ACOS OBJ 6.1) Identifying functions of the skeletal system.

http://www.youtube.com/watch?v=vKMFwAF_6Z0

Composed of 206 BonesBones- 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 TissueCartilageDense connective tissueBloodNervous 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.