Neuron

BIOLOGY 30

What is homeostasis?

The process by which biological systems maintain a stable internal environment to sustain life, despite changes in external conditions.

What is the nervous system?

A complex network of neurons and cells that transmit signals between different parts of the body, enabling coordination and response to stimuli.

What comprises the Central Nervous System (CNS)?

The brain and spinal cord.

What is the Peripheral Nervous System (PNS)?

The part of the nervous system outside the CNS, including all the nerves that branch out from the brain and spinal cord to the rest of the body.

What are neurons?

Specialized cells that transmit electrical and chemical signals in the nervous system.

What are glial cells?

Non-neuronal cells that provide support and protection for neurons in the central and peripheral nervous systems.

What are nerves?

Bundles of axons in the peripheral nervous system that transmit signals between the Central Nervous System and different parts of the body.

What are reflex arcs?

The neural pathway that mediates a reflex action, involving sensory neurons, interneurons, and motor neurons.

Dendrites

Branch-like extensions of a neuron that receive electrical messages from other cells.

What is the cell body (soma) of a neuron?

The part of a neuron containing the nucleus and organelles; it processes incoming signals and generates outgoing signals to the axon.

What is an axon?

A long, slender projection of a neuron that conducts electrical impulses away from the cell body.

What is the myelin sheath?

A fatty layer that covers the axons of some neurons, increasing the speed and efficiency of signal transmission.

What are Schwann cells?

Glial cells in the peripheral nervous system that produce the myelin sheath around neuronal axons.

What is membrane potential?

The voltage difference across a cell's plasma membrane, due to the distribution of ions.

What is resting membrane potential?

The membrane potential of a neuron when it is not transmitting a signal, typically around -70 mV.

What is polarization?

The condition of a cell membrane where the inside of the cell is negatively charged relative to the outside.

What is the sodium-potassium exchange pump?

A membrane protein that transports sodium ions out of the cell and potassium ions into the cell, maintaining the resting potential.

What is depolarization?

The process during which sodium channels open and sodium ions enter the cell, causing the membrane potential to become more positive.

Nodes of Ranvier?

Gaps in the myelin sheath along the axon that allow for rapid conduction of nerve impulses.

Action Potential

A rapid rise and fall in membrane potential that results in the transmission of a nerve impulse along an axon.

What is threshold potential?

The minimum membrane potential that must be reached to initiate an action potential.

What is repolarization?

The process of restoring the resting membrane potential following depolarization, primarily by the outflow of potassium ions.

What is the refractory period?

The time immediately following an action potential during which a neuron is unable to fire another action potential.

What is a synapse?

The junction between two neurons, where neurotransmitters are released to transmit signals between the neurons.

What is a neuromuscular junction?

A synapse between a motor neuron and a muscle cell.

What is white matter?

Tissue found deep in the brain and outer spinal cord.

What is grey matter?

The surface of the brain and inner spinal cord.

What is saltatory conduction?

A way that nerves send signals quickly by making the electrical impulses jump between gaps in the myelin covering of the axon.

Synaptic cleft

The small gap between two neurons where neurotransmitters are released.

What are neurotransmitters?

Chemicals that transmit signals across a synapse from one neuron to another.

What is the axon hillock?

The region of a neuron where the axon begins, responsible for integrating incoming signals.

What is a cell membrane?

A biological membrane that separates and protects the interior of a cell from its external environment.

What happens when an action potential arrives at the synaptic terminal?

It triggers the opening of voltage-gated calcium channels.

What causes neurotransmitter release?

The influx of calcium ions into the presynaptic terminal.

What occurs during signal reception at a synapse?

Neurotransmitters bind to specific receptors on the postsynaptic membrane.

What are the types of synapses?

Chemical synapses and electrical synapses.

How are neurotransmitters terminated?

Through reuptake, enzymatic degradation, or diffusion.