04 Revision - Nervous System

• Biology
• Further Education (Key Stage 5)

What are the basic functions of the nervous system?

Describe the two main divisions of the nervous system?

Describe the organisation of the peripheral nervous system

Sort the following into receptors and effectors

Receptors

Effectors

Position receptors in the ear 

Skeletal muscle

Touch, pressure, pain receptors in the skin

Chemical receptors in the nose and tongue

Smooth muscle

Glands

Light receptors in the eyes 

Sound receptors in the ear

Dendrite

Nucleus

Soma 

(cell body)

Axon terminal

Myelin sheath

Axon

Describe the structure and function of a myelin sheath

A. What term is used to describe the conduction of a nerve impulse down a myelinated axon?
B. How does myelination effect the speed of conduction of a nerve impulse?

Describe the role of a) sensory neurones, b) relay neurones and c) motor neurones.

Describe the features of a reflex arc and benefits of reflex actions

Identify the way in which nerve impulses are transmitted a) electrically, and b) chemically

Explain how resting membrane potential is maintained

Describe what happens during depolarisation

Explain the concept of the threshold point

Describe what happens during repolarisation

What is the refractory period?

Peak action potential

Hyperpolarisation

Repolarisation

Threshold of excitation

Resting potential

Describe how an action potential is conducted along a neurone

Identify 3 factors which affect the rate of conduction of an action potential along a neurone

When an action potential reaches the axon terminal, it triggers the opening of voltage-gated calcium channels

Calcium ions (Ca2+) diffuse into the cell and promote the fusion of vesicles (containing neurotransmitter) with the cell membrane

The neurotransmitters are released from the axon terminal by exocytosis and cross the synaptic cleft

Neurotransmitters bind to specific receptors on the post-synaptic membrane and open voltage-gated ion channels

The opening of ion channels generates an electrical impulse in the post-synaptic neurone, propagating the pre-synaptic signal

The neurotransmitters released into the synapse are either recycled (by reuptake pumps) or degraded (by enzymatic activity).