Snake Senses and Neurons

Snake Senses

  • Thermoreceptors: Snakes have an enlarged cavity on their face between their eye and nostril containing thermoreceptors, which allow them to detect heat.
  • Hearing: Snakes lack external ears, but they can hear. Their elongated lung picks up vibrations, and neurons associated with the lung interpret these vibrations as sounds. A large air sac can pick up vibrations.
  • Chemoreceptors: Snakes use their tongue to pick up chemical signals.
  • Pain: Snakes have specialized free ending nerves called nociceptors that detect pain.

Neurons and Neurotransmitters

  • Nociceptors: These are free ending nerves specialized for detecting pain.
  • Neurotransmitters: When a neuron communicates with another cell, they don't physically touch; instead, they communicate via chemicals called neurotransmitters.
  • Psychoactive Drugs: Many drugs mimic neurotransmitters in our body, including:
    • Cocaine
    • Methamphetamine
    • Adderall
    • Ritalin
    • Cradle
    • Caffeine
    • Nicotine
    • Alcohol
    • Benzodiazepines
    • Opiates (Vicodin, fentanyl, morphine, codeine, heroin)
    • THC (tetrahydrocannabinol)
  • Neurotransmitters and Pain: Nociceptors release neurotransmitters such as glutamate or substance P, depending on whether the pain is acute or chronic.
  • Glutamate: Glutamate is a common neurotransmitter.

Nervous System Communication

  • Electrical and Chemical Communication: The nervous system uses a combination of electrical and chemical communication.
    • Communication within a neuron is electrical.
    • Communication between cells is chemical.
  • Neuron Structure: A neuron consists of three major parts:
    • Dendrites
    • Cell body
    • Axon
  • Information Flow: Information typically flows into the neuron via the dendrites. Flow of information goes in one way.
  • Axon Hillock: Located at the start of the axon, it determines whether the signal will be excitatory or inhibitory.
  • Conflicting Information: Dendrites can receive conflicting information from numerous sources. The axon hillock determines which message will be sent.
  • Excitatory vs. Inhibitory: The neuron either sends a message (excitatory) or does not send a message (inhibitory).
  • Action Potentials: If the signal is excitatory, action potentials are sent down the axon.
  • Terminal Knobs: At the end of the axon, terminal knobs release neurotransmitters.
  • Synaptic Gap: There is a small gap between the terminal knobs of one neuron and the next neuron; they do not physically touch.

Nervous System Diversity Among Animals

  • Cnidarians: In cnidarians (e.g., jellyfish), there is no brain; instead, there is a nerve net.
  • Nerve Net: Neurons communicate with each other, spreading information, but there is no centralized processing center.