Homeostasis

• What are the two control systems in the body?

  Nervous system and endocrine system
• How do electrical impulses function in the nervous system?

  They are transmitted along the neurons
• What is the speed and duration of the nervous system's effects?

  Quick and temporary effects
• What is released in the endocrine system?

  Hormones
• How are hormones transported in the endocrine system?

  In the blood plasma to target cells
• What is the speed and duration of the endocrine system's effects?

  Slower and longer-lasting effects
• What does homeostasis maintain?

  Optimal conditions for enzyme function
• What happens if homeostasis fails to maintain optimal conditions?

  Enzymes may denature and reactions slow
• What is the first step in a reflex action?

  The stimulus is detected
• What type of receptor cells detect sour citric acid on the tongue?

  Sour chemical receptor cells
• What is the pathway of a reflex action starting from the stimulus?

  Stimulus → sensory neuron → relay neuron → motor neuron → effector
• What are synapses?

  Gaps between nerve cells
• What happens at synapses?

  Chemicals diffuse across the gap
• Why does the temperature near the brain increase after drinking ice-cold water?

  Blood cools in the stomach and flows to the brain
• What are the key steps in measuring reaction time?

  • Person one sits upright
  • Forearm across the table
  • Ruler held vertically
  • Measure reaction time when dropped
• Why shouldn't the student move during the reaction time test?

  Movement would release heat affecting results
• What is the function of the cerebral cortex?

  Responsible for memory and language
• What does the medulla control?

  Involuntary coordination like heart rate
• What is the function of the cerebellum?

  Responsible for voluntary coordination
• What are the three methods scientists use to study the brain?

  1. Studying brain damage effects
  2. Electrical stimulation of brain areas
  3. MRI to observe brain activity
• How does studying brain damage help scientists?

  Identifies functions of damaged brain areas
• What does electrical stimulation of the brain involve?

  Stimulating brain parts and observing effects
• What does MRI stand for?

  Magnetic resonance imaging
• How can fMRI scanners help study brain damage?

  Compare brain activity during tasks with healthy individuals
• How does the brain receive information about light?

  Through cells in the retina sensitive to light
• How is an image formed in the brain from light entering the eye?

  Light is focused by refraction and interpreted
• What is myopia?

  Inability to focus on distant objects
• What causes myopia in the eye?

  Eyeball is too long, light focuses in front
• What is hyperopia?

  Inability to see near objects clearly
• What causes hyperopia in the eye?

  Eyeball is too short, light focuses behind
• How does the eye adjust to different light levels?

  • Bright light: circular muscles contract, pupil constricts
  • Dark light: radial muscles contract, pupil dilates
• What is myopia?

  Inability to see near objects clearly
• How does myopia affect light rays?

  Light rays focus in front of the retina
• What type of lens corrects myopia?

  Concave lenses
• What is hyperopia?

  Inability to see far objects clearly
• What type of lens corrects hyperopia?

  Convex lenses
• How does hyperopia affect light rays?

  Light rays focus behind the retina
• How does the eye adjust to bright light?

  Circular muscles contract, pupil constricts
• How does the eye adjust to dark conditions?

  Circular muscles relax, pupil dilates
• What happens to the ciliary muscles for clearer images?

  Ciliary muscles contract, lens thickens