- Concentration of sodium ions outside the neuron and the negative
protein ions inside contribute to a resting potential.
- If the neuron is sufficient stimulated, sodium channels open and
sodium ions flood into the axon. Not that the potassium channels are
- Sodium channels that were open in (b) have now closed and
potassium channels behind them are open, allowing potassium ions to
exist and restoring the resting potential at the point. Sodium channels
are opening at the next point as the action potential moves down the
- Action potential (potassium ions flow out)
- Gaps between axons: gap junctions.
- Milan: To insolate the axons to speed up the flow throughout the
- All or nothing law: Sufficient stimulation or nothing.
- Function of an action potential: Communication between neurones.
- Down axons, to axon terminals.
- Synaptic space/cleft: space
- Receptor molecules: Receive the neurotransmissions.
- Enzymes: degrade the non-fitting molecules.
- Sacs (syntactical vesicles): store neurotransmitters. Move towards
membrane, fuse then release.
- SSRI: Selective Serotonin Retake Inhibiter
- Our brain is made up of millions of neurones: Communication of
neurones = how our brain works.
The nervous system
- Central nervous system: brain spinal cord
- Peripheral nervous system: nerves
Enables us to sense events in and out of the body. (input)
Enables us to responds to events with muscles and glands.
Sensory nerves (skin, muscles…) give info to the brain.
Motor nerves – muscles (ex) respond.
Somatic - sensory, sends messages from sensory organs to
brain, sends messages from CNS to muscles (voluntary movements)
Autonomic – Regulates internal environment, controls
involuntary functions, two subdivisions a) sympathetic INSTINCT
(dilates pupils, relaxes bronchi, accelerates, strengthens heart beat,
inhibits activity, contracts vessels, b) parasympathetic CALM DOWN (contracts pupils, constricts bronchi, slows heart best, stimulates
activity, dilates vessels)
Central Nervous system
- Spinal cord: conducts spinal reflects (do not require brain).
Automatic response. No conscious input but it can involve input of the
- Brain: Who you are, uses a lot of energy.
How to study the brain
1. Destruction and stimulation
Patients with brain damage.
Lesion studies (destroy part of the brain to study it)
Chemical stimulation (infuse a needle)
Electrical stimulation (electrically stimulating parts of the brain
to understand where the stimulation is coming from)
2. Electrical and magnetic detection. (brain waves)
Electrodes measure neuronal activity
Brain waves – activity of neurones
Measures activity of large groups of neurons
“Tells us when it‟s happening, but not what.”
Transcranial Magnetic Stimulation (TMS)
Virtual lesion method
Stimulate brain region of interest
“Not very precise.” Because you stimulate a group of
neurones and not a specific one.