Muscle Contraction 0.0 / 5 ? BiologyCellular processesA2/A-levelAQA Created by: MollyCreated on: 23-03-14 16:41 What are the three types of muscles? Cardiac muscles - in the heart. Smooth muscle - walls of blood vessels and gut. Skeletal muscle - attached to bone and is voluntary. 1 of 16 What are myofibrils? Fibres of muscle. 2 of 16 What are the 2 types of protein fillaments in myofibrils? Actin and myosin. 3 of 16 What is the structure of actin? Thinner and consists of two strands twisted around each other. 4 of 16 What is the structure of myosin? Which is thicker and consists of long, rod shaped fibres with bulbed heads that project to the side. 5 of 16 Why do myofibrils appear striped? Because they have alternating light and dark coloured bands. 6 of 16 What are the light bands? Isotropic bands, they are lighter because the myosin and actin do not over lap here. 7 of 16 What are the dark bands? Anistotropic bands, dark coloured because the actin and myosin do overlap in this region. 8 of 16 What is the centre of the A band? The H-zone. 9 of 16 What is the Z line? At the centre of each isotropic band. 10 of 16 What is the sarcomere? The distance between adjacent z lines. 11 of 16 What happens to the sarcomere when a muscle contracts? The sarcomere shortens. 12 of 16 What are the two proteins found in muscle? Tropomyosin - forms fibrous strands around the actin filament. Troponin - a globular protein. 13 of 16 What are the two types of muscle fibre? Slow twitch fibres and fast twitch fibres. 14 of 16 What do slow twitch fibres do? Contrast slowly and provide less powerful contractions over a long period of time. They are important in endurance work e.g. long distance running. 15 of 16 What do fast twitch fibres do? contract rapidly and produce powerful contractions but only for a short period of time. 16 of 16
Comments
No comments have yet been made