Oxbridge results for 2025 have come out, and we have received a lot of good news! This year, two of my international students have successfully received their offers to study Medicine at the University of Cambridge. Let’s look at a question from their interviews and dissect it together.

‘A snake venom causes vasodilation in the human body. Can you propose a mechanism?’

This is a classic question on human physiology and how it interacts with drugs. Let’s look at the word ‘vasodilation’ first. Vasodilation increases blood flow to the body’s tissues. In response to a need for oxygen or nutrients, tissues can release endogenous vasodilators. The result is a decrease in vascular resistance and an increase in capillary perfusion. A typical example of this vasodilation response taught in high school biology occurs during exercise.

So, how does snake venom cause vasodilation? Assuming that snake venom is a chemical that works like a hormone, we propose that it triggers the release of other hormones that cause vasodilation. Since snake bites often come with physical trauma and bleeding, it’s easy to hypothesise that inflammation would happen at the same time in the body too. A classic chemical that comes to mind is bradykinin, which causes both inflammation and vasodilation.

However, one of the more important things to remember in the interview is to tackle questions as laterally as possible and not assume any of your educated guesses as truths (unless your interviewer confirms it). Therefore, it’s essential to propose more than one mechanism. Whether our answers are correct or not is not important; it’s the thought processes that matter.

Another idea that students might propose is the release of histamine. Histamine works by binding to histamine receptors on a cell’s surface. There are four types of histamine receptors, but the most relevant one is H1 in this case. The H1 receptor typically plays a crucial role in allergic responses and is widely distributed throughout the peripheral nervous system, particularly the smooth muscle. Activation of H1 receptors can cause vasodilation and increased vessel permeability.

An alternate good attempt at the question might put more focus on the study of smooth muscle. Power strokes and muscle contraction mechanisms are studied in depth in A level and IB, so this is a good direction to take for this question too! The tunica media of the walls of blood vessels is composed of smooth muscle and controls vasodilation and vasoconstriction (relaxation of smooth muscle cells causes vasodilation). Smooth muscle is controlled by the autonomic nervous system, and contractions are dependent on the concentration of calcium ions in the cytosol. With this understanding, we can hypothesize that snake venom binds with calcium ions and lowers the concentration of calcium ions inside the cells, leading to vasodilation.

A follow-up discussion on the usage of said snake venom in medicine is common, and it’s fairly easy to suggest that it could be used in conditions like hypertension or stroke.

So, what’s the takeaway? In highly academic Oxbridge interviews, always relate the questions to concepts that you already know, try to make educated guesses, and don’t be afraid to make mistakes!

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By Anson Chung, Admissions Consulting Partner

Published 12-02-2025