Muscle types, muscles and terminology Flashcards
Three types of muscle
Smooth muscle, skeletal muscle, cardiac muscle
Smooth muscle
Found in visceral structures - blood vessels, gastrointestinal tract, uterus, bladder. Cells overlap onto each other. Movement is involuntary, controlled by the autonomous nervous system or hormones.
Skeletal muscle
Associated with the skeleton and individual muscles for movement. Consists of individual muscle cells (fibres) grouped together into bundles.
Cardiac muscle
Found in the heart and made up of branched muscle cells grouped by discs. Structure is similar to skeletal muscle.
Purpose of skeletal muscle
Movement, maintaining posture, prevents excess movement of bones and joints. Found at opening of internal tract to allow voluntary control over movement (swallowing, urination, defecation). Supports internal organs where there is no skeletal support. Barrier to external pressure and trauma. Maintains homeoastasis by generating heat through involuntary movement (shivering).
Origin of a muscle
Starting point of a muscle, contracts the least, contains the tendon of the origin.
Muscle belly
Thick, fleshy, central part of the muscle. Tapers at each end, muscle can have more than one belly that inserts at one point. The muscle then has number of heads.
Muscle insertion
Insertion point of a muscle is the muscle attachment point to the bone that moves. Opposite of the origin and contains the tendon of insertion.
Tendons connect
muscle to bone
Ligaments connect
bone to bone
Tendons and ligaments are made up of
Fibrous connective tissue bundles rich in collagen fibres. They are a strong extension of a muscle but rigid compared to elastic muscle fibres.
How do tendons attach to the bone
Collagen in the three layers of the muscle (mysia) bind with collagen of a tendon which connects to the periosteum of a bone.
Aponeuroses
Flattened sheets of connective tissue.
Skeletal muscle fibres
Long, striated, multinucleated. Each muscle fibre contains myofibrils. Myofibrils divide into sarcomere units which contain actin and myosin proteins. Myofibrils contain thousands of sarcomeres within one muscle fibre.
How skeletal muscle moves
Voluntarily by contraction, as the the bundles of prottein filaments within the muscle fibres shorten.
How muscle contraction occurs
When a nerve impulse triggers the release of calcium. It alters the environment within sarcomere to allow the attraction between myosin and actin.
Isotonic contraction
Muscle contracts when it’s working. If contraction results in movement it is isotonic contraction.