The Brain And Behaviour Flashcards
Approximately how much does the brain weigh
1400g
What are the basic building blocks of the nervous system
Neurons
What are the three main parts of neurons
Soma
Dendrites
Axon
Where is the soma in a neuron
The cell body
What are dendrites
Specialised receiving units that collect messages from neighbouring neurons and send them on to the cell body
What do axons do
Conduct electrical impulses away from the cell body to other neurons, muscles or glands
What do neurons do
Generate electricity that creates nerve impulses
Release chemicals to communicate with neurons, muscles and glands
What are the three stages neurons go through
Resting potential
Action potential
Resting potential again
What occurs during resting potential
Neuron is separated from surrounding fluid by a cell membrane; substances pass through ion channels
What causes polarisation
Inner ions are more negatively charged that outer ions, resulting in a net negative charge for the resting neuron
What is action potential
An electrical shift that occurs when a neuron is stimulated
What causes depolarisation
Positive sodium ions entering the neuron
When does polarisation occur
During resting potential
When does depolarisation occur
During action potential
What is the absolute refractory period
The recovery period that occurs after the action potential passes along each point on the axon
What is the all or none law
Action potentials occur either at uniform and maximum potential, or not at all
Define graded potentials
Changes in the negative resting potential that do not reach the action potential threshold
What is the myelin sheath
A layer of fatty insulation that surrounds the axon
What colour is myelin
White
What does the myelin do
Allows electrical conduction to take place at a higher speed than unmyelinated axons
When does the myelin completely form in many neurons
Some time after birth
What can damage to the myelin sheath cause
Multiple sclerosis
How do neurons communicate with other cells
Through synapses
What are synapses
The conjunction of an axon terminal of one neuron and the membrane of another cell