Unit 1 part 2Comprehensive Guide to Neuron Structures, Action Potentials, and Synaptic Transmission

Core Disciplines:
- Neuroanatomy: The study of the structural organization of the nervous system.
- Neurophysiology: The study of the functional processes and biological mechanics of the nervous system.
- Neurons: The core cellular units responsible for processing and transmitting signals throughout the nervous system.
Structural Components of a Neuron:
- Dendrites: The specialized branches of a neuron that receive incoming signals from neighboring cells.
- Axon: An elongated pathway that carries information along long distances from one part of the neuron to another.
- Axon Terminal: The specialized end structure of an axon that transmits signal information to the next cell in the biological chain.
Structural Definition and Function of Nerves:
- Definition: A nerve is composed of a bundle of individual axons traveling together in parallel.
- Functional Length: Nerves can be very long because they are required to transmit biological signals across extensive physical distances.
Ionic Mechanics in Neuronal Activity:
- Primary Positively Charged Ions: Positively charged sodium ions ( $\text{Na}^+$ ) and potassium ions ( $\text{K}^+$ ).
- Functional Role: The presence and directional movement of these positively charged ions are critical both when a neuron actively fires and when it is at rest.

Inter-Neuronal Signal Transmission:
- Biological signals travel along cellular pathways between pre-synaptic and post-synaptic neurons.
- Neurotransmitters are released from the axon terminal of the emitting cell and move toward the receiving cell.
- These released neurotransmitters land directly on the dendrites of the receiving neuron.
Receptor Site Dynamics:
- Dendrites contain specialized structural sites known as receptor sites.
- Signaling occurs when neurotransmitter molecules fit specifically into these receptor sites on the post-synaptic dendrites.

Resting Potential:
- Neurons maintain a slightly negative electrical charge relative to their external environment while at rest.
- Resting Charge Value: A neuron at rest is charged at exactly $-70\,mV$ .
Threshold Mechanics:
- Definition: The minimum level of electrical change required to initiate a neuronal response.
- Threshold Value: The critical threshold value is $-50\,mV$ .
Process of Firing an Action Potential:
- When neurotransmitters land on dendrites and fit into receptor sites, they induce electrical changes in the cell.
- If the electrical state shifts from the baseline resting charge of $-70\,mV$ up to the critical threshold of $-50\,mV$ , the neuron fires an action potential.

Prior Knowledge and Review:
- Prior instruction established foundational concepts of neuroanatomy, neurophysiology, and basic neuronal structures.
Instructional Interactions:
- An inquiry was made regarding whether a visual display had frozen during the instructional presentation.
- An exchange occurred regarding sending and receiving visual pictures or diagrams demonstrating the enlargement of neurotransmitter release and receptor sitebinding.