Topic 1.3.1 - The Neuron (Interneuron) & Neural Firing

Neuron

Nerve cell that’s the basic building block of the nervous system

Sensory Neuron, Motor Neuron, Interneuron

Sensory Neurons

Satires info from sense organs to CNS

Motor Neurons

Carries messages from CNS to muscles and glands

Soma

Cell body, part of neuron that contains nucleus

Dendrites

Branches extending from soma; Receives messages from other cells

Axon

Passageway from cell body to terminal branches

Terminal Branches

Ends of axons which contain terminal buttons that send messages to other cells

Myelin Sheath

Fatty tissue encasing axon; increases transmission speed

• development not complete until 25yo

• crucial to behavior, movement, and thought w/ deterioration possibly leading to multiple sclerosis

Glial Cells

Support cells that protect neurons and make up the myelin sheath

• mop up ions and neurotransmitters + play a role in thinking, learning, and memory

Action Potential

Transmission of electrical impulse down a neuron

Threshold

Level of stimulation needed to trigger an action potential; excitatory signals exceed inhibitory

All-or-None Response

Neuron either fires at full force or not at all; more stimulation doesn’t mean more intense action potential

Excitatory Neurotransmitter

Signals a trigger action

Inhibitory Neurotransmitter

Signals depress of an action

Resting State/Potential

Before an action potential, when the neuron is polarized with the outside of the axon positive and inside negative

Depolarization

When axon gates open and Na+ ions flood in to balance the charge (influenced depolarization of next section of axon)

Repolarization

When axon gates open allowing K+ ions to flow out, unbalancing the charge once more

Refractory Period

Testing period after a neuron fires an action potential in which it can’t fire anymore until it returns to its resting state

Neurotransmitter

Chemical messengers that travel across a synapse and bind to receptors on the receiving neuron to transmit a signal

Synapse (Synaptic Cleft/Gap)

Junction between axon tip of sending neuron and dendrites of receiving neuron

Reuptake

Reabsorption of neurotransmitters by sending neuron