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.

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