Topic 11.2 Movement

Understanding: Bones & exoskeletons provide anchorage for muscles & act as levers Exoskeleton = external skeleton that surrounds & protects crustaceans & insects Levers change the size & direction of forces Muscles are attached to insides of exoskeletons Muscles are attached to outside of bones

Exoskeletons

Levers in the human body

Understanding: Movement of the body requires muscles to work in antagonistic pairs. Antagonistic = opposite movements When one contracts, the other relaxes Why? Because muscles can only pull, they don’t push Example? biceps brachii – flexes forearm Triceps brachii – extends forearm

Application: Antagonistic pairs of muscles in an insect leg.

Skill: Annotation of a diagram of the human elbow Joint = point where bones meet Articulation = a movable joint Most articulated joints have cartilage, synovial fluid & joint capsule Cartilage Structure = tough, smooth tissue covering ends of bone Function = reduces friction between bones & absorbs shocks Synovial fluid Structure = fluid that fills cavity in joint between cartilages Function = lubricates joint; prevents friction Joint capsule Structure =tough, ligamentous covering of joint Function = prevents dislocation

Label a diagram of the human elbow joint, including cartilage, synovial fluid, joint capsule, named bones and antagonistic muscles (biceps and triceps)

Understanding: Synovial joints allow certain movements but not others Similarities Differences Both are synovial joints Both are involved in the movement of the leg

Understanding: Skeletal muscle fibres are multinucleate and contain specialized endoplasmic reticulum.

Fascicle vs Fiber

Understandings: Muscle fibres contain many myofibrils Understandings: Muscle fibres contain many myofibrils. Each myofibril is made up of contractile sarcomeres.

Skill: Draw a labelled diagram of the structure of a sarcomere.

Understanding: The contraction of the skeletal muscle is achieved by the sliding of actin and myosin filaments. Animation: https://www.youtube.com/watch?v=RmQzIS9IGUE

Skill: Analysis of electron micrographs to find the state of contraction of muscle fibres. Which one is contracted?

Understanding: Calcium ions and the proteins tropomyosin and troponin control muscle contractions Animation: http://www.sci.sdsu.edu/movies/actin_myosin.html

Understanding: ATP hydrolysis and cross-bridge formation are necessary for the filaments to slide

Nature of Science: Fluorescence has been used to study the cyclic interactions in muscle contraction Fluorescence = absorbing light of shorter wavelength (Xray, UV) and then emitting light of longer wavelength (visible light) Researchers injected aequorin protein into acorn barnacle giant muscle fiber Researchers attached fluorescent dye to myosin to show it “walking along” actin Demonstrated the dependency of ATP on myosin detachment from actin