Nervous System and Reflexes Quiz

A flattened cylinder of nervous tissue that runs from the base of the brain to the lumbar region. It is responsible for transmitting signals between the brain and the rest of the body.

The central, butterfly-shaped region of the spinal cord, containing cell bodies and synapses.

The outer region of the spinal cord, composed of axons coated in myelin, responsible for transmitting signals quickly.

A rapid, automatic response to a stimulus, often protective in nature.

A pathway that a nerve impulse travels along to initiate a reflex response.

The nervous system is responsible for receiving and responding to information from the environment.

A stimulus is any detectable change in the environment that can trigger a response.

Receptor cells are specialized cells that detect changes in the environment and convert them into electrical signals.

A nerve impulse is an electrical signal that travels along neurons.

Effectors are muscles or glands that carry out a response to a stimulus.

The central nervous system (CNS) is composed of the brain and spinal cord. It analyzes sensory information and coordinates responses.

The peripheral nervous system (PNS) carries information between the CNS and the rest of the body.

Neurons are specialized nerve cells that transmit nerve impulses.

A simple, decentralized network of neurons found in organisms like jellyfish and hydra. Signals travel in all directions, and it lacks the complex organization found in mammalian nervous systems.

The difference in electrical potential across the membrane of a neuron when it is not transmitting a signal. This potential is typically around -70 millivolts (mV), with the inside of the axon being more negative than the outside.

A specialized protein embedded in the axonal membrane that uses energy to actively pump sodium ions out of the axon and potassium ions into the axon. This pumping action helps maintain the resting potential.

The movement of ions across the cell membrane through specialized channels without requiring energy. During resting potential, potassium ions leak out of the axon.

The state of the neuron where there is a difference in electrical charge between the inside and outside of the axon membrane. This occurs due to the unequal distribution of ions, making the outside positively charged relative to the inside.

Substances that alter synaptic transmission by amplifying or inhibiting it.

The process of increasing synaptic transmission.

The process of decreasing synaptic transmission.

A process where drugs can directly mimic the action of a neurotransmitter, leading to amplification of the signal.

A process where drugs can block the action of a neurotransmitter, leading to inhibition of the signal.

A specialized junction where a nerve impulse is transmitted from one neuron to another, or from a neuron to a muscle or gland.

A chemical messenger that transmits signals across the synapse, from one neuron to another.

The process of neurotransmitter release from the presynaptic neuron and its binding to receptors on the postsynaptic neuron, leading to the transmission of signals.

An enzyme found in the synaptic cleft that breaks down acetylcholine, preventing its continuous stimulation of the postsynaptic neuron.

The process of actively transporting neurotransmitter molecules back into the presynaptic neuron, preventing prolonged stimulation of the postsynaptic neuron.

The minimum level of stimulation required to trigger an action potential in a neuron. If the stimulus is too weak, it won't reach the threshold and no action potential will fire.

The period of time after an action potential when another action potential cannot be generated, no matter how strong the stimulus is.

The period of time after an action potential when a stronger than usual stimulus is needed to trigger another action potential.

The influx of sodium ions (Na⁺) into the axon, making the inside of the axon more positive. This reverses the polarity of the neuron.

The movement of potassium ions (K⁺) out of the axon, making the inside of the axon more negative. This restores the neuron to its resting potential.

A brief period of hyperpolarization (more negative than the resting potential) following repolarization. This is due to the potassium channels remaining open for a short time, allowing more potassium to leave the axon.

The movement of ions across the cell membrane through specialized channels. This movement of ions creates electrical signals in neurons.

The intensity of the stimulus must reach a certain threshold to trigger a nerve impulse. Even exceeding this threshold doesn't increase the strength of the impulse, it just triggers it.

The speed at which a nerve impulse travels depends on factors like temperature, the diameter of the axon, and whether the axon is myelinated.

Myelin is a fatty substance that insulates axons, speeding up nerve impulse transmission by allowing the impulse to jump from one node to the next.

Saltatory transmission is the process where nerve impulses jump from one node of Ranvier to the next, allowing faster transmission of nerve impulses.

The axon is the long, slender projection of a neuron that carries nerve impulses away from the cell body.

The myelin sheath is a fatty, insulating layer that surrounds the axon of some neurons, greatly increasing the speed of nerve impulse transmission.

The nodes of Ranvier are gaps in the myelin sheath that expose the axon membrane, allowing for depolarization and the generation of action potentials.