Chapter 7 - The Nervous System - Tagged

Nervous System

Organ system consisting of trillions of cells in the brain, spinal cord, and periphery, responsible for communication and coordination in the body.

Central Nervous System (CNS)

Consists of the brain and spinal cord.

Peripheral Nervous System (PNS)

Nerves, ganglia, and nerve plexuses located outside of the CNS.

Neuron

Basic structural and functional unit of the nervous system that carries information in the form of electrical signals.

Glial Cells

Supporting cells in the nervous system that help neurons function.

Action Potential (AP)

A large depolarization to +30 mV that serves as an electrical impulse to communicate in the nervous system.

Depolarization

A decrease in membrane potential, making it more positive, usually due to the influx of Na+ ions.

Hyperpolarization

An increase in membrane potential, making it more negative, generally due to K+ ions exiting the cell.

Synapse

The junction between a neuron and another cell where neurotransmitter release occurs, influencing the postsynaptic cell's electrical and chemical activity.

Neurotransmitters

Chemical messengers released from presynaptic neurons to elicit a response in postsynaptic neurons.

Afferent Neuron (Sensory Neuron)

Neuron that carries information from tissues and organs to the CNS.

Efferent Neuron (Motor Neuron)

Neuron that transmits impulses from the CNS to effector organs such as muscles and glands.

Saltatory Conduction

The process by which action potentials 'jump' from one node of Ranvier to the next in myelinated axons.

Graded Potential

A temporary change in membrane potential that varies in size, often generated at dendrites.

Resting Membrane Potential

The electrical potential across a neuron's membrane at rest

Refractory Period

A time after an action potential during which a neuron is less excitable due to inactivated Na+ channels.

-70 mV

Resting Membrane Potential in mV

Absolute Refractory Period

Period during which the membrane cannot produce another action potential because Na+ channels are inactivated.

Relative Refractory Period

Period that occurs when K+ channels are open and the neuron is hyperpolarized; requires a stronger stimulus to reach threshold.

Presynaptic Neuron

Neuron undergoing action potentials (APs) in its axon that sends excitatory or inhibitory neurotransmitter (NT) messages to another neuron via the synapse.

Postsynaptic Neuron

Neuron that receives the message from another neuron via the synapse, which can either excite (depolarize) or inhibit (hyperpolarize) it.

Neurotransmitters

Chemical messengers released from presynaptic neurons to elicit a response in postsynaptic neurons.

Excitatory Postsynaptic Potential (EPSP)

A depolarization of the postsynaptic neuron due to Na+ or Ca2+ entry, making the neuron more likely to fire an action potential.

Inhibitory Postsynaptic Potential (IPSP)

A hyperpolarization of the postsynaptic neuron due to Cl- entry, making the neuron less likely to fire an action potential.