The Skeletal System Milo Mitchell and Eli Harris

Function Support Movement Protection Blood Cell Production Ion Storage Endocrine Regulation

Bones, Ligaments, Muscles, and Tendons Bones provide support Joints provide a movement point Tendons connect muscles to bones Ligaments connect bones to bones Muscles move by pulling on bones

Axial and Appendicular Skeleton Axial Skeleton (80 Bones) Formed by vertebral column, part of the rib cage, and the skull Maintains upright posture Human is able to survive with just the axial skeleton Appendicular Skeleton (126 Bones) Formed by pectoral girdles, upper limbs, pelvis, and lower limbs Enables locomotion Protects major organs (digestion, excretion, and reproduction)

Figure of a Long Bone

Types of Bone Cells Osteoblasts Derive from the bone marrow Single nucleus Responsible for the synthesis and mineralization of bone during initial bone formation and remodeling Form closely packed sheet on bone’s surface Transform into osteocytes Become flattened “lining cells” once the cavity is filled Three osteoblasts in a developing bone

Types of Bone Cells (cont.) Osteocytes Derive from osteoblasts Found within the bone Most abundant type of cell in mature bone tissue Long-lived Networked via long cytoplasmic extensions Capable of bone deposition, resorption, and remodeling Transverse Section of Bone

Type of Bone Cells (cont.) Osteoclasts Large cells with multiple nuclei Derive from bone marrow Found in pits in the bone surface (Resorption bays) Responsible for breaking down bone tissue Bone resorption

Homeostasis (Bone Growth) Calcium homeostasis regulates calcium flow to the bones. Calcium release is regulated by the parathyroid hormone.

“Animal” Skeletal System v. Human Skeletal System 3 levels of identification can distinguish human bones from animal bones: 1.Gross Skeletal Anatomy 2.Bone Macrostructure 3.Bone Microstructure

Gross Skeletal Anatomy Also have dentitional (oral) differences as humans have smaller canines, a different dental formula, and larger incisors. AnimalHuman ●Small vault ●Large face ●No chin ●V shaped mandible ●Large bulbous vault ●Small Face ●Chin ●U shaped Mandible

Bone Macrostructure and Bone Microstructure Animal Bones: Greater density Less porous Thicker in the cross section than human bones Comparative thickness of the cross section of animal versus human bone

Hydrostatic Skeleton A skeleton formed by a fluid-filled compartment called the coelom.

Exoskeleton and Endoskeleton Exoskeleton: external encasement on the surface of an animal Exoskeleton vs. Endoskeleton Endoskeleton: Structures located within the soft tissue of organisms.

Osteophytes Commonly referred to as bone spurs or parrot beak Bony projections along joint margins Can also form on vertebra (result of degeneration brought about by aging) Results from changes in formation (aging, degeneration, disease, etc.) Different from enthesophytes Bony projections along tendons or ligaments

Osteophytes (cont.) Can limit joint movement and cause pain Treatment: Non-steroidal anti inflammatory drugs and surgery Asymptotic cases typically go untreated

Works Cited Kovach, Tracy Kim. “Skeletal Structure and Function.” YouTube. Khan Academy, 21 Mar Web. 26 May 2016 Bozemanbiology. “The Skeletal System.” YouTube, 31 Mar Web. 26 May 2016 “Diseases and Conditions: Bone Spurs.” Mayo Clinic. Mayo Foundation for Medical Education and Research, 27 Feb Web. 26 May Fonseca, JE, Heidi Canhao, and J. Caetano-Lopes. “Result Filters.” National Center for Biotechnology Information. U.S. National Library of Medicine, Apr Web. 27 May “The O’ Cells.” Bone Cells. Washington University, 20 Sept Web. 27 May “Osteoblast.” Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 27 May “SEER Training:Appendicular Skeleton (126 Bones).” SEER Training:Appendicular Skeleton (126 Bones). N.p., n.d. Web. 31 May “SEER Training:Axial Skeleton (80 Bones).” SEER Training:Axial Skeleton (80 Bones). N.p., n.d. Web. 31 May 2016.

Works Cited (cont.) “Osteoclast.” Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 27 May “Osteocyte.” Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 27 May Pease, Roger W. Merriam-Webster’s Medical Dictionary. Springfield, MA: Merriam-Webster, Print. Rodan, Gideon A. "Bone Homeostasis." Proceedings of the National Academy of Sciences of the United States of America. The National Academy of Sciences, Web. 31 May "Bone and Calcium Homeostasis - Boundless Open Textbook." Boundless. Web. 31 May Watson, James, and John McLelland. "Distinguishing Human From Animal Bone." Distinguishing Human from Animal Bones. Arizona Board of Regents. Web. 31 May "Types of Skeletal Systems - Boundless Open Textbook." Boundless. Web. 31 May 2016.