Reading ECG’s and the great skull failure… (Day 45)

Heart physiology dog ecg vet school diary

Today is the last day of lessons this week as tommorow is a Rectors day (a day off agreed by the Rector of the university) for the Matriculation Ceremony. Being Thursday I have Anatomy and Physiology today with an exam on the skull, in addition I spent last night revising so have not had the chance to sleep. Pretty bouncy from so much caffiene as well so all in all going be pretty interesting today.

Today started with the anatomy lecture which went over the structures of the skull again, for something that I’ve just thought of as the container for the brain its pretty amazing how many different parts it has. The skull is not actually a single bone but a collection of different bones all fused together.

It was then onto the Physiology practical, today was following the cardiovascular (heart and circulation) theme and we started looking at ECG’s and actually understanding what they actually mean in relation to the contraction of the heart. So we had a demonstration of the taking of the ECG on a dog, and were then given a copy of the results to work from.

Heart physiology dog ecg vet school diaryI found this pretty cool as though I knew the basics previously I did not understand the physiology to link these to what is actually occuring within the body. The different leads show the potential differences at different parts of the body, and from this using Einthovens triangle we can even work out the position of the heart with the chest cavity (now how cool is that!!!). When looking at an ECG the first peak is the depolarisation of the artriums (the smaller chambers of the heart) before the big peak being the depolarisation of the ventricles which are the larger chambers of the heart.

So its finally time for anatomy and I am confident on my internal structures of the skull, as well as the common landmarks. The first question was like a slap across the face, I remembered reading about it, I just couldn’t remember what the hole was that the tweezers were pointing at… Moving on I named every process and bone until again we come back to another hole… And my mind stays blank. I knew the horse inside out, I even knew the dog, this cow skull in front of me however was a nightmare. Every species has differences, sometimes subtle, sometimes obvious. Instead of having a single large opening like the foramen lacerum in the horse which is split into different sections the cow has 3 completely seperate openings. I ended today with a C… If it had been a horse I would have scored much higher….

And then to add insult to injury, the practical session was based on all the internal structures I had spent so long learning for next weeks test… Looks like I should be back to an A next week! Anways after Anatomy this evening I walked to Tesco Hyper with a friend as I needed to get my suit dry cleaned for tommorow.

Bones, Cartilage and the Heart … (Day 35)

Osteons in Compact Bone Histology

Start of week 5 of vet school and what a day it has been! Sometimes nature simply amazes me with just how much it can do with so little… When you think of how the world is based on just 90 naturally occuring elements, and in fact life itself is based on just a small subset of around just 25 of these elements. Actually there are just 11 elements that are vital to every living thing, and even within these just 4 (Carbon, Oxygen, Hydrogen and Nitrogen) form up to around 99% of the total atoms which make up the body.

The first lecture today was Histology and this lecture was spent looking at bone development and cartilage which give the body its structural skeleton. Its kinda pretty cool to be able to look at how bone is actually formed and understand why it is that way. When thinking about compact bone which forms the harder outer layer I cannot stop myself thinking about the way trees are formed from rings.

Osteons in Compact Bone Histology
Haversian systems – Osteons in Compact Bone

Ok so thats pretty cool 🙂 Structually and physically the cone/cylindral/round tube shape is designed to withstand force yet also give the ability to transport liquids. Its actually amazing how many times this shape appears in the body with different fibres and functions (muscles, gut, blood vessels etc). You’ve then got growth plates which form the basis for the growth of bone during development or ossification where the chondrocytes (bone cells) replicate and then stack up within what is called the proliferative zone ready to be used.

Ossification - Proliferative zone with chondrocytes stacking up
Ossification proliferative zone with chondrocytes stacking up

Anyways on from Histology I then had Physiology, this was all about the heart and electrical conductivity which was pretty cool. Really intense lecture however extremely cool topic. When you consider just how reliant this signal is on just a few chemical elements you start to wonder how something so complicated can be built out of something so simple. Anyways the heart is kind of interesting, as the cells responsible for carrying the electrical signal regulating contraction of the chambers are specialised to both speed it up, and at the Atrial-Ventricular node slow it down to give the chamber the chance to expand and fill with blood.

Another interesting thing about the heart is that the valves between the chambers work on a pressure system and do not involved muscle. This I find very cool as when you think about it having something so complicated made by nature it kinda boggles the mind.