Synaptic Transmission and Behaviour Lecture Notes

Vocabulary flashcards covering synaptic transmission, neuron types, action potentials, neurotransmitter classes, and the four major activating systems of the Central Nervous System.

Neurons

The core component of the Nervous System, including the brain, spinal cord, and ganglia of the peripheral Nervous System, consisting of a cell body (soma), dendrites, and an axon.

Soma

A compact cell body from which the axon and dendrites extrude.

Axon hillock

A swelling where the axon leaves the soma.

Afferent (sensory) neurons

The simplest form of neuron that conveys information from tissues and organs into the Central Nervous System.

Efferent (motor) neurons

Neurons located in the lower brainstem and spinal cord that transmit signals from the brain to effectors such as muscles.

Interneurons

Also called association neurons, these connect neurons within specific regions of the Central Nervous System and link sensory and motor neurons.

Neurotransmission (synaptic transmission)

The process by which neurons communicate via the synapse using chemical and electrical signals.

Ligand channel

A gated channel that allows ions to pass through the membrane in response to the binding of a chemical messenger.

Mechanically gated channels

Ion channels that open in response to mechanical stress.

Voltage gated channels

Ion channels activated by changes in the electrical membrane potential near the channel, typically located at the axon and the synapse.

Resting potential

The electrical charge of a neuron when not active, typically $-70\,mv$, characterized by a negative charge inside relative to the outside.

Depolarisation

A rapid positive change in voltage at the inner side of the cell membrane caused by an influx of positively charged sodium ($Na^+$) ions.

Refractory period

The limit to how often action potentials can occur.

Excitatory (type 1) synapse

A synapse where an action potential in a presynaptic neuron increases the probability of an action potential occurring in a postsynaptic cell by moving the membrane potential towards the threshold.

Inhibitory (type 2) synapse

A synapse where a neurotransmitter decreases the chance of an action potential in the postsynaptic neuron by hyperpolarising or stabilising the neuron.

Small molecule neurotransmitters

Neurotransmitters derived from food that are packaged ready to use in axon terminals and are quickly replaced following release.

Peptide neurotransmitters

Neurotransmitters made on the neuron's cell body that are packaged in the membrane and transported to the axon terminal; they are produced slowly and not easily replaced.

Acetylcholine (Ach)

A primarily excitatory neurotransmitter fundamental to the cholinergic system and the parasympathetic nervous system, playing a key role in muscle activation and forebrain networks.

Serotonin

A small molecule neurotransmitter found in the raphe region of the pons and upper brain stem that regulates mood, sleep, appetite, and arousal.

Endorphins

Endogenous opioid peptides that act as inhibitory neuropeptides to reduce the transmission of pain signals.

Norepinephrine (NE)

A neurotransmitter that mobilises the brain and body for action, increasing arousal and alertness, and is highest during situations of stress or danger.

Cholinergic system

An activating system using acetylcholine, implicated in cognitive functions like attention, memory, and emotional processing.

Nigrostriatal pathway

A dopaminergic pathway projecting from the substantia nigra to the striatum; its degeneration results in Parkinson's disease.

Mesolimbic pathway

Also called the reward pathway, it begins in the ventral tegmental area and connects to the nucleus accumbens, amygdala, and hippocampus.

Locus coeruleus

One of the midbrain areas where noradrenergic neurons originate.

Dorsal raphe

A midbrain area on the midline of the brainstem where the serotonergic system originates.