Organism level systems

• Causes of nervous system damage


  • Injury
  • Disease (cancer)
  • Genetic diseases (Huntington's)
  • Ingesting toxic chemicals (lead)
• Computed Tomography [CT]


  1. rays are used to build up a 3D map of the brain
• Computed Tomography [CT]


  • Risk: radiation over-exposure
• Magnetic resonance imaging (MRI)


  Uses a powerful magnet that helps to map blood flow to active regions of the brain
• Functional [fMRI]


  Maps blood flow in real time, while patient performs a function such as a calculation
• Functional [fMRI]


  • Less risk due to a lack of radiation being used
• Phineas Gage


  Injury affected his personality
• Case studies involve few people and do not reflect a wide population
• Brain surgery: electrode placement on the brain


  Affect different muscle groups
• Consent needed. Often tested on animals which is unethical
• Stroke victims


  Loss of function/movement linked to the part of the brain that is damaged
• Brain structure


  • Hypothalamus
  • Pituitary gland (master)
  • Medulla (unconscious breathing, heart rate)
  • Cerebral Cortex (conscious thinking, calculating, problem solving, intelligence)
  • Cerebellum (muscular activity + balance)
• The structure of the eye


  • Adjust lens
  • Shape
  • Suspensory ligaments
  • Cornea (transparent, refracts light)
  • Pupil (hole)
  • Iris (adjusts pupil size)
  • Lens
  • Ciliary muscles
  • Sclera (protects from damage)
  • Retina (light receptors)
  • Optic nerve
• Cones


  Receptor cells for colour
• Humans have 3 types of cone cell - responding to red, green and blue light
• Colour blindness


  An inherited disorder, more common in men, where either 1 or 2 of these types of cone cell do not form properly or there is a problem with how they connect to neurones and form a pathway to the brain
• A person with red-green colour blindness would not be able to see the letter 'C' in this image
• Pupil dilation and constriction in dim and bright light


  1. Radial muscles contract, pupil dilates (gets bigger) in dim light

  2. Circular muscles contract, pupil constricts (gets smaller) in bright light
• Accommodation for distant and close objects


  1. Suspensory ligaments contract, ciliary muscles relax, lens stretched flatter, less refraction/bending of light rays for distant objects

  2. Suspensory ligaments relax, ciliary muscles contract, lens thicker, more refraction/bending of light rays for close objects
• Correcting sight problems


  • Short-sightedness (myopia): Lens too curved or eyeball too long, can't see distant objects
  • Long-sightedness (hyperopia): Lens too thin or eyeball too short, can't see close objects
  • Corrected with concave lens for short-sightedness, convex lens for long-sightedness
• Endocrine System


  The system of glands that secrete hormones directly into the bloodstream to regulate the body's functions
• Pituitary gland


  • Hormones
  • Originate at glands
  • Travel in blood
• Nervous System


  • Neurons
  • Originate at receptor
  • Signal type: electrical
• Thyroid gland


  • Hormone: thyroxine
  • Duration: long-lasting
• Adrenal gland


  • Hormone: adrenalin
  • Duration: short
• Ovaries


  • Hormone: -
• Pancreas


  • Hormone: insulin
  • Signal type: chemical
• Testes


  • Hormone: -
• Speed of action of endocrine system: rapid
• Speed of action of nervous system: rapid
• Pituitary

  Produces FSH and LH hormones
• FSH

  Stimulates the ovaries to mature eggs
• LH

  Triggers ovulation
• Oestrogen

  Produced by the ovaries, thickens the uterus lining
• Progesterone

  Produced by the ovaries, maintains the uterus lining
• Ovulation

  1. FSH and LH release

  2. Egg matures

  3. Egg released
• Menstruation

  Shedding of the uterus lining
• Forms of contraception

  • Combined hormones (oestrogen and progesterone)
  • Progesterone only
  • Barrier
  • Intra-uterine
  • Abstinence
  • Surgery
• Combined pill/patch

  Take each day, side effects include DVT, breast cancer, increased blood pressure
• Progesterone only

  Pill, injection, implant - less side effects