Lesson 2 Neurons

Question 1

Structure of the neuron

Answer 1

Neurons are specialised nerve cells that move electrical impulses to and from the Central Nervous System (CNS).

Question 2

Different parts of the neuron

Answer 2

Cell body, nucleus, dendrites, axon, myelin sheath, Schwann cells and nodes of Ranvier

Question 3

Cell body

Answer 3

Control centre of the neuron

Question 4

Nucleus

Answer 4

Contains genetic material

Question 5

Dendrites

Answer 5

Receives an electrical impulse (action potential) from other neurons or sensory receptors (e.g. eyes, ears, tongue and skin)

Question 6

Axon

Answer 6

A long fibre that carries the electrical impulse from the cell body to the axon terminal.

Question 7

Myelin sheath

Answer 7

Insulating layer that protects the axon and speeds up the transmission of the electrical impulse

Question 8

Schwann cells

Answer 8

Make up the Myelin sheath

Question 9

Nodes of Ranvier

Answer 9

Gaps in the myelin sheath. They speed up the electrical impulse along the axon.

Question 10

Three types of neurons

Answer 10

Sensory neuron, motor neuron and relay neuron

Question 11

Sensory neuron

Answer 11

Sensory neurons are found in sensory receptors. They carry electrical impulses from the sensory receptors to the CNS (spinal cord and brain) via the Peripheral Nervous System (PNS). Sensory neurons convert information from sensory receptors into electrical impulses. When these impulses reach the brain they are converted into sensations, such as heat, pain etc. so that the body can react appropriately. Some sensory impulses terminate at the spinal cord. This allows reflexes to occur quickly without the delay of waiting for the brain to respond.

Question 12

Motor neuron

Answer 12

Motor neurons are located in the CNS but project their axons outside of the CNS. They send electrical impulses via long axons to the glands and muscles so they can affect function. Glands and muscles are called effectors. When motor neurons are stimulated they release neurotransmitters that bind to the receptors on muscles to trigger a response, which leads to movement.

Question 13

Relay neuron

Answer 13

Relay neurons are found in the CNS. They connect sensory neurons to motor neurons so that they can communicate with one another. During a reflex arc (e.g. you put your hand on a hot hob) the relay neurons in the spinal cord are involved in an analysis of the sensation and decide how to respond (e.g. to lift your hand) without waiting for the brain to process the pain.