Muscles and Movement

The three types of muscle in mammals are:

1. Cardiac- (this you learnt about earlier when we did transport in animals)

2. Smooth– also known as involuntary muscle as the individual has no control over it.

3. Striated– these muscles are attached to the bone and are also called voluntary muscles as they are often controlled consciously. As you can see below, there are striations (stripes) in this muscle

The diagrams above show how the cardiac muscle, smooth muscle and striated muscle looks (respectively).

Note: You don’t need to be able to draw these diagrams.

How muscles cause movement

Muscles contract (get shorter) by using energy from respiration. When they do this, they allow movement to occur. Since muscles vary, the way they contract will also vary. Cardiac muscles are the only muscles in the body that will never tire. They do not need to be controlled by the brain but the brain may alter its rate of contraction.

In the walls of the alimentary canal, the smooth muscle operates similarly to the cardiac muscle during peristalsis. In other places, however, the smooth muscle needs to be stimulated by nerves.

The following diagram shows the relaxation and contraction of muscles