| A | B |
|---|
| periosteum | a tough layer of connective tissue that surrounds the bone |
| Haversian canal | a network of tubes that runs through the bones |
| bone marrow | a soft tissue that is contained within bones |
| cartilage | connective tissue that composes the skeleton of a newborn baby |
| ossification | the process whereby cartilage is replaced by bone |
| joint | depending on its type of movement, it is classified as immovable, slightly movable or freely movable |
| ligament | strips of tough connective tissue |
| myosin | the thick filaments that contain a protein |
| actin | the thin filaments that are made up mainly of a protein |
| neuromuscular junction | the point of contact between a motor neuron and a skeletal muscle cell |
| acetylcholine | a neurotransmitter that is release by the vesicles, or pockets, in the axon terminals of the motor neuron |
| tendon | skeletel muscles that are joined together by tough connective tissue |
| epidermis | the outer layer of the skin |
| keratin | a tough, fibrous protein |
| melanin | cells that are a dark brown pigment |
| dermis | the inner layer of the skin |
| hair follicle | are tubelike pockets of epidermal cells that extend into the dermis |
| a | a |
| b | b |
| c | c |
