Nervous System

What is the nervous system made up of?

The central nervous system (CNS) and the peripheral nervous system (PNS).

What is the central nervous system (CNS)?

The brain and spinal cord, which coordinates all responses.

What is a synapse?

A junction between two neurons where a chemical transmitter passes the impulse from one neuron to the next.

What carries electrical impulses towards the cell body of a neuron?

Dendrites.

What carries electrical impulses away from the cell body of a neuron?

The axon.

What is the role of sensory neurons?

To carry impulses from receptors in the sense organs to the CNS.

What is the role of relay neurons?

To connect sensory and motor neurons within the CNS, passing the impulse through the nervous system.

What is the role of motor neurons?

To carry impulses from the CNS to effectors (muscles or glands) to bring about a response.

What is a reflex action?

A rapid, automatic response to a stimulus that does not involve conscious thought.

What is the reflex arc?

The pathway followed by a nerve impulse in a reflex action: stimulus → receptor → sensory neuron → relay neuron → motor neuron → effector → response.

Why are reflex arcs important?

They enable very fast responses to potential dangers, helping to protect the body from harm.

Give one example of a reflex action.

Quickly pulling your hand away from a hot object.

What is the role of the brain in voluntary responses?

The brain processes information from the senses and decides on a conscious response, which is then sent via motor neurons.

What is the role of the spinal cord?

To carry impulses between the brain and the rest of the body and to coordinate some reflex arcs.

What are receptors?

Cells or structures that detect a change in the environment (a stimulus), such as light, sound, or temperature.

What are effectors?

Muscles or glands that bring about a response when they receive a nerve impulse.

Why are relay neurons important in the nervous system?

They allow different parts of the nervous system to communicate and help process information before sending it to effectors.

How does information travel along a neuron?

As an electrical impulse along the axon.

How does information travel across a synapse?

As a chemical neurotransmitter, which diffuses across the gap and triggers an impulse in the next neuron.

Why are reflex arcs faster than responses involving the brain?

Reflex arcs go straight through the spinal cord without the signal going to and being processed by the brain, so the response is quicker.