musculoskeletal system

-nerve signals send an influx of Ca2+ into sarcoplasmic reticulum -Ca2+ binds to troponin that is bound to tropomyosin that sits over actin binding sites -myosin attaches to actin (myosin cross bridges form) -ATP is released and a power stroke pulls the actin -actin pulled past myosin -brings Z-lines together (sarcomere shortens) -ATP needed for each activation of myosin- it releases myosin from the actin binding site after power stroke

-mitochondria -skeletal muscles require a lot of ATP -energy is acquired from cellular respiration occurring in mitochondria

-Compact bone contains osteons whereas spongy bone does not/contains trabeculae -Spongy bone is porous whereas compact bone is denser -Spongy bone contains red marrow whereas compact bone does not

<p>Treat / manage the condition: -Can be treated by increasing calcium intake/vitamin D 1 -Appropriate weight bearing exercises to increase bone density 1 -Prevent condition (any one point from the following): -Adequate calcium and vitamin D -exercise -reduce smoking</p> Signup and view all the answers

<p>fibrous: -no movement -sutures in skull</p> <p>cartilaginous -slight movement -pubic symphysis, intervertebral discs</p> <p>synovial -freely moveable -ball and socket, hinge</p> Signup and view all the answers

<p>-Thin actin slides over thick myosin / myofilaments overlap -Myosin heads bond to actin/cross-bridges form -Myosin heads pull on actin filaments / power stroke occurs -Z lines move closer together -Sarcomere shortens</p> Signup and view all the answers

<p>-Muscle contraction is an active process -because energy is needed for the shortening of the muscle fibres / actin to slide over myosin</p> Signup and view all the answers

<p>-Pairs of muscles that work together -One is the prime mover, the other is the antagonist -Biceps &amp; triceps / hamstrings and quadriceps / etc</p> Signup and view all the answers

<p>-Stabilise the origin of the agonist (primary muscle responsible for movement) -Allowing one part of the body to perform a movement while another remains stable / fixed, so that the agonist can perform the function with greater precision/more efficiently</p> Signup and view all the answers

<p>-The biceps and triceps form an antagonistic muscle pair, meaning they work in opposition to each other. -The elbow joint is a synovial hinge joint. -A hinge joint allows movement in one plane, enabling the limb to open and close (flex and extend). -The bones involved are the humerus (upper arm) and the radius and ulna (lower arm). -Muscles contract, pulling on bones to create movement. -The muscle origin is attached to a fixed bone via tendons—biceps and triceps attach to the humerus and scapula near the shoulder joint. -The muscle insertion is attached to a moving bone via tendons—biceps and triceps connect to the radius and ulna at the elbow joint. -Synergistic muscles around the elbow stabilize the joint during flexion (bending) and extension (straightening).</p> <p>FLEXION: decrease angle btwn articulating bones / bring lower limb closer to the upper</p> <ol> <li>Biceps contracts 2.Biceps pulls on TENDON attached to radius 3.Lower arm moves UPWARDS</li> </ol> <p>EXTENSION: increase angle btwn articulating bones / move lower limb away from upper -triceps contract -triceps pull on tendon attached to lower arm (ulna) -lower arm moves DOWNWARDS</p> Signup and view all the answers

<p>-Myocytes (muscle cells or muscle fibers) are specialized cells designed to contract when stimulated. -Muscle fibers contain myofibrils, which are made of proteins. -Myofibrils consist of myofilaments. -The thick myofilament is made of myosin. -The thin myofilament is made of actin. -The arrangement of actin and myosin creates the striated appearance of muscle cells. -Myofibrils are divided into functional units called sarcomeres, which are responsible for muscle contraction. -The A band represents the length of the myosin filaments (appears as a dark band). -The I band is the region containing only actin, located between the ends of myosin in adjacent sarcomeres (appears as a light band, crossing the Z line). -H-zone: The area between the ends of the actin filaments within a sarcomere. -Z-line: The point where actin filaments from adjacent sarcomeres connect. -M-line: The structure that holds the myosin filaments together at the center of the sarcomere.</p> Signup and view all the answers

<p>A nerve signal from the brain triggers the release of calcium ions into the muscle cell.</p> <p>Actin binding sites are exposed to myosin as calcium ions cause troponin to shift tropomyosin, revealing the binding sites.</p> <p>ATP is required to prepare the myosin heads for binding to actin.</p> <p>Myosin heads bind to actin, initiating muscle contraction.</p> <p>Cross-bridges form between the thick myosin and thin actin filaments.</p> <p>The myosin heads pull on the actin filaments, releasing ADP and P during this movement.</p> <p>This pulling action is called a power stroke.</p> <p>A new ATP molecule is needed to release the myosin from actin and reset the cycle.</p> <p>The thin actin filaments slide over the thick myosin filaments; the myosin remains stationary while actin moves.</p> <p>This sliding causes the H-zone and I-bands to shorten, and the Z-lines move closer together.</p> <p>When the Z-lines are closest together, the muscle is in its fully contracted state.</p> <p>The shortening of the sarcomeres leads to the shortening of the muscle fiber.</p> <p>A new signal to relax prevents calcium from being released, and troponin and tropomyosin cover the actin binding sites again.</p> <p>Without calcium, myosin can no longer bind to actin, stopping the pulling motion, and the myofilaments return to their relaxed positions.</p> <p>This cycle gives muscle cells their properties of elasticity, extensibility, and contractility.</p> Signup and view all the answers

<p>Trabeculae form the structure of spongy bone, while osteons make up compact bone.</p> <p>Spongy bone is less dense, porous, and more flexible, whereas compact bone is dense and solid.</p> <p>Spongy bone contains red bone marrow, while compact bone holds yellow bone marrow.</p> <p>Spongy bone is found in the epiphysis (ends of bones), while compact bone is present in both the diaphysis (shaft) and epiphysis.</p> <p>Spongy bone has an irregular and branched arrangement of trabeculae.</p> <p>Trabeculae are branches of bony matrix layers (lamellae), with spaces between them for blood vessels, nerves, marrow, and lymph.</p> <p>Compact bone has a uniform arrangement of osteons and canals that run parallel to the long axis of the bone.</p> <p>Compact bone features a central canal surrounded by concentric rings of bony matrix, known as lamellae.</p> Signup and view all the answers

<p>Shape of the articular surface/bones: Allows bones to fit together smoothly without rubbing against each other.</p> <p>Ligaments: Connect bones to other bones and restrict excessive movement to stabilize the joint.</p> <p>Joint capsule/fibrous capsule: Surrounds and supports the joint, enclosing it and lining the inside with a synovial membrane that produces fluid for lubrication.</p> <p>Meniscus/fibrocartilage: Improves the fit between adjacent bones, providing additional stability and cushioning within the joint.</p> Signup and view all the answers

<p>Similarity</p> <ol> <li>Both contract and relax</li> <li>Both are involuntary</li> <li>Both have single nuclei per cell / uni-nucleated</li> </ol> <p>Differences</p> <ol> <li>Cardiac muscle is striated, whereas smooth muscle is not striated</li> <li>Cardiac muscle is myogenic (it can contract without any input from the nervous system) whereas smooth muscle is not myogenic</li> <li>Cardiac muscle has long, branching cells, whereas smooth muscle are thin, spindle-shaped cells</li> <li>Cardiac muscle is found in the heart, whereas smooth muscle is found in blood vessels/ wall of digestive system</li> <li>Cardiac muscle has intercalated discs, smooth muscle does not</li> <li>Cardiac muscle contracts quickly, smooth muscle contracts slowly</li> </ol> Signup and view all the answers