bio-psych

• what is the nervous system

  specialised network of cells in the human body and is our primary internal communication system. its functions are to collect, process and respond to information in the environment. divided into central nervous system and peripheral nervous system
• what is the central nervous system

  brain and spinal cord. passes messages to and from the brain and connects nerves to the pns
• what is the peripheral nervous system


  Sends information to the CNS from the outside world, and transmits messages from the CNS to muscles and glands in the body. further divided into autonomic nervous system and somatic nervous system
• What is the autonomic nervous system?


  governs all vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress responses. further divided into sympathetic and parasympathetic
• What is the sympathetic nervous system?

  prepares the body for action and stress, called the flight or fight
• What is the parasympathetic nervous system?

  calms the body and helps the body to conserve energy. rest and digest.
• what is the somatic nervous system

  controls muscle movement and receives information from sensory receptors
• What is the endocrine system?

  Hormones are chemical messengers secreted from glands in the body which pass through the bloodstream to cause changes in our body or behaviour. The network of glands is called the endocrine system.
• What is the pituitary gland?


  master gland and controls release of hormones from many of the glands. divided into the anterior and posterior.
• thyroid gland


  secretes thyroxine and regulated metabolic rate and protein synthesis
• adrenal medulla


  secreted adrenaline and noradrenaline. causes the flight or fight response
• adrenal cortex


  secretes corticosteroids and releases glucose and fats for energy. suppression of the immune system
• testes


  secrete testosterone, male sexual characteristics and muscle mass
• ovaries


  secretes oestrogen, female sexual characteristics, menstruation and pregnancy
• pineal


  melatonin (sleep/wake cycle)
• what is the process of the fight or flight response

  - stressor perceived

  - hypothalamus triggers activity in sympathetic branch of the autonomic nervous system,

  - meaning ans is now in the sympathetic state instead of the parasympathetic resting state

  - adrenaline (stress hormone) released from the adrenal medulla into bloodstream

  - adrenaline triggers physical changes which creates physiological arousal

  - once threat has passed. the parasympathetic nervous system returns the body to its resting state.

  - parasym acts as a brake and reduces the activities if the body
• what are characteristics of the fight or flight response

  increased heart rate

  increased breathing

  dilated pupils

  inhibits digestion

  inhibits saliva production

  contracts rectum
• sensory neuron


  carry messages from the pns to the cns
• relay neuron


  connect the sensory neuron to motor or other relay neurons
• motor neuron


  connect the cns to the effectors such as muscles and glands.
• what is the structure of a neuron

  - cell body

  - nucleus (genetic material)

  dendrites (carry nerve impulses from neighbouring neurons towards the cell body)

  - axon (covered in myelin sheath that protects the axon and speeds up the electrical transmission of the impulse)

  - myelin sheath which is segmented by gaps called nodes of ranvier which speed up transmission of the impulse by forcing it to jump across the gaps following the axon

  - terminal buttons ( communicate with the next neuron the the chain across a gap called synapse
• electric transmission


  when a neuron is in its resting state inside the cell, it is negatively charged compared to the outside. when a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a second, causing an action potential to occur, this creates and electrical impulse that travels down the axon and towards the end of the neuron
• What is synaptic transmission?


  electrical impulse reaches end of the neuron, it triggers the release of neurotransmitters from sacs called synaptic vesicles. these then diffuse across the synaptic cleft. then its taken up by the postsynaptic receptor site. the chemical is converted back into an electrical impulse.
• excitation


  When a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neuron. This increases the likelihood that the neuron will fire and pass on the electrical impulse.
• inhibition


  When a neurotransmitter, such as serotonin, makes the charge of the postsynaptic neuron more negative. This decreases the likelihood that the neuron will fire and pass on the electrical impulse.
• summation


  decides whether a postsynaptic neuron will fire. if the net effect of a neuron is inhibitory, then the neuron is less likely to fire. if the net effect is excitatory, momentarily, inside of the neuron becomes positively charged. once the electrical impulse is created, action potential can occur.
• localisation of function: localisation vs holistic theory


  19th century, broca and wernicke argued that different parts of the brain perform different tasks and are involved w different parts of the body

  - if a certain area of the brain becomes damaged through illness or injury, the function associated w that area will also be affected

  - before, holistic theory was that all parts of the brain were involved in the processing of thought and action
• hemispheres of the brain

  some of our physical and psychological functions are controlled by a particular hemisphere - lateralisation
• cerebral cortex


  outer layer of both hemispheres which covers the inner parts of the brain

  - 3mm thick and is what separates us from other animals bc the human cortex is more developed

  - appears grey due to the location of cell bodies
• motor areas


  back of frontal lobe in both hemispheres

  - controls voluntary movement in the opposite side of body

  - damage to this area may result in loss over fine movements
• somatosensory area


  front of parietal lobes

  - separated from the motor area by a valley valley central sulcus

  - where sensory info from the skin related to heat, touch and pressure is represented
• visual area


  in the occipital lobe at the back of the brain

  - each eye sends info from right visual field to left visual cortex and vice versa

  - means that damage to the left hemisphere can produce blindness in the right visual field of both eyes
• auditory area


  temporal lobes

  - analyse speech based info

  - damage may produce partial hearing loss

  - damage to a specific area of the temporal lobe, wernickes area, may affect the ability to comprehend language
• language area of the brain

  - restricted to the left side of the brain

  - broca identified a small area in the left frontal lobe responsible for speech production

  - damage to brocas area caused broca's aphasia characterised by speech that is slow, laborious and lacking in fluency

  - wernicke described patients who had problem producing language but difficulties understanding it meaning the speech they produced was fluent but meaningless

  - wernickes area in the left temporal lobe responsible for language comprehension which would result in Wernicke's aphasia when damaged

  - often produce nonsense words
• eval: brain scan evidence of localisation

  - petersen et al used brain scans to demonstrate how wernickes area was active during a listening task and brocas area was active during a reading task, suggesting that these areas of the brain have different functions

  - long term memory study by tulving revealed that semantic and episodic memories reside in different parts of the prefrontal cortex
• neurosurgical evidence


  neurosurgery used today in extreme cases of ocd and depression

  - dougherty et al reported on 44 people w ocd who had undergone a cingulotomy - a neurosurgical procedure that involves leisoning og the cingulate gyrus

  - post surgical follow up after 32 weeks, a third had met the criteria for successful response to the surgery and 14% for partial response

  - success of the procedures strongly suggests that symptoms and behaviours associated w serious metal disorders are localised.
• case of phineas gage

  survived a steel rod that went through his head, most likely through his frontal lobe, but there were significant changes to his personality making him more disinhibited and this supports the idea that disinhibition is common for people with frontal lobe damage
• lashley research


  suggests that higher cognitive functions such as processes involved in learning are not localised but distributed in a more holistic way in the brain

  - lashley removed areas of the cortex between 10 and 50% in rats that were learning a maze

  - no area was proven to be more important than any other area in terms of the rats ability to learn the maze

  - process of learning appeared to require every part of the cortex rather than being confined to a particular area

  - suggests that learning is too complex to be localised and requires the involvement of the whole brain
• plasticity


  when brain has been damaged through illness or accident, and a particular function has been lost or compromised, the rest of the brain appears ale to reorganise itself in an attempt to recover the lost function

  - lashley described this as the law of equipotentiality whereby surviving brain circuits chip in so that the same neurological action can be achieved

  - although does not happen every time, stroke victims have been able to recover these abilities that were seemingly lost as a result of the illness
• plasticity and functional recovery of the brain after trauma: brain plasticity


  - plastic in the sense that it has the ability to change throughout life

  - during infancy, the brain experiences a rapid growth in the no of synaptic connections it has

  - as we age, rarely use connections are deleted ad frequently used connections are strengthened (process known as synaptic pruning)

  - recent research suggests that at any time in life existing neural connections can change or can be formed as a result of learning and experience (plasticity)