Coordinating Movement, etc.! Nerve Systems

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Coordinating Movement, etc.! Nerve Systems
nucleus
output
input
transmission
Released from vesicles
Electrical Transmission -- Chemical Connection.
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In peripheral nerves, the tissue is mostly axons,
tightly packed like the wires in a complex phone
cable!
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Conduction of action potential along neuron
A bit slower than electrical wire, but does not
need heavy, rigid metal and, for typical organism
sizes, is fast enough!
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Myelin Sheath Increases Rate of Transmission
Electrical current passes rapidly (150 vs 30 m/s)
down the sheathed axon segments

• Multiple Sclerosis and Guillain-Barré Syndrome

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Coordinating Movement, etc.! Nerve Systems
Regulation by ACH or NE.
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Neurotransmitter Roles
Opposing Muscles
Glands
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Neurotransmitter diffusion is fast enough

• Because the synapse gap is about 0.001 mm

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AcetylCholine

• Stimulates muscle contraction in the
  neuromuscular junction.
• Atropine blocks Ach receptionrelaxation of iris
• Slows the pacemaker in the heart.

Adrenaline (nor-epinephrine)

• Promotes nutritional release to blood
• Speeds the pacemaker in the heart.
• Higher blood pressure, more oxygenation
• Fright, Flight, or Fight stimulant

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Simple Nervous Systems

• gt dendrite
• O soma
• ------- axon
• gt synaptic terminal
• S sensor
• M muscle cell
• gtO------------gt neuron
• --gtgtOgtgtO--- interneuron
• gtO------------gtM motor neuron
• SgtO----------gt sensory neuron
• Reflex Arc
• SgtO----------gtgtOgtgtO------------M (one of each)
• tendon spinal cord muscle

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A neuron can have many synaptic terminals

• These synaptic terminals are neuromuscular
  junctionshow can you tell?

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The spinal cord has cell bodies surrounded by
dendrites and axons

• Reflex arcs connect via interneurons here in the
  spinal cord!

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Complex Nervous Systems

• Cell bodies in ganglia in peripheral nerves
• Cell bodies in spinal cord and brain
• Much of Central Nerve System are interneurons
• Connect to Sensors, Muscles, Glands, etc.
• Connect to each other!

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Mapping a Portion of the Brain

• Here you can see where portions of the brain map
  out to body parts.
• You might notice that the body has biases in
  terms of mapping various areas.
• The head and face covers as much neural tissue as
  the rest of the body.

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The Sensory Inputs

• Taste sensors have receptors for molecules of
  interest to the organism.
• Taste cells transduce receptor-molecule complex
  into action potential.
• Action potential is transmitted to sensory neuron
  with soma in a nearby ganglion.
• Sensory neuron may be connected to a reflex arc
  and/or the central nervous system.

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The sensitive tongue of reptiles is for tasting
the air!
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Chemotaxis is Signal Tranduction Too!

• Bacterium movement haphazard without signal
• Straight line movement in signal path
• Haphazard movement when off-target
• Restored straight line movement on path

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The Largest Organ of the Body has Many Sensors!

• Dendrites (nerve endings) for pain, and itch
• Pressure sensors
• Stretch receptors to hair shafts
• Touch and pressure receptors
• Temperature flow sensors can be confused!
• Sensor density varies over the bodyface and
  hands are dense!

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Arthropod legs have chemical, pressure, and other
sensors
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Sound Waves

• Sound travels as pressure waves
• Wavelength (frequency) is pitch (shortfasthigh)
• Amplitude (height) is intensity (decibels)
• gt100 damaging

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The Sound Transducer

• Sound collected by outer ear
• Pressure waves vibrate eardrum
• Former jawbones amplify the vibrations
• Tapping on Cochlea (inner ear) vibrates
  fluid-surrounded ciliated transduction cells
• Action potential sent to auditory nerves
• Auditory nerves connect to CNS
• Perception of sound in CNS
• Cultural appreciation based upon experience
• Plants cannot do this!

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The antennae of a moth are for chemical and sonic
stimuli