Exciting cells: an introduction to neurobiology

The University of Cambridge has long been instrumental in shaping what we know about the function of excitable cells, several Nobel Prizes in this area having been awarded to Cambridge researchers. In this short course, Dr Matt Mason from the Department of Physiology, Development & Neuroscience will draw on this rich history to explain how nerve, muscle and other excitable cells work.

We shall begin with the fundamental topic of electrochemical gradients, which drive ions across membranes. Electrochemical gradients arise from an imbalance between electrical and concentration-based forces, and we shall explore where these come from and how we could calculate an ion’s ‘equilibrium potential’, at which point forces are balanced. If an ion is maintained away from that point, we can harness its tendency to cross a membrane in a particular direction, a principle which is central to cellular physiology in all organisms. Excitable cells such as sensory receptor cells, neurons and muscle cells are special in that they can exploit electrochemical gradients to develop and propagate electrical signals - a phenomenon ultimately underlying everything that humanity has ever accomplished! Dr Mason will explain how these cells work from basic principles, going on to explore how nerve cells intercommunicate, activate muscles, make decisions and transduce information from the environment into the electrical signals that our brains can understand. The four lectures will be supported by an experimental class in which you will be able to stimulate and record electrical signals from your own arm, and measure the conduction velocity of your ulnar nerve.

This course represents an introduction to the fundamentals of neurobiology, at a level equivalent to what we teach first-year science students here in Cambridge. It will be particularly suitable for biology undergraduates/graduates with limited neurobiology experience, who would like to know more about the physical and chemical basis of electrical signalling within cells. 

Learning outcomes

The learning outcomes for this course are:

• To have a deeper understanding of the fundamental processes underlying the electrical signalling properties of excitable cells;
• To appreciate how we use excitable cells within the body for the purposes of sensation and communication;
• To appreciate how biological experimentation, combined with an understanding of some basic physics and chemistry, has contributed to what we know about the function of excitable cells, focusing on the particular contributions of Nobel Laureates who have worked in Cambridge.  

Classes

1. Electrochemical gradients and resting potentials
A proper understanding of how nerves use electrical signalling requires that we first consider the basics. In this session, we shall explore the nature of the driving forces on ions which might make them tend to cross a membrane in one direction or another. We shall explore the concepts of electrochemical gradients, Nernst equilibrium potentials and, bringing this all together, where the resting membrane potential of a cell really comes from – avoiding common misconceptions about the role of the sodium pump! We shall see how electrochemical gradients are put to use not just for electrical signalling by excitable cells, but for driving secondary active transport processes in all living cells.

2. Action potentials
Now that we understand why there is an electrochemical gradient for sodium ions causing them to want to enter a nerve cell, we can now explore how the cell harnesses this in order to propagate the electrical signals called action potentials. Action potentials are the means by which nerve cells can send information long distances around the body, at velocities which can exceed 100 metres/second! We will look at how the experiments of Nobel Laureates from the University of Cambridge, including the famous work on squid giant axons by Alan Hodgkin and Andrew Huxley, contributed to our current understanding of how nerves work.

3. Synapses
Nerve cells must communicate with other cells in order to pass on their messages, often through chemical synapses. We shall examine the neuromuscular junction, between a nerve fibre and a skeletal muscle cell, as an example of how and why this chemical communication takes place, and look at how it can be disrupted by poisons such as botox. The more complicated synapses between neurons within the brain and spinal cord allow for decision-making, and we shall investigate how this process works too.

4. Ulnar nerve practical class (This session will take place at The Department of Physiology, Development and Neuroscience)
We will be stimulating and recording electrical signals from our own arms. We will stimulate our ulnar nerves with small electrical shocks (generating a strange sensation, which isn’t painful!) and record the compound action potentials elicited in the muscles of our hand. We can use this simple experiment to explore properties of nerve stimulation, conduction velocity and neuromuscular transmission which we have examined in the first three lectures.

5. Sensory receptors
Electrical signals in nerve fibres are not normally initiated through the application of an external electrical shock, as performed in yesterday’s class! They can originate in sensory receptors, located around the body – but how? In today’s final lecture, we will see how external environmental stimuli can be translated by sensory receptors, directly or indirectly, into electrical signals. We will look at examples including the eye, the ear and some of the receptors in the skin. 

Typical week: Monday to Friday

For each week of study you select a morning (Am) and an afternoon (Pm) course, each course has five sessions, one each day Monday to Friday. The maximum class size is 25 students. Your weekly courses are complemented by a series of two daily plenary lectures, exploring new ideas in a wide range of disciplines. To add to the learning experience, we are also planning additional evening talks and events.

Evaluation and Academic Credit 

If you are seeking to enhance your own study experience, or earn academic credit from your Cambridge Summer Programme studies at your home institution, you can submit written work for assessment for one or more of your courses. 

Essay questions are set and assessed against the University of Cambridge standard by your Course Director, a list of essay questions can be found in the Course Materials. Essays are submitted two weeks after the end of each course, so those studying for multiple weeks need to plan their time accordingly. There is an evaluation fee of £65 per essay.

For more information about writing essays see Evaluation and Academic Credit.

Certificate of attendance

A certificate of attendance will be sent to you electronically within a week of your courses finishing.