nervous + endocrine system

• nervous system:

  • specialised network of cells
  • primary internal communication system
  • based on electrical and chemical signals
• functions of nervous system:

  • collect, process and respond to info in the environment
  • coordinates working of different organs and cells in the body
• central nervous system (CNS):

  • brain
  • spinal cord
• peripheral nervous system (PNS):

  • somatic nervous system
  • autonomic nervous system - sympathetic nervous system (flight or flight), parasympathetic nervous system (rest or digest)
• brain:

  • centre of conscious awareness
  • outer layer = cerebral cortex, highly developed in humans
  • divided into 2 hemispheres
• spinal cord:

  • passes messages to and from brain
  • connects nerves to PNS
  • responsible for reflex actions
• PNS function:

  • transmits messages via millions of neurons to and from CNS
• autonomic functions:

  • vital functions e.g breathing, heart rate, digestion, sexual arousal
  • divided into sympathetic and parasympathetic
• somatic functions:

  • muscle movement and recieves from sensory receptors
  • controls voluntary movements
• endocrine system:

  • network of glands
  • works alongside nervous system to control vital functions
  • acts more slowly, but widespread and powerful effects
  • glands release hormones into bloodstream - affect any cell in body that has specific receptors
• gland examples:

  • adrenal = adrenaline
  • thyroid = thyroxine
  • pancreas = insulin
  • ovaries = oestrogen
• flight or fight response:

  • stressor perceived
  • hypothalamus activates pituitary gland
  • ANS changes to sympathetic state
  • adrenaline released from adrenal medulla
  • flight or fight
  • once threat passes, parasympathetic system returns body to resting state
• sympathetic effects:

  • gut - slows digestion
  • salivary glands - inhibits saliva production
  • heart - increased heart rate
  • liver - stimulates glucose production
  • bladder - stimulates urination
  • eye - dilates pupils
  • lungs - bronchi dilate
• parasympathetic effects:

  • opposite of sympathetic effects
  • + liver = stimulates bile production