PowerPoint Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Tenth Edition Shier w Butler w Lewis Chapter 7 7-1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Chapter 7 Skeletal System Bone Classification Long Bones Short Bones Flat Bones Irregular Bones Sesamoid Bones 7-2

Bone shape

Parts of a Long Bone epiphysis diaphysis compact bone spongy bone distal proximal diaphysis compact bone spongy bone articular cartilage periosteum endosteum medullary cavity trabeculae marrow red yellow 7-3

Compact and Spongy Bone 7-4

Microscopic Structure of Compact Bone osteon central canal perforating canal osteocyte lacuna bone matrix canaliculus 7-5

Bone Development Endochondral Ossification Intramembranous Ossification bones originate within sheetlike layers of connective tissues broad, flat bones skull bones (except mandible) intramembranous bones Endochondral Ossification bones begin as hyaline cartilage most bones of the skeleton endochondral bones 7-6

Intramembranous ossification

Intramembranous Osteogenesis/Development Mesenchyme( embryonic connective tissue), appear in the sites of future bones, differentiate into osteoblasts( bone forming cells). These cells deposit bony matrix and are surrounded by extra cellular matrix( ECM)( this matric later will give rise to canaliculi). Osteoblasts will be located in lacunae which are now called osteocytes ( bone cells). Blood vessels will surround bony matrix. Spongy bones forms in different directions along with blood vessels.

Endochondral Ossification hyaline cartilage model primary ossification center secondary ossification centers epiphyseal plate osteoblasts vs. osteoclasts 7-7

Growth at the Epiphyseal Plate First layer of cells Zone of resting cartilage closest to the end of epiphysis resting cells anchors epiphyseal plate to epiphysis Second layer of cells Zone of proliferating cartilage many rows of young cells undergoing mitosis 7-8

Growth at the Epiphyseal Plate Third layer of cells Zone of hypertrophic cartilage older cells left behind when new cells appear cells enlarging and thickening the epiphyseal plate, starting to becoming calcified Fourth layer of cells Zone of calcified cartilage thin dead cells calcified intercellular substance 7-9

Homeostasis of Bone Tissue Bone Resorption – action of osteoclasts and parathyroid hormone Bone Deposition – action of osteoblasts and calcitonin 7-10

Factors Affecting Bone Development, Growth, and Repair Deficiency of Vitamin A – retards bone development Deficiency of Vitamin C – results in fragile bones Deficiency of Vitamin D – rickets, osteomalacia Insufficient Growth Hormone – dwarfism Excessive Growth Hormone – gigantism, acromegaly Insufficient Thyroid Hormone – delays bone growth Sex Hormones – promote bone formation; stimulate ossification of epiphyseal plates Physical Stress – stimulates bone growth 7-11

Vitamin D

Vitamin D formation

Role of hormones

Role of hormones

Bone Function Support and Protection gives shape to head, etc. supports body’s weight protects lungs, etc. Blood Cell Formation hematopoiesis red marrow Inorganic Salt Storage calcium phosphate magnesium sodium potassium Body Movement interacts with muscles bones act as rigid bar of a lever 7-12

Skeletal Organization Axial Skeleton head neck trunk Appendicular Skeleton upper limbs lower limbs pectoral girdle pelvic girdle 7-15

Skeletal Organization 7-16

Infantile Skull Fontanels – fibrous membranes 7-30

Vertebral Column cervical vertebrae (7) thoracic vertebrae (12) lumbar vertebrae (5) sacrum coccyx 7-31

Life-Span Changes decrease in height at about age 30 calcium levels fall bones become brittle osteoclasts outnumber osteoblasts spongy bone weakens before compact bone bone loss rapid in menopausal women hip fractures common vertebral compression fractures common 7-61

The diagram shows the negative feedback mechanism with the involvement of thyroid and parathyroid glands.