Nervous system

• Describe CNS

  • Consists of brain and spinal cord
  • Origin of all complex commands and decisions
  • Associated with higher functioning
• How is the Human nervous system divided?

  • Divided into the Peripheral NS and Central NS
  • CNS divides into brain and spinal cord
  • PNS divides into autonomic and somatic NS
  • Autonomic divides into sympathetic and parasympathetic NS
• Describe peripheral nervous system function

  • Sends information to CNS from outside world
  • Transmits messages from CNS to muscles and glands in body
• Describe somatic nervous system function

  • Transmits information from receptor cells in the sense organs to CNS
  • Consists of sensory and motor neurons to carry information to CNS
  • Receives information from CNS that directs muscles to act (sensory input) enabling reflex actions
• Describe autonomic nervous system function

  • Transmits information to and from internal bodily organs
  • Operates automatically/involuntary
  • Plays role in homeostasis
  • 2 main divisions (parasympathetic and sympathetic)
• What is the nervous system?

  A specialised network of nerve cells in the human body, our primary internal communication system
• Overall nervous system function?

  • Collects, processes and responds to information in the environment
  • Co-ordinates working of organs and cells in body
• How does the sympathetic NS work?

  • Fight or flight response/impulses when faced with a threatening situation
  • Increases heart rate, breathing rate
  • Pupils dilate
  • Inhibits digestion and saliva production
  • Contracts rectum
• How does the parasympathetic NS work?

  • Rest and digest response
  • Body is relaxed and rates are slowed
  • Decreases heart and breathing rate
  • Constricts pupils
  • Stimulates digestion and saliva production
  • Relaxes rectum
• Outline how the endocrine system works with the ANS for fight/flight response

  • stressor is perceived, the hypothalamus triggers activity in the sympathetic branch of the ANS.
  • ANS changes from its normal resting state, parasympathetic, to the physiologically aroused, sympathetic
  • Sends message to adrenal gland
  • Adrenaline (stress hormone) is then released from the adrenal medulla (area from the adrenal gland) into the bloodstream.
  • Adrenaline triggers physiological changes in the body necessary for fight or flight responses (e.g. increased heart rate)
  • Once the threat has passed, the parasympathetic nervous system returns the body to its resting state
  • working in opposition to the ANS. (rest and digest response)
• Limitation for fight or flight response (AO3)

  • BETA BIAS
  • minimises differences between men and women in the FF response
  • TAYLOR ET AL found women in stressful situations are more inclined to protect themselves using a 'tend and befriend' response
  • They do this by caring for their young or forming alliances with others
  • Therefore limitation as FF responses generalises/assumes the response is the same for both genders, however it is not and may result in limited explanaotry ability over gender differences in emotional responses to threats
  • Reinforced by genetic differences bewteen men and women (LEE AND HARLEY) where male as a SRY gene, the Y chromosome being responsible for FFR which women do not contain
• Limitation in being unfinished/overly simplistic (AO3)

  • GRAY (1988)
  • Found animals exhibit as 'freeze' response as third option to fight/flight
  • This may in order to gather information on what is the best reaction in order to survive whilst staying hyper-vigilant
  • Limitation as f/f may not account for this option, suggesting a decrease in internal validity (?)
• Limitation of FF response efficacy- modern situations (AO3)

  • Negative impact on health in modern day times
  • This is because in the past it may have been more of an adaptive response to truly threatening situations requiring an energetic response
  • E.g. encountering animal predators
  • However in modern day society, stressors are not as extreme (e.g. exam stress) and therefore do not require an energetic response
  • However these stressors repeatedly trigger our FF which may result in serious health conditions such as high blood pressure -> blood disease
  • therefore may not be as useful as previously suggested for survival
• Strengths of nervous system (AO3)

  • Adaptive Value: Quick reflexes in the SNS for responding to threats (fight or flight)
  • ANS homeostasis ensures physiological balance. Without proper PSNS function, the body would struggle to maintain homeostasis, potentially remaining in a constant state of heightened arousal in which may lead to neurological and physiological conditions
  • Real-life Applications: Understanding ANS function helps in anxiety treatments (beta-blockers reduce sympathetic arousal)
  • Allowing individuals to reduce anxiety and function properly leading to better QOL
• Limitations (AO3)

  • Reductionism Critique
  • While dividing the NS helps clarity, real responses involve interplay of many systems (e.g., hormonal and neural)
  • For example response to a harmful stressor triggers SNS but also requires influences from endocrine system and the release of stress hormone adrenaline for body to be physiologically prepared, therefore not just relied on NS