B2

• Homeostasis

  An organism's ability to regulate internal conditions even when external conditions change
• Importance of homeostasis

  • Allows crucial chemical reactions involving enzymes to happen at an Optimum rate
  • Regulates blood glucose concentration, temperature, and water levels
• Nervous system regulation of homeostasis

  1. Receptor detects change

  2. Electrical signal travels to spine through sensory and relay neurons

  3. Signal travels across synapse by neurotransmitter

  4. Signal goes to brain

  5. Conscious decision to act

  6. Signal goes back to effector via relay and motor neurons
• Reflex

  Signal bypasses the brain and goes straight through the spine to the effector
• Effectors

  Glands that produce specific chemicals the body needs
• Investigating reaction time

  1. Hold ruler between finger and thumb

  2. Drop ruler without warning

  3. Measure distance fallen before caught

  4. Repeat multiple times and take mean average
• Parts of the brain

  • Cerebral cortex - responsible for higher level functions like memory, speech, and problem solving
  • Cerebellum - responsible for motor skills, movement, balance, and coordination
  • Medulla oblongata - controls unconscious actions like heart rate and breathing
• MRI scans

  Magnetic resonance imaging - way of seeing brain activity safely
• Accommodation in the eye

  For far objects: Ciliary muscles relax, suspensory ligaments tighten, lens becomes thin

  For near objects: Ciliary muscles contract, suspensory ligaments slacken, lens becomes fatter
• Pupil

  Hole in the iris that can change size depending on light intensity