Unit 2: Nerve Cells Flashcards
Describe the main features of a neurone
- cell body
- dendrons
- axons
What do dendrons do?
carries nerve impulses to cell body
What does the axon do?
carries nerve impulses away from the cell body
What is a nerve?
a discrete bundle of 1000s of neurone axons
Which direction does a nerve impulse pass from one neurone to the next? (in terms of parts of the neurone)
From the axon of one neurone to the dendron of another across a synapse.
What is the advantage of having numerous of dendrites on one neurone?
Provides a large surface area for the neurone to connect with other neurones
What are Schwann cells?
cells wrapped around the axon in a spiral to form a thick lipid layer called the myelin sheath
What is myelin?
a fatty substance that surrounds axons and dendrites in certain neurones
What does the myelin sheath do?
provides physical protection and electrical insulation for the axon
What are the spaces in between the myelin sheath along a neurone called?
Nodes of Ranvier
What are the three types of neurones in humans?
Sensory Neurones, Motor Neurones and Intermediate (Relay) Neurones
Describe the shape of a sensory neurone
Cell body sticks out in the middle of the neurone
Long dendron and axon
What do sensory neurones do?
transmit nerve impulses from sensory receptors to central nervous system
Describe the shape of a motor neurone
Cell body at one end with dendrites
Long axon
What do motor neurones do?
transmit nerve impulses from central nervous system to effectors in the body
Describe the shape of intermediate neurones
Cell body in the centre with dendrites attached, short axon
What do relay neurones do?
Connect sensory neurones to motor neurones. They make up 99% of CNS.
