Topic B5

• What is reaction time?

  The time it takes to respond to a stimulus
• What factors can affect reaction time?

  Age, gender, or drugs
• How can caffeine affect reaction time?

  Caffeine can speed up reaction time
• What is the procedure to measure reaction time using a ruler?

  1. Sit with arm resting on a table
  2. Hold a ruler vertically between thumb and forefinger
  3. Let go of the ruler without warning
  4. Catch the ruler as quickly as possible
  5. Measure the distance caught on the ruler
  6. Repeat and calculate the mean distance
• How should the ruler be positioned before dropping?

  The zero end should be level with the thumb
• What does a higher number on the ruler indicate?

  A slower reaction time
• What should be done after the initial reaction time test?

  Have a caffeinated drink and wait
• Why is it important to control variables in the reaction time test?

  To ensure a fair test
• What can too much caffeine cause?

  Unpleasant side-effects
• How can reaction time be measured using a computer?

  1. Click mouse or press key upon seeing a stimulus
  2. Computers provide precise measurements
  3. Reaction time is recorded in milliseconds
  4. Reduces human error in measurement
• What is a synapse?

  The connection between two neurones
• How is a nerve signal transferred across a synapse?

  By chemicals that diffuse across the gap
• What are reflexes?

  Rapid, automatic responses to stimuli
• How do reflexes help prevent injury?

  They reduce the chances of being injured
• What is a reflex arc?

  The passage of information in a reflex
• What are the steps in a reflex arc?

  1. Stimulus detected by receptors
  2. Impulses sent along sensory neurone
  3. Relay neurone processes the impulse
  4. Impulses sent along motor neurone
  5. Effector (muscle) contracts
• What does the CNS consist of in vertebrates?

  The brain and spinal cord
• What are sensory neurones responsible for?

  Carrying information to the CNS
• What are effectors?

  Muscles and glands responding to impulses
• What is the role of the CNS?

  • Coordination centre for responses
  • Receives information from receptors
  • Decides on appropriate responses
  • Sends information to effectors
• What happens when a bird spots a cat?

  It flies away to safety
• What is homeostasis?

  • Maintaining a stable internal environment
  • Regulating conditions for cell function
  • Involves nervous and hormonal systems
• Why is homeostasis important?

  Cells need right conditions to function
• What are the components of automatic control systems in the body?

  • Receptors
  • Coordination centres (brain, spinal cord, pancreas)
  • Effectors
• How does negative feedback work in homeostasis?

  1. Receptor detects a stimulus
  2. Coordination centre processes information
  3. Effector produces a response to counteract change
• What happens when the level of something is too high?

  The receptor detects the stimulus
• What occurs if the level is too low?

  The coordination centre organizes a response
• How does negative feedback prevent overcorrection?

  Receptors detect if levels become too different
• What is the primary function of hormones in the body?

  To send information around the body
• How do hormones affect target organs?

  They only affect particular cells or organs
• What are endocrine glands?

  Glands that produce and secrete hormones
• What is a characteristic of hormones regarding their effects?

  They tend to have long-lasting effects
• Why is the pituitary gland referred to as the 'master gland'?

  It regulates other glands' hormone release
• What hormone do ovaries produce?

  Oestrogen
• What hormone do testes produce?

  Testosterone
• What is the role of thyroxine?

  Regulates metabolism, heart rate, and temperature
• What does adrenaline prepare the body for?

  Fight or flight response
• What does the pancreas produce to regulate blood glucose levels?

  Insulin
• How does the body respond when blood glucose levels are too high?

  Insulin is added to lower glucose levels
• What happens when blood glucose levels are too low?

  Glucagon is added to raise glucose levels