Nervous System

A communication system that coordinates rapid responses using nerve impulses.

A communication system that uses hormones to coordinate responses over longer periods.

Any change in the environment that causes a reaction from an organism.

The action taken by an organism in reaction to a stimulus.

A type of neurone that carries signals from sensory receptors to the brain.

A type of neurone that transmits signals from the brain to muscles for movement.

Chemical messengers used by the endocrine system to communicate bodily functions.

Electrical signals transmitted by nerve fibres in the nervous system.

A column of nervous tissue within the vertebral column for protection.

The central region of the spinal cord containing cell bodies and synapses.

Surrounds grey matter in the spinal cord and contains myelinated neurons.

Composed of the brain and spinal cord, controlling most functions.

Nerves that branch from the brain and spinal cord to the rest of the body.

The pathway of neurons involved in a reflex action.

A reflex action that occurs via the spinal cord, bypassing the brain.

A change in membrane potential when a stimulus exceeds the threshold value.

An electrical impulse that travels along a sensory neurone to communicate signal.

Links sensory neurones and motor neurones in the spinal cord.

The muscle or gland that responds to a nerve impulse, like the biceps muscle.

Automatic responses that do not require conscious thought, aiding survival.

The benefit of reflex actions in promoting survival and protecting the body.

The electrical charge difference across a neurone membrane when at rest.

A membrane that restricts passage of sodium and potassium ions across the axon.

Potassium ions are attracted back into the axon due to its negative charge and repelled by surrounding tissues' positive charge.

Large proteins in the axon cytoplasm create a negative charge that contributes to the axon's overall negative state.

A balance between chemical and electrical gradients where there is no net movement of ions.

The process where the membrane potential becomes less negative, leading to action potential generation.

Channels that open or close to control the flow of potassium and sodium ions during action potential.

The depolarization level needed to open all voltage-gated sodium channels, typically -5 to -15 mV.

A process where sodium ion influx causes more sodium channels to open, amplifying depolarization.

Specialized structures that receive stimuli from the environment.

The control center of the body, consisting of the brain and spinal cord.

Specialized cells that transmit nerve impulses throughout the body.

Insulating layer around axons that speeds up nerve impulse transmission.

Gaps in the myelin sheath that facilitate rapid impulse transmission.

Channels that remain open for ions to diffuse across the membrane.

Protein that actively transports sodium out and potassium into the axon.

Condition where the inside of the axon is negatively charged compared to the outside.

Difference in ion concentration across the axon membrane.

Difference in charge between the inside and outside of the axon due to ion movement.

The axon membrane is 100 times more permeable to potassium than sodium.