b3

• what is the difference between the central nervous system and the peripheral nervous system?

  • the central nervous system is the brain and the spinal cord
  • the peripheral nervous system is every other part of the nervous system
• stimulus


  change in the environment
• central nervous system

  A) relay neurone

  B) motor neurone

  C) sensory neurone

  D) stimulus

  E) stimulus

  F) receptor

  G) impulses

  H) sensory

  I) relay

  J) motor

  K) impulses

  L) effector

  M) response

  
• effector


  a part of a body that brings about the response to a stimulus like a muscle or a gland
• what is the cornea and what is its function?

  • the transparent outer layer of the eye
  • its function is to refract light and protect the eye
• what is the iris and what is its function?

  • the coloured ring around the pupil
  • its function is that it can regulate the amount of light that can enter the retina by controlling the diameter or the pupil
• what is the pupil and what is its function?

  • the pupil is the whole in the middle of the iris
  • its function is to let light into the eye
• what is the optic nerve and what is its function?

  • the nerve coming out the back of the eye
  • its function is to send signals to the brain
• function of the lens


  focuses the light rays onto the retina
• what is the retina and what is its function?

  • the retina is the back part of the eye
  • its function is that it converts visual stimuli into electrical impulses
• what do the ciliary body and suspensory ligaments do? 


  control the shape of the lens (accomodation)
• what defect in the eye causes short sightedness?

  the lens focuses light rays in front of the retina so far away objects appear blurry
• how is short sightedness corrected?

  by wearing glasses that have concave lenses
• what defect in the eye causes long sightedness?

  the lens focuses light behind the retina so nearby objects appear blurry
• how is long sightedness corrected?

  by wearing glasses that have convex lenses
• what is colour blindness?

  • an inherited condition where people find it difficult to tell the difference between colours
  • caused by a defect in the retina and there is currently no cure
• structure of the eye

  A) suspensory ligament

  B) cornea

  C) iris

  D) pupil

  E) lens

  F) ciliary muscle

  G) sclera

  H) retina

  I) fovea

  J) optic nerve

  
• where is the cerebrum located and what is its function?

  • located at the front of the brain
  • controls conscious functions, memory and language
• where is the cerebellum located and what is its function?

  • located at the back bottom of the brain
  • controls muscular movement and balance
• where is the medulla located and what is its function?

  • located in the brainstem in the middle at the bottom
  • controls unconscious functions like heart rate and breathing
• what is the function of the hypothalamus?

  • acts as the regulatory centre
  • controls things like body temperature, water content and salt balance
• what is the function of the pituitary gland?

  • releases hormones into the blood
• two reasons why it is difficult to investigate brain function

  • surgery is not risk free
  • people with brain disorders may be unable to consent
• why is it difficult to treat brain disorders?

  • the brain and spinal cord are very difficult to access
  • tissues in the CNS cannot regenerate
  • drugs cannot penetrate the blood-brain barrier
• structure of the brain

  A) hypothalamas

  B) cerebrum

  C) cerebellum

  D) spinal cord

  E) medulla oblongata

  F) pituitary gland

  
• hormones

  hormones are chemical messengers that are secreted by glands of the endocrine system into the bloodstream
• target cells

  cells with the specific receptor for a hormone that produce an effect when the hormone binds
• what does the hormone thyroxine control in the body?

  metabolic rate
• describe thyroxine as a negative feedback system

  • when the level of thyroxine decreases the pituitary gland produces thyroid stimulating hormone (TSH) which causes the thyroid gland to produce more thyroxine
  • when the level of thyroxine increases, the pituitary gland produces less TSH
• when is adrenaline secreted?

  during times of fear, anxiety or stress
• three effects of adrenaline in the body

  • increases heart and breathing rate
  • increases blood glucose concentration
  • dilates the pupils
• what does oestrogen do?

  causes the uterus lining to thicken
• what hormone does oestrogen inhibit?

  follicle stimulating hormone (FSH)
• what does progesterone do?

  maintains the womb lining
• what hormone does progesterone inhibit?

  follicle stimulating hormone (FSH)
• what does follicle stimulating hormone (FSH) do?

  stimulates the follicle to mature and release oestrogen
• what does luteinising hormone (LH) do?

  a surge in LH causes the release of an egg from a follicle (ovulation)
• how do oestrogen pills work to prevent pregnancy?

  oestrogen pills inhibit FSH which stops the egg from maturing
• how do progesterone pills work to prevent pregnancy?

  progesterone pills cause a sticky mucus to form at the cervix which prevents the sperm from fertilising the egg
• one advantage and one disadvantage of hormonal contraception (e.g. the pill)

  • advantage - more than 99% effective
  • disadvantage - it can cause side effects like weight gain