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A* Alevel Psychology Notes - Biopsychology
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A* Alevel Psychology Notes - Biopsychology
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AQA AS Psychology Unit 2:Biopsychology
Introduction
Biopsychology is a branch of psychology that analyses how the brain and neurotransmitters
influence our behaviours, thoughts and feelings. This field can be thought of as a combination of
basic psychology and neuroscience.
Many psychology programs use alternate names for this field, including biopsychology, physiological
psychology, behavioural neuroscience and psychobiology. Biopsychologists often look at how
biological processes interact with emotions, cognitions and other mental processes. The field of
biopsychology is related to several other areas including comparative psychology and evolutionary
psychology.
If you are seeking to understand the field of biopsychology, then it is important to have an
understanding of biological processes, anatomy and physiology.
Key knowledge areas for the exam include:
The Nervous System
The Structure and Function of Neurons
The Endocrine System
The Fight-or-Flight Response
The Nervous System
This refers to the complex network of nerve cells that carry messages to and from the brain,
controlled by the brain through billions of neural cross-connections. The nervous system can be
divided into two sub-components; the central nervous system and the peripheral nervous system.
The CNS
The CNS consists of the brain and spinal cord with two main functions; controlling behaviour and
regulation of physiological processes. The brain receives input from sensory modalities, and through
the spinal cord sends messages to muscles and glands in order to coordinate bodily functions.
-The Brain
The brain can be divided into four main areas:
The cerebrum: This is the largest part of the brain, consisting of four different lobes each
with a different primary function. The cerebrum is split into cerebral hemispheres,
specialised for particular behaviour and linked through the corpus callosum. The cerebrum
lobes are as follows:
o The frontal lobes are involved with functions such as speech, thought and learning
o The parietal lobes process sensory information with particular focus on the touch
modality
o The occipital lobes process visual information
o The temporal lobes are involved with the auditory modality and memory
, The cerebellum sits at the rear and bottom of the brain, and coordinates motor skills and
balance, coordinating muscles.
The diencephalon lies between the cerebrum and brain stem, and contains the thalamus and
hypothalamus.
o The thalamus directs sensory input information from nerve impulses received from
the modalities to appropriate parts of the brain
o The hypothalamus regulates hunger, temperature and thirst and links the endocrine
system to the nervous system, controlling pituitary hormone release
The brain stem regulates automatic functions like your breathing and heartbeat. It also
forms the gateway for impulses to pass between the brain and spinal cord.
-The Spinal Cord
The spinal cord refers to a cluster of nerve cells that run up the spinal column and attach to the
brain. The main function is simply to provide the relay between brain and body, allowing the brain to
both monitor and regulate bodily processes and coordinate motor functioning. Spinal nerves
connect the cord to specific muscles and glands. The cord also contains circuited groups of nerve
cells that enable simple reflex motor action without direct control of the brain. Damage to the spinal
cord can be serious as any nerves below the damaged area will be cut off from the brain.
The Peripheral Nervous System
All nerves extraneous to the CNS are part of the peripheral nervous system, which functions to relay
nerve impulses from the CNS to the body and vice versa. It has two main divisions.
-The Somatic Nervous System
Consists of 12 pairs of cranial nerves (emerging directly from the brain) and 31 pairs of spinal nerves
(emerging from the spinal cord). These nerves have both sensory neurons to relay messages to the
CNS and motor neurons to relay information from the CNS. The somatic system is also involved in
reflex actions sans CNS.
-The Autonomic Nervous System
Involuntary actions are regulated by the ANS, as these functions would use up valuable energy to
consciously regulate. It can be further divided into the sympathetic and parasympathetic nervous
systems, which regulate the same organs but have contrasting effects. The sympathetic system
generally uses the neurotransmitter noradrenaline, which has stimulatory effects, whilst the
parasympathetic system uses acetylcholine, which has inhibiting effects.
The SNS is involved in emergency processes such as the fight-or-flight response, increasing
both heart rate and blood pressure. Neurons from the SNS travel to nearly every organ and
gland to prepare the body for rapid action under threat. Inhibits non relevant processes such
as digestion and urination.
The PNS relaxes the body once a threat has passed, slowing the heartbeat and reducing
blood pressure. Digestion is aroused again, and energy is conserved rather than released.
, Neurons & Synapses
Most of the brain consists of glial cells and astrocytes. These include neurons; cells that transmit and
receive electrical impulse messages. There are around 100 billion in the average human brain, each
connected on average to 1000 other neurons creating complex neural networks.
Structure & Function of Neurons
A neuron consists of the following key parts:
Dendrites: Finger like structures extending from the cell body, they form the information-
receiving network for the neurone.
Cell body: Houses the nucleus, which contains genetic information and controls cellular
activity
Axon: Hose like extension of the cell that sends information to a target cell
Axon terminal: An enlarged axon ending used to make contact with other neurones
Myelin Sheath: Jelly like substance that protects the cell axon
They can be subdivided into:
Sensory neurons that convert sensory information obtained from receptors into neural
impulses to send to the brain where they can be processed. Some neurons terminate early
in the spinal cord for reflex actions that needs to subvert the extra delay of sending
impulses to the brain.
Relay neurons are the largest category, and lie between sensory input and motor output
allowing communication between other neurons. They lie wholly within the CNS.
Motor neurons are located in the CNS but project axons outside the CNS to indirectly or
directly control muscles, controlling their contractions via the synapses at the axon ends.
When stimulated the neuron releases neurotransmitters that bind to receptors on the
muscle and contract with a strength relative to the neurons rate of fire. Relaxation is caused
by inhibition of the motor neuron.
Synaptic Transmission
Axon terminals contact other cells at the dendrites. A small gap exists between a dendrite and an
axon terminal, referred to as a synapse. On the dendrite side of the synaptic cleft there are receptors
that receive neurotransmitters sent by neighbouring neurons. Each receptor is made to fit one and
only one type of neurotransmitter. When a neurotransmitter binds to a receptor successfully, a
response is triggered.
In order for such communication to take place, an electrical message must be passed on. An
electrical impulse is generated at the head of the pre-synaptic neurons axon, and travels down until
it reaches the axon terminal, where it causes the calcium channel proteins to open, allowing calcium
ions through the cell membrane and into the neurone itself.
When calcium ions enter the neurone, they bind with vesicles, tiny packages that carry
neurotransmitters. This causes the vesicles to rush to the cell membrane at the end of the axon
terminal. When they reach the membrane their contents are released into the synaptic cleft, where
they diffuse across the synaptic junction and bind with receptors on the post-synaptic neurone. This
is referred to as exocytosis.
As they bind, an excitatory or inhibitory response is triggered, allowing an electrical impulse to
continue its way down the post-synaptic neurone. Neurotransmitters are released back into the
cleft, where more vesicles are manufactured to recycle them for further neural action. This is known
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