NEURONS

NEURONS

• Neurons create the body's information system
• Billions of interconnected cells
• Definition: a nerve cell that consists of many parts

PARTS OF A NEURON

• Cell body
• Axon
• Dendrite
• Neural impulse
• Myelin sheath

PARTS OF THE NEURON CONT

• Terminal braches of axon

CELL BODY

DENDRITES

AXON

MYELIN SHEATH

TERMINAL BRANCHES OF AXON

NEURAL IMPULSE

ACTION POTENTIAL

• Same thing as a neural impulse
• Brief electircal charge that travels down the axon
• Generated by the movement of poistively charged atoms in and out of channels in the axons membrane
• Depolarization: positive ion enters a neuron and makes it more prone to firing an action potential
• Hyperpolarization: negative ion enters a neuron and makes it less prone to firing an action potential

ACTION POTENTIAL CONT

• The minimum amount of stimulation needed to start a neural impulse is called a threshold
• After a neuron fires an action potential, it needs to rest
• You need sleep everyday because you work hard and your body it tired. It keeps you rested and recharges your body.
• When the level of stimulation increases above the threshold, it will not increase the neural impulse's intensity
• This is called all-or-none response

SYNAPSE

NEUROTRANSMITTERS

HOW NEURONS COMMUNICATE

• Signal reaches synapse
• Triggers neurotransmitters
• Activated receptors generate electric signals of variable intensity
• Signals converage to base on its axons
• If signal is strong enough, axon will propagate further

HOW NEURONS COMMUNICATE

• If not, the signal will stop
• This is called a reuptake

HOW NEUROTRANSMITTERS INFLUENCE US

• We have several neurotransmitter pathways
• Serotonin, dopamine are main ones

AGONIST

• Similar in structure to nt
• Mimics its effects on the receiving neuron
• I.e. Morphine mimics endorphins

ANTAGONIST

• Similar enough to nt to occupy its site and block its action
• But not similar enough to mimic receptor