unit 1.3

• Neuron anatomy

  A) nucleus

  B) dendrites

  C) soma

  D) myelin sheaths

  E) axon terminals

  F) axon

  
• cell body/soma: cell's life support
• dendrite: branching extensions that relieves/integrates messages conducting impulses
• axon: passes the message to the terminal branches to other neurons/muscles/glands
• axon terminals: change electrical impulses into chemical messages in the form of neurotransmitters
• myelin sheath: fatty tissue that insulates the impulse and speeds them up
• glial cell: provides nutrients; protects cells
• threshold: minimum electrical current required to fire an action potential

  • if threshold is not met, neuron will not fire
• all-or-nothing principle: if neuron fires, then it will always fire at the same intensity; all action potentials have the same energy
• refractory period: period after a neuron fires to recharge itself

  • cannot generate another action potential
• resting potential: electrical potential across the membrane of a neuron when it is in the resting state
• synapse or synaptic cleft: gap between the axon terminal of one neuron and the dendrite of another

  • neurons communicate with each other across synapses
• reuptake: unused neurotransmitters in the synapse that are reabsorbed into sending neurons
• reuptake inhibitors: stops/delays the body from reabsorbing a neurotransmitter

  • leaves more of a neurotransmitter available in a synapse
  • selective serotonin reuptake treats depression
• multiple sclerosis (disorder caused by disruptions in the nervous system)

  • autoimmune disorder where the body attacks itself
  • destroys the myelin that coats and protects nerves in the central NS
  • symptoms: fatigue, bladder/bowel issues, sexual problems, pain, cognitive/mood changes, muscular changes, and visual changes
• myasthenia gravis (disorder caused by disruptions in the nervous system)

  • autoimmune disorder in which antibodies destroy muscle/nerve communication between neurons and muscles
  • weakens skeletal muscles
  • worsens over time/with use
• neurotransmitters: bind to the receptors of a receiving neuron in a lock and key mechanism
• agonists: mimics neurotransmitters

  • excitatory effects make it more likely to fire
  • morphine mimics endorphines
• antagonists: blocks neurotransmitters

  • inhibitory effect makes neuron firing less likely
  • curare (poison) blocks ACh receptors involved in muscle receptors
• psychoactive drugs: chemical substance that alters preceptions and mood
• ways drugs can affect behavior/mental processes

  • tolerance, addiction, withdrawl
• hallucinogen: distorts perceptions and evokes sensory images in the absence of sensory input

  • LSD
  • Peyote
  • marijuana
• depressants: reduces neural activity and slows bodily functions

  • alcohol
  • barbituates
  • opiates
  • morphine
• stimulants: excites neural activity speeds up bodily functions

  • caffeine/nicotine
  • amphetamines
  • ecstasy
  • cocaine
• opioids: temporarily reduces pain/anxiety

  • morphine
  • heroin
  • methadone
  • codeine
  • opium