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Summary AQA A-Level Psychology Knowledge Organiser Biospychology
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Full Knowledge Organiser for AQA A-Level Psychology Biopsychology
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DIVISIONS OF THE NERVOUS SYSTEM:• the human nervous system is divided into the central nervous system and peripheral nervous system, with each
of these further divided in different components, each with a different function but all working together
• Central Nervous System (CNS) = comprises the brain and the spinal cord, it receives information from the sense and -
------------------------------------------- controls the body’s responses
• Peripheral Nervous System = the part of the nervous system that is outside the brain and the spinal cord THE PERIPHERAL NERVOUS SYSTEM:
o all the nerves outside the CNS make up the peripheral nervous system
• Autonomic Nervous System (ANS) = governs the brain’s involuntary activities and is self-regulating
o this function of this part of the nervous system is to relay nerve impulses from the CNS to the rest of the body
→ is divided into the sympathetic branch (fight-or-flight) and parasympathetic branch (rest and digest)
and from the body back to the CNS
• Somatic Nervous System = the part of the peripheral nervous system responsible for carrying sensory and motor ----- o there are two main divisions of the peripheral nervous system:
------------------------------------ information to and from the central nervous system → the somatic nervous system
• Brain = part of the CNS responsible for coordinating sensation, intellectual, and nervous system → the autonomic nervous system
• Spinal Cord = bundle of nerve fibres enclosed within the spinal column, connects nearly all parts of body with brain
THE SOMATIC NERVOUS SYSTEM:
THE CENTRAL NERVOUS SYSTEM: • the somatic nervous system is made up of 12 pairs of cranial nerves and 31 pairs of spinal nerves
o the CNS has two main functions: control of behaviour and regulation of the body’s physiological processes → Cranial Nerves = nerves that emerge directly from the underside of the brain
o in order to do this, the brain must be able to receive information from the sensory receptors and be able to → Spinal Nerves = nerves that emerge from the spinal cord
send messages to the muscles and glands of the body – this involves the spinal cord
• these nerves have both sensory neurons and motor neurons
THE SPINAL CORD: → Sensory Neurons = relay messages to the CNS
• the main function of the spinal cord is to relay information between the brain and the rest of the body → Motor Neurons = relay information from the CNS to other areas of the body
→ this allows the brain to monitor and regulate bodily processes and to coordinate voluntary movements • is also involved in reflex actions without the involvement of the CNS, which allows the reflex to occur very quickly
• spinal cord is connected to different parts of the body by spinal nerves, which connect to specific muscles and glands
• the spinal cord also contains circuits of nerve cells that enable us to perform some simple reflexes without the THE AUTONOMIC NERVOUS SYSTEM:
direct involvement of the brain, for example pulling tour hand away from something that is hot • the body carries out some actions without your conscious awareness, e.g. heart beat and digestion
→ if the spinal cord is damaged, areas supplied by spinal nerves below the damaged site will be cut off from the → involuntary actions such as these are regulated by the ANS
brain and will stop functioning → this system is necessary because vital bodily functions such as heartbeat and digestion would not work so
efficiently if you had to think about them
THE BRAIN:
The brain can be divided into four main areas: the cerebrum, cerebellum, diencephalon, and brain stem • the ANS has two parts: the sympathetic and the parasympathetic
→ both of these divisions tend to regulate the same organs but have opposite effects
• Cerebrum = largest part, further divided in 4 different lobes, each of which has a different primary function
→ this is because of the neurotransmitters associated with each division
→ the cerebrum is split down the middle into two halves called cerebral hemispheres
→ generally, the sympathetic division uses the neurotransmitter noradrenaline, which has stimulating effects, and
→ each hemisphere is specialised for particular behaviours, and the two halves communicate with each other
the parasympathetic division uses acetylcholine, which has inhibiting effects
through the corpus callosum
• Cerebellum = it is involved in controlling a person’s motor skills and balance, coordinating the muscles to allow ----- • Sympathetic Nervous System: primarily involved in responses that help us to deal with emergencies, such as --------
--------------------precise movements sits beneath the back of the cerebrum ---------------------------------increasing heart rate and blood pressure and dilating blood vessels in muscles
→ abnormalities can result in a number of problems, including speech and motor problems and epilepsy → neurons from the SNS travel to virtually every organ and gland within the body, preparing the body for the
rapid action necessary when the individual is under threat
• Diencephalon = lies beneath the cerebrum and on top of the brain stem → for example, the SNS causes the body to release stored energy, pupils to dilate and hair to stand on end
→ within this area are two important structures, the thalamus, and the hypothalamus → it slows bodily processes that are less important in emergencies, such as digestion and urination
• Thalamus = acts as a relay stations for nerve impulses coming from the sense, routing them to the appropriate part • Parasympathetic Nervous System: relaxes people once the emergency has passed
--------------- of the brain where they can be processed → whereas the SNS causes the heart to beat faster and blood pressure to increase, the PNS slows the heartbeat
• Hypothalamus = has a number of important functions, including body temperature regulation, hunger, thirst down and reduces blood pressure
→ also acts as link between endocrine and nervous system, controlling release of hormones from pituitary gland → another benefit is that digestion (inhibited when the SNS is aroused) begins again under PNS influence
• Brain Stem = responsible for regulating the automatic functions that are essential for life (inc. breathing, heartbeat) → because the PNS is involved with energy conservation and digestion, it is sometimes referred to as the body’s
→ motor and sensory neurons travel through brain stem, allowing impulses to pass between brain and spinal cord rest and digest system
,THE STRUCTURE AND FUNCTION OF NEURONS: SYNAPTIC TRANSMISSION:
Synaptic Transmission = refers to the process by which a nerve impulse passes across the synaptic cleft from one -------
Neurons = cells specialised to carry neural information throughout the body ---------------------------------neuron (the presynaptic neuron) to another (the postsynaptic neuron)
→ neurons can be one of three types: sensory neurons, relay neurons, or motor neurons
→ neurons typically consist of a cell body, dendrites, and an axon • synaptic transmission is the process by which one neuron communicates with another
• information is passed down the axon of the neuron as an electrical impulse known as action potential
• dendrites at one end of the neuron receive signals from other neurons or from sensory receptors • once the action potential reaches the end of the axon it needs to be transferred to another neuron
→ dendrites are connected to the cell body, the control centre of the neuron • it must cross over the synaptic gap between the presynaptic neuron and post-synaptic neuron
• at the end of the neuron (in the axon terminal) are the synaptic vesicles, which contain chemical messengers,
• from the cell body, the impulse is carried along the axon, where it terminates at the axon terminal known as neurotransmitters
• in many nerves there is an insulating layer that forms around the axon – the myelin sheath • when the electrical impulse (action potential) reaches these synaptic vesicles, they release their contents of
→ this allows nerve impulses to transmit more rapidly along the axon neurotransmitters
→ if the myelin sheath is damaged, impulses slow down • neurotransmitters then carry the signal across the synaptic gap
• they bind to receptor sites on the post-synaptic cell, completing the process of synaptic transmission
• the length of a neuron can vary from a few millimetres up to one metre
→ excitatory neurotransmitters (e.g. adrenaline) make the post synaptic cell more likely to fire
→ inhibitory neurotransmitters (e.g. serotonin) make them less likely to fire
Sensory Neurons = carry nerve impulses from sensory receptors to the spinal cord and the brain
• are found in various locations in the body → summation is the net effect of the EPSPs and IPSPs (adding up the positive and negative charges)
• they convert information from these sensory receptors into neural impulses
EXCITATORY AND INHIBITORY NEUROTRANSMITTERS:
• when these impulses reach the brain, they are translated into sensations of, for example, visual input, heat, pain,
etc, so that the organism can react appropriately Neurotransmitter = chemical substances that play an important part in the nervous system by transmitting nerve -------
• not all sensory information travels as far as the brain, some neurons terminate in the spinal cord ---------------------------impulses across a synapse
• this allows reflex action to occur quickly without the delay of sending impulses to the brain → neurotransmitters can be classified as either excitatory or inhibitory in their action
• Excitatory Neurotransmitters = increase the likelihood an excitatory signal is sent to the postsynaptic cell, which is --
Relay Neurons = these neurons are the most common type of neuron in the CNS, they allow sensory and ------------------
----------------------------------------- then more likely to fire – e.g. adrenaline
---- motor neurons to communicate with each other
• Inhibitory Neurotransmitters = generally responsible for calming the mind and body, inducing sleep, and filtering ---
• most neurons are neither sensory or motor, but lie between sensory input and motor output
------------------------------------------out unnecessary excitatory signals – e.g. serotonin
• relay neurons allow sensory and motor neurons to communicate with each other
• these relay neurons lie wholly within the brain and spinal cord Binding with a Postsynaptic Receptor:
• Excitatory: causes electrical change in the membrane of the cell, resulting in an excitatory post---------------------
Motor Neurons = form synapses with muscles and control their contractions synaptic potential (EPSP), meaning postsynaptic cell is more likely to fire
• refers to neurons which conduct signals from the CNS to effector organs such as muscles • Inhibitory: results in an inhibitory postsynaptic potential (IPSP), less likely the cell will fire
• their cell bodies may be in the CNS, but they have long axons which form part of the PNS
• motor neurons form synapses with muscles and control their contractions • a nerve cell can receive both EPSPs and IPSPs at the same time
• when stimulated, the motor neuron releases neurotransmitters that bind to receptors on the muscle and triggers → therefore, likelihood of cell firing is determined by adding the excitatory and inhibitory synaptic input
a response which leads to muscle movement → the net result of this calculation (known as summation) determines whether or not the cell fires
• when the axon of a motor neuron fires, the muscle with which it has formed synapses with contracts • the strength of an EPSP can be increased in two ways
• strength of muscle contraction depends on the rate of firing axons of motor neurons that control it → Spatial Summation = a large number of EPSPs are generated at many different synapses on the same ---------------
• muscle relaxation is caused by inhibition of the motor neuron ---------------------------- postsynaptic neuron at the same time
→ Temporal Summation = a large number of EPSPs are generated at the same synapse by a series of high -------------
--------------------------------frequency action potentials on the presynaptic neuron
• the rate at which a particular cell fires is determined by what goes on in the synapses
→ if excitatory synapses are more active, the cell fires at a high rate
→ if inhibitory synapses are more active, the cell fires at a much lower rate, if at all
, Endocrine System = network of glands in the body that manufacture and secrete chemical messengers (hormones) PITUITARY GLAND:
Pituitary Gland = the ‘master gland’, primary function is to influence the release of hormones from other glands, and --
----------------------- in doing so, regulate many of the body’s functions
GLANDS AND HORMONES:
• is controlled by the hypothalamus, a region of the brain just above the pituitary gland
Endocrine Glands = special group of cells in endocrine system, function is to produce and secrete hormones • the hypothalamus receives information from many sources about the basic functions of the body, the uses this
information to help regulate these functions
• major glands of endocrine system include pituitary gland, adrenal glands, and reproductive organs
• one of the ways to does this involve controlling the pituitary gland
• each gland produces different hormones, which regulate activity of organs and tissues in the body
• as the ‘master gland’, it produces hormones that travel in the bloodstream to their specific target
• the endocrine system is regulated by feedback
• these hormones either directly cause changes in physiological processes in the body or stimulate other glands
→ e.g. a signal is sent from hypothalamus to pituitary gland in the form of a ‘releasing hormone’
to produce other hormones
→ this causes the pituitary to secrete a ‘stimulating hormone’ into the bloodstream
• high levels of hormones produced in other endocrine glands can stop the hypothalamus and pituitary releasing
→ this hormone then signals the target gland (e.g. the adrenal gland) to secrete its hormone more of their own hormones
→ as levels of this hormone rises in the bloodstream, the hypothalamus shuts down secretion of the • this is called negative feedback, and prevents hormone levels from rising too high
releasing hormone and the pituitary gland shuts down secretion of stimulating hormone
→ this slows down secretion of the target gland’s hormone, resulting in stable concentrations of hormones HORMONES PRODUCED BY THE PITUITARY GLAND:
circulating in the bloodstream • pituitary gland has two main parts: the anterior (front) pituitary and the posterior (back) pituitary
→ these two parts release different hormones, which target different parts of the body
Hormones = body’s chemical messengers, each hormone ‘excites’/stimulates a particular part of the body → the two sections of the pituitary gland produce a number of different hormones, which act on different
→ they travel through the bloodstream, influencing many different processes including mood, the stress target glands or cells
response and bonding between mother and new born baby
• Anterior Pituitary releases:
• although hormones come into contact with most cells in the body, a given hormone usually affects only a → ACTH = stimulates the adrenal glands to produce cortisol – releases as a response to stress
limited number of cells, known as target cells • Posterior Pituitary releases:
→ target cells respond to a particular hormone because they have receptors for that hormone → Oxytocin = stimulates contraction of uterus during childbirth, important for mother- infant bonding
→ cells that do not have such a receptor cannot be influenced directly by that hormone
THE ADRENAL GLANDS:
• when enough receptor sites are stimulated by hormones, a physiological reaction occurs in target cell
• the two adrenal glands sit on top of the kidneys
→ timing of hormone release is critical for normal functioning, as are levels of hormones released
• the name ‘adrenal’ relates to their location
→ too much or too little at the wrong time can result in dysfunction of bodily systems
• each adrenal gland is made up of two distinct parts
→ for example, too high a level of cortisol can lead to Cushing’s syndrome, characterised by high blood
• the outer part of each gland is called the adrenal cortex and the inner region is known as the adrenal medulla
pressure and depression
• the adrenal cortex and the adrenal medulla have very different functions
• one of the main distinctions between them is that the hormones released by the adrenal cortex are necessary
• most common cause of excess cortisol is a tumour in the pituitary gland
for life, those released by the adrenal medulla are not
→ which makes too much of a hormone called adrenocorticotrophic hormone (ACTH) which stimulates
adrenal glands to make too much cortisol
HORMONES PRODUCED BY THE ADRENAL GLANDS:
• Adrenal Cortex produces:
→ Cortisol = regulates variety of bodily functions (inc. cardiovascular and inflammatory functions)
- cortisol production is increased in response to stress
- low cortisol level results in blood pressure, poor immune function, and an inability to deal with stress
• Adrenal Medulla releases: hormones that prepare the body for fight or flight
→ Adrenaline = helps the body response to a stressful situation
- e.g. by increasing heart rate and blood flow to the muscles and brain and helping with the conversion
of glycogen to glucose to provide energy
→ Noradrenaline = constricts the blood vessels, causing blood pressure to increase
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