Welcome back to the EverythingABUAD study portal! This page is a complete, student-written study companion for PHS 220 – Introduction to Endocrine Physiology, prepared for ABUAD 200 Level Pharmacy students (Second Semester).
The endocrine system keeps your internal environment stable using chemical messengers called hormones. Most students lose marks here by mixing up the three hormone classes and the way each one signals to its target cell. Below we break the foundations down in plain language, flag the comparisons examiners reuse year after year, 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: Homeostasis & hormones, hormone classes, receptors, feedback control, the hypothalamo-pituitary axis
- Best for: Continuous assessment + final exam revision
Topics Covered in PHS 220: Endocrine Physiology
1. Homeostasis & the Endocrine System
Endocrine physiology is really the study of how the body holds a stable internal state while the outside world keeps changing. Hormones are secreted in tiny amounts into the blood and travel to distant target cells that carry the matching receptor. Exam tip: be able to distinguish the five signalling types — endocrine (bloodstream), paracrine (neighbouring cells), autocrine (same cell), neurocrine (via a neuron), and juxtacrine (direct contact) — with one example each.
2. The Three Classes of Hormones
This is the highest-yield comparison in the whole topic. Peptide/protein hormones are water-soluble, act on cell-surface receptors, and work fast through second messengers. Steroid hormones are made from cholesterol, are lipid-soluble, cross the membrane, and act slowly on nuclear receptors to change gene transcription. Amine hormones (from tyrosine) are the hybrids. Exam tip: build one table — class, solubility, receptor location, speed, example — and you can answer almost any hormone-class question.
3. Hormone Receptors & Second Messengers
A receptor binds its hormone with high affinity and triggers the cell's response. Learn the GPCR families by their second messenger: Gs raises cAMP, Gi lowers it, and Gq drives the IP3/DAG → calcium pathway. Receptor tyrosine kinases (e.g. insulin) work differently again. Exam tip: match a given hormone to its receptor type and second messenger — examiners love this pairing.
4. Principles of Feedback Control
Feedback keeps hormone levels in range. Negative feedback (the rule) switches secretion off once the target level is reached; positive feedback (the exception, e.g. the LH surge or oxytocin in labour) amplifies a response to completion; feedforward anticipates a change. Exam tip: be ready to trace a negative-feedback loop through the hypothalamus → pituitary → target gland and explain what happens when the end-organ fails.
5. Pulsatile Secretion, Rhythms & the HP Axis
Hormones are not released at a steady drip — many are pulsatile or follow a circadian rhythm (cortisol peaks in the early morning), which is why sample timing matters clinically. The hypothalamo-pituitary axis is the master control: the hypothalamus releases tropic factors, the anterior pituitary releases its hormones, and the posterior pituitary stores ADH and oxytocin. Exam tip: know which hormones come from the anterior vs posterior pituitary — a classic quick-fire question.
6. Principles of Endocrine Disease
Endocrine disease is usually framed as too much (hyperfunction) or too little (hypofunction) of a hormone, and can be primary (the gland itself), secondary (the pituitary), or tertiary (the hypothalamus). Exam tip: when given a hormone level plus its tropic hormone, you can locate the lesion — e.g. low thyroid hormone with high TSH points to a primary thyroid problem.
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. What property of a hormone determines whether it acts on a cell-surface receptor or a nuclear receptor?
Answer: Its solubility. Water-soluble hormones (peptides, catecholamines) cannot cross the membrane, so they bind surface receptors and signal through second messengers. Lipid-soluble hormones (steroids, thyroid hormone) cross the membrane and bind intracellular/nuclear receptors that directly regulate gene transcription.
Q. Which second messenger is generated by a Gq-coupled receptor, and name one hormone that uses it.
Answer: Gq activates phospholipase C, producing IP3 and DAG, which raise intracellular calcium and activate protein kinase C. GnRH, TRH and oxytocin all act through Gq-coupled receptors.
Q. A patient has a low circulating thyroid hormone level but a high TSH. Where is the defect?
Answer: In the thyroid gland itself (primary hypothyroidism). The pituitary is working correctly — it senses the low thyroid hormone and raises TSH to compensate — but the gland cannot respond, so the negative-feedback loop stays 'switched on'.
How to Study PHS 220 (Endocrine Physiology) Effectively
- Master the three-hormone-class table first — almost every other concept hangs off solubility and receptor location.
- Learn second messengers by GPCR family (Gs ↑cAMP, Gi ↓cAMP, Gq →calcium) rather than memorising hormone by hormone.
- Practise tracing one full negative-feedback loop out loud; if you can narrate it, you can answer the variations.
- Use this guide to understand the principles, then use the workbook to self-test under timed conditions.
Download the Full PHS 220 Endocrine Physiology Study Guide
Ready to revise? Use the interactive reader below to read the full endocrine physiology 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 endocrine physiology 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.
