The Nervous System

• Examples of receptors include glucose sensing cells, skin temperature cells and skin pressure cells.
• Examples of effectors include insulin producing cells, muscle cells, hair cells and gland cells.
• Gland cells produce hormones and enzymes.
• The central nervous system is made up of the brain and spinal chord.
• -

  A) cell body

  B) dendrite

  C) nerve ending

  D) myelin

  E) axon

  F) nucelus

  
• Dendrites communicate with other neurons.
• The axon is the main wire of the neuron.
• The synaptic terminal is where neurons communicate with one another.
• Label this sensory neuron.

  A) direction of impulse

  B) synaptic terminal

  C) axon

  D) myelin sheath

  E) dendrite

  F) nucleus

  G) cell body

  H) dendrites

  
• The myelin sheath insulates the gain or loss of voltage and signals.
• A reflex arc is NOT voluntary.
• Reflex arcs do not send electrical impulses to the brain.
• When you experience a strong stimulus, an electrical impulse is sent from the sensory neurone to the spine, then to a relay neuron, then to a motor neuron, and then to the effector [muscle or gland] which will trigger a response.
• An electrical impulse arrives at the pre-synaptic neuron. Neurotransmitter chemicals are released. This diffuses across the synaptic cleft, and then binds to the receptors on the post-synaptic neuron membrane. This triggers an electrical impulse in the post-synaptic neuron.
• Synapses decrease the speed of transmission, so reflex arcs contain as little of them as possible.