Paper 2

• What does homeostasis mean?

  body balance
• What does ectotherm mean?

  cold blooded
• What does endotherm mean?

  warm blooded
• What is negative feedback?

  counteractive feedback in order to regulate homeostasis
• Why do we need our nervous system?

  to maintain homeostasis
• What are effectors?

  muscles or glands that bring about a response
• What are receptors?

  cells that detect changes in the environment
• What are stimuli?

  changes in the environment
• What are coordination centres?

  areas that receive and process information, they coordinate a response
• What do sensory neurones do?

  carry electrical signals ( nerve impulses )towards the central nervous system (spinal cord and brain)
• What is the central nervous system?

  Spinal chord and brain
• What do motor neurones do?

  carry nerve impulses away from the central nervous system. The neurone ends in either a muscle or gland
• How does a coordination of a response work?

  stimulus -> receptor (sensory neurone) -> coordinator (central nervous system)(motor neurone) -> effector (muscle glands) -> response
• What is a synaptic cleft? (Also referred to as a synapse)

  the gap between the neurone and the cell it will impact (post synaptic cell)
• What is a neurotransmitter?

  a chemical released at a synapse
• What is accomodation?

  the process of changing the shape of the lens of an eye to focus on near or distant objects
• What happens to the lens when looking at distant objects?

  it is stretched and becomes thinner
• What happens to the lens when looking at nearer objects?

  Becomes shorter and fatter
• What is myopia?

  short sightedness
• What is the lens like in myopia?

  too thick and curved
• What does elongated mean?

  the distance between the retina and the lens is too great
• What is the eyeball like in myopia?

  too elongated
• What does both the ciliary muscle and the suspensory ligament do in the eye?

  changes the shape of the lens when it contracts and relaxes
• What does the lens do in the eye?

  focuses light on the retina
• What is the pupil in the eye?

  the hole that allows light to enter
• What is the cornea of the eye?

  the protective layer over the eye
• What is the iris of the eye?

  the coloured ring in your eye, the muscles change the size of the pupil and how much light enters
• What is the optic nerve in the eye?

  neurones that carry nerve impulses from cones and rods to the brain
• How do light sensitive cells in the retina respond to light?

  cones respond to colour and rods respond to brightness
• What is hyperopia?

  long sightedness
• What is released across a synapse gap?

  neurotransmitter
• What part of the eye controls how much light enters?

  the iris
• What temperate should the body be kept at roughly and why?

  roughly 37°C as it is where enzymes work best
• How is the temperature of the body kept at a constant level?

  due to a negative feedback system where if the temperature gets too high or too low, the body responds to bring the temperature back to the optimum
• How does negative feedback respond to a rise of body temperature?

  the receptors detect change and send impulses to the thermoregulatory centre (in the brain) which acts as a coordination centre, it processes the information and sends impulses to the effectors which respond and the body temperature drops
• How does negative feedback respond to a fall in body temperature?

  The receptors detect a change and send impulses to the thermoregulatory centre (in the brain) which acts as a coordination centre, it processes the information and sends impulses to the effectors, which respond and body temperature rises
• What is a gland?

  an organ that contains cells which produce particular substances
• What does an exocrine gland do?

  releases what it produces on to a surface, often through a tube or duct
• What is an example of an exocrine gland?

  sweat glands in the skin
• What do endocrine glands produce?

  hormones