Biopsychology PART 1 Influence of biological structures on behaviour - The fight-or-flight response :)


Nervous system

Nervous system: provides the biological basis for psychological experience 

Nervous system is divided into central nervous system and peripheral nervous system

Central nervous system compromises the brain and the spinal chord

Peripheral nervous system is the nerves outside the brain and the spinal chord

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Central Nervous System

Central nervous system: concerned with all life functions and psychological processes 

The brain controls many of the body's functions including sensation, thought, movement, awareness, and memory.

Brains main job is to ensure that life is maintained. involved in higher functions and psychological processes 

Different parts of the brain. Some more primitive and concerned with vital functioning other parts involved in higher order thinking. Like planning 

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Central Nervous System 2

Spinal cord receives and transmits info to and from the brain to teh PNS. Fluctuates the transferal of messages to and from the brain to pns. Also involved in reflex actions

The spinal cord connects to the brain via the brain stem and then runs down through the spinal canal located inside the vertebra.

The spinal cord carries information from various parts of the body to and from the brain. Some reflex movements, responses are controlled by spinal pathways without involvement from the brain.

Involved in reflex actions such as the startle response. 

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Peripheral Nervous System

PNS includes all of the nervous system throughout the rest of the body 

Extends beyond CNS and transmits messages to whole of body from brain and messages from whole of body to brain 

PNS is divided into the somatic system and the autonomic system  

Autonomic system: transmits and receives info from internal organs  to sustain life processes 

Somatic system: transmits and receives info from the senses like visual and auditory info. to and from central nervous system. Also directs muscles to react and move. 

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Peripheral Nervous System 2

Autonomic system is divided into sympathetic system and para sympathetic system. 

Parasympathetic nervous system: conserves the bodes natural activity levels by decreasing activity or maintaining it.  

Sympathetic nervous system: increases bodily activities 

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Endocrine System

endocrine system= all of the hormones and all of the glands that release that hormone.

The endocrine system is made up of glands that produce and secrete hormones, chemical substances produced in the body that regulate the activity of cells or organs.

endocrine system has a series of glands which release chemicals (hormones)throughout the body via the blood and other bodily fluids. 

endocrine responses are slower than autonomic nervous system as hormones travel via blood= slower  

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Endocrine System 2

pituitary gland = ‘master gland’. controls whole of endocrine system. also monitors it. 

during a stressful situation, pituitary gland releases ACTH(the main stress hormone) this hormone travels through the blood to reach the adrenal glands. adrenal medulla then releases adrenaline.  

specialist glands in the body which form part of this system. 


adrenal gland= adrenaline


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Endocrine System 3

behaviour is thought to be influenced by hormones. each hormone thought to affect behaviour in a different way. 

pituitarygland - some of hormones released important for regulating endocrine system. ‘master gland’ 

Adrenal gland - important part of the fight-or-flight response as it facilitates the release of adrenaline 

Overies - facilitate the release of oestrogen and progesterone 

Testes- facilitate the release of testosterone 

The hormone oxytocin, released by the pituitary gland, is thought to be important for reproductive behaviour. High levels of oxytocin encourage strong bonding between couples. This is also the case for mother/child bonding 

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Fight-or-Flight response.

Fight or flight response generated from the autonomic nervous system. specifically sympathetic branch

It is a reflex response designed to help an individual manage physically when under threat

Also activated at times of stress because body percieves stress to be a threat. 

Fight-or-Flight helps individuals to react quicker than normal

It facilitates optimal functioning so that the individual can fight threat or run away from it. 

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Fight-or-Flight response. 2

The Fight-or-Flight response involves two elements that work simultaneously. Fast autonomic response and a slow endocrine response. 

It occurs in a series of steps:

Hypothalamus recognises that there is a threat

It then sends a message to the adrenal gland (adrenal medulla) 

This triggers the release of adrenaline to teh endocrine system and noradrenaline in the brain. 

This then prompts physical changes such as, 

Increased heat rate,  faster breathing rate, muscle tension, pupil dilation, the production of sweat, reduced functioning of teh digestive and immune systems. 

Physical changes help individual to fight or run away from potentially threatening situation. 

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Fight-or-Flight response. 3

When a  stressor is detected by Hypothalamus, Autonomic nervous sytem is initiated. Pituitary gland is also stimulated which then triggers the endocrine response. 

Physical changes prompted because... 

Increased heart rate - to speed up the blood flow to vital organs and improve spread of adrenaline around body. 

Faster breathing rate- to increase oxygen intake

Muscle tension- to improve reaction time and speed

Pupil dilation- to improve vision

Production of sweat- to facilitate tempreature regulation 

Reduced functioning of digestive and immune systems - to save energy for prioritised functions such as running. 

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Fight-or-Flight response. 4

Sypathetic branch in Fight-or-Flight response prepares body for action

Parasympathetic branch restores body back down to normal. 

Symphathetic INCREASES bodily activities

Parasymphathetic DECREASES bodily activities 

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Biological structures EVALUATION

Assessing extent to which biological structures affect behaviour can be difficult

Can be argued that they are tools to make behaviour happen and not the cause

Cause and effect not established in most research because much of research is corrolational 

Means that only teh relationship between biological influence and the behaviours can be investigated

People respond to stressors in different ways according to personality types 

Biological structures that underpin behaviour can be seen as REDUCTIONIST 

It attempts to reduce human behaviour and cognitive processes down to biological processes 

It is too simplistic. Within biological processes there is a further reduction down to a specific component. Like the level of a hormone. 

Physical nature of bodily systems means that research is scientific. measures are objective. This increases the reliability of the results. 

Connection between biological structures and human behaviours HAS been established 

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A neuron is a specialised nerve cell that receives, processes, and transmits information to other cells in the body.

A neurone is specialised for communication 

Fixed number of neurons, which means they do not regenerate. 

Around 100 billion neurons in the brain and 1 billion neurons in the spinal cord 

In all neurons, dendrite/receptor cell recieves signal and it then travels through the neuronto the pre- synaptic terminal. 

All neurons have axons, myelin sheath, axon terminals, a nucleus and dendrites 

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Motor Neurons

Motor neurons relay impulses from the CNS to the muscles. this helps both organs including glands and muscles function 

Motor neurons are multipolar, send and receive messages from many sources = much variation anatomically 

Dendrite cell receives signal.  Travels through neurone to the pre synaptic terminal 

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Sensory Neurons

Sensory neurons tell rest of brain about the external and internal environment 

They do this by processing info taken from 1 of 5 senses. 

They relay impulses from these sense organs to the CNS  

Sensory neurons only transmit messages so are unipolar 

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Relay Neurons/ Inter connector neurons

Relay  neurons carry messages from one part of cns to another. 

Relay neurons connect motor and sensory neurons.  

Relay neurons send and receive messages from many sources so are multipolar. 

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Synaptic Transmission

Synaptic transmission= process by which nerve impulses are carried across small gap ( the synapse )between one neurone and another

Synapse= specialised gap between neurons through which the electrical impulse from the neurone is transmitted chemically. 

Nerve impulse= an electrical signal which is carried by chemicals called neurotransmitters 

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Synaptic Transmission 2

Electricalnerve impulse travels down the neurone and prompts release of neurotransmitters at the pre-synaptic terminal 

Neurotransmitters chemicals then released into synaptic fluid in synapse. 

Adjacent neurone takes up neurotransmitters from the fluid and converts them into an electrical impulse

This impulse then travels down neurone to next pre-synaptic terminal. 

Neurotransmitters= chemicals in the brain 

Neurotransmitters like dopamine and seretonine. 

It occurs at HIGH SPEED 

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Excitation and Inhibition

Not all messages prompt activation in same way. 

This depends on 'action potential' of the post-synaptic neuron and the message type recieved. 

Only certain neurotransmitters can unlock a message channel in certain receptors in post-synaptic neuron

When right neurotransmitter meets right receptor, specific ion channel in membrane is opened up. 

Ions then flow through membrane into neuron along specific pathways. 

Flooding of ions can cause a potential in dendrites

These potentials are excitatory or inhibitory

Exhitatory potentials- make it more likely for neurons to fire. If a synapse is more likely to cause post-synaptic neuron to fire it = excitatory synapse 

Inhibitory potentials - make it less likley to fire. If message is likely to be stopped at post-synaptic neuron = inhibitory synapse 

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