ACOS OBJ 6.1) Identifying functions of the skeletal system.

 F_6Z0 F_6Z0

 Composed of 206 Bones  Bones- Organs of the Skeletal System ▪ Provide points of attachment for muscles, ▪ Protect & Support softer tissues ▪ House blood-producing cells ▪ Store inorganic salts ▪ Contain passageways for blood vessels and nerves.

What are Bones Made Of? Bones are made of several different things: Bone Tissue Cartilage Dense connective tissue Blood Nervous Tissue

Osteocytes -Bone Cells -Transport nutrients & wastes to and from nearby cells. Extracellular Matrix of bone tissue is largely composed of collagen & inorganic salts - collagen= strength & resilience - inorganic salts= cause bone to be hard and resistant to crushing.

 Processes- Bony projections that provide sites for ligaments & tendons to attach.  Grooves & Openings- Form passageways for blood vessels & nerves.

 Epiphysis- located at the end of bone. Forms a joint with another bone.  Articular Cartilage: hyaline cartilage located on outer surface of epiphysis. (Articulating Portion) -Diaphysis- Shaft of the bone located between the epiphyses.

 Periosteum- Tough, vascular covering of fibrous tissue that completely encloses the bone. Helps to form and repair bone tissue.  Medullary Cavity- Semi rigid tube with a hollow chamber.  Formed by compact bone  Lined with a thin layer of bone forming cells= endosteum  Filled with soft connective tissue known as marrow.

 1. Compact Bone= Composes wall of diaphysis.  Tightly packed  NO Gaps  Resists Bending

 2. Spongy Bone  Found in Epiphyses beneath a layer of thin compact bone.  Helps to reduce the bone’s weight

 Red Marrow= Functions in the formation of Red blood cells(erythrocytes), white blood cells(leukocytes), and blood platelets.  In an adult found in: skull, ribs, sternum, clavicles, vertebra, and hipbones.  Yellow Marrow= Replaces red marrow as we age.  Stores fat and is inactive in blood cell production.

 Bones can form 2 ways  1. Intramembranous bones originate between sheet-like layers of connective tissues. EX: Flat bones of the skull  2. Endochondral bones begin as masses of cartilage that bone tissue later replaces. Majority of bones in the skeletal system are endochondral. ▪ Osteoblasts- Bone forming Cells ▪ Osteoclasts- Break down calcified matrix.

 1. Give shape to structures like the head, face, thorax, and limbs.  2. Provide support & protection  EX: Bones of lower limbs, pelvis, & backbone support the body’s weight.  Bones of the skull protect eyes, ears, & brain.  Rib cage & shoulder girdle protect the heart and lungs.

 3. Body Movement  4. Blood Cell Formation (Hemopoiesis)  Blood cells are made in the liver, spleen, and bone marrow. ▪ Marrow is located in the medullary cavity, irregular spaces of spongy bone, & large canals of compact bone tissue.

 5. Storage of inorganic salts  Intercellular matrix of bone tissue rich in calcium salts.  Calcium phosphate ▪ VITAL metabolic processes require CALCIUM. ▪ Blood clot formation ▪ Nerve impulse conduction ▪ Muscle cell contraction

 Hole’s Essentials of Human Anatomy& Physiology.