5. Each skeletal muscle features 3 layers of connective tissue that encloses it and provides structure. List the 3 layers of connective tissue from outermost to innermost. (3 points) Outermost Connective Tissue Layers Found Within Muscle Tissue Innermost 6. Write the correct number beside each step of the sliding filament model of muscle contraction to put them in the correct sequence. (6 points) Order, Description of Sliding Filament Model Steps As actin filaments slide inward along the myosin filaments, the sarcomere shortens in length. The shortening of many sarcomeres results in muscle contraction. Calcium ions bind to troponin molecules on actin filaments, causing them to change shape, which pulls tropomyosin proteins away from myosin-binding sites on actin. At a neuromuscular junction, a nerve impulse from a motor neuron causes the release of eurotransmitter acetylcholine at a neuromuscular junction. Myosin heads attach to actin to form cross-bridges. Myosin heads use energy found in ATP to rock forward, causing actin filaments to slide inwards along the myosin filaments. Acetylcholine passes across the synapse of the motor neuron to stimulate the muscle fiber membrane, which passes the impulse deep into the fiber via transverse tubules. Impulse triggers the release of calcium ions from the sarcoplasmic reticulum into the sarcoplasm. Calcium ions now surround the actin filaments.

Here is a jumbled summary of steps involved in muscle contraction. Put them into the correct order in the following chart, and then place the number for each step in the correct location on the preceding diagram. 1. Nerve impulse arrives at the neuromuscular junction. 2. Acetylcholine is released from synaptic vesicles. 3. Acetylcholine binds to receptors on the muscle fibers. This allows Na+ ions to rush, causing depolarization. 4. Depolarization continues across the sarcolemma and down the transverse tubule system. 5. Calcium ions bind to troponin molecules of thin filaments. 6. Ca++ is released from cisterns of the SR (sarcoplasmic reticulum). 7. The troponin/tropomyosin complex is moved so the myosin-binding site of actin is exposed. 8. Myosin heads rotate, bind the actin, and pull the actin fibers toward the center of the sarcomere. 9. In the presence of Ca++, myosin acts as an enzyme. It catalyzes the breakdown of ATP. Energy is transferred from ATP to the myosin head; myosin is activated. Steps of Muscle Contraction: 1. Nerve impulse arrives at the neuromuscular junction. 2. Acetylcholine is released from synaptic vesicles. 3. Acetylcholine binds to receptors on the muscle fibers. This allows Na+ ions to rush, causing depolarization. 4. Depolarization continues across the sarcolemma and down the transverse tubule system. 5. Calcium ions bind to troponin molecules of thin filaments. 6. Ca++ is released from cisterns of the SR (sarcoplasmic reticulum). 7. The troponin/tropomyosin complex is moved so the myosin-binding site of actin is exposed. 8. Myosin heads rotate, bind the actin, and pull the actin fibers toward the center of the sarcomere. 9. In the presence of Ca++, myosin acts as an enzyme. It catalyzes the breakdown of ATP. Energy is transferred from ATP to the myosin head; myosin is activated.

Madhur L.

Question

Instant Answer