Skip to content
Clear highlightsClear Highlight Report a problem

Neurones

There are three types of neurones:
  • sensory neurones
  • motor neurones
  • relay neurones
All neurones have a cell body, dendrons and axons.The cell body contains a nucleus and organelles and is connected to extensions of the cell body and long fibres called dendrons and axons. The cell body contains large amounts of rough endoplasmic reticulum for the synthesis of proteins and neurotransmitters.Dendrons are extensions of the cell body which branch into smaller fibres called dendrites. Dendrites carry nerve impulses towards the cell body.Axons are a single long fibre that carry impulses away from the cell body.Schwann cells are cells that wrap around the axon to provide electrical insulation. Layers of membrane containing a fatty substance called myelin provide the electrical insulation. Schwann cells also carry out phagocytosis of cell debris and are involved in nerve regeneration.The nodes of Ranvier occur between Schwann cells every 1-3mm in humans and are about 2-3μm long.

Read the text

Read the text and highlight anything you think is important. When you go on, the text is hidden and you answer from memory.

Next

Specification: AQA Biology (7402), A-level, 3.6.2.1 Nerve impulses. Topic: Neuronal Communication.

Key terms in this lesson

ATP
Adenosine triphosphate, the universal energy currency of cells, formed by adding an inorganic phosphate to ADP and hydrolysed to release energy for cellular reactions.
photosystem
A light-harvesting cluster of photosynthetic pigments in the thylakoid membrane that channels absorbed light energy to a reaction-centre chlorophyll a molecule.
chemiosmosis
The synthesis of ATP by ATP synthase, driven by the flow of protons down their concentration gradient across a membrane.

More in Neuronal Communication

All 38 lessons in Neuronal Communication · All AQA A-level Biology topics