Neuronal processes are vital extensions from the cell body of neurons, serving as conduits for signaling within the nervous system.
There are two main types of neuronal processes: dendrites and axons.
Cell Body (Soma): Contains the nucleus and is where most metabolic activities occur.
Process: Refers to the extensions that emerge from the neuron’s soma, primarily including dendrites and axons.
Sensory Neurons: Primarily located in the peripheral nervous system, they carry signals from sensory receptors to the central nervous system (CNS).
Motor Neurons: Carry signals from the CNS to muscles or glands, involved in movement.
Association Neurons (Interneurons): Connect sensory and motor neurons, playing key roles in reflexes and neuronal processing.
Function: Dendrites receive incoming signals.
Structure: Often branched and covered with dendritic spines, which enhance the surface area for signal reception.
Dynamic Nature: Dendrites can change in structure in response to stimulation (neuroplasticity).
Function: Transmit signals away from the cell body.
Structure: Generally longer than dendrites; can be myelinated or unmyelinated.
Axon Hillock: The cone-shaped area of the axon that generates action potentials.
Terminals: The endpoint of axons where neurotransmitters are released.
Neurotransmitters: Chemicals released from the axon terminals into the synaptic cleft, responsible for signaling between neurons.
Signal Transmission: Happens through the generation of action potentials along the axon, triggered by depolarization processes.
Resting Potential: The neuron at -70 mV, stable and inactive.
Depolarization: Sodium channels open, causing a rapid increase towards +30 mV.
Repolarization: Potassium channels open, bringing voltage back down to reset.
Hyperpolarization: The membrane potential becomes more negative than resting potential due to prolonged potassium channel activity.
Myelin Sheath: Fatty insulation around axons that speeds up signal transmission.
Nodes of Ranvier: Gaps in the myelin sheath that facilitate rapid saltatory conduction of impulses.
Importance: Myelination is crucial for quick responses in emergency situations (e.g., sympathetic responses triggered by danger).
Astrocytes: Maintain blood-brain barrier and supply nutrients to neurons.
Oligodendrocytes: Form myelin in the central nervous system.
Microglia: Act as immune defense in the nervous system.
Ependymal Cells: Line the cavities and produce cerebrospinal fluid.
White Matter: Composed of myelinated axons (tracks in the CNS).
Gray Matter: Composed mainly of neuronal cell bodies and unmyelinated fibers (nuclei in the CNS).
Neurotransmitters influence emotions and mental health.
Issues such as anxiety and depression can be linked to the functioning of neurotransmitters and the health of neural connections.
Sympathetic vs. Parasympathetic Responses: Fast reactions (fight or flight) vs. slow reactions (rest and digest) driven by the type of signals processed by the neurons.
The balance of neurotransmitters is crucial to maintaining emotional health and stability.
Negative emotions can result from imbalances in neural activity, often necessitating professional help or therapy.