Biology, 9th ed, Sylvia Mader Chapter 41 Chapter 41 Locomotion and Support Systems Locomotion and Support Systems
Diversity of Skeletons Outline Diversity of Skeletons Hydrostatic Skeleton Exoskeletons Endoskeletons Human Skeletal System Axial Skeleton Appendicular Skeleton Human Muscular System The Muscles Muscle Contraction
Hydrostatic Skeleton Functions Source Supports body form Provides resistance for the contraction of muscles to act against Source Some organisms use their fluid-filled gastrovascular cavity Others use their fluid-filled coelom
Locomotion in an Earthworm
Exoskeletons and Endoskeletons Exoskeleton - External Skeleton Molluscs - composed of calcium carbonate Arthropods - composed of chitin Endoskeleton - Internal Skeleton Echinoderms and vertebrates Mineralized bone and cartilage Grows as the animal grows Does not limit space for internal organs Supports greater weight
Exoskeleton
The Vertebrate Endoskeleton
Bones store calcium and phosphate ions Human Skeletal System Functions Supports and protects the body Permits movement Provides resistive foundation for muscles to act against Bones store calcium and phosphate ions Certain bones produce red blood cells
Bone Growth and Renewal Cartilage structures in early development act as models for future bones Calcium salts deposited in matrix by cartilage cells and later by osteoblasts Endochondral ossification Osteoclasts Break down bone Remove worn cells Deposit calcium in the blood Work with osteoblasts to heal broken bones
Anatomy of a Long Bone Gross Details Main shank Spongy bone at ends Thick outer cylinder of compact bone Medullary cavity in center Spongy bone at ends Details Compact bone Unit of structure called osteon Concentric lamellae arranged around central canal Osteocytes lie in lacunae at lamellar boundaries Spongy bone Numerous bars and plates separated by irregular spaces Spaces filled with red bone marrow
Anatomy of a Long Bone
The Human Skeleton
Lies in the midline of the body Consists of The Axial Skeleton Lies in the midline of the body Consists of The skull The vertebral column The sternum, and The ribs
Formed by cranium and facial bones The Skull Formed by cranium and facial bones Major bones are named after The lobes of the brain, and The facial bones Foramen magnum Opening at base of skull Where spinal cord connects to brain Bones of cranium surround sinuses
The Skull
Segments (from superior to inferior) Vertebral Column Vertebral column Supports the head and trunk Protects the spinal cord and roots of spinal nerves Segments (from superior to inferior) Cervical - Neck Thoracic - Thorax Lumbar - Small of back Sacral - Sacrum Coccyx - Tailbone Intervertebral disks of fibrocartilage act as padding
Protects the heart and lungs, and assists breathing Rib Cage Protects the heart and lungs, and assists breathing Support by the thoracic vertebrae Twelve pairs of ribs True ribs Connect directly to sternum Seven pairs “False” ribs Do not connect directly to sternum Five pairs
The Rib Cage
The Appendicular Skeleton Consists of The bones within the pectoral and pelvic girdles The attached limbs Pectoral girdle – Bones of the shoulder Anterior Supports the arms and hands Pelvic girdle - Bones of the pelvis Posterior Supports the legs and feet
Bones of the Pectoral Girdle, the Arm, and the Hand
Bones of the Pelvic Girdle, the leg, and the Foot
Classification of Joints Fibrous Joints Immovable Between cranial bones Cartilaginous Joints Slightly Movable Between vertebrae Synovial Joints Freely Movable Bones separated by a cavity Ligaments bind bones together at joint
The Knee Joint
Human Muscular System Skeletal muscles Attached to the skeleton by cable-like fibrous connective tissue called tendons Arranged in antagonistic pairs Can only contract, cannot push When one muscle contracts, it stretches its antagonistic partner A muscle at “rest” exhibits tone (minimal contraction) A muscle in tetany is at maximum sustained contraction
Human Musculature
Antagonistic Muscles
Microscopic Anatomy and Physiology Sarcolemma Plasma membrane Sarcoplasmic Reticulum Modified endoplasmic reticulum Myofibrils Contractile structures in sarcoplasm Sarcomeres Units of contraction Consist primarily of proteins Myosin Actin
Skeletal Muscle Fiber Structure and Function
Sliding Filament Model Actin filaments at both ends of sarcomere One end of each filament attached to a Z-plate at one end of the sarcomere Other end suspended in sarcoplasm Myosin filaments suspended in between Z-plates Myosin filaments contain cross-bridges which pull the actin filaments inward Causes Z-plates to move toward each other Shortens sarcomere Sarcomeres stacked together in series and cause myofiber to shorten Working muscles require ATP Myosin breaks down ATP Sustained exercise Requires cellular respiration Regenerates ATP
Neuromuscular junction Muscle Innervation Neuromuscular junction The synaptic contact between a nerve fiber and a muscle fiber Nerve impulses bring about the release of a neurotransmitter that cross the synaptic cleft Signals the muscle fiber to contract
Neuromuscular Junction
The Role of Calcium and Myosin in Muscle Contraction
Diversity of Skeletons Review Diversity of Skeletons Hydrostatic Skeleton Exoskeletons Endoskeletons Human Skeletal System Axial Skeleton Appendicular Skeleton Human Muscular System The Muscles Muscle Contraction
Biology, 9th ed, Sylvia Mader Chapter 41 Ending Slide Chapter 41 Locomotion and Support Systems Locomotion and Support Systems