The nervous system coordinates responses to stimuli, maintaining homeostasis through negative feedback mechanisms. This system includes the central nervous system (CNS) and peripheral components like sensory and motor neurones. Key structures such as the brain, spinal cord, and synapses enable rapid information transmission and processing. Reflexes provide automatic responses to certain stimuli, while reaction time measures responsiveness. The eye's complex structure allows for visual perception and adaptation to different lighting conditions.

• The nervous system maintains internal stability through homeostasis and negative feedback
• Sensory and motor neurones transmit information between the CNS and body
• Synapses enable neurone communication, while reflexes provide rapid, automatic responses
• The brain's structure and function can be studied through various techniques
• The eye's components work together to focus light and enable vision