Muscles, Protection, Support, and Movement Tristan Beasley-Painter and Nicholas Ravn Structures to be Discussed •Bones •Muscles •Ligaments •Tendons •Joints •Nerves Bones Role of Bones •Provide a rigid structure to support body oHumans have an "endoskeleton" rather than an "exoskeleton" like arthropods; no molting needed Protects vital internal organs oSkull protects brain, rib cage protects heart and lungs, vertebrae protect spinal cord Provides sites for muscle attachment An important storage reservoir for ions oAll bones have a matrix of calcium phosphate Produces blood cells oBlood cells and blood elements produced in red bone marrow in skull, ribs, sternum, pelvis, and long bones • • • • Bones (cont.) •Born with about 350 bones; fuse to form around 206 by adulthood http://www.teach pe.com/images/ anatomy/skeleto n.jpg Invertebrate Skeletons •Cnidarians, flatworms, roundworms, and annelids have a hydrostatic skeleton oGastrovascular 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 http://www.emc.maric opa.edu/faculty/farab ee/biobk/hydroskel2. gif Invertebrate Skeletons (cont.) •Molluscs and arthropods typically have exoskeletons (external skeletons) oComposed of calcium carbonate (molluscs) or chitin (arthropods) Provide protection and muscle attachment points like an internal skeleton Strength improved through thickness oDecreases available space for internal organs Exoskeleton of mollusc grows with organism Arthropods must molt when exoskeleton becomes too small oSuffer a period when new one must dry and form • • • • Nonliving Exoskeletons •The exoskeletons of molluscs and arthropods are nonliving oMollusc 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) oProduced and dried once; does not continue growing with organism Arthropods must molt as a result • Nonliving vs. Living Skeletons •Echinoderms and vertebrates have endoskeletons •Echinoderms' are nonliving oComposed of spicules and plates of calcium carbonate embedded in living tissue •Vertebrates' are living tissue oOffers many benefits Grows with organism, molting not required Supports high weight without limiting space Protected by external soft tissue Jointed, allowing complex movements Vertebrate Skeleton •Two components of the vertebrate skeleton: oAxial skeleton oAppendicular skeleton http://upload.wikimedia.org/wikipedia/commons/ thumb/8/8b/Axial_skeleton_diagram.svg/250pxAxial_skeleton_diagram.svg.png http://en.wikipedia.org/wi ki/File:Appendicular_ske leton_diagram.svg Axial Skeleton •Lies in middle of the body oSkull, vertebral column, Total of 80 bones thoracic cage, sacrum, coccyx •Skull protects brain oCranium 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 oDirectly or indirectly serves as an anchor for all other bones of the skeleton • 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 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) oOsteoclasts form in small concentrations to remove an area of the bone oOsteoblasts 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 Muscles Role of Muscles •Three types of muscle tissue in humans: oSmooth oCardiac oSkeletal •Skeletal muscle (striated voluntary muscle) is probably of greatest obvious importance to most people oImportant in maintaining posture oProvides support oAllows movement oMaintains homeostasis/body temperature Contraction causes ATP breakdown and releases heat throughout the body Muscles (cont.) •Around 700 skeletal muscles •40% of weight of average human http://en.wikipedia.org/wiki/Mu scle 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 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” http://www.ucl.ac.uk/~sjjgsca/Muscleslidingfilament1.gif http://www.ucl.ac.uk/~sjjgsca/MuscleSarcomere.gif 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.” How do Muscles Get Their Energy? • • Myosin breaks down ATP o Makes bridges to pull actin toward sarcomere center ATP provides energy for contraction o Muscle fibers contain myoglobin (stores oxygen) cell respiration does not provide all needed ATP rely on phosphocreatine (storage) o anaerobically regenerates ATP with: creatine-P + ADP -> ATP + creatine Occurs during sliding filaments o most efficient way for muscles • • How do Muscles Get Their Energy? (cont.) • • When all creatine-P is expended, fermentation produces ATP sans oxygen o builds lactate muscle ache and fatigue are the result We do deep breathing after exercise to metabolize lactate and restores cells o We must "pay back"/"fix" the oxygen debt o The lactate goes to the liver 20% broken down into CO2 and H2O ATP gained from this converts remaining lactate to glucose • So This Energy Process Means: • Regular exercise o Increases mitochondria for ATP process Less fermentation reliance Less lactate produced, less oxygen debt o Reduced fatigue: increased fitness/endurance • Muscles can be Fast or Slow • • Muscles are Fast Twitch or Slow Twitch Slow Twitch Muscles (Type I) o More efficient with resperation Densely packed with capillaries o Thus they become fatigued much slower However they are considered weaker o They can effectively use fats and carbohydrates Aerobic Muscles can be Fast or Slow • • Fast Twitch Muscles (Type II) o Less efficient with resperation o Has less cappilaries This explains its paler color o Stronger than slow twitch o Certain types are anaerobic, explaining why they tire quickly Smooth Cardiac and Striated Muscles Respond Differently • • • Skeletal muscles are voluntary o We can willingly control them o React through conscious impulses from the brain Smooth muscles are involuntary o Automatically controlled by our medulla oblongata o Found in stomachs and bladders Cardiac muscles are also involuntary o Controlled by medulla oblongata o Found only in the heart o Structured like that of a skeletal muscle It is striated Look at Electron Micrographs Skeletal Muscles Look at Electron Micrographs Smooth Muscles Look at Electron Micrographs Cardiac Muscle Tendons Role of Tendons • • Connects muscles to bones o Works in union with muscles Without it, muscles would not have anything to grab onto Ligaments Role of Ligaments •Made of fibrous connective tissue •Extend across the cavity separating synovial joints (freely movable) oBind the two bones of the joint together •Form a "joint capsule" around the joint oLined by synovial membrane Produces synovial fluid - lubricant for the joint Joints Role of Joints • Located where two bones make contact • Allows range of movement at key points in the body o Muscles control the direction of movement • Primarily classified in three groups o No mobility o Little mobility o Free movement Immovable Joints • • • Also called synarthrosis Joined fibrous joints, there is almost no motion permitted Key example is the skull Slightly Movable Joints • Also known as amphiarthrosis • Permits a little movement, but not a large amount • Mostly cartiliginous o A cartilage plate protects the bones from grinding on each other • Primarily found in the vertebrae Freely Movable Joints • Also known as synovial joints • Permits a large amount of free movement • Protected by a synovial cavity o Provides a fluid that decreases friction • Can be strengthened by ligaments Human Elbow Outlined • • • • Synovial Cavity o A space that isolates a packet from the rest of the body Synovial Fluid o The liquid that inhabits said packet o Reduces friction Joint Capsule o The lining of the synovial cavity o Protects the space Cartilage o Helps lube up an area Hip vs. Knee Joint Movement http://www.youtube.com/watch?v=w4LSWmJnniw • Ball-and-socket (hip joint) • Hinge (knee, elbow, fingers) • More in-depth:: http://www.youtube.com/watch?v=ZWcdMj8wRos Joint Diseases • • • Rheumatoid Arthritis o The body creates an inflammatory response against joints o Causes swelling of the synovium Osteoarthritus o Caused by the loss of cartilage o The lack of a buffer causes the bones to grind on each other Both lead to pain and discomfort, however they are nonfatal Skin 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 Nerves Role of Nerves • Nerves are what control our muscles • Somatic nervous system control voluntary muscles • Autonomic nervous system controls involuntary muscles Bibliography •Biology, 10th edition. By Sylvia S. Mader. •http://www.classbrain.com/artaskcb/publish/article_145.shtml •http://www.nsbri.org/humanphysspace/focus6/ep_development.html