Nervous system
AO1: CNS = brain and spinal cord – controls our behaviour and regulates thinking process,
the brain – higher order thinking and vital functions, spinal cord = collection of nerve cells
that connects to brain, sends messages from brain to body and regulates processes like
digestion, breathing and voluntary muscle movement. PNS (peripheral) = contains
autonomic and somatic nervous system, all the nerve cells outside the CNS are in the PNS,
receives info from CNS and sends to body and vice versa. ANS (autonomic) = automatic
functions and contains sympathetic and parasympathetic nervous system. Sympathetic =
fight/flight and when body is stressed – increased heart rate, increase breathing rate,
increased sweat, dilates pupils, inhibits digestion, contracts rectum. Parasympathetic = rest
and digest and relaxing – decreased heart rate, decreased breathing rate, pupils constrict,
rectum relaxes, sweat decreases, stimulates digestion. SNS (somatic) = sensory and motor
neurons.
Endocrine system
AO1: The network of glands that release hormones into the body via blood and bodily fluids
that help communicate messages to organs. Master gland = pituitary gland. Adrenal gland =
releases adrenaline which has physiological effects like increased heart rate. Testes gland =
releases testosterone which is linked to masculine characteristics and aggression. Ovary
gland = oestrogen and progesterone for female characteristics. Pituitary gland = 6 main
hormones and oxytocin during orgasm, lactation, mother-baby bonding, and pregnancy
contractions. Also ACTH to stimulate adrenal cortex to release cortisol during stress.
Neurones and synaptic transmission
AO1: Sensory = sends messages from PNS to CNS, processes info from sense, long dendrite
and short axons. Relay = connects sensory neuron to motor neuron or other relay neurons,
short dendrites and short axons. Motor = connects CNS to effectors like muscles/glands,
short dendrite and long axons. Diff between motor/relay and sensory neuron is that they
send and receive messages whereas sensory can only transmit messages. Only relay
neurones are found in the spinal cord. The structure of a neuron: cell body (contains
nucleus), axon (send nerve impulse away from cell body down the length of the neuron),
myelin sheath (fatty layer protects axon and speeds up electrical transmission), nodes of
ranvier (gaps within axon that increase speed of transmission by making impulse jump over
gaps), axon terminal, synapse (gap between neurons where communication occurs),
dendrite (branch structures that carry nerve impulse from previous neurone to cell body),
nucleus (contains genetic info), schwann cell. Whether a neuron fires or not depends on the
sum of excitatory and inhibitory NT. GABBA is an inhibitory NT that has a calming effect on
the nervous system making the neuron less likely to fire. Adrenaline is an excitatory NT that
makes the neuron more likely to fire. Stimulation of the post-synaptic receptors by an
inhibitory NT results in the inhibition of the post-synaptic membrane. When the inhibitory
NT binds to the post-synaptic receptor the neuron is less likely to fire. If there are more
inhibitory NT than excitatory NT the excitation is cancelled out and there is an inhibition of
, any action potentially occurring due to the decrease in overall activity. Synaptic
transmission is when messages are transmitted from one neuron to another across a
synapse. Across the nerve cell the impulse is electrical but in the synapse it becomes
chemical. The chemical (NT) is released from synaptic vesicles at the presynaptic membrane
into the synapse. The NT is taken by the postsynaptic neuron and converted into an
electrical impulse to continue the transmission. There are receptor sites for certain NT like a
lock and key system. Only certain NT can unlock the message of presynaptic receptors.
Fight or Flight response
AO1: Fight or flight response is when the nervous system and the endocrine system work
together to face a life-threatening situation quickly. The role of ANS in the fight or flight
response is that the hypothalamus detects the threat and sends a message to the adrenal
medulla through the nervous system to release adrenaline into the blood stream and
noradrenaline into the brain. The ANS then uses sympathetic nervous system connections
to prompt physical changes: increased heart rate to increase blood flow to organs,
increased breathing rate to increase oxygen intake, increased sweat production for
temperature regulation, dilation of pupils for improved vision, and inhibition of digestion to
focus energy on fighting threat. The role of endocrine system in fight or flight response is
that the pituitary gland releases ACTH which stimulates the adrenal cortex to release
cortisol which shuts off the immune system, helps with inflammation, and increases blood
sugar levels.
AO3: Not useful in modern world for sedentary jobs (more useful for cavemen) as effects of
cortisol are not maladaptive. Prolonged exposure to threat during fight of flight releases
cortisol which is not useful as it suppresses the immune system creating vulnerability for
illness. Due to the release of stored energy not being made up, this can lead to CHD due to
hypertension and increased blood pressure. Implications for economy about treatment for
stress - £15b lost due to absences and a third is due to mental health/stress related issues.
Thus, treating stress related issues can cause people to return to workplace and contribute
to economy. Cognitive treatments for stress result in less likeliness of relapse so although
initial costs are more than drugs the long-term benefit is economically beneficial.
Implications for the interventions of flight or fight response include stress management
programmes to deal with prolonged exposure to threat. Also, anti-anxiety drugs, exercise,
and cog therapies. Alternative approach to threat is when the parasympathetic nervous
system gets involved and causes the freeze response where the individual thinks before
acting in the face of threat. Taylor’s research showed that women are more likely to use the
tend and befriend response as it is more likely to protect their offspring.
Localisation of function in the brain (language centres) (2017 specimen 2) (2022)
(2019)
AO1: Localisation of function is that each part of the brain is responsible for different
activities. Frontal lobe = controls high processing functions like planning, organising,
thinking. Temporal lobe = concerned with language and auditory info. Occipital lobe =
processes visual info. Parietal lobe = general sensory info and making sense of world.
Auditory cortex = analyses speech-based info. Motor cortex = sends nerve impulses to
muscles and controls voluntary muscle movements. Somatosensory cortex = processes
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