We are three Erasmus students from Germany and Portugal studying Medical Engineering and Biomedical Engineering. We therefore still have to get used to the system, hence why this week’s blog post is our first. We are taking the course ‘Structure and operation of the human brain’ and we want to document our learning progress in this blog. Reflecting the lectures as we write our posts will hopefully help us in learning more effectively early on.
The first lecture was on the structure of neurons, but since we already had the second one, well will focus on that.
We discussed the structure of the membrane with the in-built ion channels. The electrical voltage inside and outside the cell are due to a difference in concentrate of Na+, K+, Ca2+ and Cl–. Active ion pumps and passive ion channels keep up the voltage at about -70 mV, which we call resting potential. Whenever there is a stimulus, which exceeds the threshold, an action potential is evoked. Exceeding the threshold means that the voltage decreases to a certain degree or more. This happens by an opening of sodium channels, which results in Na+ flowing into the cell. An action potential is subdivided into a rising phase, an overshoot, a falling phase and an undershoot. Only after going through all the phases a new action potential can be evoked. To speed up the process of forwarding the signal, an insulating material, called myelin sheets, covers the axon. The signal now jumps from Ranvier node to the next, which are non-covered spots in between the myelin sheets.
The questions for the first exercise were varied in type which will allow us to consolidate what we learnt from reading the book in a more efficient way. The exercise session provided a good opportunity to clarify any doubts we had.
In order to prepare ourselves for the next lesson, we are reading two chapters of the book ‘Neuroscience – Exploring the brain’ by Bear. This will explain more about the action potential and the synaptic transmission.