Involuntary muscle
- It is controlled by the autonomic nervous system so is non conscious movement
- It does not appear striated whereas voluntary and cardiac do (long strands)
- The of the muscle cells are known as 'spindle shaped'
- They contain small bundles of actin and myosin
- Each cell has one nucleus
- Contraction is slow and steady but tires very slowly
Examples include:
1) Walls of the intestine which have circular and longitudinal (length ways) bundles of muscle cells that work to move food along the intestine
2) Iris of the eye which has circular and radial bundles of muscle cells that control the intensity of the light entering the eye - contraction causes the radial muscles to dilate, contraction of the circular muscle constricts the pupil
3) The walls of the arteries and around the arterioles contain circular bundles that can contraction to reduce blood flow or relax to increase blood flow, this is important in exercise and temperature regulation
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