Welcome back to the EverythingABUAD study portal! This page is a complete, student-written study companion for PHS 220 – Special Senses, prepared for ABUAD 200 Level Pharmacy students (Second Semester).
The special senses build directly on nerve physiology and reward students who understand how each receptor converts a stimulus into a nerve signal. Diagrams score heavily here. Below we break each sense down in plain language, flag the high-yield drawing questions, and give you original practice questions with worked answers. The full study guide is available in the interactive reader at the end as a free bonus.
- Course: PHS 220 – Physiology II
- College / Department: College of Pharmacy / Pharmacy
- Level / Semester: 200 Level, Second Semester
- Topics covered: Vision & phototransduction, eye movements, auditory transduction, hearing disorders, the vestibular system, smell & taste
- Best for: Continuous assessment + final exam revision
Topics Covered in PHS 220: Special Senses
1. Vision & the Eye
Light is focused onto the retina, where rods and cones sit. Exam tip: learn the structures light passes through in order, and that rods handle dim light/peripheral vision while cones handle colour and detail.
2. Phototransduction
In the dark, photoreceptors are depolarised and release transmitter; light causes hyperpolarisation by closing sodium channels — the opposite of most receptors. Exam tip: this 'light hyperpolarises the photoreceptor' point is counter-intuitive and therefore heavily examined.
3. Eye Movements & the Visual Pathway
Signals travel from retina along the optic nerve, through the chiasm, to the visual cortex. Exam tip: a lesion at a specific point in the pathway causes a specific visual-field defect — be able to draw the pathway and predict the deficit.
4. Hearing & Auditory Transduction
Sound vibrations move the basilar membrane in the cochlea, bending hair cells that convert movement into nerve impulses. Exam tip: the cochlea is tonotopic — different frequencies stimulate different points along the basilar membrane.
5. Disorders of Hearing
Hearing loss is conductive (outer/middle ear) or sensorineural (cochlea/nerve). Exam tip: know how Rinne and Weber tests distinguish the two — a common applied question.
6. Vestibular System, Smell & Taste
The vestibular apparatus detects head position and movement; olfaction and gustation are chemical senses with their own receptor types. Exam tip: know the basic receptor and pathway for each, and that smell is unusual in projecting to the cortex without a thalamic relay.
Sample Practice Questions (With Answers)
Here are a few representative questions, written in our own words, with the reasoning explained so you understand the why — not just the answer:
Q. How does a photoreceptor respond to light, and why is this unusual?
Answer: Light causes the photoreceptor to hyperpolarise (not depolarise). In the dark the cell is depolarised and releasing transmitter; light closes sodium channels, hyperpolarising the cell and reducing transmitter release. This is the opposite of how most sensory receptors respond, which is why it is so often examined.
Q. What is meant by the cochlea being 'tonotopic'?
Answer: Different sound frequencies maximally stimulate different positions along the basilar membrane: high frequencies near the base and low frequencies near the apex. This spatial mapping of frequency is called tonotopic organisation and is preserved up to the auditory cortex.
Q. How do the Rinne and Weber tests help distinguish conductive from sensorineural hearing loss?
Answer: They compare air and bone conduction. In conductive loss, bone conduction beats air conduction (abnormal Rinne) and the Weber test lateralises to the affected ear. In sensorineural loss, air conduction still beats bone conduction and the Weber lateralises to the better ear.
How to Study PHS 220 (Special Senses) Effectively
- Practise drawing and labelling the eye and the visual pathway — these are high-yield drawing marks.
- Memorise the counter-intuitive rule that light hyperpolarises photoreceptors.
- Learn each sense as 'stimulus → receptor → transduction → pathway' for a consistent answer structure.
- Understand the concepts here, then test recall with the workbook before your exam.
Download the Full PHS 220 Special Senses Study Guide
Ready to revise? Use the interactive reader below to read the full special senses study guide with diagrams and worked detail. You can read it directly on the page or download it for offline revision before your exam.
Frequently Asked Questions
Is this PHS 220 material free?
Yes — every resource on EverythingABUAD is completely free for ABUAD students.
Does this cover the full PHS 220 syllabus?
This guide covers the special senses portion of the PHS 220 syllabus. Work through it alongside the other PHS 220 topic guides on EverythingABUAD, and always cross-check against your lecturer’s current outline.
Will these exact questions appear in my exam?
No. These are original practice questions written for revision only and are not a prediction of the actual exam.
About this resource: All summaries, explanations, study tips, and practice questions on this page were written, paraphrased, and adapted by the EverythingABUAD student team to support exam revision. This is an original study aid, not an official ABUAD document, and it is not a prediction of any future exam.
