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Muscular and Skeletal System

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Presentation on theme: "Muscular and Skeletal System"— Presentation transcript:

1 Muscular and Skeletal System
Nestor T. Hilvano, M.D., M.P.H. (Images Copyright Discover Biology, 5th ed., Singh-Cundy and Cain, Textbook, 2012.)

2 Learning Objectives Explain how muscle and skeleton interact to cause movement. Describe the structure and arrangement of filaments in a muscle cell. Explain how a muscle cell contracts. Give the functions of skeletal system. Describe the 3 main types of skeletons and give examples of each. Distinguish between axial and appendicular skeletons in human. Describe the 3 main types of joints and provide examples of each. Describe the complex structure of a long bone.Explain why bones break and how we can help them heal.

3 Word stem endo- within hydro- water myo- muscle fibro- fiber
sarco- flesh mere- a part

4 Figure 31.7 Specialized Types of Muscles for Different Types of Movement
(a) Muscles associated with the skeleton have a banded, or striated, appearance. (b) Cardiac muscle is also banded, and its muscle fibers are branched. (c) Smooth muscle does not have bands.

5 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

6 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++

7 Sliding-Filament Model of Muscle Contraction
Fig Sarcomere 0.5 µm Z M Z Relaxed muscle Contracting muscle Fully contracted muscle Contracted Sarcomere 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 (Ca2+) bind to troponin, remove tropomyosin, active actin site open, myosin-actin slides. ATP needed.

8 Myosin-binding sites blocked
Figure 30.10B Myosin-binding sites blocked Tropomyosin Ca2-binding sites Actin Troponin complex Ca2 floods the cytoplasmic fluid Figure 30.10B Thin filament, showing the interactions among actin, regulatory proteins, and Ca2+ Myosin-binding sites exposed Myosin-binding site 8

9 Sarcomere Dark band Z Z Relaxed muscle Contracting muscle
Figure 30.9A Sarcomere Dark band Z Z Relaxed muscle Contracting muscle Figure 30.9A The sliding-filament model of muscle contraction Fully contracted muscle Contracted sarcomere 9

10 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

11 Functions of Skeletal System
Support Protection Movement Mineral storage Blood cell formation

12 Skeletal System: Subdivisions
I – Axial skeleton Skull Thoracic (rib) cage - sternum - rib - thoracic vertebrae c) Vertebral column II – Appendicular skeleton 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

13 Axial Skeleton Skull – cranial bones and facial bones: Thoracic cage:
cranial bones= Frontal (bone of forehead), parietal, temporal and occipital bones facial bones= Zygomatic bone (cheek bone); Nasal bone (bridge of nose); Maxillae (upper jaw), and Mandible (lower jaw) Thoracic cage: Sternum: manubrium, body, & xiphoid process Ribs (12 pairs): 1st to 7th pairs (true ribs), 8th to 10th ribs (false ribs), 11th to 12th pairs (floating ribs) Vertebrae – cervical (neck), thoracic (chest), lumbar & sacral (back), and coccyx (tail bone)

14 Appendicular Skeleton
Upper limbs and pectoral girdles - clavicle (collarbone) - scapula (shoulder blade) - humerus (arm) - radius* *(forearm) - ulna* - carpal (wrist), metacarpals (palm), phalanges (digits/fingers) Lower limbs and pelvic girdles - pelvis (os coxae)= hip bones - femur (thigh) - patella (knee cap) - tibia and fibula (leg) - tarsals, metatarsals, & phalanges (ankle, sole, & digits/toes)

15 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

16 Figure 31.4 Joints Combine Rigidity and Flexibility to Enable Movement
The human knee illustrates how rigidity and flexibility together enable movement. Fluid-containing synovial sacs are shown in purple; cartilage, in gray.

17 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)

18 Fracture Break in the continuity of bone. Bone healing by:
- immobilization - surgical intervention Replacement

19 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

20 Homework 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. Describe the structure of sarcomere (components). Discuss the mechanism of contraction of skeletal muscle (sliding theory of myofilaments). Compare and contrast the 3 types of muscles. Describe the movement of the following joints and give an example for each: ball and socket, hinge, pivot joints 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).

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