The three compared
Eight rows tell the three muscle tissues apart completely. Two of the rows are enough on their own.
Assignment 1.2
Compare the characteristics of smooth muscle, skeletal muscle and cardiac muscle tissues. Work it out on paper first, then check it against the table below.
| Feature | Smooth | Skeletal | Cardiac |
|---|---|---|---|
| Cell shape | Spindle-shaped | Long and cylindrical | Cylindrical |
| Branched? | Not branched | Not branched | Branched |
| Nuclei | One | Many | One |
| Position of the nucleus | In the middle of the cell | At the periphery | In the middle of the cell |
| Cross striations | Absent | Present | Present |
| Fatigue | Does not tire quickly | Tires when worked excessively | Never tires, from birth to death |
| Control | Involuntary | Voluntary | Involuntary |
| Where found | Walls of the gut, blood vessels, bladder and uterus | Attached to the skeleton — biceps, triceps, leg and face | The heart, and nowhere else |
Rows 2 and 3 are enough on their own
Branched with one nucleus can only be cardiac. Unbranched with many nuclei can only be skeletal. Unbranched with one nucleus and no striations is smooth. Two questions identify any of the three, which is why examiners ask them.
Branching and nuclei identify the tissue
Smooth: spindle-shaped, unbranched, one central nucleus, unstriated, involuntary. Skeletal: cylindrical, unbranched, many nuclei at the edge, striated, voluntary, tires. Cardiac: branched, one nucleus, striated, intercalated discs, involuntary, never tires.