Biology paper 2

• order of control system

  receptors - coordination - effectors
• receptors detect change in the enviroment
• coordination centre interprets and organises a response
• effectors

  muscles contract

  and glands release hormones
• motor neurones send signals out to effectors
• cerebellum


  Responsible for balance and muscle coordination
• cerebral cortex


  controls

  Consciousness

  Intelligence

  memory

  language
• medulla


  Breathing and beating of the heart
• The hypothalamus is responsible for regulating our body temperature.
• cornea


  A transparent layer at the front of the eye which refracts light
• cone cells enable you to see in colour
• The point where light focuses on the retina is called the fovea.
• circular and radial muscles make up the iris
• when pupils are exposed to light they constrict
• the lens bends light rays so that they focus onto the retina
• When focousing on a close object ciliary muscles contract inwards and suspensory ligaments relax
• When focusing on a distance object ciliary muscles relax pulling out the ligaments to create a flat lens
• thermoregulation controls the inner body temperature
• warming up


  constrict blood vessel so less blood travels near the surface

  hair stands up to conserve warm air

  shivering uses muscle contraction which realises heat energy
• cooling down


  hairs fall flat

  sweating which evaporates taking heat energy with it
• pituitary gland


  master gland

  realises lots of hormones

  tells other glands to release hormones

  located in the brain
• Thyroid gland releases thyroxine which controls metabolism and growth
• adrenal glands realease adrenaline
• blood glucose concentration

  the amount of sugar in our blood
• insulin binds to receptors on certain cells
• liver and muscle cells absorb the glucose and turn it into glycogen
• glycogen is long term storage for glucose
• Glucagon increases glucose blood levels
• glucagon hormones breaks down glycogen into glucose in the liver
• what if glucose levels fall to low

  there won't be enough glucose in tissues to respire
• type 1 diabetes is when the pancreas stops producing insulin
• type 2 diabetes is when the cells become resistant to insulin
• function of kidneys


  remove urea

  regulate water levels

  regulate ion levels
• ADH increases water levels in our body
• consequences of kidney failure

  unable to regulate ion and water levels

  waste substances build up in bloodstream
• treatment for kidney failure

  kidney transplant

  Dialysis
• dialysis machine filters the patients blood
• dialysis has a semi-permeable membrane so small molecules can transfer across but not large ones
• main risk for kidney transplant is rejection of the new kidney by the immune system
• role of FSH


  stimulates egg to mature in the ovaries