Transcript muscle
Module 11: Human Health and Physiology II 11.2 Muscles and Movement 11.2.1 State the roles of bones, ligaments, muscles, tendons and nerves in human movement. Attached to bones for movement Also acts as source of blood cells/storage of minerals 11.2.2 Label a diagram of the human elbow joint, including cartilage, synovial fluid, joint capsule, named bones and antagonistic muscles (biceps and triceps). Joint capsule The elbow is a hinge joint that acts similarly to a door. (Also called a synovial joint) Antagonistic pair Scapula Arm flexed1. Biceps contracted (Thick and short) 2. Pull up Radius Arm extended1. Triceps contracted (Thick and short) 3. Triceps relaxed (Long and thin) 2. Pull down Ulna Radius Ulna Look at the video 3. Biceps relaxed (Long and thin) 11.2.3 Outline the functions of the structures in the human elbow joint named in 11.2.2. Joint Part Cartilage Synovial fluid Joint capsule Tendons Ligaments Biceps muscle Triceps muscle Humerus Radius Ulna Function 11.2.4 Compare the movements of the hip joint and the knee joint. Hinge Joint: Knee joint Ball and socket: Hip joint Both of these joints are also referred to as diarthrotic joints – joints that are freely movable 11.2.4 Compare the movements of the hip joint and the knee joint. Task: Complete the following table using page 294 for reference, Characteristic Hip joint Knee joint Diarthrotic? Yes Yes Type of movements Multiple angular motions Rotational Angular motion in one direction Possible movements Flexion, extension, abduction, adduction, circumduction, rotation Ball that fits into depression Flexion and extension Structure Convex surface fits into concave surface 11.2.4 Compare the movements of the hip joint and the knee joint. 11.2.5 Describe the structure of striated muscle fibres, including the myofibrils with light and dark bands, mitochondria, the sarcplasmic reticulum, nuclei and the sarcolemma. Striated (skeletal) muscle 1. Tendons 2. Muscle 3. Muscle bundle 4. Muscle fibre (cell) 4. Muscle cells are multi-nucleated and the plasma membrane is called the sarcolemma. Each cell is made up of multiple myofibrils. The sarcoplasmic reticulum is like the ER. 11.2.5 Describe the structure of striated muscle fibres, including the myofibrils with light and dark bands, mitochondria, the sarcplasmic reticulum, nuclei and the sarcolemma. Myofibril 4. Light band Sarcomeres are repeating units of movement that make up myofibrils (from Z line to Z line). It’s made up of myosin and actin filmaents Dark band 11.2.6 Draw and label a diagram to show the structure of a sarcomere, including Z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands. Myosin head 11.2.6 Draw and label a diagram to show the structure of a sarcomere, including Z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands. Task: Complete the following table by looking at the diagram Actin H zone A band I band M line Myosin What happens during muscle contraction? Sarcomere before and after: 11.2.7 Explain how skeletal muscle contracts, including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross-bridges, the sliding of actin and myosin filaments, and the use of ATP to break cross-bridges and re-set myosin heads. The Sliding Filament Theory of Muscle Contraction 1. Action potential arrives at the neuromuscular junction. Achetylcholine is released and binds to receptors on the sarcolemma. T tubules spread the action potential and the sarcoplasmic reticulum releases Ca2+ into the sarcoplasm troponin tropomyosin Rest myosin complex ADP Pi actin filament myosin filament At rest, the actin-myosin binding site is blocked by tropomyosin, held in place by troponin Myosin heads cannot bind to actin filaments Myosin is bound to ATP (ADP + Pi) troponin Ca2+ Ca2+ (from sarcoplasmic reticulum) binds to troponin, changing its shape As a result, tropomyosin is pulled out of the binding site and this exposes the myosin binding site on actin Ca2 + ADP Pi Ca2+ activates ATPase, breaking down ATP to ADP + Pi Myosin binds to actin to form crossbridge after the Pi is released Energy provided moves the myosin head forward, pulling acting filament along in what is known as the power stroke. The ADP is released in the process Free ATP binds to head, changing myosin back to its original shape Actin-myosin cross bridge breaks (site if occupied by ATP) The head returns to original shape With continued stimulation the cycle is repeated If stimulation ceases, Ca2+ is pumped back into sarcoplasmic reticulum Troponin and tropomyosin return to original positions Muscle fibre is relaxed Important points to note: The lengths of actin and myosin DO NOT change; they simply slide over each other The I band and H band disappear Myosin heads move towards the middle pulling actin towards the M line. 11.2.7 Explain how skeletal muscle contracts, including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross-bridges, the sliding of actin and myosin filaments, and the use of ATP to break cross-bridges and re-set myosin heads. Task 1: Using the link, complete the assessments and make any necessary additions to your notes: http://brookscole.cengage.com/chemistry_d/template s/student_resources/shared_resources/animations/m uscles/muscles.html Task 2: Arrange the key events of the sliding filament theory into the correct order 11.2.8 Analyse electron micrographs to find the state of contraction of muscle fibres. Which one is contracted and which one is relaxed? How do you know?