biopsychology

• • when a neutron is activated by a stimulus it becomes positively charged causing an action potential to occur
  • the electrical impulse travels along the axon of the transmitting neuron
  • this triggers the release of neurotransmitters from synaptic vesicles that are present on the pre-synaptic membrane
  • the neurotransmitters diffuse across the synapse to the next neuron
  • the neurotransmitter is then reabsorbed into the pre-synaptic neuron which is called re-uptake
  • the neurotransmitter is broken down by enzymes and converted back into an electrical impulse and the process of transmission starts again
• • an excitatory neurotransmitter will increase the positive charge of the post-synaptic neuron making it more likely to fire e.g. adrenaline has a positive effect
  • an inhibitory neurotransmitter will make the neighbouring neuron become negatively charged and less likely to fire e.g. serotonin
  • the summation of inhibitory and excitatory influences determine whether a neuron fires
  • the excitatory and inhibitory influences are summed
  • if the net effect is inhibitory the post-synaptic neuron is less likely to fire
  • if the net effect is positive it is more likely to fire
• • the endocrine system instructs glands to release hormones directly into the blood stream which are then carried towards target organs
  • it acts slower than the nervous system but has more powerful and widespread effects
  • thyroid gland - produces thyroxine which is increases heart and metabolic rates
  • key endocrine gland is the pituitary gland - it is located in the brain and known as the 'master gland' as it controls the release of hormones from all other endocrine glands
  • adrenal gland - response for f or f response, secretes adrenaline from adrenal medulla
• • the endocrine system and the autonomic nervous system work together in a stressful event
  • when a stressor is perceived the hypothalamus activates the pituitary gland which triggers activity in the sympathetic branch of the ANS
  • the ANS changes from its resting state (parasympathetic)
  • the stress hormone adrenaline is released from the adrenal medulla from adrenal gland into the blood stream
  • adrenaline triggers psychological changes in the body which creates psychological arousal necessary for the fight or flight response
  • this happens as soon as the threat is detected - immediate effect