Central Nervous System Classification

Pain and Sensory Pathways

• Fast pain is carried by A-delta fibers, which transmit sharp, localized pain sensations.
• Opioids inhibit the release of substance P, a neurotransmitter involved in pain transmission.
• The dorsal column-medial lemniscal pathway discriminates touch and proprioception, allowing for fine sensory discrimination.
• The spinothalamic tract is responsible for transmitting crude touch sensations, as well as temperature and pain.

Neuron Functionality

• The primary role of the spinocerebellar tracts is to convey proprioceptive information from the body to the cerebellum for coordination of movement.
• Neurotransmitters stored in vesicles are released from the presynaptic neuron through exocytosis, often triggered by the influx of calcium ions.
• Inhibitory postsynaptic potentials (IPSP) cause partial local hyperpolarization of the postsynaptic membrane, making it less likely to fire an action potential.
• Integrating inputs from multiple presynaptic terminals results in summation, influencing the likelihood of the postsynaptic neuron firing.

Ion Channels and Synapses

• Opening chloride ion channels on the postsynaptic membrane typically causes hyperpolarization, counteracting excitatory signals.
• Excitatory postsynaptic potentials (EPSP) lead to depolarization and increased likelihood of an action potential, while inhibitory postsynaptic potentials (IPSP) lead to hyperpolarization and decreased likelihood.
• The somatic nervous system primarily controls voluntary movements and processes sensory information from external stimuli.

Synapse Types and Nervous Systems

• Electrical synapses allow direct cytoplasmic connections between adjacent cells, facilitating rapid signal transmission.
• The primary function of the integrative nervous system is to process sensory information and coordinate appropriate responses.
• A typical axon has several branches at its terminal end, enhancing its ability to communicate with multiple target cells.

Neurotransmitters and Nervous System Functions

• Neurotransmitters involved in chemical synapses include dopamine, serotonin, norepinephrine, and acetylcholine, which convey signals between neurons.
• The autonomic nervous system regulates involuntary bodily functions, controlling processes such as heart rate and digestion.
• Chloride and potassium channels in the postsynaptic neuron primarily function to stabilize resting membrane potential and modulate neuronal excitability.

Sensory Receptors

• Mechanoreceptors are activated by pressure or changes in pressure, detecting mechanical stimuli.
• Hair cells in the organ of Corti function as mechanotransducers, converting sound vibrations into electrical signals for hearing.
• Chemoreceptors detect changes in chemical concentrations, playing a critical role in taste and smell.
• Baroreceptors in the carotid sinus and carotid arch monitor blood pressure, sending signals to the brain to help regulate cardiovascular functions.
• Photoreceptors in the retina detect light, converting it into electrical signals that contribute to vision.