Skeletal System

1. Skeletal System • Chapter 6 & 7 http://faculty.lonestar.edu/rchute/ap1chap/chapt6.htm

2. Skeletal System: Cartilage • Skeletal cartilage consists primarily of water. (80%) • Cartilage contains no nerves or blood vessels. • Chondroblasts =new cell growth cells • Chondrocytes = mature cells • Lacunae = groups of cavities that contain the chondrocytes

3. Three types of cartilage Fibrocartilage Tensile strength with the ability to absorb compressive shock • Hyaline Cartilage • Most abundant • Elastic cartilage • Maintains shape while allowing great flexibility

4. Skeletal System Organization of the skeletal system Axial skeleton =revolves around the vertical axis of the skeleton Appendicular skeleton =make up the limbs that have been appended to the axial skeleton

5. Skeleton • Consists of: • bones • Cartilage • Membranes that Line the bones.

8. Types of Bones: 1.Long bones are longer than they are wide. 2. Short bones are cubelike, about as long as they are wide. 3. Flat bones, such as ribs and skull bones, are thin or flattened. 4. Irregular bones, such as vertebra, facial bones, have specific shapes unlike the other types of bones.

9. Functions of bones • Support= bones provide a framework for the attachment of muscles and other tissue • Protection= bones such as the skull and rib cage protect internal organs from injury • Movement= bones enable body movements by acting as levers and points of attachment for muscles. • Mineral storage. Bones serve as a reservoir for calcium and phosphorus, essential minerals for various cellular activities throughout the body. • Blood cell production= the production of blood cells (hematopoietic) occurs in the red marrow found within the cavities of certain bones. • Energy storage= lipids(fats) stored in adipose cells of the yellow marrow serve as an energy reservoir

10. Bone • Bone is an organ that includes • Connective tissue(bone, blood, cartilage, adipose, and fibrous connective tissue) • Nervous tissue • Muscle and epithelial tissues (within the blood vessels)

11. Bone Structure: Gross Anatomy

12. Two types of bone tissue • Compact bone is the hard material that makes up the shaft of long bones and the outside surfaces of other bones.

13. Two types of bone tissue • Spongy bone consists of thin, irregularly shaped plates called trabeculae, arranged in a latticework network.

16. Long bone structure Epiphyseal line • Location of Hematopoietic tissue in bones • Red marrow located within cavities of spongy bone of long bones and in the diploe of flat bones • Infants all areas of spongy bone contain red blood cells • Adults in the head of the femur and humerus, flat bone of sternum, and irregular bone of the pelvis

18. Microscopic Structure of Bone

19. Chemical Composition of Bone • Bone consists of organic and inorganic components • Organic components include the cells (osteoblasts, osteocytes, and osteoclasts) and Osteoids • Inorganic components include hydroxyapatites (mineral salts) largely calcium phosphates

20. Organic bone cells • Osteoblasts - bone-forming cells • Osteocytes - mature bone cells • Osteoclasts - large cells that resorb or break down bone matrix • Osteoid - unmineralized bone matrix composed of proteoglycans, glycoproteins, and collagen

22. Bone Markings • The external surface of bones are rarely smooth and featureless. • These marking are named in many different was. • http://www.studystack.com/menu-210122 http://www.studystack.com/studytable-210122

23. Bone Development • Osteogenesisand ossification are synonyms indicating the process of bone tissue formation • Occurs when? • Embryos = leads to formation of the bony skeleton • Bone growth = until early adulthood to increase in size (bones are capable of growing in thickness throughout life.) • Ossification in adults serves mainly for remodeling and repair of bones

24. Formation of the Bony Skeleton • Begins at week 8 of embryo development • 1.Intramembranous ossification– bones develops from a fibrous membrane • Formation of most flat bones of the skull and the clavicles • 2.Endochondral Ossification –bone formation that occurs by replacing hyaline cartilage • Begins in the second month of development • Uses hyaline cartilage “bones” as models for bone construction • Requires breakdown of hyaline cartilage prior to ossification

28. Postnatal Bone GrowthBone Growth in length • 1. Epiphyseal plate or cartilage growth plate • cartilage cells are produced by mitosis on epiphyseal side of plate • cartilage cells are destroyed and replaced by bone on diaphyseal side of plate • Between ages 18 to 25, epiphyseal plates close. • cartilage cells stop dividing and bone replaces the cartilage (epiphyseal line) • Growth in length stops at age 25

29. Growth in length of long bones

30. Hormonal Regulation of bone growth during youth • Initially promote adolescent growth spurts • Cause masculinization and feminization of specific parts of the skeleton • Later induce epiphyseal plate closure, ending longitudinal bone growth • Initially promote adolescent growth spurts • Cause masculinization and feminization of specific parts of the skeleton • Later induce epiphyseal plate closure, ending longitudinal bone growth

31. Bone Remodeling • In adult skeletons, bone remodeling is balanced bone deposit and removal, bone deposit occurs at a greater rate when bone is injured, and bone resorption allows minerals of degraded bone matrix to move into the blood.

32. Control of Remodeling • The hormonal mechanism is mostly used to maintain blood calcium homeostasis, and balances activity of parathyroid hormone and calcitonin. • Nutrition - Ca, P, Mg, vitamins, A, C and D. • In response to mechanical stress and gravity, bone grows or remodels in ways that allow it to withstand the stresses it experiences

33. Calcium • The human body contains some 1200-1400 g of calcium • Over 99% of which is present as bone minerals • Normal range is narrow= 9-11 mg per 100ml of blood by the hormonal control loop • Calcium is absorbed from the intestine under the control of vit. D metabolism • Daily req: birth to 10yrs = 400-800 mg 11 to 24 yrs = 1200-1500 mg

34. Wolff's law - a bone grows or remodels in response to the forces or demands placed upon it

35. Comparing Skeletons • Adult= 206 • Child = 275 • Adult = Higher % of yellow marrow and lower % of red marrow(sternum, pelvis, femur) • Child = Higher % of red marrow and lower % of yellow marrow • Adult = higher % of bone and lower % of cartilage • Child = higher % of cartilage and lower % of bone

36. Fractures

37. Stages in the healing of a bone fracture

40. 1. Osteomalacia 2. Rickets 3. Osteoporosis 4. Paget’s disease 5. achondroplasia 6. bony spur 7. ostealgia 8. osteitis 9. osteomyelitis 10. osteosarcoma 11. Pathologic fracture 12. traction Homeostatic imbalances of Bone

41. Osteomalacia and Rickets

42. osteoporosis

43. Paget’s disease

44. achondroplasia

45. Bony spur

46. osteitis

47. osteomyelitis

48. osteosarcoma

49. Joints (articulations)= site where two or more bones meet • Function to give the body mobility and to hold bones together • Joints are the weakest parts of the skeleton • Functional Classification: • Synarthroses= immovable joints • Amphiarthroses= movable joints • Diarthroses = freely moveable joints

50. Classifying joints based on structure (PAGE 251) • Fibrous= Sutures