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The Nervous SystemThe Master System
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Nervous SystemNervous SystemBy the end of the lesson you should be able to
Describe the transmission of impulses from
senses to central nervous system and back tomuscles.
Describe the reflex action and the pathwayof the reflex arc.
Describe the function of reflex response.
Describe the role of the central nervoussystem.
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The System
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A system that controls all of theactivities of the body.
The nervous system is made of:
The brain
The nerves
The spinal cord
The senses
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nervous system
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Anatomy
http://www.dorlingkindersley-uk.co.uk/nf/ClipArt/Image/0,,239033_1582296_,00.html
Central Nervous System PeripheralNervous System
(CNS) (PNS)
-Brain -Nerve Network of the
Body-Spinal Cord
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Basic Neurons
Sensory neurons carry signalsfrom the outer parts of your body(periphery) into the centralnervous system.
Motor neurons (motoneurons)carry signals from the centralnervous system to the outer parts(muscles, skin, glands) of yourbody.
Interneurons connect variousneurons within the brain andspinal cord.
Receptors sense the environment(chemicals, light, sound, touch)and encode this information intoelectrochemical messages thatare transmitted by sensoryneurons.
http://health.howstuffworks.com/brain2.htm
http://healthmad.com/conditions-and-diseases/brain-
anatomy-for-nurses-made-simple-self-learn-series/
Bipolar
(Interneuron)Pyramidal Cell
Motor Neuron
(multipolar)
Sensory Neuron
(unipolar)
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Basic nerve cell structureBasic nerve cell structure
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3 main types of nerve cells3 main types of nerve cells
sensory
neuronrelay
neuron
motor
neuron
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Classifying Neurons
The nerve cell bodies are generally located ingroups. Within the brain and spinal cord, thecollections of neurons are called nuclei andconstitute the gray matter, so-called because oftheir color. Outside the brain and spinal cord thegroups are called ganglia. The remaining areasof the nervous system are tracts of axons, thewhite matter, so called because of white myelin
sheath. Tracts carrying information of a specifictype, such as pain or vision, generally havespecific names.
http://webschoolsolutions.com/patts/systems/nervous.htm
http://www.cerebromente.org.br/n07/fundamentos/neuron/rosto_i.htm
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Sensory neuronsSensory neurons
Carries impulses from receptors e.g painreceptors in skin to the CNS( brain or spinalcord)
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Relay neuronRelay neuron
Carries impulses from sensory nerves tomotor nerves.
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Motor neuronMotor neuron
Carries impulses from CNS to effector e.g.muscle to bring about movement or gland to
bring about secretion of hormone e.g ADH
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The CellularComponents
Neurons
-Function: transmit
information
-There are 28 billion inthe human body
-Longest neuron is alittle over 1 meter
Glial Cells
-Function: support neurons in
place and provide insulation
-These cells outnumber the
neurons by 1 to 10 ratio
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Transmission of signals
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The Synapse
parkinsons
parkinson
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NERVOUS SYSTEM
CNS (Central Nervous System)
SegmentationPNS (Peripheral Nervous System)Spinal NervesNeuron Types
Autonomic Nervous System
(how many nervous systems are thereanyways?)
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Central Nervous System (CNS)
Brain and Spinal CordCentral CommandPNS (Peripheral Nervous System) arenerves that go out to targets in body
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The Central Nervous System controls all of the bodys activities.
* The Central Nervous System is made of two main organs.
1. The brain
2. The spinal cord
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The Central Nervous System is made of the brain and the spinal cord.
The Central Nervous System controls everything in the body.
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An organ that controls your emotions, your thoughts, and everymovement you make.
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Peripheral Nervous System (PNS)
All nerves that leave the CNSTwo Modalities:
Sensory/Afferent
(info. In)
Motor/Efferent
(commands out)
Somatic
Visceral/Autonomic
Somatic
Visceral/Autonomic
--smooth mm.
--heart--glands
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BrainCranial Cavity of SkullSpinal Cord
Vertebral ArchesCranial Nerves I-XII (offbrain)Spinal Nerves
C--8 prs (L,R)T--12 prsL--5 prsS--5 prs
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Transverse View (x-section)
vertebral body
vertebral arch
vertebral foramen
spinal cord
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Sagittal View
vetebral body, arch
intervertebral discspinal cordspinal nerves (where?)
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Zebra-Man
DermatomesEach is sensory area ofone spinal nerve
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Segmental Spinal nerve
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Autonomic Targets
All have dual
sympathetic and
parasympathetic
innervation
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The nervous system also allows you to react to a stimulus.
A stimulus is a change in the environment.
Example: A hot stove
Or tripping over a rock
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Your reactions are automatic.
Automatic means that you do not have to think about your reactions.
Example: If a bug flies by your eye,
you will blink.
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The Outer Nervous System is made of the nerves and the sense organs.
Nerves Sense organs
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Messages carried throughout the body by nerves.
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The Neuron
-the cell body, containing the nucleus (genetic material)
-dendrites, hair-like structures surrounding the cell body,which conduct incoming signals-the axon (or nerve fiber), varying in length from a millimeter
to a meter, which conduct outgoing signals emitted by theneuron. Axons are encased in a fat-like sheath, calledmyelin, which acts like an insulator and, along with theNodes of Ranvier, speeds impulse transmission
http://webschoolsolutions.com/patts/systems/nervous.htm
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Glia
-Astrocyte - provides physical and nutritional support for
neurons; digests part of dead neurons as well as regulates theextracelullar fluid around the neuron.
-Microglia - digests part of dead neurons
-Oligodendroglia - provides insulation for neurons (myelin)
-Satellate cell- provides physical support for neurons in PNS
-Schwann cell- provides insulation for neurons (myelin)
http://library.thinkquest.org/C0126536/main.php?currentchap=1¤tsect=neuron.htm&pagenum=6
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How does it work?
When at rest a neuron ispolarizedthat is, it has anegative charge on theinside of the cell relativeto the outside of the cell.This is because it has a
higher concentration ofnegatively charged ionson the inside. Whenstimulated, the nerve cellmembrane becomespermeable to sodium ions,which rush in temporarilycausing a positive chargeto build up on the insiderelative to the outside.When the electricalimpulse reaches the endof the axon it istransferred to the nextnerve cell so the messagehttp://www.naturalhealthschool.com
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More Shapes and Sizes
http://www.mind.ilstu.edu/curriculum/neurons_intro/neurons_intro.php
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Somatosensory Receptors
Input (afferent system) to the nervous system is in the formof our five senses: touch/pain, vision, taste, smell, andhearing. Pain, temperature, and pressure are known assomatic senses. Sensory receptors are classified
according to the type of energy they can detect andrespond to.
Mechanoreceptors: hearing and balance, stretching.
Photoreceptors: light.
Chemoreceptors: smell and taste mainly, as well asinternal sensors in the digestive and circulatory systems.
Thermoreceptors: changes in temperature.
Electroreceptors: detect electrical currents in thesurrounding environment.
http://webschoolsolutions.com/patts/systems/nervous.htm
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Physiology (function)
http://webschoolsolutions.com/patts/systems/nervous.htmhttp://www.biologymad.com/NervousSystem/nervoussystemintro.htm
In the PNS, collections of
neurons are called ganglia
In the CNS, collections of
neurons are called nuclei
Involuntary Control Voluntary Control
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Physiology ofAutonomic Nervous
System
http://www.biologymad.com/NervousSystem/nervoussystemintro.htm
Sympathetic
(stimulate
function)
Parasympathetic
(calms)
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Thank you
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