3.1.1 CNS Flashcards
what does the cns consist of?
brain and spinal cord
explain the function of the central nervous system
- the central nervous system consists of the brain and spinal cord
- it is the central processing system and control point for all human behaviour
- the brain processes all incoming information from the senses
- the spinal cord connects the brain and the rest of the body, and allows messages to be passed between the body and the brain
explain the role of a neuron (2)
- neurons are cells within the central nervous system which communicate chemical messages between each other in a huge network, through synaptic transmission
- to change behaviour, such as mood
explain the role of a neurotransmitter
- neurotransmitters are chemicals which pass messages across the synaptic gap between neurons through synaptic transmission (1).
- neurotransmitters affect mood, attention and memory (1).
describe how messages travel along a neuron
- Neurons consist of a cell body which contains the nucleus (1).
- Attached to the cell body are dendrites that receive messages from other neurons (1)
- in order to trigger an action potential (electrical impulse) which travels down the axon (1).
- Fatty deposits called myelin sheath provide insulation helping to speed up message transmission(1).
- Breaks between the myelin sheath are called nodes of Ranvier (1).
- At the end of the axon are axon terminals with terminal buttons containing vesicles that store neurotransmitters (1).
Describe how neurotransmitters could affect human behaviour (2)
- Neurotransmitters are chemical which pass messages between neurons,
- for example serotonin is associated with mood regulation so a lack of it can cause depression
what are the 3 types of neurons?
- sensory - carry messages from sensory receptors along nerves in the PNS to the CNS
- motor - carry messages from CNS, along nerves in the PNS, to effectors in the body (e.g. muscles and glands)
- relay - connect sensory and motor neurons together, and also connect to other relay neurons
explain the process of synaptic transmission (5)
- An action potential (electrical impulse) travels along an axon
- This triggers the nerve-ending of a neuron to release neurotransmitters from vesicles
- They diffuse across the synaptic gap and bind with specific receptor sites on the postsynaptic neuron (eg dopamine binds to D2)
- This stimulates the second neuron to create an action potential, transmitting the message
- Any neurotransmitter molecules which haven’t been absorbed by the postsynaptic neuron, get absorbed back into the presynaptic neuron (this is known as reuptake) or are destroyed.
what is reuptake?
unused neurotransmitter molecules are absorbed back into the presynaptic neuron and is then either destroyed by enzymes within the neuron or is reused.
cns and neuro - supporting evidence
evaluation
P = Supporting evidence of the role neurotransmitters in behaviour.
E = Depression is thought to be caused by low levels of sero. which regulates mood. SSRI’s block the reuptake of sero. so there is more in the synaptic gap, improving mood.
T = Thus neurotrans. play a role in behaviour
cns and neuro - contradicting evidence
evaluation
P: there is evidence to contradict the neurotrans. explanation
E: The Royal College of Psychiatry found only 50-60% of patients with depression improved after taking antidepressants
T: Thus neurotrans. can’t be the only cause of depression, limiting the validity of the explanation
cns and neuro - application
evaluation
P: Neurotrans. explanation has application in treating addiction
E: Methadone, a synthetic opiate is used as a heroin substitute, because it’s an agonist which binds to opioid receptors, stopping withdrawal symptoms.
T: Thus neurotrans. explanation is useful to society to help individuals change unwanted behaviour.
cns and neuro - ignores nurture
evaluation
P: it reduces complex behaviour down to neurotrans.
E: SLT suggests addiction is learnt through observing RM using drugs which is imitated because of vicarious reinforcement eg. seeing RM gain social status.
T: Thus the neurotrans. explanation ignores the role of nurture, so validity can be questioned
cns and neuro - conclusion
evaluation
In conclusion, the neurotransmitter explanation has played a vital role in
developing our understanding of behaviours such as mental health and addiction, improving people’s quality of life. However, despite it’s scientific status we should also consider the role of alternative explanations to achieve a holistic approach to explain behaviour in the most effective way.
