the nervous system and neurons

• the nervous system is our main internal communication system
• What’s missing?

  somatic nervous system

  
• What’s missing?

  autonomic nervous system

  
• What’s missing?

  parasympathetic nervous system

  
• What’s missing?

  sympathetic nervous system

  
• What’s missing?

  the central nervous system (CNS)

  
• What’s missing?

  brain

  
• What’s missing?

  spinal cord

  
• The CNS:

  the brain deals with higher order thinking skills such as problem solving.

  the spinal cord relays information from the brain to the body, and deals with some reflex responses
• autonomic nervous system- transmits and receives messages from the organs.

  it is made of the sympathetic (bodily arousal) and parasympathetic (bodily calm) of the NS.

  this is involuntary.
• somatic nervous system- transmits and receives messages from the senses and controls muscle movement, this is under conscious control.
• What’s missing?

  Soma

  
• What’s missing?

  Nucleus

  
• What’s missing?

  Axon

  
• What’s missing?

  Myelin Sheath

  
• What’s missing?

  Axon terminal

  
• 1: sensory neuron

  2: relay neuron

  3: motor neuron

  
• Sensory neuron: they send signals from your sense organs to the brain.

  They have short axons but long dendrites.

  Relay neuron: these connect the sensory neurons to the motor or other relay neurons.

  They have short axons and short dendrites.

  Motor neuron: these connect the CNS to effectors such as muscles and glands.

  They have long axons but short dendrites.
• Synaptic transmission: signals cross between neurons at the synapse.
• Neurotransmitters are chemicals that diffuse across the synapse to the next neuron.

  Neurotransmitters can either be excitatory or inhibitory in their action.
• This process is called synaptic transmission

  
• Synaptic transmission process

  1. Electrical impulse (action potential) triggers

  2. Vesicles containing neurotransmitters move to pre-synaptic cell membrane

  3. Vesicles fuse with membrane and release neurotransmitters into synaptic cleft

  4. Neurotransmitters diffuse across and bind to receptor sites

  5. Enough receptors have neurotransmitters bound, signal is transmitted
• Enough receptors have neurotransmitters bound

  Results in either excitation or inhibition (more or less likely to fire)
• Summation

  Net effect to the excitatory or inhibitory potentials (adding up the positive and negative charges)