebral Angiogram: picture of the brain’s blood
vessels after a contrast has been injected
• Reflexes: involuntary muscle contractions responding
to a stimulus
• Babinski’s : reflex on bottom of foot
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• Concussion: injury to brain from impact
• Coma: abnormal deep sleep wit or no response to
stimuli
• Brain contusion: bruise to brain
• Shaken baby syndrome: closed head trauma; brain
hitting skull
• Alzheimer’s: degeneration of neurons in the brain
• Amnesia: loss of memory
• CVA: stroke, cerebrovascular accident; lack of o2 to
brain
• Epilepsy: seizure; abnormal electrical impulse
– Aura: the feeling before a seizure
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• Hydrocephalus: injury to brain from impact
• Tourette syndrome: neurological disorder with
uncontrollable sounds and tics
• Paralysis: loss of feeling and movement
– Hemiplegia
– paraplegia
• Syncope: fainting
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