Neurons

Neurons

The human brain

Thought experiment• Scientist have discovered that the brain has

about 83 billion neurons.

• How do they know?

General Morphology of a Neuron

Axon Hillock Nodes of

Ranvier

Biology of a Neuron

Neurons are Diverse

Neurons Can be Classified by Morphology

The Axon is a Long Process• Moving a protein from one

end of a (6ft) long sensory neuron to the other would take weeks.

• For faster communication the neuron uses the electronic potential of the cell membrane.

• This electronic transfer allows information to travel 6 feet in about 2/100ths of a second.

Cell membrane

Ion Channels

Voltage gated Ligand gated Leak

Action Potential

Na+

K+

Resting

Threshold

Thought experiment• How can a neuron encode information?

• How can one neuron communicate to an entire brain?

Myelin Sheath

Myelin Sheath Increases the Speed of Action Potential Propagation

Unmyelinated

Myelinated

Synapse

Presynaptic terminal

Synaptic vesicle

Mitochondria

Synaptic Cleft

Postsynaptic boutonNeurotransmitter receptor

Post synaptic potentials

Neurons form neural networks

Neuroglia

Fun fact: Glia outnumber neurons in the brain 3 to 1.