Biopsychology notes - Psychology AQA B

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The structure and function of neurons
Humans have two control systems in order to respond to the environment:
1. The nervous system
2. The endocrine system
The organisation of the human nervous system is
shown here.
The human nervous system is divided into two
main sub-systems:
The central nervous system which consists of
the brain and spinal cord
The peripheral nervous system which consists
of millions of neurons that carry messages to
and from the central nervous system. These
neurons are known as motor, sensory and
interconnecting neurons.
Motor neurons (efferent)
Motor neurons carry messages away from the brain and spinal cord to the organs and muscles in
the body.
A motor neuron has a cell body with many dendrites branching off it. These dendrites have a large
surface area in order to connect with other neurons and carry nerve impulses towards the cell
body.
The axon then carries the nerve impulse away from the cell body. Surrounding the axon are special
cells known as Schwahn cells that wrap around the axon to form an insulating layer called a myelin
sheath. At its end the axon divides into a number of branches known as synaptic terminals. These
synaptic terminals do not actuall touch the next neuron; there is a small gap between the synaptic
terminals and the dendrites of the receiving neuron known as a synapse.

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Sensory neurons (afferent)
Sensory neurons carry messages from the receptors in the body to our brain and spinal cord.
Receptors such as our sense organs, muscles, skin or joints detect physical and chemical changes
in the body and relay these messages via sensory neurons to the brain or spinal cord.
Interconnecting neurons
Interconnecting (relay) neurons are found only in our visual system, brain and spinal cord.…read more

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Motor Neuron Interconnecting Neuron Sensory Neuron
Function Carries messages from the Transfers messages from Carries messages from the
CNS to effectors such a sensory neurons to other PNS to the brain and spinal
muscles and glands interconnecting or relay cord (CNS)
neurons
Length of Short dendrites and long Short dendrites and either Long dendrites and short
Fibres axons short or long axons axons
Synaptic transmission
Action potential: electrical impulse along a neuron
Synapse: The gap between the end of one neuron and the dendrites of…read more

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Localisation of cortical function
During 19th Century, scientists such as Paul Broca and Karl Wernike discovered that certain areas
of the brain held particular functions/actions­ known as `localisation of cortical function'
They also discovered that some functions such as speech and language are controlled by a
particular hemisphere (or side of the brain) ­ known as `lateralisation of cortical function'
Localisation: specific areas of the cerebral cortex are associated with particular physical and
psychological functions
Lateralisation: the dominance of one hemisphere of the brain for…read more

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The cerebrum
The cerebrum has an outermost layer known as the cerebral cortex. The cortex appears grey
because of the location of cell bodies- which is why it is known as grey matter. Beneath the cortex
lie myelinetated axons which appear as white- hence it is known as white matter. Each of our
sensory systems sends messages to and from this cerebral cortex.
The cerebrum is composed of the right and left hemispheres which are connected by a bundle of
fibres called the corpus callosum.…read more

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The amount of somato sensory area associated with a particular part of the body is
related to its use and sensitivity.
The visual area ­ the occipital lobes primary function is vision. Here nerve fibres from the inner
half of the retina of each eye cross at the optic chiasm and travel to the opposite sides of the
brain. (Damage to the left hemisphere may affect the right eyes vision).…read more

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Methods of studying cortical specialisation
Invasive methods
An invasive procedure is one in which the body is "invaded" or entered by a needle, tube, device,
or scope
1. Post mortem studies
A post-mortem examination, or autopsy, is an examination of a corpse in order to
determine the cause of death.…read more

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A non-invasive procedure is one in which there is no break in the skin or any invasion of healthy
tissue. There are four non- invasive methods:
Electroencephalogram (EEG)
Computerised axial tomography (CAT)
Positron emission tomography (PET)
Magnetic resonance imaging (MRI)
1. EEG
Electroencephalogram (EEG) is a non-invasive measurement of electrical activity in
the brain. When the brain cells send messages to each other, they produce tiny
electrical signals. In an EEG test, electrodes (flat metal discs) are placed onto the
scalp using a sticky substance.…read more

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Positron emission tomography (PET) involves producing computer-generated pictures of the brain.
A tracer (a small amount of radioactive glucose) is injected into the body. This can be picked up
and formed into a picture of the amount of tracer absorbed, which can indicate which area of the
brain/body is functioning when individuals are asked to perform tasks such as solving problems.
The PET scan measures blood flow and oxygen use.
4. MRI scan
Magnetic resonance imaging (MRI) uses magnetic and radio waves.…read more

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Human nervous system
Autonomic nervous system (ANS)
Function: controls the functions of blood vessels, glands and the internal organs of the body (e.g.
bladder, stomach and heart)
It mainly operates automatically i.e. without conscious control
The ANS is sub-divided into the sympathetic and parasympathetic nervous system.…read more

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AS Resources

nice, but quite a few mistakes

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