- Unit 3 Biological psychology
- Summary notes 35 pages
- Includes all topics from Edexcel specification (content, methods, studies, key question and practical)
- Includes exam style answers as well as detailed A01 and A03
- 3.1.1 The central nervous system (CNS) and neurotransmitters in
human behaviour, including the structure and role of the neuron, the
function of neurotransmitters and synaptic transmission.
- 3.1.2 The effect of recreational drugs on the transmission process in
the central nervous system.
- 3.1.3 The structure of the brain, different brain areas
- 3.1.4 The role of evolution and natural selection to explain human
behaviour, including aggression.
- 3.1.5 Biological explanation of aggression as an alternative to Freud’s
psychodynamic explanation, referring to the different parts of the
personality (id, ego, superego), the importance of the unconscious,
and catharsis.
- 3.1.6 The role of hormones (e.g. testosterone) to explain human
behaviour such as aggression.
- 3.1.7 Individual differences
- 3.1.8 Developmental psychology
3.2 Methods
- 3.2.1 Correlational research
- 3.2.2 Analysis of correlational data
- 3.2.3 Other biological research methods: Brain-scanning techniques
(CAT, PET, and fMRI). One twin study and one adoption study, e.g.
Gottesman and Shields (1966); Ludeke et al. (2013).
3.3 Studies
Classic study
- 3.3.1 Raine et al. (1997) Brain abnormalities in murderers indicated by
positron emission tomography. One contemporary study from the
following
- 3.3.3 Brendgen et al. (2005) Examining genetic and environmental
effects on social aggression: A study of 6-year-old twins.
3.4 Key questions
3.5 Practical investigation
,What is the central nervouse system and how does it work
- The CNS consists of the brain and spinal cord.
- It is the central processing and control point for all human behaviour.
- The brain processes all incoming info from the senses and is then responsible
for controlling behaviour that may result in this info.
- The spinal cord connects the brain to the rest of the body and allows
messages to be passed from the body to the brain and also from the brain to
other parts of the body
- The cells in the CNS are known as neurons and these cells communicate
around 1000 other cells in huge networks.
Structure of a neuron
, Role of a neuron
Role of the neuron: The purpose of the neuron is to transmit messages around the
body. There are networks of millions of neurons in your brain and body that are all
connected and communicate with each other
Communication along the neurons happen in the following stages:
1)The dendrite receives a message often 2)This triggers an action potential - an
from another neuron. electric message within the cell body
3)The action potential travels down the 4)The action potential than reaches the
axon. The myelin sheath and Nodes of axon terminals and the terminal
Ranvier help to make this process fast. buttons.
5)The terminal buttons will pass this 6)If it is a neuron stages one to five will
message to the next part of the body. happen again.
This could be another neuron, a muscle,
or a gland.
What is an action potential?
- Refers to the method by which the nerve impulse passed down the
axon of the neuron to stimulate the release of the neurotransmitters.
- This is a tiny electrical impulse that is triggered by a change in the
electrical potential of the neuron itself.
- Neurons have a resting membrane potential of about 70mph
- Inside of the neuron has a slightly negative charge in relation to
outside of the neuron.
- When a neuron receives a message from another neuron this chemical
message can either:
1. Stimulate an excitatory postsynaptic potential: slightly depolarise
the neuron reducing its charge.
2. Hyperpolarise the neuron increasing its charge and stimulating an
inhibitory post synaptic potential.
- When a neuron has received enough excitatory messages or more in
comparison to the inhibitory messages that are strong enough to
reach the neurons own threshold an action potential is reached
- This usually happens when the neurons charge reaches approx 55 mv
- The action potential sends and impulse along the axon of the neuron
towards the axon terminals at the end on the neuron.
, Synaptic transmission
Communication along two neurons happen in the following stages:
1.An electrical message (action 2.Eventually the action potential it
potential) is sent along the axon of the reaches the end of the neuron, also
presynaptic neuron after the receptors known as the axon terminal. Now the
on the dendrites received a message neuron can pass its message to further
that triggered an action potential in neurons across the synaptic gap/cleft
the cell body.
3.Neurotransmitters are released into 4.The neurotransmitters attach to the
the synaptic cleft and diffuse across receptors on the dendrite of the post
the space between the two neurons. synaptic neuron
Each neuron is responsible for
producing a certain chemical or
neurotransmitter and when the action
potential reaches the axon terminal
calcium channels flow open. Flooding
the terminal button with calcium ions.
Vesicles containing the
neurotransmitter substance will then
be released and travel down to the
outer membrane of the terminal button
where the casting of the vesicle will
fuse with the membrane. This allows
the neurotransmitter to be released
from its vesicles into the synaptic gap
5.When enough receptors are activated 6.Nurotransmitter that remains in the
a new action potential is created on synapse is taken back into to the
the next neuron. presynaptic neuron in a process known
as reuptake – any neurotransmitter
molecules that have not been absorbed
by the receptors of the postsynaptic
neuron will be destroyed by enzymes in
the synaptic gap/cleft
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