Homeostatis & response

• What is homeostasis?

  Maintenance of a constant internal environment
• Why is homeostasis necessary for the body?

  It is needed for enzyme action and cell functions
• What does homeostasis control in the human body?

  • Blood glucose concentration
  • Body temperature
  • Water levels
• What role do nervous and hormonal communication play in homeostasis?

  They are involved in automatic control systems
• What are the components of control systems in homeostasis?

  • Receptors: detect stimuli
  • Coordination centres: process information
  • Effectors: bring about responses
• What are receptors in the context of homeostasis?

  Cells that detect stimuli in the environment
• What is the function of coordination centres?

  Process information received from receptors
• What are effectors in homeostasis?

  Muscles or glands that bring about responses
• What is the role of the nervous system?

  Allows reaction to surroundings and coordinates actions
• What do receptor cells convert into an electrical impulse?

  A stimulus
• What travels along sensory neurons to the CNS?

  An electrical impulse
• What happens in the CNS after receiving information?

  Information is processed and response coordinated
• What do motor neurons do?

  Send impulses to effectors
• What is a reflex?

  An automatic response before thinking
• What is a reflex arc?

  1. Stimulus detected by receptors
  2. Impulses sent along sensory neuron
  3. Impulse passes to relay neuron in CNS
  4. Impulses sent along motor neuron
  5. Impulse reaches effector for response
• What are synapses?

  Gaps between two neurons
• What happens when an impulse reaches the end of a neuron?

  A chemical is released into the synapse
• What does the chemical do in the synapse?

  Triggers the impulse to begin in the next neuron
• How is reaction time measured?

  With the ruler drop test
• What is the brain made up of?

  Many connected neurons
• What does the cerebral cortex control?

  Consciousness, intelligence, memory, and language
• Where is the cerebellum located?

  Bottom/back of the brain
• What does the medulla control?

  Unconscious actions like breathing and heart rate
• Why is investigating brain function difficult?

  • Complex and delicate structure
  • Easily damaged
  • Drugs may not reach the brain
  • Unclear functions of brain regions
• How do neuroscientists map brain regions?

  1. Studying patients with brain damage
  2. Electrically stimulating brain parts
  3. Using MRI scanning techniques
• What does the retina do?

  Contains light-sensitive cells that create images
• What is the function of the optic nerve?

  Carries impulses from the retina to the brain
• What is the sclera?

  White outer layer supporting the eye's structures
• What does the cornea do?

  Bends and focuses light onto the retina
• What is the function of the iris?

  Controls the size of the pupil
• How does the pupil size change in bright light?

  • Circular muscles contract
  • Radial muscles relax
  • Pupil becomes smaller
• How does the pupil size change in dim light?

  • Circular muscles relax
  • Radial muscles contract
  • Pupil becomes larger
• What is accommodation in the eye?

  • Process of focusing on near or distant objects
  • Involves ciliary muscles and suspensory ligaments
• What happens to the lens to focus on a near object?

  • Ciliary muscles contract
  • Suspensory ligaments loosen
  • Lens becomes thicker and more curved
• What happens to the lens to focus on a distant object?

  • Ciliary muscles relax
  • Suspensory ligaments tighten
  • Lens becomes thinner
• What is myopia?

  Short sightedness
• What causes myopia?

  The lens is too curved
• What is hyperopia?

  Long sightedness
• What causes hyperopia?

  The lens is too flat
• What are the treatment methods for eye defects?

  • Spectacle lenses
  • Contact lenses
  • Laser eye surgery
  • Replacement lens