The Skeletal System Izzy Cassandra-Newsam, Riley Street

FUNCTION OF THE SKELETAL SYSTEM ❏ Supports the body ❏ Protects important internal organs ❏ Attaches muscles ❏ Stores ions ❏ Produces bloods cells (in bone marrow)

Types of Bones ❏ Long bones: support weight and help movement ❏ Short bones: help stabilize the body ❏ Flat bones: protect vital internal organs ❏ Irregular bones: have complex and varying shapes and functions ❏ Sesamoid bones: support tendons

STRUCTURE OF (LONG) BONES ❏ Compact bone: outer, solid, layer of the bone, act as shell to protect the bone ❏ Cancellous “spongy” bone: underneath the compact bone, spaces between parts of bone ❏ Like a net ❏ Articulatory cartilage: layer or cartilage at the end of each bone ❏ Lessens friction between bones ❏ Bone Marrow: produces red and white blood cells ❏ Blood Vessel: carries blood supply to the bones ❏ Helps with circulation throughout the entire body ❏ Endosteum: layer that lines the bone cavities ❏ Periosteum: a membrane that coats the outside of the bones ❏ Only when not covered with articulatory cartilage.

Structure of a (Long) Bone (continued)

MECHANICAL FUNCTIONS OF BONES ❏ 206 Bones in the body ❏ Protect organs ❏ Skull protects brain ❏ Rib cage protects heart and lungs ❏ Hardness nature of bones provides shape to the body ❏ Helps with movement ❏ Works with ligaments, muscles, joints, and tendons

SYNTHETIC FUNCTIONS OF BONES ❏ Creates blood cells using bone marrow ❏ Red Bone Marrow: Produces red and white blood cells using Hematopoietic stem cells -> hematopoiesis ❏ Yellow Bone Marrow: Occurs as people age, red bone marrow turns fatty and is no longer able to go through hematopoiesis

LIGAMENTS ❏ Made up of fibrous tissue ❏ Connects one bone to another bone = Joint ❏ Allows Joint Movement ❏ Ligaments are flexible/stretchy, but also limit the range of motion for a joint. ❏ Thus protecting joints from any movement that is harmful. ❏ Ligament Damage ❏ Very common if a movement exceeds the flexibility of a ligament.

MUSCLES ❏ Form around the bones and skin ❏ Skeletal Muscle Tissue: made of voluntary muscles that contract to allow locomotion ❏ Provide force and motion ❏ Protein filaments made of actin and myosin slide against each other to make contractions. ❏ Contractions work with tendons to form a movement ❏ Helps with strength, balance, and posture Epimysium - Connective tissue, covering entire muscle Perimysium - Connective tissue from muscle to Muscle Fibre Muscle Fibre - Group of muscle cells

TENDONS ❏ Connective tissue that attaches the Muscles to bones ❏ Made up of collagen fibers ❏ Can withstand a great amount of force ❏ “Tensile Strength” ❏ Skeletal Movement ❏ The muscle contracts, which pulls the tendon up, and the tendon pulls the bone

HYDROSTATIC SKELETON ❏ Found in cold-blooded mammals (including vertebrates) ❏ Coelom (fluid-filled cavity) that is surrounded by muscles ❏ The muscles and the fluid provide structure for the soft-bodied organisms ❏ Pressure of the fluid helps organisms move ❏ Jellyfish have a hydrostatic skeleton

EXOSKELETON ❏ All crustaceans have exoskeletons ❏ Outside the body ❏ Protection ❏ Animals are small -> large animals can’t be supported by exoskeletons ❏ Soft and thin -> so it can bend when needed ❏ Larger exoskeletons are shells

ENDOSKELETON ❏ Humans ❏ Found inside the body ❏ “Framework of the animal” ❏ Muscles, tissues are formed around the bones ❏ support

AXIAL vs. APPENDICULAR ❏ 80 bones ❏ Vertebral column, rib cage, skull ❏ Supports and protects the brain ❏ Includes the spinal column ❏ “Helps maintain upright posture” ❏ Protect the internal organs from damage ❏ Attaches to and “stabilizes” bones of the appendicular system ❏ 126 bones ❏ Made up of the upper and lower limbs, and the pectoral and pelvic girdles ❏ Help with movement and protect digestion and excretory organs ❏ Allow flexibility and movement at joint ❏ Anchor the muscles ❏ Think: APPENDicular -> APPENDage

HOMEOSTASIS ❏ Makes Red Blood Cells ❏ Red Bone Marrow ❏ Stores Mineral Ions ❏ Located in the center of the bone ❏ Calcium and Phosphorus in bones ❏ Stores Fats ❏ Yellow Bone Marrow

OSTEOPOROSIS ❏ Common in older people ❏ Results in loss of bone tissue ❏ Bones lose calcium → become thinner, may even disappear completely ❏ Caused by vitamin D and calcium deficiencies ❏ Bones become weak and are more susceptible to fracture ❏ Slightly more common in women than men over the age of 50

Bone Dance! 0:25

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