Chapter 10.1 – Movement and Muscle Tissue

1. Chapter 10.1 – Movement and Muscle Tissue (pages 332-342)

2. Muscle tissue converts chemicalEkineticE • Three types of muscle tissue: • skeletal • smooth • cardiac

3. Smooth Muscle: • Cells: • long and tapered • one nucleus • arranged in parallel lines forming sheets • found in: walls of vessels, iris, along GI tract • involuntary contraction • slow to contract; do not fatigue easily

4. Cardiac muscle: • walls of the heart • Cells: • tubularandstriated • one nucleus • branched, “net-like” structure • involuntary contraction

5. Skeletal muscle: • Cells: • tubular and striated • multiple nuclei • voluntary contraction • organized cells are called fibres

6. Functions of skeletal muscles: • supports the body – contraction of skeletal muscle opposes the force of gravity, enabling us to stand and remain upright. • makes the bones move – accounts for the movement of the arms, legs, eyes and breathing.

7. helps maintain constant body temperature – muscle contraction released energy form ATP, releasing heat. • help protect internal organs and stabilize the joints – muscles pad the bones that protect the organs. Tendons hold the bones together at the joints.

8. What to do: summarize the information from the three muscle types in the table below:

9. The Cooperation of Skeletal Muscles • Muscles shorten with contraction • Muscles can only pull; they cannot push • Work is done during a contraction • Passive state during relaxation • Muscles are present in pairs (ie. bicep and tricep) • For the action of each muscle, there is another muscle that has the oppositeaction

10. The Structure of Skeletal Muscles • Muscle in the body lies along the length of abone • Tendons are tough, heavy bands of tissue • Tendons attach ends of muscle to a different bone • Muscle fibres can be up to 20 cm long • Muscle fibres are organized into largerbundles

11. A muscle consist of clustersof large fibre bundles • Connective tissue wraps around each fibre, bundle, and entire muscle • Blood vessels and nerves run between bundles • Nerves trigger and control muscle contractions

16. Chapter 10.1 – Movement and Muscle Tissue (pages 332-342)

18. The Mechanism of Muscle Fibre Contraction • Muscle fibre contains two types of myofilament: • Actinmyofilament • Myosin myofilament

19. Actinmyofilament • two strands of protein wrapped around each other • Like two strands of beads

20. Myosin myofilament: • two strands of protein wrapped around each other • one end consists of long rod • one end consists of double head

21. Contraction • Headsof the myosin move, like flexing your hand towards your wrist • Myosin heads are chemically bonded to actin filament and move it along • ATP used to re-position myosin head to flex again • Myosin head bonds to actin farther down actin filament • Actin filament is “walked along” in the direction of the flex

23. The Sliding Filament Model • One end of the actin myofilament is anchoredat the Z line • Movement of the actin along the myosin pullsthe “anchor” with it • Z lines on opposite ends of the myosin filament are pulled towards each other • Results in a shorteningof the muscle fibre (contraction)

26. The Role of Calcium Ions in Contraction Calcium and Muscle Contraction • Ca2+pumped into microfibrils when contraction nerve impulse is signaled • High concentrations of Ca2+ required to expose binding site between actin and myosin • ATP is used in the process • Ca2+pumped out when the nerve signal stops; the binding site no is longer accessible

28. 1. Measurements show that the distance between the two Z lines varies between 1.5 µm and 3.0 µm. How do these measurements relate to the sliding filament model as shown above? The distance between the Z lines is 3.0 µm at rest and 1.5 µm when contracted.

29. 2. Use the diagram to explain why there is a limit to how much a muscle can shorten as it contracts. a muscle contracts, the Z lines are pulled closer to the ends of the myosin filaments. When the Z line bumps into the myosin, further shortening of the muscle is impossible.

30. 3. As ATP is spent in causing the myofilaments to slide, some of its energy is released as “wasted” heat. In what way is this heat wasted? In what way is it useful to muscle contraction? The heat from ATP breakdown is wasted in the sense that it does not power the reactions between actin and myosin as chemical energy does. However, the heat is useful in warming the muscle, reducing the friction between the myofilaments and increasing the force exerted by the entire muscle as it warms up.

31. Energy for Muscle Contraction • ATP reserves are used up very fast during strenuous activity • Muscles may acquire ATP three ways: • breakdown of creatine phosphate (anaerobic process) • aerobic cellular respiration • fermentation (anaerobic process)

32. Creatine Phosphate Breakdown • creatine phosphate: • high energy molecule • used to regenerate ATP from ADP • occurs in the sliding filaments • fastest way to make ATP for muscles • provides enough energy for 8 seconds of intense activity • rebuilt while muscle is resting

34. Aerobic Cellular Respiration • Takes place in the mitochondria • provides mostof the ATP to the muscle • heat produced helps to warm the entire body

35. Fermentation • aerobic process • accumulation of lactic acid • prolonged fermentation causes cramping and fatigue

36. Chapter 10.2 – Muscles, Health and Homeostasis (pages 344-349)

37. Even when muscles appear to be at rest, some of their fibres are always contracting. Continuous “low-level” activity results in muscle tone Why do astronauts on the ISS have to develop a daily workout routine?

38. Complications of the Muscle System Muscles are especially vulnerable to injuries that result from sudden and intense stress placed on them and on tendons.

40. Atrophy: reduction in size, tone, and power of muscle Temporary reduction in muscle use may lead to atrophy Atrophy is temporarily reversible Extreme atrophy results in permanent loss of function

41. Hypertrophy: exercise induced increase in muscle mass Due to increase in the size of the muscle fibres Regular exercise allows muscles to use energy more efficiently Enzymes become more active and mitochondria more numerous Muscles develop additional blood vessels and can store more glycogen

42. Muscle Twitch • muscle twitch:the action of a single contraction • Slow twitch fibres: • contract slowly • resist fatigue • produce most of their energy aerobically • tire only when fuel supply is gone • have many mitochondria • dark in color due to myoglobin(respiratory pigment) • surrounded by dense capillary beds • have a reserve of glycogen and fat

43. Fast-twitch fibres: • adapted for rapid generation of power • fibres are rich in glycogen • light in color due to little or no myoglobin • fewer mitochondria • fewer blood vessels • produce power from anaerobic cellular respiration • accumulation of lactate causes fibres to fatigue quickly

44. Predict which muscle contains slow and fast twitch fibres.