H zone
The H Zone is a term used to refer to an area within a sarcomere.
A sarcomere is the repeating functional unit of "striped" or "striated" muscle.
"Striated muscle" is also known as "skeletal muscle", "voluntary muscle", and "cardiac muscle". Its striated (stripey) appearance is due to the alternating (dark) A bands and (light) I bands.
The relative sizes of the H Zone, the A band, and the I band of sarcomeres are determind by, and provide information about, the state of contraction or relaxation of the muscle tissue of which the sacromere is a part.
This is illustrated below:
Above: Diagram of the unit within a muscle cell that is known as a sarcomere
The H Zone is at the centre of the A band of each sarcomere.
This is the region in which there are only thick filaments, and no thin filaments.
This section consists of short summaries about the
structures that form the muscles of the body.
This list is not exhaustive but is intended to be appropriate for students
of A-Level Human Biology, ITEC courses in massage and related subjects,
and other courses in health sciences. For more general information about muscles see
the pages about:
This section is about the
anatomical structures of muscles.
- Anterior Muscles
- Posterior Muscles
- Facial Muscles
- Muscle Terminology (Definitions)
- 1. Structure of Muscle
- 2. Structure of Muscle Cells
- 3. Muscle Filaments
- 4. Sliding Filament Theory
- 5. Neuromuscular Junction
- 6. Actions at Neuromuscular Junction
- Types of Muscle Contractions
- Muscular Disorders
- Effects of exercise on muscles
