Sense Organs

Syllabus tag: KCSE | Biology | Form 4 | Topic 3 Reception, Response and Co-ordination

Lesson objectives

By the end of this topic, you should be able to:

• Describe the structure of the mammalian eye and how an image is formed.
• Explain accommodation, the pupil reflex and defects of vision.
• Describe the structure of the ear and its role in hearing and balance.
• Describe the skin, tongue and nose as sense organs.

Summary

Sense organs contain receptors that detect stimuli and convert them into nerve impulses. The eye forms an image by refracting light onto the retina, focusing by changing the shape of the lens — a process called accommodation. The ear detects sound and also maintains balance through the semicircular canals.