Musculo-Skeletal System

In my previous lesson, we learnt about the musculo-skeletal system. The musculo-skeletal system consists of all the bones in your body and your muscles. We was taught what a joint was; a joint is the point where two bones meet. A good example of a joint is the elbow, your humorous and radius meets at your elbow and your body allows you to bend it because its not a straight bone, its like a hinge on a door, very flexible. To protect your to bones from rubbing together at a joint, you have a thick layer around the end of the bone called 'cartalidge'. There's also a bag of liquid inbetween where the two bones meet, that's called 'synoval fluid.' In your life you tend to move all your joints a lot, so when you get older you can get such things as tennis elbow. Tennis elbow is a repetitive strain injury in your arm where your bones rub together because your cartalidge and synoval fluid has worn away because they've been rubbing together as you've been moving your joints all your life. It's a very painful thing, because when there is nothing to protect your joints from rubbing together, the nerves on the end of the bones clash together, and because nerves are very sensitive it can feel really painful.
We also learnt about how your muscles work in pairs. A good example of this is your tricep and bicep muscle in the top of your arm. When your pushing something your bicep stretches, so your tricep relaxes in order for that to happen, and same thing if it was the other way around. Your bones are connected to your muscles via tendon. The tendon is a thin tissue that allows your muscles to move because its attached between the muscle and the bone. Before excersice your muscles are quite stiff and not as flexible during and after excersice. The reason being is because during and after excersice your muscles are constantly moving, and the friciton between them heat them up, so the more hotter they are, the more flexible they are.

Sometimes you must wonder how your muscles get bigger. Your muscles get bigger because when you excercise the fibre inside of your muscle tears and they build upon each other. So the more you excersice, the more your fibres tear and build, so the more your muscles gets bigger! Also sometimes you may see people with VERY big muscles, like wrestlers. The reason their muscles are so big is because some of them take a pill called a 'steroid.' A steroid allows you to train much longer because it numbs the pain in your muscles that you get when you train for a long period of time. Because they can train much longer than a person that hasn't taken the pill, there fibres in their muscle rips a lot more, so it grows a lot bigger.
Over weight people are very weak people because they don't move their body very much. In order for your muscles to build you have to excercise or move a lot, but over weight people don't move very much so their fibres never build upon each other, and if you don't move your muscle very much, it wears away. For example, if you break your arm and you take the cast off your broken arm, it will feel much lighter than your other arm because your body has been eating away your muscle in the broken one.