Neuron
Receives stimuli and transmits action potentials.
Axons (Nerve Fibers)
- Slender processes of uniform diameter and may vary in length from a few millimeters to more than a meter.
- Transmits signals to other neuron dendrites or tissues.
Collateral Axons
Usually there is only one unbranched axon per neuron, rare branches, if present are called collateral axons.
Endoneurium
Surrounds individual axons.
Perineurium
Bounds groups of axons (fascicles) together.
Epineurium
Hold together fascilces that form the nerve.
Nerve Tracts (CNS)
Nerves (PNS)
Bundles of processes
Trigger Zone
Where the axon originates and where action potential is generated from.
Features of A Neuron
- Dendrites
- Axon
- Axon Terminal
- Myelin Sheath
Dendrites
Receives signals from neighboring neurons.
Axon
Transmits signals over a distance.
Axon Terminal
Transmits signals to other neuron dendrites or tissues.
Myelin Sheath
Speeds up signal transmission.
Action Potential
Electrical impulses due to a temporary shift (from negative to positive) in the neuron’s membrane caused by ions suddenly flowing in and out of the neuron.
Neurotransmitters
Endogenous chemical messengers which transmit signals across a chemical synapse, form one neuron to another “target” neuron, muscle cell, or gland cell.
Where are neurotransmitters released?
Neurotransmitters are released from the synaptic vesicles in synapses into the synaptic cleft, where they are received by neurotransmitter receptors on the target cells.
Stimulatory NT
Let’s in Sodium
Ex.
* Epinephrine
* Norepinephrine
* Acetylcholine
Inhibitory NT
Let’s in Chlorine
Ex.
* Gamma-aminobutyric Acid (GABA)
