unit 5 homeostasis bad flashcards

focus on near object

• ciliary muscles contract

• suspensory ligaments lossen

• lens is then thicker and more curved, which refracts the light more

• muscle tension low

focus on distant object

• culinarily muscles relax

• suspenders ligament tighten

• the lens is then pulled thin and only slightly refracts light rays

• muscle tension high

the brain

• controls complex behaviour

• made of billions of interconnected neutrons and different regions carry out different functions

cerebal cortex

• split into 2 hemispheres and is highly folded

• controls intelligence, personality, conscious thought, and high level functions

  • e.g. language and verbal memory

cerebellum

• controls balance, co-ordination, movement and muscular activity

medulla

• controls unconscious activities such as heart/breathing rate

hypothalamus

• regulating centre for temperature and water balance

endocrine system

• composed of glands which secrete chemicals called hormones directly into the bloodstream

• blood carries the hormone to the target organ where it produces an effect

• effect slower than nervous system but lasts longer

pituitary gland

• the master gland

• secretes several hormones into the blood in response to body conditions

• these hormones in turn act on other glands to stimulate other hormones to be released to bring about effect

short sightedness

• cannot properly focus on distant objects caused by":

  • eyeball being elongated so the distance between the lens and retina is too great

  • lens is too thick and curved, light focused in front of retina

• correct by placing a concave lens in front of the eye

cornea

• see through layer at the front of the eye

• allows light through and curved surface bens and focuses the light into retina

• refracts light

iris

• muscles that surround the pupil, contract/relax

  • bright light circular muscles contract and radical muscles relax make pupil smaller to avoid damage to the retina

  • dim light: circular muscles relax and radical muscles contract to make pupil larger so more light can enter to build a better image

ciliary muscles and suspensory ligaments

hold lens in place and control its shape