Sense Organs | Biology for GCSE/IGCSE - Year 11 PDF Download

Sense Organs as Receptors

• Receptors consist of specialized cells that identify changes in the environment.
• When stimulated, they generate electrical impulses.
• Sense organs house receptor groups, each responding to specific stimuli.

• Once activated, receptor cells produce electrical impulses.
• These impulses travel through sensory neurons to the central nervous system.
• Decision-making and response occur in the central nervous system, forwarding impulses through motor neurons.
• Motor neurons transmit impulses to effectors, such as muscles or glands.
• Effectors execute the response.

Sense Organs

• The Eye
  • The eye is a complex organ responsible for vision.
  • It consists of various parts such as the cornea, iris, lens, and retina.
  • Light enters through the cornea and is focused by the lens onto the retina.
  • The retina contains photoreceptor cells called rods and cones.
• The Ear
  • The ear is involved in both hearing and balance.
  • It consists of the outer ear, middle ear, and inner ear.
  • Sound waves are collected by the outer ear and transmitted through the middle ear to the inner ear.
  • The inner ear contains the cochlea, which is responsible for converting sound vibrations into electrical signals.
• The Nose
  • The nose is responsible for the sense of smell.
  • It contains olfactory receptors that detect odors in the environment.
  • When you smell something, molecules in the air stimulate these receptors, sending signals to the brain.
• The Tongue
  • The tongue is essential for the sense of taste.
  • It contains taste buds that can detect sweet, sour, bitter, salty, and umami flavors.
  • These taste buds send signals to the brain, allowing us to perceive different tastes.