I. Skeletal SystemA. Functions1. Protection2. Support3. Movement4. Mineral storage5. Hematopoietic (Blood production) *Is a major characteristic of spongy bone6. Energy storageB. 4 main cell types1. Osteoprogenitors – stem cells of the skeleton, unipotent, first bone makers. Are mitotic and give rise to osteoblasts.2. Osteoblasts – Nonmitotic and secrete the bone matrix (calcium and phosphorous salts).3. Osteocytes - Nonmitotic mature osteoblasts that no longer secrete the matrix and do regular cell functions. Are the brains of bones4. Osteoclasts – Cells that break down bone to access and release minerals. (Ex – Calcium). Pregnant women loose a lot of bone density when they’re pregnant because the fetus uses so much calcium. White blood cells give rise to osteoclasts; specifically monocytes. Secrete enzymes and acids. The enzymes break down proteins and the acids dissolve calcium salts and release them to the blood stream. Osteoclasts help to shape and form osteons and trabeculae.C. Bone Tissue1. Osteona) 35% of compact bone is Collagen. Gives bone flexibility and tensile strengthb) 65% is calcium salts. They have the ability to mineralize and osteosize (harden the bone). Function for strength against compressionc) Bone is strong without being brittle.d) Bone is ½ as strong as steel against compression.e) Bone is equal to steel in tensile strength.f) Osteoporosis – A condition of bones loosing collagen and osteoblasts being less functional leading to brittle bones. Is typical of age. Calcium helps with this disease because since osteoblasts are laying down calcium salts, taking a supplement replaces their function when they stop working.2. Trabeculae- Fundamental unit of spongy bone, they form spicules. This leaves many porous spaces which are great spots for blood vessels to goD. Bone Morphology1. Flat bones  Include all of the skull bones, sternum, scapula, and ribs. Is mostly spongy bone internally with a thin sheath of compact bone making up the outside2. Short bones  Include the wrist bones (carpals), ankle bones (tarsals), and the patella. Cube shaped; are about as wide as they are tall. There is a greater compilation of compact bone with less spongy bone on the inside, making them a little bit stronger.3. Long bones  Include the femur, tibia, Humerus, radius, ulna, metacarpals, and metatarsals.4. Irregular bones Include the coxal bones and vertebrae.BIO 240 1st Edition Lecture 12 Outline of Last Lecture II. Appendicular SkeletonIII. Bones of the Upper AppendagesIV. Bones of the Lower AppendagesOutline of Current Lecture I. Skeletal SystemA. FunctionsB. 4 Main cell typesC. Bone TissueD. Bone MorphologyCurrent LectureI. Skeletal SystemA. Functions1. Protection2. Support3. Movement4. Mineral storage5. Hematopoietic (Blood production) *Is a major characteristic of spongy bone6. Energy storageB. 4 main cell typesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. Osteoprogenitors – stem cells of the skeleton, unipotent, first bone makers. Are mitotic and give rise to osteoblasts.2. Osteoblasts – Nonmitotic and secrete the bone matrix (calcium and phosphorous salts).3. Osteocytes - Nonmitotic mature osteoblasts that no longer secrete the matrix and do regular cell functions. Are the brains of bones4. Osteoclasts – Cells that break down bone to access and release minerals. (Ex – Calcium). Pregnant women loose a lot of bone density when they’re pregnant because the fetus uses so much calcium. White blood cells give rise to osteoclasts; specifically monocytes. Secrete enzymes and acids. The enzymes break down proteins and the acids dissolve calcium salts and release them to theblood stream. Osteoclasts help to shape and form osteons and trabeculae. C. Bone Tissue1. Osteona) 35% of compact bone is Collagen. Gives bone flexibility and tensile strengthb) 65% is calcium salts. They have the ability to mineralize and osteosize (harden the bone). Function for strength against compressionc) Bone is strong without being brittle. d) Bone is ½ as strong as steel against compression. e) Bone is equal to steel in tensile strength.f) Osteoporosis – A condition of bones loosing collagen and osteoblasts being less functional leading to brittle bones. Is typical of age. Calcium helps with this disease because since osteoblasts are laying down calciumsalts, taking a supplement replaces their function when they stop working.2. Trabeculae- Fundamental unit of spongy bone, they form spicules. This leaves many porous spaces which are great spots for blood vessels to goD. Bone Morphology1. Flat bones  Include all of the skull bones, sternum, scapula, and ribs. Is mostly spongy bone internally with a thin sheath of compact bone making up theoutside2. Short bones  Include the wrist bones (carpals), ankle bones (tarsals), and thepatella. Cube shaped; are about as wide as they are tall. There is a greater compilation of compact bone with less spongy bone on the inside, making them a little bit stronger. 3. Long bones  Include the femur, tibia, Humerus, radius, ulna, metacarpals, and metatarsals.4. Irregular bones Include the coxal bones and