Full notes on the biopsychology chapter of the aqa psychology paper 2 exam, including AO1 and AO3 (outlines and evaluations). These notes go exactly with the specification, and got me an A* in my exam.
THE CENTRAL NERVOUS SYSTEM
Brain and Spinal Cord - 2 main functions:
1. Control of behaviour
2. Regulation of the body’s
physiological processes
Spinal Cord: relays information between
the brain and the rest of the body,
allowing the brain to monitor & regulate
bodily processes - connected to parts of
the body by pairs of spinal nerves which
connect with different muscles & glands.
● Contains circuits of nerve cells -
enabling us to perform simple
reflexes without direct brain involvement.
Brain: 4 main areas - cerebrum, cerebellum, diencephalon, & brain stem.
Cerebrum = 4 lobes and 2 hemispheres
> frontal lobe = speech., logic, planning
> temporal lobe = processes auditory information
> occipital lobe = processes visual information
> parietal lobe = integrates info from the senses, spatial navigation
Cerebellum = motor skills and balance, coordinating muscles.
Diencephalon = thalamus and hypothalamus.
Brain Stem = regulates essential automatic functions like breathing and heartbeat.
THE PERIPHERAL NERVOUS SYSTEM
All the nerves outside of the CNS - function: to relay nerve impulses from the CNS to the rest of the
body and vice versa. Two main divisions:
Somatic Nervous System - 12 pairs of cranial nerves & 31 pairs of spinal nerves. Its role is to carry
sensory information from the outside world to the brain & provide muscle response via motor pathways
Autonomic Nervous System - governs the brain’s involuntary activities (homeostasis) e.g. heartbeat,
and it is self regulating - necessary as vital bodily functions would not work so well if you had to think
about them. Consists only of motor pathways, 2 components:
● Sympathetic (SNS) - noradrenaline. Fight or flight = responses e.g. raising heartbeat, sweat
glands stimulated, inhibits less important processes like digestion. SNS neurons travel to every
gland & organ to prepare to deal with threats.
● Parasympathetic (PNS) - relaxes body once threat has passed, slows heart beat & reduces
blood pressure. Also called the ‘rest & digest system’ - digestion begins again under PNS
Sensory Neurons
= found in receptors
e.g. the eyes, ears,
tongue, and skin.
Carry nerve
impulses to the
CNS, where they
are translated to
sensations e.g.
vision
Relay Neurons =
found between
sensory input and
motor output in the
CNS. They allow
the other neurons
to communicate.
Motor Neurons = form synapses with muscles and control their contractions from the CNS. When
stimulated, they release neurotransmitters that bind to the receptors on muscles to trigger a response.
SYNAPTIC TRANSMISSION
Processes of nerve impulse passing across the synaptic cleft from a presynaptic to postsynaptic neuron.
1. Action potential arrives at the terminal button at the end of the axon to be transferred across the
synaptic gap.
2. The neurotransmitter diffuses across the gap, where it binds to specialised receptors on the
surface of the cell that recognise it, and are a ctivated by that particular neurotransmitter.
3. Once they have been activated, the receptor molecules produce either excitatory or inhibitory
effects on the postsynaptic neuron.
4. The effects are terminated at most synapses by ‘reuptake’, where the neurotransmitters are
taken back up by the presynaptic neuron to be stored & made available for later release
5. The quicker it is taken back, the shorter the effects on the postsynaptic neuron
EXCITATORY & INHIBITORY NEUROTRANSMITTERS
Excitatory - transmitters, e.g. noradrenaline increase the likelihood that an excitatory signal is sent to the
postsynaptic cell = more likely to fire
Inhibitory - transmitters, e.g. GABA decreases the likelihood of that neuron firing. Generally responsible
for calming the mind & body, like sleep (the nervous system’s ‘off switch’).
Excitatory neurotransmitter binding with a postsynaptic receptor = electrical change in cell membrane,
resulting in an Excitatory Post-Synaptic Potential (EPSP), so postsynaptic cell is more likely to fire.
● IPSP = opposite
The strength of an EPSP can be increased in 2 ways:
1. Spatial summation - large number of EPSPs generated at many different synapses on same
postsynaptic neuron at same time.
2. Temporal summation - large number of EPSPs generated at the same synapse by a series of
high frequency action potentials on the presynaptic neuron
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