The Nervous System

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The Nervous System

• Controls and coordinates the bodys responses to
  changes in the environment
• HOW
• Stimulus a change in the external or internal
  environment which initiates an impulse
• Impulse an electro-chemical charge generated
  along a neuron

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The Nervous System

• Receptors structures specialized to detect
  certain stimuli
• Response a reaction to a stimulus
• Effectors what responds to a stimulus such as
  muscles or glands

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Neurons

• Neuron Basic Unit of the Nervous System
• Neurons conduct impulses throughout the nervous
  system.
• A neuron is a long cell that consists of three
  regions a cell body, dendrites, and an axon.

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Neurons

• Dendrites receive impulses and carry them
  toward the cell body
• Axon carries impulses away from the cell body
  and toward other neurons, muscles, or glands.
• Cell body contains the nucleus

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Myelin sheath coating
signal direction

• Axon coated with insulation made of myelin cells
  speeds signal
• signal hops from node to node
• 330 mph vs. 11 mph

myelin coating

• Multiple Sclerosis
• immune system (T cells) attacks myelin coating
• loss and/or slowing of signal impulse

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Facts about neurons

• Most specialized cell in animals
• Longest cell
• blue whale neuron
• 10-30 meters
• giraffe axon
• 5 meters
• human neuron
• 1-2 meters

Nervous system allows for 1 millisecond response
time
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Types of Neurons

• 3 Types of neurons
• 1. Sensory neurons carry impulses from the body
  to the spinal cord and brain (sense receptors)
• 2. Motor neurons carry the response impulses away
  from the brain and spinal cord to a muscle or
  gland. (effectors)
• 3.Interneurons connect sensory motor neurons
  within the brain and spinal cord

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Types of neurons
sensory neuron (from senses)
interneuron (brain spinal chord)
motor neuron (to muscle)
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How an impulse is transmitted

• 1. Resting no impulse, cell is polarized ( on
  outside - on inside)
• Sodium/Potassium pump in axon using ATP maintains
  this polarity (active transport)slower

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How an impulse is transmitted

• 2.Impulse stimulus excites neuron
• Na channels open
• Na goes inside, therefore inside becomes more
• Depolarization occurs a nerve impulse
• Impulse moves in one direction
• Depolarization works with concentration gradient

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Synapse a connection

• Junction between nerve cells
• Connection between neurons effector cells

synapse
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Synapse a connection

• 1st cell releases chemical (neurotransmitter) to
  trigger next cell
• where drugs affect nervous system

synapse
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The Nervous Systems

• Central nervous system (CNS)
• brain spinal cord
• Peripheral nervous system (PNS)
• nerves from senses
• nerves to muscles/glands
• Both systems work together

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Anatomy of the brain

• Cerebrum
• Conscious activities
• Intelligence
• Memory
• Language
• Voluntary activity
• Cerebellum
• Coordinates motor activity balance

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Anatomy of the brain

• Midbrain
• reptilian brain (instincts, emotions)
• Hindbrain/Brain stem
• Medulla Oblongata involuntary activities such as
  breathing heart rate

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The Nervous System
Nervous System
Peripheral Nervous System (PNS)
Central Nervous System (CNS)
Somatic Nervous System (voluntary) Relays
information to and from skin and skeletal muscles.
Autonomic Nervous System (involuntary) Relays
information to internal organs.
Sympathetic Nervous System Controls organs in
times of stress.
Parasympathetic Nervous System Controls organs
when body is at rest