The Nervous System

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The Nervous System
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Nervous System

• Nervous System Collects information, processes,
  and responds to internal and external environment

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Overview of Nervous System

• Stimulus Something in environment causes a
  response
• Neuron Cell that receive, conduct, and transmit
  impulses
• Response Reaction to environmental conditions

synapse
RESPONSE!
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The Neuron

• Neurons build into nerves!

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Parts of the Neuron

• Dendrites
• Receive messages from previous neurons
• Send message to cell body
• Cell Body
• Contains nucleus and cytoplasm

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Parts of the Neuron Contd

• Axon
• Long fiber that carries messages away from the
  cell body
• Myelin Sheath
• Insulating membrane helps send the signal down
  the axon
• Nodes of Ranvier
• Gaps between Schwann Cells
• Impulse jumps from one node to next
• Schwann Cells
• Supporting cells that wrap around the myelin
  sheath

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Parts of the Neuron Contd

• Axon Terminals
• Branches at the end of an axon
• Contain synapses where neurotransmitters are
  released

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Synapses

• Synapse
• Space between neurons
• Carry messages or impulses from one nerve to the
  next
• Neurotransmitters
• Chemical messages sent between neurons
• Diffuse to next neuron

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How does a neuron work? Summary

• Neurotransmitter received from another neuron in
  dendrites through cell body
• Impulse travels down the axon
• Neurotransmitter released into synapse
• Neurotransmitter received by protein receptors in
  dendrites of next neuron

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A closer look at how an impulse travels down the
axon

• Polarization- differences in charge ( or -)
• Electrical charges are different inside a neuron
  compared to outside
• Caused by K and Na
• K and Na can move through channels within the
  axon membrane

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A closer look at how an impulse travels down the
axon

• Impulse is carried down the axon
• Resting
• Negative inside (-70 mV)
• Active- Impulse in progress
• Positive inside (40 mV)

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How does a neuron work?

• http//outreach.mcb.harvard.edu/animations/actionp
  otential.swf

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Types of Neurons
Motor Neuron (Spinal Cord and Brain ? Muscles and
Glands)
Receptor Sensory Neurons (Sensory Organs
?Spinal Cord and Brain)
Interneurons Sends Messages between Nerves
(Sensory, Receptor, Motor, and other Interneurons)
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Reflex Arc
No brain involved!
Receptor
Afferent Neurons
Sensory Neuron
Spinal Cord
Interneuron
Efferent Neurons
Motor Neuron
Effector (Muscle)
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Central Nervous System (CNS)

• Consists of the brain and spinal column

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Spinal Cord

• Gray Matter
• Consists of cell bodies
• White Matter
• Consists of axons

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Parts of the Brain
Meninges- protective covering of the brain/spinal
cord
Corpus Collasum
Occipital
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Brain Area Function
Meninges Protection of spinal cord and brain
Cerebrum Memory center
Cerebellum Coordination and balance
Medulla Involuntary processes
Spinal Cord Nerves from brain
Thalamus Relay center between brain and spinal cord
Occipital Vision Hearing
Hypothalamus Homeostasis- hunger, thirst, hormones Links endocrine to nervous system
Corpus Collasum Connects left and right brain
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Peripheral Nervous System

• Peripheral Nervous System- connects the central
  nervous system to the rest of the body
• Somatic- voluntary
• Autonomic- involuntary
• Parasympathetic- at rest
• Sympathetic- fight or flight

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Malfunctions

• Meningitis- swelling of meninges
• Cerebral Palsy- birth defect, affects muscle
  coordination
• Stroke- blood clot to the brain
• Polio- viral illness
• Multiple sclerosis (MS)- break down of myelin
  sheath- impairs movement

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Malfunctions

• Drug Addictions
• Stimulants
• Increase the number of neurotransmitters
• Depressants
• Decrease the number of neurotransmitters