BIO201 – Topic 22: Sensory Organs and Sensory Physiology
© Lesuyai Organic Guides 2025
(Original | Educational | Professional | Plagiarism■Free | A4 Academic Format)
22.1 Introduction
Sensory physiology explains how the body detects, interprets, and responds to internal and
external stimuli.
22.2 Definition of Sensory Organs
Sensory organs are specialized structures that detect specific stimuli and convert them into nerve
impulses.
22.3 General vs. Special Senses
General senses: touch, pressure, pain, temperature, proprioception.
Special senses: vision, hearing, taste, smell, equilibrium.
22.4 Structure and Physiology of the Eye (Vision)
The eye contains cornea, lens, iris, pupil, retina, and optic nerve. Photoreceptors (rods and cones)
convert light into impulses interpreted by the brain.
22.5 Structure and Physiology of the Ear (Hearing & Balance)
Outer, middle, and inner ear. Cochlea detects sound vibrations; semicircular canals maintain
balance.
22.6 Skin and Somatic Sensations
The skin contains receptors for touch, temperature, and pain. Signals travel via sensory neurons to
the CNS.
22.7 Olfactory System (Smell)
Olfactory receptors in the nasal cavity detect chemical molecules and send signals to the olfactory
bulb.
22.8 Gustatory System (Taste)
Taste buds detect sweet, sour, salty, bitter, and umami via chemoreceptors on the tongue.
22.9 Common Disorders of Sensory Organs
Examples: myopia, hyperopia, cataracts, otitis media, hearing loss, anosmia, neuropathy.
22.10 Summary
Sensory organs enable detection of environmental changes, allowing the body to respond and
maintain survival.
EXAM SECTION – STRUCTURED QUESTIONS WITH ANSWERS
1. Define a sensory receptor.
Answer: A sensory receptor is a specialized cell that detects stimuli and converts them into nerve
impulses.
2. State two differences between rods and cones.
Answer: Rods detect dim light; cones detect bright light and color. Rods provide low detail; cones
provide high detail.
3. Name two parts of the inner ear.
Answer: Cochlea and semicircular canals.
4. What is proprioception?
Answer: Proprioception is the sense of body position and movement.
ESSAY QUESTION WITH ANSWER
Discuss the structure and functions of the human ear.
© Lesuyai Organic Guides 2025
(Original | Educational | Professional | Plagiarism■Free | A4 Academic Format)
22.1 Introduction
Sensory physiology explains how the body detects, interprets, and responds to internal and
external stimuli.
22.2 Definition of Sensory Organs
Sensory organs are specialized structures that detect specific stimuli and convert them into nerve
impulses.
22.3 General vs. Special Senses
General senses: touch, pressure, pain, temperature, proprioception.
Special senses: vision, hearing, taste, smell, equilibrium.
22.4 Structure and Physiology of the Eye (Vision)
The eye contains cornea, lens, iris, pupil, retina, and optic nerve. Photoreceptors (rods and cones)
convert light into impulses interpreted by the brain.
22.5 Structure and Physiology of the Ear (Hearing & Balance)
Outer, middle, and inner ear. Cochlea detects sound vibrations; semicircular canals maintain
balance.
22.6 Skin and Somatic Sensations
The skin contains receptors for touch, temperature, and pain. Signals travel via sensory neurons to
the CNS.
22.7 Olfactory System (Smell)
Olfactory receptors in the nasal cavity detect chemical molecules and send signals to the olfactory
bulb.
22.8 Gustatory System (Taste)
Taste buds detect sweet, sour, salty, bitter, and umami via chemoreceptors on the tongue.
22.9 Common Disorders of Sensory Organs
Examples: myopia, hyperopia, cataracts, otitis media, hearing loss, anosmia, neuropathy.
22.10 Summary
Sensory organs enable detection of environmental changes, allowing the body to respond and
maintain survival.
EXAM SECTION – STRUCTURED QUESTIONS WITH ANSWERS
1. Define a sensory receptor.
Answer: A sensory receptor is a specialized cell that detects stimuli and converts them into nerve
impulses.
2. State two differences between rods and cones.
Answer: Rods detect dim light; cones detect bright light and color. Rods provide low detail; cones
provide high detail.
3. Name two parts of the inner ear.
Answer: Cochlea and semicircular canals.
4. What is proprioception?
Answer: Proprioception is the sense of body position and movement.
ESSAY QUESTION WITH ANSWER
Discuss the structure and functions of the human ear.
