1. Muscles: A Closer Look

2. Types of Muscles

3. 1.Skeletal Muscle Attached to bone – skeletal movements Conscious and voluntary control Basic unit  muscle fibre with many nuclei Striated (transverse streaks) Act independently of neighbouring muscle fibres

4. 2. Smooth Muscle Walls of hollow internal organs (i.e. blood vessels, gastrointerstrial tract, bladder & uterus) Involuntary control Non-striated (smooth) muscle cells – spindle shaped 1 central nuclei

5. 3. Cardiac Muscle Only in walls of heart Involuntary movement 1 central nuclei Striated Rectangular in shape

6. Types of Muscle Contraction 1.Concentric Muscle fibres shorten 2.Eccentric Muscle fibre lengthen 3.Isometric Muscle fibres do not change in length

7. Contraction During Exercise Isotonic Exercise – Controlled shortening & lengthening of muscles – i.e. Chin-ups, push-ups & sit-ups Isometric Exercise – Constant length throughout contraction – No motion – Against an immovable surface or object Isokinetic Exercise – Involve machines to control speed of contractions with range of a muscle’s motion

8. Isotonic Contraction Isometric Contraction

11. Anatomy of a Skeletal Muscle Epimysium - outermost layer, surrounds entire muscle Perimysium - separated and surrounds the fascicles (bundles) of muscle fibres Endomysium - surrounds each individual muscle fibre – Beneath endomysium lies plasma membrane (sarcolemma) – contains muscle cell’s cytoplasm (sarcoplasm) Each fibre contains: – Contractile machinery & cell organelles – Each fibre has capillaries that supply nutrients & eliminates waste

13. Anatomy of a Skeletal Muscle Bundles of Muscle fibres  Muscle Fibre  Myofibrils  Myofilaments 2 types of myofilaments 1.Actin – thin filaments 2.Myosin – thick filaments