Neurotransmission and Synapses

The process of transmitting an electrical signal from one neuron to another neuron or to a target tissue. This involves both the propagation of an action potential along an axon and the transmission of the signal across the synapse.

The transfer of an electrical signal within a neuron, achieved through a series of action potentials triggered by voltage-gated ion channels along the axon.

The region where a neuron communicates with another neuron or a target tissue.

A rapid change in membrane potential caused by the opening and closing of voltage-gated ion channels. It is a self-propagating event that travels along the axon.

Special proteins embedded in the cell membrane that open and close in response to changes in membrane potential. They play a crucial role in generating action potentials.

The part of the neuron that transmits information to other neurons or target tissues.

The region of the neuron where action potentials are initiated.

The influx of sodium ions into the cell during depolarization, which triggers the opening of voltage-gated sodium channels in adjacent regions of the axon, further propagating the action potential.

Specialized gaps in the myelin sheath, exposing the axon membrane.

The process where an action potential 'jumps' from one node of Ranvier to the next along a myelinated axon.

The covering of Schwann cells around the axon.

Regions of the axon covered by the myelin sheath.

The rapid increase in membrane potential caused by sodium ions rushing into the cell during an action potential.

The movement of electrical signals along the axon.

The period after an action potential where the axon cannot fire another action potential.

The energy required to maintain the concentration gradient of ions across the cell membrane.

A type of nerve fiber with a large diameter and a thick myelin sheath, resulting in fast signal transmission.

The influence of axon diameter on the speed of signal transmission. Larger axons have more surface area, allowing for more voltage-gated sodium channels and faster signal propagation.

The amount of myelination around an axon influences the speed of signal transmission. More myelination leads to faster transmission due to reduced leakage and improved signal jump.

The process where an electrical signal travels continuously down an unmyelinated axon.

The effect of temperature on the speed of signal transmission. Cooler temperatures slow down signal propagation due to the slower function of voltage-gated channels.

The speed at which a signal travels along a nerve fiber.

Type B fibers are lightly myelinated and have a medium diameter. They conduct signals slower than Type A fibers but faster than Type C fibers, with speeds ranging from 3 to 15 meters per second. They are primarily involved in the autonomic nervous system, which controls functions like smooth muscle contraction, heart rate, and glandular secretions.

Type C nerve fibers lack myelination and have the smallest diameter. They transmit signals the most slowly, at about 2 meters per second or less. These fibers also belong to the autonomic nervous system, playing a role in involuntary bodily functions.

A synapse is a specialized junction between neurons or between a neuron and a target cell. It allows for communication between these cells through the transmission of signals across a small gap.

The neuron that sends the signal across the synapse is called the presynaptic neuron. It contains vesicles filled with neurotransmitters, chemical messengers, and releases them into the synaptic cleft to interact with the next neuron.

The neuron or target cell that receives the signal from the presynaptic neuron is called the postsynaptic neuron. It has receptors that bind to neurotransmitters, initiating a response in the postsynaptic cell.

A graded potential that occurs in the postsynaptic membrane, causing the membrane to become more positive and closer to threshold for an action potential.

A graded potential that occurs in the postsynaptic membrane, causing the membrane to become more negative and farther from threshold for an action potential.

The process of combining multiple EPSPs or IPSPs at a single location on the postsynaptic membrane.

The process of combining multiple EPSPs or IPSPs over time at a single location on the postsynaptic membrane.

The threshold potential is the level of membrane potential that must be reached for an action potential to be generated.

The process of a neurotransmitter binding to its receptor on the postsynaptic membrane, initiating a change in membrane potential.

The process of reducing the intensity of sensory signals before they reach the brain.

The part of the brain responsible for relaying sensory information to the cortex.

These are excitatory postsynaptic potentials (EPSPs) that increase the likelihood of the postsynaptic neuron firing an action potential. They are caused by the influx of positive ions.

These are inhibitory postsynaptic potentials (IPSPs) that decrease the likelihood of the postsynaptic neuron firing an action potential. They are caused by the influx of negative ions or the efflux of positive ions.

The combined effect of EPSPs and IPSPs determines whether the postsynaptic neuron will reach threshold. If the excitatory signals outweigh the inhibitory signals, the neuron will fire an action potential.

The process of combining EPSPs and IPSPs, which may come from multiple neurons or from a single neuron in rapid succession, to determine whether a neuron will fire an action potential.

The change in the membrane potential of a neuron that is not strong enough to trigger an action potential. This is a temporary, localized change in voltage.