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

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

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

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

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

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

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

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

10 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 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. Axial skeleton - the vertebral column

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

12 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 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. Appendicular skeleton

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

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

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

16 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 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 Bone tissue

17 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 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 Joints

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

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

20 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 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 Body movements depend on skeletal muscles

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

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

23 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 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).

24 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 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.

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

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

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

28 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Muscles have three sources of ATP for contraction: 1.The creatine-phosphate (CP) pathway is simple and rapid 2.The anaerobic fermentation produces two ATP per glucose molecule 3.The cell respiration produces diverse ATP molecules in aerobic conditions Muscles contraction

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

30 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 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 Exercise has many benefits