IB Biology Topic C2.2: Neural Signalling Key Definitions

Acetylcholine is a neurotransmitter found in many types of synapses, including neuromuscular junctions (where nerves connect to muscles).

The action potential is the rapid electrical signal generated when the neuron's membrane potential reaches a threshold.

Consciousness refers to the state of being aware of and able to think about one's own existence, thoughts, and surroundings.

A change in the membrane potential of the presynaptic neuron, making it more positive.

Organisms that rely on external environmental conditions to regulate their body temperature.

A depolarizing change in the postsynaptic membrane potential that makes the postsynaptic cell more likely to fire an action potential.

Exocytosis is a process that occurs when a cell moves large materials from inside the cell to the outside of the cell using small spheres of membrane called vesicles.

Inhibitory neurotransmitters are chemicals that make it less likely for the postsynaptic neuron to generate an action potential.

The difference in charge across the membrane, where the inside of the cell is negative relative to the outside.

Membrane potential is the difference in electrical charge between the inside and outside of a cell.

Myelin is a fatty substance that wraps around the axons of neurons, forming an insulating layer.

Neurotransmitters are chemical signals used by neurons to communicate across synapses, the tiny gaps between nerve cells or between nerve cells and other target cells.

A sensory neuron with free nerve endings that detects noxious (potentially damaging) stimuli such as extreme heat, intense pressure, or harmful chemicals, and transmits this information to the central nervous system where it can be interpreted as pain.

Gaps in the myelin sheath where the axonal membrane is exposed.

A device that measures and displays electrical signals, allowing the visualization of changes in membrane potential over time.

The phase in which the membrane potential returns to a more negative state as potassium ions exit the neuron.

The process by which an action potential jumps from one node of Ranvier to the next, rather than traveling continuously along the axon.

Summation refers to the process by which multiple signals (neurotransmitters) from presynaptic neurons are combined at the postsynaptic neuron to determine if it will fire an action potential.

A chemical synapse is the point where two neurons meet or where a neuron meets an effector cell.

The critical membrane potential that must be reached for the action potential to be initiated.