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2. Immagini e concetti della biologia Sylvia S. Mader
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

3. C4 - Skeletal and muscular system
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

4. Skeletal system Functions: Movement and scaffolding
Protects internal organs
Assists breathing
Stores and releases calcium
Assists lymphatic and immune systems
Helps digestion
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

5. Types of skeletal system in animals
Hydrostatic: fluid-filled body cavity surrounded by muscles (i.e. annelids and nematodes).
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

6. Types of skeletal system in animals
Exoskeletons: rigid external skeleton to which muscles attach (i.e. mollusks and arthropods).
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

7. Types of skeletal system in animals
Endoskeletons: rigid internal skeleton protected by soft tissue surrounding it (in vertebrates the endoskeleton is jointed).
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

8. Axial skeleton
The axial skeleton consists of the skull, vertebral column and rib cage.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

9. Axial skeleton - the skull
Cranium and facial bones of the skull protect the brain.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

10. Axial skeleton - the vertebral column
The vertebral column is composed of vertebrae separated by shock-absorbing discs. It protects spinal cord and nerves and anchors all other bones.
Intervertebral discs allow movement of the vertebrae. 10
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

11. Axial skeleton - the rib cage
The rib cage is composed by 24 ribs, costal cartilage and sternum and protects heart and lungs.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

12. Appendicular skeleton
The appendicular skeleton is composed by bones in the girdles and limbs.
It is the part of the skeleton that is adapted to allow the body to move.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

13. Appendicular skeleton
The bones of the pectoral girdle (shoulder) and the upper limbs are connected by ligaments and flexible.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

14. Appendicular skeleton
The pelvic girdle (hipbones) and lower limbs are adapted for strength and support.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

15. Osteoporosis Decreasing in bone mass weakens bone strength.
Protection against osteoporosis includes assumption of adequate calcium quantities and exercise.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

16. Bone tissue Bones have:
a medullary cavity, containing yellow bone marrow
articular cartilage covering the end of the bone
a dense and hard compact bone containing osteons
a spongy bone at the ends containing red bone marrow
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

17. Joints Joints are where two bones meet.
Different types of joints allow different movements.
Fibrous joints are immovable
Cartilaginous joints are slightly movable
Synovial joints are freely movable
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

18. Synovial joints
Synovial joints are filled with synovial fluid, provide stability and absorb shock.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

19. Synovial joints
Ball-and-socket joints allow movements in all planes, including rotation.
Hinge joints allow movements in one direction only.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

20. Body movements depend on skeletal muscles
Skeletal muscles have various structural and functional roles:
Support the body
Make bones move
Help maintenance of body temperature
Assist body movement in veins
Protect internal organs
Stabilize joints
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

21. Skeletal muscles
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

22. Skeletal muscles contract in units
Muscles are attached to bones by tendons and work in antagonistic pairs.
Extension
Flexion
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

23. Skeletal muscles contract in units
A motor unit is composed of muscle fibers controlled by the same motor neuron. Motor units can be stimulated by one nerve impulse (twitch contraction) or diverse nerve impulses (tetanus contraction).
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

24. Muscles cell
A single skeletal muscle cell (or muscle fiber) contains many myofibrils, rod-like unit composed of long proteins. Myofibrils contain repeating sections of sarcomeres.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

25. Muscles cell Sarcomeres contain actin and myosin filaments.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

26. Muscles contraction “SLIDING FILAMENT MODEL”
Muscle contraction occurs when sarcomeres shorten and actin filaments slide past myosin filaments. The process is supported by ATP.
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

27. Muscles contraction
Muscle contraction is activated by axon terminals at the neuromuscular junction.
Neuromuscular junction
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

28. Muscles contraction Muscles have three sources of ATP for contraction:
The creatine-phosphate (CP) pathway is simple and rapid
The anaerobic fermentation produces two ATP per glucose molecule
The cell respiration produces diverse ATP molecules in aerobic conditions
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

29. Muscles fibers There are two types of muscle fibers:
Fast-twitch fibers
Slow-twitch fibers
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

30. Exercise has many benefits
Improves muscular strength, endurance and flexibility
Improves cardiorespiratory endurance
Helps prevent cancer
Improves strength and density of bones
Relieves depression
Enhance mood
Help fight diseases
Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012