Topic 11 – Human health & physiology

1. Topic 11 – Human health & physiology 11.2 – Muscles and Movement

2. Rheumatology – branch of medicine devoted to joint diseases and conditions. • Joints provide mobility and hold the body together. • Joints include: bones, ligaments, muscles, tendons, and nerves. JOINTS

3. joints http://www.youtube.com/watch?v=SOMFX_83sqk

4. Bones are composed of many different tissues, considered organs. • Function • Framework for support • Protect soft tissues • Levers for movement • Bone marrow  blood cells • Storage of minerals Bones

5. Muscles Tendons Attach muscles to bone. Cords of dense connective tissue. • Provide force for movement to occur. • Antagonistic pairs – constriction then release for return to original position. For movement to occur, it is essential that skeletal muscles are attached to bones.

6. Ligaments Nerves Help to prevent over-extension of the joint and its parts. • Tough, band-like structures that serve to strengthen the joint. Ligaments have many different types of sensory nerve endings to monitor positions of joint parts

8. Include: cartilage, synovial fluid, joint capsule, named bones and antagonistic muscles (biceps and triceps). Label a diagram of the human elbow http://sambal.co.uk/?page_id=238

9. The elbow joint involves the humerus, radius and ulna bones. The synovial fluid is present within the synovial cavity. This cavity is located within the joint capsule. The joint capsule is composed of dense connective tissue that is continuous with the membrane of the involved bones. The parts of the elbow

10. Provides an opening-and-closing type of movement (imagine hinges on a door). • The knee is a similar joint. • Freely movable joints. • Freely movable – diarthrotic joints. The elbow is a hinge joint

12. Notice that the Tibia and Femur do not actually make contact. • Although the knee is a hinge joint it also allows for some pivotal movement. The knee

13. Ball-and-socket joint (allow the greatest degree of movement) • Head of femur (thigh bone) fits into cup-like depression of the hip bone called the acetabulum. The hip

14. Hip Joint Knee Joint Freely movable Angular motion in one direction Motions possible are flexion and extension Convex surface fits into a concave surface • Freely movable • Motion in many directions and rotational movements • Motions possible are flexion, extension, abduction, adduction, circumduction and rotation • Ball-like structure fits into a cup-like depression Comparison: Knee to Hip

15. Flexion = decrease in angle between connecting bones • Extension = increase in angle between connecting bones • Abduction = movement of bone away from body midline • Adduction = movement of bone toward midline • Circumduction = distal or far end of a limb moves in a circle • Rotation = a bone revolves around its own longitudinal axis http://www.midsouthorthopedics.com/education.html definitions

16. 3 types: skeletal (striated), cardiac, and smooth (non-striated) • Striated muscle – skeletal muscle (involved in skeletal movement) muscle

17. Muscles made up of cells • Cellular arrangement produces banded appearance • Muscle cell elongated shape = muscle fibers • Contain multiple nuclei • Membrane of muscle cells called sarcolemma • Cytoplasm of muscle fibers called sarcoplasm Striated muscle cells

18. Sarcoplasmic reticulum is a fluid-filled system of membranous sacs surrounding muscle myofibrils (much like smooth ER) • Myofibrils – rod-shaped bodies that run the length of the cell • Many myofibrils running parallel to each other • Numerous mitochondria squeezed in between • Contractile elements of muscle cells • Reason for striation More muscle cell structure

19. Made up of sarcomeres (units that allow movement) • Z lines mark ends of sarcomere • A bands (both myosin and actin) = dark • H bands (only myosin) = light in middle of A bands Myofibril structure

20. Support protein in middle of myosin produces the M line (holds myosin filaments together) • I bands (contain only actin) = light color • Two types of filaments (myofilaments) cause banded appearance of muscle fiber • Composed of two contractile proteins Sarcomere structure

21. Actin Myosin Thick filaments (16 nm in diameter) Contains myosin heads that have actin-binding sites Individual molecules form a common shaft-like region with outward protruding heads Heads are referred to as cross-bridges and contain ATP-binding sites and ATPase enzymes • Thin filaments (8nm in diameter) • Contains myosin-binding sites • Individual molecules form helical structures • Includes two regulatory proteins, tropomyosin and troponin Two contractile proteins

22. Muscle contract when actin myofilaments slide over myosin myofilaments. • The myofilaments do not actually shorten. • When the actin component slides over the myosin, the sarcomere is shortened. • With multiple fibers and sarcomeres in a muscle working together, this causes the movements necessary for the organism. Muscle contraction and the sliding filament theory

23. Action potential reaches neuromuscular junction Neurotransmitter (acetylcholine) into gap between axon terminal and sarcolemma Acetylcholine binds to receptors on the sarcolemma Sarcolemma ion channels open and sodium ions move through the membrane This generates a muscle action potential Key events of muscle contraction

24. Muscle AP moves along membrane and through T tubules • Acetylcholinesterase ensures one directional AP propagation • Muscle AP releases calcium ions from sarcoplasmic reticulum (Caions flood sarcoplasm) • Ca ions bind to troponin on actin myofilaments exposing myosin-binding sites • Myosin heads include ATPase (releases energy from ATP) • Myosin heads bind to myosin-binding sites on the actin with help of protein tropomyosin Muscle contraction cont…

25. The myosin-actin cross-bridges rotate toward the center of the sarcomere. This produces the power or working stroke • ATP binds to myosin head resulting in detachment of myosin from actin • No more AP = fall of Ca ions in sarcoplasm; troponin-tropomyosincomplex returns to original position blocking myosin-binding sites; muscle relaxes More muscle contraction

28. Bacteria Clostridium botulinum • Blocks release of acetylcholine and prevents muscle contraction • Can affect diaphragm so breathing stops and death may occur • Active ingredient in Botox • Typically used to relax the muscles that cause facial wrinkles Little extra - Botox

29. Little more extra When a person dies calcium ions leak and bind to troponin ATP production has stopped and the actin slides causing rigor mortis (rigidity of death) Lasts for ~24 hours until further muscle deterioration occurs Any questions?