Tissues in Action
Muscles and nerves
Learn how muscles move us and nerves control us.
Some movements you choose: running, writing, lifting a bag. These are voluntary. Others happen by themselves: food moving through your intestines, your heart beating. These are involuntary. Different muscles do each.
Three kinds of muscle:
| Skeletal | Smooth | Cardiac | |
|---|---|---|---|
| Movement | Voluntary | Involuntary | Involuntary |
| Where | Attached to the skeleton | Stomach, intestines | Only in the heart |
| Cells | Long, cylinder-shaped, not branched, many nuclei | Spindle-shaped (thick in the middle, pointed at the ends), one nucleus | Cylinder-shaped, branched, one nucleus |
| Stripes (striations) | Yes, light and dark bands | None | Faint |
| Works | When you decide | Slowly and steadily, as in digestion | In a steady rhythm, all your life |
Pause and thank your heart muscle: it has been beating since before you were born, and it never takes a rest.
Muscles can't decide anything by themselves. Nervous tissue is the body's control and messaging network, and the brain is the control centre. When you exercise, the brain signals the heart to beat faster.
A nerve cell is called a neuron. It has three parts:
- the cell body, with the nucleus;
- dendrites, short branches that receive signals;
- an axon, a long fibre that carries the message to its ends (axon terminals), which pass it on to the next cell.
Practise this lesson
Questions that get harder as you improve, a Tutor that helps without giving the answer away, and progress you can see. Free for every learner.
No account, no email address. Opens the real product.