Paper 2

• Short sighted=Myopia
• Long sighted=Ciliary muscles relax, suspensory tighten, thin lens
• short sighted=Ciliary muscles contract, suspensory ligaments loosen, thick lens
• Hyperopia sighted=Hyperopia
• Retina=back of eye,light is directed towards it, contains rod and cone cells
• rod cells=only detects light intensity
• cone cells are specialized for color vision
• diverging=away from each other
• converging=towards each other
• lens=flexible structure behind iris which focuses light onto retina
• ciliary muscles=muscles that control the shape of lens
• optic nerve=bundle of axons carrying impulses to brain
• cornea= outer layer of eye
• thermoregulation=brain detects blood temperature and then sends nervous and hormonal signals to effectors
• effector= muscle or gland that responds to the nervous system and produces a response
• receptor= sensory neurone that detects a stimulus and sends a signal to the CNS
• If body gets hot(vasodilation) blood vessels dilate and blood flows to skin-sweat as a response
• Chemical messengers sent across synapses= neurotransmitters
• Synapse=gap between neurones
• If body gets cold(vasoconstriction)blood vessels contract-shivering or hairs standing up as a reponse
• Shivering=muscles produce heat
• Hairs standing up=traps air-insulation
• Sweat=water produced which takes away heat
• cerebral cortex= outer layer of brain, responsible for conscious thought, memory, language, and intelligence
• cerebellington= back part of the brain that controls balance and coordination
• medulla oblongata=bottom of brain and controls unconcious actions such as breather and signals to adrenal glands
• mri scans=doctors can see brain activity without surgery
• pituitary gland=sends signals to other glands
• adrenal glands=controls adrenaline
• Thyroid=controls growth and metabolism
• pancreas= produces insulin and glucagon, regulates blood glucose
• type 1 diabetes=pancreas can’t produces enough insulin(genetic)
• type 2 diabetes=insulin resistant due to getting too much sugar-obesity increases risk of developing
• if too much water in cells due to osmosis then they become turgid and can burst
• if not enough water in cells due to water moving out cell becomes flaccid and dosent work
• kidneys=control water and filters out glucose,minerals and ions
• dialysis= a process whereby the blood and waste is filtered by a machine if kidney dosent work properly
• FSH=produced by pituitary gland and causes egg to mature and ovaries to produce
• oestrogen=thickens uterus lining and inhibits FSH so no more eggs mature in that cycle
• LH=causes egg to be released