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Unit 5 Skeletal system.

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Presentation on theme: "Unit 5 Skeletal system."— Presentation transcript:

1 Unit 5 Skeletal system

2 Composed of cartilage and bone
Skeletal system Composed of cartilage and bone

3 Functions Support soft tissue Prtects delicate organs Movement
Storage area ( Calcium, phosphorus, fats Hemopoiesis: blood cell formation

4 Cartilage: consists of chondrocytes living in a cavity (lacuna) and is avascular with cells being nourished by diffusion

5 Bone consist of osteocytes living in lacunae and a great deal of non-living matrix with collagen fibers However is highly vascularized The matrix contains 33% collagenous fibers and 67% mineral salts ( calcium phosphate, calcium carbonate called hydroxy-apatites) Embryonic skeleton is all cartilage but slowly ossifys

6 Bone structures Diaphysis: the shaft ( compact bone)
Epiphysis: ends ( thin layer of compact bone covering spongy bone Metaphysis: region where epiphysis and diaphysis come together, region of epiphyseal plate

7 Bone structures Articular cartilage: thin hyaline cartilage covering of epiphyseal surface at joints Medullary cavity (marrow cavity): space within diaphysis

8 Bone structures Periosteum: dense irregular, white fibrous layered covering of a bone. Is composed of 2 layers: Fibrous layers: outer layer composed of bibrous connective tissue containing blood vessels Osteogenic layer: layer closer to bone that contains elastic fibers, blood vessels, osteoclast and osteroblast

9 Functions of periosteum
Growth Repair Nutrition Attachments for ligament and tendons


11 Classification of bones by shape
Long: longer than they are wide ex: most extremities, phalanges Short: wider than they are long ex: carpals and tarsals Flat: ex: cranium, ribs, shoulder girdle Irregular: vertebrae and facial Sessamoid: patella Wormian: grows between bones of skull

12 2 Types of bone tissue Compact:
Covers spongy bone, is dense and provides strength Structural unit of compact bone is the osteon

13 Osteon The osteon is a hard bone matrix arranged in rings (lamellae) around a haversian canal Volkman’s canal: carry blood vessels and nerves from the periosteum into the haversian canal and on into the medullary cavity Osteocytes: mature osteoblasts, live in the lacunae between lamellae

14 Canaliculi: are tiny canals which connect lacunae with each other and with the haversian canal.
Inside canaliculi are cellular extensions of osteocytes creating a network for nutrients and distribution Areas between osteons where the lamellae are only partially circled are called interstitial lamellae. They are the remnants of old partially destroyed osteons.




18 Types of bone tissue Spongy bone
Consists of a lattice work of bone called trabeculae In between the trabeculae are spaces filled with red bone marrow and blood vessels There is no network of canals because the blood can reach the osteocytes by diffusion through marrow spaces Is less dense and less strong and is found in the epiphysis of long bones and the bulk of flat bones or irregular bones

19 Bone formation ( osteogenesis or ossification
Embryo’s skeleton is made of cartilage and fibrous membranes At around 8 weeks after conception and throughout childhood ( until about age 20) this connective tissue model is slowly ossified ( turned to bone)

20 Intramembraneous ossification
Results in formation of flatbones and some irregular ones by ossification of pre existing fibrous connective tissue The osteoblasts begin secreting bone matrix eventually forming spongy bone …later the outer layers are reconstructed into compact bone

21 Intramembraneous ossification
The original connective tissue which encloses the “growing” bone becomes the periosteum Some osteoblasts trap themselves in the matrix (lacunae) and are now called osteocytes Bones are destroyed and reformed many times before adulthood and final size and shape

22 Endochondral ossification
Most bones formed this way Involves replacement of hyaline cartilage with bone Embryonic skeletons are cartilage enclosed by connective tissue called perichondrium Once a blood vessel penetrates the perichondrium of the embryonic bones the chondrocytes become osteoblasts which begin forming bone matrix

23 Endochondral ossification
Perichondrium is now periostium Area where bone begins to form is called primary ossification center (central located on bone) Between ages 1-5 blood vessels enter epiphyses and secondary ossification centers occur (at birth ends of bones are still cartilage) So primary and secondary ossification centers grow toward each other, replacing cartilage with bone.

24 Endochondral ossification
The cartilage between these ossification centers is called epiphyseal plate (don’t ossify until about 18-25) Growth in diameter is due to osteoblasts in periosteum adding new osseous tissue to outside surface of bones Initially all bone growth begins with spongy bone which is later remodeled into compact bone.

25 Bone Remodeling The continuous balance between bone formation and bone reabsorption, occurs at all periosteal and endosteal surfaces Bone is constantly replacing itself throughout adult life.

26 Bone disorders Rickets: childhood disease due to lack of vitamin D (sunlight) causes cartilage not to be calcified, bones are soft and malformed Osteomalacia: adult rickets… too little vitamin D Solution: both need dietary calcium and sunlight (vitamin D) Both disorders can also be due to either kidney or liver disease and resultant is a poor processing of calcium

27 Bone disorders Osteoporosis: character sized by a decrease in bone mass due to decease osteoblast activity. Generally age related ( decrease in hormone activity, females often due to menopause) Also due to insufficient exercise, resulting in brittle porous bones Bones are easly broken, decreased height, hunched back etc… Solution: exercise, calcium and vitamin supplements and maybe hormones

28 Bone disorders Osteomyelitis: includes all infectious disease of bone

29 Divisions of skeletal system
Axial skeleton: forms midline of skeleton 80 of 206 bones in human body are axial ( 28 in skull alone Appendicular: remiainng 126 bones Found in arms, legs, pectoral and plevic girdle







36 Fractures: breaks in bones
Simple: Bone breaks cleanly, but does not penetrate skin Compound; broken ends of bone protrude trough skin Comminuted: bone fragments into many pieces Compression: bone is crushed

37 Depression: broken bone portion is pressed inward
Impacted: broken bone ends are forced into each other Spiral: ragged break occurs when excessive twisting forces are applied to a bone Greenstick: bone breaks incompletely, much in the way a green twig breaks

38 Colle’s fracture: fracture of distal end of lateral forearm (radius) in which distal fragment is displaced posterior Stress fracture: microscopic fissures in bone that form without evidence of injury to other tissue no visible break. Pott’s fracture: fracture at distal end of lateral legbone (fibula)) with serious injury of distal tibial articulation



41 Intramembraneous ossification



44 4 steps of fracture repair
Hematoma: swelling, blood clotting, influx of fibroblasts and granulation tissue Fibrocartilagineous callus: collagen fibers bridge broken gap forming a callus Bony callus: collagen is calcified Remodeling: of spongy to compact bone and removal of excess callus




48 Articulations (joints)
Functional classification synarthroses: immovable joint (skull sutures) Amphiarthroses: slightly moveable (between vertebrae or in pelvis) Diarthrosis: freely moveable

49 Structural Classification
Fibrous joints: no join cavity, bones held together by fiberous connective tissue Cartilaginous joints: still no cavity, bones held together by cartilage Synovial joints: have cavities, free moving Have articular cartilage (haline) Have articular capsule (units articular bones) Has synovial fluid Has reinforcing ligaments

50 Types of Fibrous joints
Sutures: only in skull, bones touch joined by connective tissue (synathrotic) Syndesmosis: bones slightly separated (amphiarthrotic) ex tibia, fibula Gomphosis: peg in a socket ex teeth

51 Types of Cartilaginous joints
Synchondrosis: immovable, connective tissue is hyaline cartilage ex rib to sternum Symphysis: connective tissue is fibrocartilage disk, little movement. Ex between vertebrae, pubic symphysis

52 Bursae and Tendon sheaths
Little sac-like synovial membrane bags filled with synovial fluid and serving as friction reducing cushions between tendons, ligaments, muscles and bones It keeps these from rubbing each other ( inflammation of bursa is Bursitis)

53 Factors limiting synovial joint movement
Structure/shape of articulating bones Ligament tension and arrangement Muscle tone/tension Apposition of soft parts

54 Miscellaneous Intervetebral discs: fibrocartilage between vertebrae, acts as a shock absorber Dislocation: bones forced out of normal position in a joint cavity Sprain: twisting or tearing of a joint ligament or other connective tissue without dislocation

55 Strain: less severe, overstretched muscle
Sinuses: mucous membranes line cavities in skull, are open to nasal passages and thus to infections Bunions: swelling of bursa in joint between metatasals and phalange (big toe)

56 Arthritis: catch all term referring to 100+ types of joint diseases
Rheumatoid arthritis: chronic inflammatory disorder affects women three times more often than men A disorder in which the body’s immune system attempts to destroy its own tissue Gouty arthritis: metabolic disorder in which uric acid crystal s build up in soft tissues inflaming joints. Most common in males and typically affects a single joint

57 Tendinitis: inflammation of sheaths around tendons
Osteoarthritis: most common, non-inflammatory “wear and tear” arthritis

58 Factors in bone Physiology
1. sufficient dietary calcium phosphorus Calcium needed in nerve impulses Phospherous: in ATP 2. Vitamins: 3. Hormones

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