Presentation on theme: "Muscular and Skeletal System Nestor T. Hilvano, M.D., M.P.H. (Images Copyright Discover Biology, 5 th ed., Singh-Cundy and Cain, Textbook, 2012.)"— Presentation transcript:
Muscular and Skeletal System Nestor T. Hilvano, M.D., M.P.H. (Images Copyright Discover Biology, 5 th ed., Singh-Cundy and Cain, Textbook, 2012.)
Learning Objectives 1.Explain how muscle and skeleton interact to cause movement. 2.Describe the structure and arrangement of filaments in a muscle cell. 3.Explain how a muscle cell contracts. 4.Give the functions of skeletal system. 5.Describe the 3 main types of skeletons and give examples of each. 6.Distinguish between axial and appendicular skeletons in human. 7.Describe the 3 main types of joints and provide examples of each. 8.Describe the complex structure of a long bone.Explain why bones break and how we can help them heal.
Word stem endo- within hydro- water myo- muscle fibro- fiber sarco- flesh mere- a part
Introduction: Muscle Contraction Movement is a fundamental characteristic Muscle Cells capable of shortening (it pull) Converting the chemical energy of ATP into mechanical energy Skeleton provides a rigid structure to which muscles attach Movements require antagonistic pair of muscles
The structure of Skeletal Muscle Skeletal muscle cell (fiber) is composed of myofibrils (fibrils) Each fibril consists of myofilaments Myofilaments of contractile proteins= actin (thin) filaments and myosin (thick) filaments Troponin (binds w/ Ca++), tropomyosin (covers active site of actin) = regulatory proteins Sarcomere – is a functional unit, bordered by Z lines (discs); A band (dark), I band (pale), H band (zone), M line, Sarcoplasmic reticulum – releases Ca++
Fig Z Relaxed muscle M Z Fully contracted muscle Contracting muscle Sarcomere 0.5 µm Contracted Sarcomere Sliding-Filament Model of Muscle Contraction Myosin-binding sites on the thin filament are blocked by the regulatory protein tropomyosin at rest; For a muscle fiber to contract, myosin-binding sites must be uncovered when calcium ions (Ca 2+ ) bind to troponin, remove tropomyosin, active actin site open, myosin-actin slides. ATP needed.
Figure 30.10B Myosin-binding sites blocked Myosin-binding sites exposed Myosin-binding site Ca 2 floods the cytoplasmic fluid Actin Tropomyosin Ca 2 -binding sites Troponin complex
Figure 30.9A Relaxed muscle Contracting muscle Fully contracted muscle Dark band Sarcomere Contracted sarcomere ZZ
Motor Neuron, Motor Unit, and NMJ Motor neuron stimulates muscle contraction Motor unit – consists of a motor neuron and all the muscle fibers it controls. Neuromuscular junction – a region between motor nerve fiber and muscle fiber. Action potential is transmitted to the fiber
Functions of Skeletal System Support Protection Movement Mineral storage Blood cell formation
Skeletal System: Subdivisions I – Axial skeleton a)Skull b)Thoracic (rib) cage - sternum - rib - thoracic vertebrae c) Vertebral column II – Appendicular skeleton a)Upper limbs and pectoral (shoulder) girdle b) Lower limbs and pelvic (hip) girdle Exercises: What subdivision of skeletal system provides movements? Protects vital organs (brain, heart, lungs)? a. Axial skeleton b. Appendicular skeleton
Axial Skeleton Skull – cranial bones and facial bones: a)cranial bones= Frontal (bone of forehead), parietal, temporal and occipital bones b)facial bones= Zygomatic bone (cheek bone); Nasal bone (bridge of nose); Maxillae (upper jaw), and Mandible (lower jaw) Thoracic cage: a)Sternum: manubrium, body, & xiphoid process b)Ribs (12 pairs): 1 st to 7 th pairs (true ribs), 8 th to 10 th ribs (false ribs), 11 th to 12 th pairs (floating ribs) Vertebrae – cervical (neck), thoracic (chest), lumbar & sacral (back), and coccyx (tail bone)
Joints Bones meet together; lever for movement Ball and socket joints – allow movement in all directions; ex. Shoulder joint, hip joint Hinge joints – movement in single plane; ex. Elbow joint, knee joint Pivot joints – rotate (spin) in its longitudinal axis; ex. Radio-ulnar joint
Structure of Long Bone Diaphysis – shaft/middle part; compact bone covered by periosteum; medullary cavity with yellow BM Epiphysis - ends of long bone; outer layer of compact bone and inner layer of spongy bone (red BM) Articular cartilage on joint surface Bone is composed of collagen proteins and calcium phosphates Growth of long bone occurs at epiphysis (epiphyseal plate of cartilage) Osteocytes (mature bone cells) Osteoblasts (bone forming cells) Osteoclasts (bone destroying cells)
Fracture Break in the continuity of bone. Bone healing by: - immobilization - surgical intervention Replacement
Osteoporosis Softening of bone Factors – changes in diet, lack of weight bearing exercise, lifestyle habits (smoking) and diseases (DM) Treatment – calcium, vitamin D, and drug therapy
Homework 1.Define terms: motor neuron, motor unit, neuromuscular junction, sarcoplasmic reticulum, actin filament, myosin filament, troponin, tropomyosin, axial skeleton, appendicular skeleton, joint, fracture, osteoporosis, diaphysis, epiphysis, tendon, osteocyte, osteoblast, and ligament. 2.Describe the structure of sarcomere (components). 3.Discuss the mechanism of contraction of skeletal muscle (sliding theory of myofilaments). 4.Compare and contrast the 3 types of muscles. 5.Describe the movement of the following joints and give an example for each: ball and socket, hinge, pivot joints 6.Identify the bones of human skeleton as described: bone of forehead, bone that protects the brain, cheek bone, upper jaw, lower jaw, breast bone, shoulder blade, collar bone, bone of the arm, bones of the forearm, wrist bones, bones of the palm, hipbone, knee cap, thigh bone, leg bones, ankle bones, bones of digits (fingers and toes).