Homeostasis and response

• What are the two main systems that carry messages in the body?

  Nerves and hormones
• How do nerves and hormones differ in their message delivery?

  Nerves act quickly, hormones act slowly
• What indicates a quick response in the body?

  It's probably a nervous response
• What happens when a response lasts for a long time?

  It's probably a hormonal response
• What hormone is released during a shock?

  Adrenaline
• What is the role of hormones in the body?

  They control constant adjustments in organs
• Where are hormones produced?

  In glands
• What is the endocrine system?

  It consists of glands producing hormones
• What is the function of the pituitary gland?

  Regulates body conditions
• Why is the pituitary gland called the 'master gland'?

  It directs other glands to release hormones
• What hormone do ovaries produce?

  Oestrogens
• What hormone do testes produce?

  Testosterone
• What does the thyroid gland produce?

  Thyroxine
• What is the role of adrenaline?

  Prepares the body for 'fight or flight'
• What does the pancreas produce?

  Insulin
• How do nerves respond to stimuli?

  Very quickly and for a short time
• What happens if a response is long-term?

  Cells must be ready to react slowly
• What is reaction time?

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

  Age, gender, or drugs
• How can you measure reaction time using a ruler test?

  1. Sit with arm resting on a table
  2. Hold a ruler vertically
  3. Let go without warning
  4. Catch the ruler
  5. Measure the distance caught
  6. Repeat and calculate mean distance
• Why should variables be controlled in a reaction time test?

  To ensure a fair test
• How can reaction time be measured using a computer?

  By clicking when a stimulus appears
• What advantage do computers have in measuring reaction time?

  They provide precise measurements
• What is a reflex action?

  A quick, automatic response to stimuli
• How do reflexes help prevent injury?

  They provide quick responses without thinking
• What is the reflex arc?

  The pathway of information in a reflex
• What happens when a stimulus is detected in a reflex arc?

  Impulses are sent along sensory neurones
• What is the role of synapses in reflex arcs?

  They transfer nerve signals between neurones
• Why are reflexes quicker than normal responses?

  They bypass conscious thinking
• What is the function of the central nervous system (CNS)?

  Coordinates responses and processes information
• How does the CNS respond to a stimulus?

  It sends information to effectors
• What is the role of sensory neurones in the nervous system?

  Carry information from receptors to CNS
• What happens when the CNS receives information from receptors?

  It decides the appropriate response
• What is the connection between neurones called?

  A synapse
• How is a nerve signal transferred across a synapse?

  By chemicals that diffuse across the gap
• What do chemicals released at a synapse do?

  Set off a new electrical signal in the next neurone
• What is the main function of the nervous system?

  To detect and react to stimuli
• How do multicellular organisms respond to their environment?

  Through a nervous and hormonal communication system
• What type of responses do jellyfish exhibit?

  Reflex responses
• What is the role of the nervous system?

  • Detects stimuli
  • Coordinates behavior
  • Ensures reactions to surroundings