Neural signaling

• What do sensory neurons transmit?

  Nerve impulses from sense receptors
• Where are interneurons located?

  Within the CNS
• What do motor neurons transmit impulses from?

  CNS to effector
• What does CNS stand for?

  Central Nervous System
• What is resting potential in a neuron?

  Electrical potential difference when not stimulated
• What is the resting potential value?

  -70mV
• How is resting potential maintained?

  By sodium-potassium pump via active transport
• How many sodium ions are pumped out by the sodium-potassium pump?

  3 sodium ions
• How many potassium ions are pumped into the neuron?

  2 potassium ions
• What is a nerve impulse?

  An action potential propagating along nerve fibers
• How does animal size affect nerve impulse speed?

  Speed decreases as size increases
• What adaptations do large animals have for nerve impulses?

  Wider axons and myelination
• How large can the axon of a giant squid grow?

  Up to 1mm
• What is myelin?

  Multilayer of phospholipids and proteins
• What is the function of myelin?

  Insulates axons and reduces impulse speed
• What is a synapse?

  Junction between two neurons or effector cells
• What are neurotransmitters?

  Signaling chemicals used in synaptic transmission
• What happens during synaptic transmission?

  Neurotransmitters diffuse across the synaptic cleft
• What triggers the opening of voltage-gated calcium channels?

  Arrival of action potential at axon terminal
• What is excitatory postsynaptic potential?

  Increases likelihood of an action potential
• What neurotransmitter is involved in neuromuscular junctions?

  Acetylcholine
• What happens when acetylcholine binds to receptors?

  Opens voltage-gated sodium channels
• What is the threshold potential for initiating an action potential?

  -55mV
• What occurs during depolarization?

  Sodium enters the cell, membrane potential becomes positive
• What happens during repolarization?

  Potassium leaves the cell, membrane potential becomes negative
• What is hyperpolarization?

  Membrane potential falls below resting potential
• How do excitatory neurotransmitters affect action potentials?

  They increase the likelihood of an action potential
• How do action potentials propagate along axons?

  They propagate along the whole length of the axon fiber
• What is saltatory conduction?

  Action potential jumps from node to node
• What are nodes of Ranvier?

  Gaps in the myelin sheath
• What are exogenous chemicals?

  Chemicals that interfere with synaptic transmission
• How do neonicotinoids affect synaptic transmission?

  They prevent acetylcholine binding
• What is the effect of cocaine on dopamine transporters?

  Cocaine prevents dopamine reuptake
• What is the result of excess dopamine in the synaptic cleft?

  Causes a euphoric feeling
• What do inhibitory neurotransmitters do?

  Decrease the likelihood of action potential
• How do inhibitory neurotransmitters cause hyperpolarization?

  By allowing anions to enter the neuron
• What is summation in the context of neurotransmitters?

  Combined influence determines action potential occurrence
• What is the significance of the all-or-nothing principle?

  Action potentials occur fully or not at all
• How can fMRI be used in pain visualization?

  It visualizes action potential triggering pain
• What do nociceptors detect?

  Stimuli that cause pain