CRAM

• Homeostasis


  The regulation of the conditions inside a cell or whole organism in order to maintain the optimum or best conditions for function in response to changes both internally and externally
• Examples of changes homeostasis pathways control

  • Blood glucose concentration
  • Body temperature
  • Water levels
• Homeostasis pathways


  1. Specialized cells called receptors detect a stimulus

  2. Coordination center like the brain, spinal cord or pancreas decides what to do

  3. Response carried out by an effector like a muscle or gland
• Homeostatic responses


  • Nervous responses brought about by the nervous system
  • Chemical responses brought about by the endocrine system
  • Combination of the two
• Nervous system


  Relays information along neurons using electrical impulses, rapid but responses last a shorter time
• Endocrine system


  Works by releasing chemical messengers called hormones into the bloodstream, changes happen slowly but last longer
• Reflex reaction


  1. Stimulus detected by receptor

  2. Electrical impulse passed to relay neuron in spinal column

  3. Impulse passed to motor neuron

  4. Effector (muscle or gland) responds
• Measuring reaction times


  • Partner drops a ruler which you try to catch, distance travelled by ruler before caught acts as a surrogate for reaction time
  • Always use the same hand and ruler in the same position
  • Partner drops ruler without warning
• Brain tissues you need to know

  • Cerebrum
  • Cerebral cortex
  • Cerebellum
  • Medulla
  • Pituitary gland
  • Hypothalamus
• Cerebral cortex:

  
  

  Main part of the brain, controls consciousness, intelligence, memory and language
• cerebellum

  Coordinates muscular control for voluntary movements
• Medulla


  Responsible for involuntary movements like heart beating and breathing
• Pituitary gland


  Master gland that releases hormones like FSH, LH and ADH
• Hypothalamus


  Contains the thermoregulatory centre, responsible for controlling body temperature
• Scientists have used MRI scanning, studying patients with brain damage, and electrical stimulation to work out what different brain regions do
• Studying the brain is challenging due to the difficulty in isolating damage to one region, ethical concerns, and the complexity of the organ
• Tissues of the eye

  • Sclera
  • Cornea
  • Pupil
  • Iris
  • Lens
  • Retina
  • Optic nerve
• Cornea


  Focuses about 70% of the light entering the eye
• Pupil


  Small hole surrounded by the iris, which can contract and relax to control pupil size
• Lens


  Changes shape to focus light from near and far objects (accommodation)
• Retina


  Contains rod cells for light intensity and cone cells for color detection
• Pupil adjustment


  1. In dim light, radial muscles contract and circular muscles relax to dilate pupil

  2. In bright light, radial muscles relax and circular muscles contract to constrict pupil
• Accommodation


  The eye's ability to focus light from near and far objects by changing the shape of the lens
• Myopia


  Blurry vision caused by light focusing before the retina, treated with concave lenses
• Hyperopia


  Blurry vision caused by light focusing behind the retina, treated with convex lenses
• Thermoregulation


  1. Thermoregulatory center in hypothalamus detects temperature changes

  2. Vasodilation increases blood flow to skin to lose heat

  3. Sweating increases to cool the body

  4. Vasoconstriction and shivering increase heat production when too cold
• Endocrine glands


  • Pituitary
  • Pancreas
  • Thyroid
  • Adrenal
  • Ovaries/Testes
• Pituitary gland


  Master gland that releases hormones to act on other glands
• Thyroid gland


  Produces thyroxine, responsible for basal metabolic rate
• Adrenal glands


  Produce adrenaline, important for the fight-or-flight response
• Pancreas


  Produces insulin and glucagon to regulate blood glucose levels
• Type 1 diabetes


  Pancreas stops producing insulin, often diagnosed in younger patients, requires insulin injections
• Type 2 diabetes


  Cells become resistant to insulin, often associated with obesity, treated with diet and exercise
• Type 1 diabetes


  Pancreas stops making enough insulin, blood glucose levels go high, need to take insulin injections to survive
• Diagnosis of type 1 diabetes

  The four T's: Toilet, Thirsty, Tired, Weight loss
• Type 2 diabetes


  Pancreas produces enough insulin but body cells stop responding, often associated with obesity
• Treatment of type 2 diabetes

  Carbohydrate control diet, exercise regime
• Osmoregulation


  Controlling the level of water in the blood to prevent red blood cells from shrivelling or bursting
• Osmoregulation


  1. Taking in water when eating/drinking

  2. Losing water through breathing, sweating, kidneys

  3. Balancing water intake and loss
• Removing nitrogen-based waste


  1. Digestion produces amino acids

  2. Amino acids deaminated to produce ammonia

  3. Ammonia converted to urea

  4. Urea filtered out by kidneys