Biopsych

• Divisions of the nervous system

  • Central
  • Peripheral (somatic and autonomic)

  
• Nervous system


  A collection of neurons across the body that detects information from the environment and processes this, then directs the body to take action via the muscles and/or glands

  
• Components of the nervous system

  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)

  
• Central nervous system (CNS)


  Responsible for complex processing, consisting of the brain and the spinal cord
• Peripheral nervous system (PNS)

  The portion of the nervous system that is outside the brain and spinal cord, connecting the brain and spinal cord to the rest of the body and the external environment
• Components of the peripheral nervous system

  • Somatic nervous system
  • Autonomic nervous system

  
• Somatic nervous system


  Connects the central nervous system with the senses and controls bodily movement

  
• Autonomic nervous system


  Controls bodily arousal, body temperature, homeostasis, heart rate and blood pressure
• Components of the autonomic nervous system

  • Sympathetic nervous system
  • Parasympathetic nervous system

  
• Sympathetic nervous system


  Involved in preparing the body for fight or flight, causing increased arousal
• Parasympathetic nervous system


  Involved in returning the body to its normal state after the fight or flight response, causing decreased arousal
• Under normal conditions there is a balance between the sympathetic and parasympathetic systems in order to maintain homeostasis
• Similarities between the brain and spinal cord


  • Both control involuntary processes
• Differences between the brain and spinal cord

  • The brain provides conscious awareness and allows for higher-order thinking, while the spinal cord allows for simple reflex responses
  • The brain consists of multiple regions responsible for different functions, whereas the spinal cord has one main function

  
• Similarities between the sympathetic nervous system and somatic nervous system

  • Both respond to external stimuli
• Differences between the autonomic and somatic nervous systems

  • The autonomic nervous system consists of two sub-components, whereas the somatic nervous system only has one
  • The somatic nervous system has sensory and motor pathways, whereas the autonomic nervous system only has motor pathways
  • The autonomic nervous system controls internal organs and glands, while the somatic nervous system controls muscles and movement

  
• Endocrine system


  A series of glands located across the body which release hormones that enter the bloodstream and send messages to other parts of the body
• Hypothalamus


  Connected to the pituitary gland and responsible for stimulating or controlling the release of hormones from the pituitary gland, acting as the control system for the endocrine system
• Pituitary gland


  Sometimes known as the 'master gland' as the hormones it releases control and stimulate the release of hormones from other glands in the endocrine system, divided into anterior and posterior lobes
• Pineal gland


  Releases melatonin, responsible for important biological rhythms including the sleep-wake cycle
• Thyroid gland


  Releases thyroxine, responsible for regulating metabolism
• Pancreas


  Releases insulin to lower blood glucose levels and glucagon to raise blood glucose levels
• Parts of the adrenal gland

  • Adrenal medulla
  • Adrenal cortex
• Adrenal medulla


  Responsible for releasing adrenaline and noradrenaline, which play a key role in the fight or flight response
• Adrenal cortex


  Releases cortisol, which stimulates the release of glucose to provide the body with energy while suppressing the immune system
• Testes


  Release androgens, including the main hormone testosterone, responsible for the development of male sex characteristics and promoting muscle growth
• Ovaries


  Release oestrogen, which controls the regulation of the female reproductive system, including the menstrual cycle and pregnancy
• Stress


  Experienced when a person's perceived environmental, social and/or physical demands exceed their perceived ability to cope
• Fight or flight response


  A hard-wired evolutionary adaptation designed to increase an organism's chances of survival in life-threatening situations
• Systems involved in the fight or flight response

  • Sympathomedullary Pathway
  • Hypothalamic Pituitary-Adrenal System
• Sympathomedullary Pathway


  Deals with acute (short-term, immediate) stressors
• Hypothalamic Pituitary-Adrenal System


  Deals with chronic (long-term, on-going) stressors
• Adrenal medulla


  Part of the autonomic nervous system, secretes the hormone adrenaline to get the body ready for a fight or flight response
• Adrenaline


  Leads to the arousal of the sympathetic nervous system and reduced activity in the parasympathetic nervous system, creating changes in the body such as decreases (in digestion) and increases (sweating, increased pulse and blood pressure)
• Hypothalamic Pituitary-Adrenal (HPA) System


  1. Stressor activates the Hypothalamic Pituitary Axis

  2. Hypothalamus stimulates the pituitary gland

  3. Pituitary gland secretes adrenocorticotropic hormone (ACTH)

  4. ACTH stimulates the adrenal glands to produce the hormone corticosteroid

  5. Adrenal cortex releases stress hormone cortisol
• Adequate and steady blood sugar levels help person to cope with prolonged stressor, and helps the body to return to normal
• Criticisms of the fight or flight response

  • Humans may engage in an initial 'freeze' response before fight or flight
  • The fight or flight response is typically a male response, while females adopt a 'tend and befriend' response
  • Early research was conducted primarily on males, leading to a beta bias in generalising findings to females
  • The fight or flight response may be maladaptive in modern life, as it can have negative consequences on health when repeatedly activated
• Adrenaline


  Increases blood supply to the brain and muscles, prepares the body for action, and increases perspiration/sweating
• Noradrenaline


  Increases the formation and retrieval of memories, focuses attention, and promotes vigilance and alertness
• Sensory neurons


  Found in receptors such as the eyes, ears, tongue and skin, carry nerve impulses to the spinal cord and brain