Neurons, Synapses, & Signaling

Neurons, Synapses, & Signaling

1. Amino acids and amines

   • neuropeptides
     • relatively short chains of amino acids that serve as neurotransmitters that operate via metabotropic receptors.
   • Glutamate
     • the neurotransmitter at the neuromuscular junction. Is also an amino acid.
   • dopamine
     • an amine made from tyrosine. It affects sleep mood, attention, and learning.
   • serotonin
     • an amine made from tryptophan. It affects sleep, mood, attention, and learning.
   • norepinephrine
     • an amino acid made from tyrosine. Also is an excitatory neurotransmitter in the autonomic nervous system.

2. Neuron Structure

   • axon
     • an extension that transmits signals to other cells. Axons are longer than dendrites.
   • synapse
     • the branched end of an axon that transmits information to another cell at a junction.
   • dendrites
     • numerous highly branched extensions attached to the cell body
   • neurotransmitters
     • chemical messengers that pass information from the transmitting neuron to the receiving cell.

3. Neuron Communication

   • ligand-gated ion channel
     • the receptor protein that binds and responds to neurotransmitters. Binding to a particular part of the receptor opens the channel & allows specific ions to diffuse across the membrane.
   • excitatory postsynaptic potential (EPSP)
     • when the ligand-gated ion channel opens (and its permeable to both sodium and potassium), the membrane potential depolarizes. This brings the membrane potential to a threshold.
   • temporal summation
     • when 2 EPSPs occur at a single synapse in rapid succession that the neuron's membrane potential has not returned to resting potential before the arrival of the second EPSP.
   • spatial summation
     • EPSPs produced nearly simultaneously by different synapses on the same postsynaptic neuron can cause this.

4. Ion pumps

   • membrane potential
     • the charge difference, or voltage of energy in a cell
   • ion channels
     • pores formed by clusters of specialized proteins that span the membrane
   • sodium-potassium pump
     • pump uses ATP hydrolysis to actively transport sodium out of the cell and potassium into the cell