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Muscles, Protection, Support, and Movement

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  1. Muscles, Protection, Support, and Movement Tristan Beasley-Painter and Nicholas Ravn

  2. Structures to be Discussed • Bones • Muscles • Ligaments • Tendons • Joints • Nerves

  3. Bones

  4. Role of Bones • Provide a rigid structure to support body • Humans have an "endoskeleton" rather than an "exoskeleton" like arthropods; no molting needed • Protects vital internal organs • Skull protects brain, rib cage protects heart and lungs, vertebrae protect spinal cord • Provides sites for muscle attachment • An important storage reservoir for ions • All bones have a matrix of calcium phosphate • Produces blood cells • Blood cells and blood elements produced in red bone marrow in skull, ribs, sternum, pelvis, and long bones

  5. Bones (cont.) • Born with about 350 bones; fuse to form around 206 by adulthood

  6. Invertebrate Skeletons • Cnidarians, flatworms, roundworms, and annelids have a hydrostatic skeleton • Gastrovascular cavity or fluid-filled coelom • Resist muscle contraction, resulting in movement • Analogous to a garden hose stiffening when water flows through • Allows organism to move and change shape

  7. Invertebrate Skeletons (cont.) • Molluscs and arthropods typically have exoskeletons (external skeletons) • Composed of calcium carbonate (molluscs) or chitin (arthropods) • Provide protection and muscle attachment points like an internal skeleton • Strength improved through thickness • Decreases available space for internal organs • Exoskeleton of mollusc grows with organism • Arthropods must molt when exoskeleton becomes too small • Suffer a period when new one must dry and form

  8. Nonliving Exoskeletons • The exoskeletons of molluscs and arthropods are nonliving • Mollusc shells grow with the organism, but are still acellular • Grow through secretion of more material by organism • Arthropods have exoskeleton of chitin (a nitrogenous polysaccharide) • Produced and dried once; does not continue growing with organism • Arthropods must molt as a result

  9. Nonliving vs. Living Skeletons • Echinoderms and vertebrates have endoskeletons • Echinoderms' are nonliving • Composed of spicules and plates of calcium carbonate embedded in living tissue • Vertebrates' are living tissue • Offers many benefits • Grows with organism, molting not required • Supports high weight without limiting space • Protected by external soft tissue • Jointed, allowing complex movements

  10. Vertebrate Skeleton • Two components of the vertebrate skeleton: • Axial skeleton • Appendicular skeleton

  11. Axial Skeleton • Lies in middle of the body • Skull, vertebral column, thoracic cage, sacrum, coccyx • Total of 80 bones • Skull protects brain • Cranium and facial bones • Cranium bones have same names as lobes of the brain (for those psychology students out there) • Vertebral column supports head and trunk and protects the spinal cord • Directly or indirectly serves as an anchor for all other bones of the skeleton

  12. Axial Skeleton (cont.) • The thoracic vertebrae are those that are part of the thoracic cage (rib cage) • The sacrum and coccyx are at the end of the spine and attach to the pelvis

  13. Bone Growth/Remodeling • Bone consists of both living tissue and nonliving material • The living tissue includes blood vessels, nerves, collagen • Important to growth are osteoblasts (form bone) and osteoclasts (remove old bone) • Osteoclasts form in small concentrations to remove an area of the bone • Osteoblasts form next, laying down new bone material over months (affected by nutrition, age, etc.) • This process begins to slow around age 40, leading to more brittle bones • Deterioration of osteoblasts leads to osteoporisis

  14. Muscles

  15. Role of Muscles • Three types of muscle tissue in humans: • Smooth • Cardiac • Skeletal • Skeletal muscle (striated voluntary muscle) is probably of greatest obvious importance to most people • Important in maintaining posture • Provides support • Allows movement • Maintains homeostasis/body temperature • Contraction causes ATP breakdown and releases heat throughout the body

  16. Muscles (cont.) • Around 700 skeletal muscles • 40% of weight of average human

  17. Vertebrate Muscles' Macroscopic Functions and Physiology - Muscle cells are quite unique, resulting in them being called muscle fibers - They have the normal parts of a cell along with special components - Skeletal muscles are muscle fibers in bundles - “The sarcolemma, or plasma membrane, forms a T (transverse) system. The T tubules penetrate, or dip down, into the cell so that they come into contact (but do not fuse) with expanded portions of modified endoplasmic reticulum, called the sarcoplasmic reticulum.” - Store calcium ions - SR encases myofibrils - what contracts the muscle

  18. Macroscopic Physiology (cont.) - Myofibrils run along muscle fibers - Have light and dark bands called striations - Being why skeletal muscle appears striated - Contractile units called sarcomeres form these bands as a result of their protein placement - When muscles are relaxed, a sarcomere extends between two dark lines called Z lines - Two types of protein filaments - Thick myosin - Thin actin “The I band is light colored because it contains only actin filaments attached to a Z line. The dark regions of the A band contain overlapping actin and myosin filaments, and its H Zone has only myosin filaments”



  21. Macroscopic Physiology and Sliding Filament Model - Muscle contraction means that muscles have shortened - So, muscles can only pull and not push - Skeletal muscles must work in antagonistic pairs - For example, biceps contract to bend the arm in and triceps contract to straighten the arm out - One of the muscles in the pair must be relaxed to allow the other to shorten and result in pulling movement - “When a sarcomere shortens, the actin filaments slide past the myosin filaments and approach one another. The causes the I band to shorten and the H zone to nearly or completely disappear. The movement of actin filaments in relation to myosin filaments is called the sliding filament model.”

  22. How do Muscles Get Their Energy? • Myosin breaks down ATP • Makes bridges to pull actin toward sarcomere center • ATP provides energy for contraction • Muscle fibers contain myoglobin (stores oxygen) • cell respiration does not provide all needed ATP • rely on phosphocreatine (storage) • anaerobically regenerates ATP with: • creatine-P + ADP -> ATP + creatine • Occurs during sliding filaments • most efficient way for muscles

  23. How do Muscles Get Their Energy? (cont.) • When all creatine-P is expended, fermentation produces ATP sans oxygen • builds lactate • muscle ache and fatigue are the result • We do deep breathing after exercise to metabolize lactate and restores cells • We must "pay back"/"fix" the oxygen debt • The lactate goes to the liver • 20% broken down into CO2 and H2O • ATP gained from this converts remaining lactate to glucose

  24. So This Energy Process Means: • Regular exercise • Increases mitochondria for ATP process • Less fermentation reliance • Less lactate produced, less oxygen debt • Reduced fatigue: increased fitness/endurance

  25. Muscles can be Fast or Slow • Muscles are Fast Twitch or Slow Twitch • Slow Twitch Muscles (Type I) • More efficient with resperation • Densely packed with capillaries • Thus they become fatigued much slower • However they are considered weaker • They can effectively use fats and carbohydrates • Aerobic

  26. Muscles can be Fast or Slow • Fast Twitch Muscles (Type II) • Less efficient with resperation • Has less cappilaries • This explains its paler color • Stronger than slow twitch • Certain types are anaerobic, explaining why they tire quickly

  27. Smooth Cardiac and Striated Muscles Respond Differently • Skeletal muscles are voluntary • We can willingly control them • React through conscious impulses from the brain • Smooth muscles are involuntary • Automatically controlled by our medulla oblongata • Found in stomachs and bladders • Cardiac muscles are also involuntary • Controlled by medulla oblongata • Found only in the heart • Structured like that of a skeletal muscle • It is striated

  28. Look at Electron Micrographs Skeletal Muscles

  29. Look at Electron Micrographs Smooth Muscles

  30. Look at Electron Micrographs Cardiac Muscle

  31. Tendons

  32. Role of Tendons • Connects muscles to bones • Works in union with muscles • Without it, muscles would not have anything to grab onto

  33. Ligaments

  34. Role of Ligaments • Made of fibrous connective tissue • Extend across the cavity separating synovial joints (freely movable) • Bind the two bones of the joint together • Form a "joint capsule" around the joint • Lined by synovial membrane • Produces synovial fluid - lubricant for the joint

  35. Joints

  36. Role of Joints • Located where two bones make contact • Allows range of movement at key points in the body • Muscles control the direction of movement • Primarily classified in three groups • No mobility • Little mobility • Free movement

  37. Immovable Joints • Also called synarthrosis • Joined fibrous joints, there is almost no motionpermitted • Key example is the skull

  38. Slightly Movable Joints • Also known as amphiarthrosis • Permits a little movement,but not a large amount • Mostly cartiliginous • A cartilage plate protects the bones from grinding on each other • Primarily found in the vertebrae

  39. Freely Movable Joints • Also known as synovial joints • Permits a large amount of free movement • Protected by a synovial cavity • Provides a fluid that decreases friction • Can be strengthened by ligaments

  40. Human Elbow Outlined • Synovial Cavity • A space that isolates a packet from the rest of the body • Synovial Fluid • The liquid that inhabits said packet • Reduces friction • Joint Capsule • The lining of thesynovial cavity • Protects the space • Cartilage • Helps lube up an area

  41. Hip vs. Knee Joint Movement • Ball-and-socket (hip joint) • Hinge (knee, elbow, fingers) • More in-depth::

  42. Joint Diseases • Rheumatoid Arthritis • The body creates an inflammatory response against joints • Causes swelling of the synovium • Osteoarthritus • Caused by the loss of cartilage • The lack of a buffer causes the bones to grind on each other • Both lead to pain and discomfort, however they are nonfatal

  43. Skin

  44. Role of Skin • Also known as epithelium • It covers our entire body • In some invertebrates, the skin secretes a cuticle • an example being oysters • Epithelium can also secrete lubricants, which facilitate movement and gas exchange • Some vertebrates, such as reptiles, have strong epitheliums, scales, that act like armor • Bird’s feathers and mammal’s fur act as a way to insulate and maintain temperature

  45. Nerves

  46. Role of Nerves • Nerves are what control our muscles • Somatic nervous system control voluntary muscles • Autonomicnervoussystemcontrolsinvoluntarymuscles

  47. Bibliography • Biology, 10th edition. By Sylvia S. Mader. • •