The Human Body – Body Tissues

The Tissues Of The Human Body

I’ve been thinking about tissue tolerances. This is the tolerance of the human body’s tissues to cope with this or that amount of physical stress and how we tend to overdo it so often.

Sport is probably the worst offender. Mostly it doesn’t matter a whole heap but sometimes pushing ourselves can lead to injury or worsening of pain conditions. And then it can get important.

So before I get going on tissue tolerances, overdoing, activity cycling and pacing, I thought I’d review the different tissues of the human body as a starting point, a baseline from which we can go on to more complex ideas.

Bone

Bone is the structural tissue, it holds us up, our muscles attach to it and it takes the weight of our bodies as we move about. Our bones are an active tissue and constantly changing in response to the stresses we put on our bodies. Runners have denser bones than non-runners in their legs, indicating that bone changes like any other tissue but it’s just not as obvious or as quick.

Muscle

Muscle is the movement tissue. Its second and  very important function is to hold us up posturally in all the positions we take up. If we are standing still there’s no movement but many of our muscles are working hard to maintain us upright. Muscles also react to activity or inactivity by changing and this can be fast.

If we work out muscles hard, beyond their easy capacity, we damage them to a small degree. This is why the muscle can feel stiff or sore the next day or so. This minor damage is the stimulus the muscle needs to repair and as it repairs it gets stronger and larger. Bodybuilders do this to an extreme degree! However, this response occurs in all of us when we work our muscles a bit harder than normal.

Tendon

Tendons are the force tranmission tissue. Muscles have connective tissue through their structure, but at each end of the muscles this connective tissue thickens into a band or a rope-like shape. Tendons connect muscles to the bone. To be able to move anything, a muscle needs to be attached to a bone and it’s the tendons which do this job.

Tendons are also often neat and small so that they’re strong enough but don’t get in the way. There’s no room for big forearm muscles down near the wrist and hand and if you look at your hand when you’re moving your fingers you’ll see the long, slim tendons doing their jobs.

Nerve

Nerves are the irritable tissue. Their job is to be irritated in some way or other and communicate that input up to the brain where it can be processed. Nerves report back to the brain on a whole list of things going on around or in us – to pressure, heat, cold, touch, joint position and pain. And that’s not counting vision and hearing.

Nerves have a surprising degree of “plasticity”, meaning that they can react very differently to a stimulus depending on what’s been happening to them recently. They are not just on/off switches but change the volume of their responses.

Ligament

Ligaments are the binding tissue. Ligaments bind all our joints together and prevent them from going beyond their limits. Bend your finger back with your other hand and you’ll see it’ll only go so far. Push any further and you will feel pain. That’s your ligaments objecting to being stretched too far.

Joint

Joints are the hinge tissues. They allow movement in one direction or a number of directions so we can do what we want. An example is the shoulder joint – its job is to put our hands in front of our faces so we can see them and do things with them. Joints vary from large weight bearing ones such as the hip and spine, to small ones such as the fingers and toes.

Cartilage

Cartilage is the anti-friction tissue. Joint cartilage covers both surfaces of many of our joints and is very slippery and low friction. This allows us to move around easily even when there’s a big load on a joint such as going upstairs. It doesn’t really feel any different to going down apart from being a bit more work. This is important as we are large animals in the scheme of things and so weigh a lot.

Activity or inactivity has effects on each of these tissues of the human body although we are often not aware of the changes at the time.

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