Homeostasis & response

• which two structures, refract light entering the eye ?

  1. cornea
  2. lens
• when light passes into that I wear on the retina, should the light be focused


  fovea
• what happens when the eye focuses on a distant object ?

  1. the ciliary muscle relaxes
  2. lens is pulled tall and thin
  3. the suspensory ligaments are pulled taunt
• what does long-sighted mean ?

  • Hyperopia
  • the eye is unable to focus on nearby objects
• why does our body have to maintain a temperature of 37. 


  It’s the optimum temperature for enzymes to function
• what is a stimuli?

  a change in the environment
• Where are temperature receptors found in the body?

  1. Skin
  2. Blood vessels
• how does shivering from the body?

  • shivering involves muscle contraction and relaxing automatically. This requires a lot of energy from respiration, which releases a lot of heat energy.
• what is vasodilation?

  • blood vessels near the skin become wider
  • Increasing the flow of blood in skin capillaries
• how does sweat keep us cool?

  as sweat evaporates it removes heat energy from the skin
• what are the functions of the kidneys ?

  1. remove urea
  2. regulate water levels
  3. regulate ion levels
• if we have too much water in the body, what could happen to our cells?

  they could gain water, and burst
• what are two ways ions can be removed from the body?

  • by sweating
  • By the kidneys
• when is adrenaline produced by the adrenal glands?

  is produced during the flight or fight response. When you get scared stressed.
• what does adrenaline Do?

  1. Increases heart rate
  2. Increases blood pressure
  3. Increases blood flow to muscles
  4. Increases blood sugar levels by stimulating the liver to break down glycogen into glucose
• what does thyroxine do?

  thyroxine stimulates, protein synthesis for growth and development and regulates the metabolic rate
• what happens if thyroid levels are too low?

  1. the pituitary gland will Release TSH
  2. This stimulates the thyroid gland to release more thyroxine
  3. Increasing levels of thyroxine back to normal