1. Mrs. Rago BCTHS Anatomy & Physiology

2.  Support & stabilize  Protect vital organs  Assists in movement  Makes blood cells ◦ Hematopoiesis  Storage area

3.  Cartilage ◦ Connective tissue ◦ Framework for bones in fetus  Ligaments ◦ Tough connective tissue ◦ Attachment point for other bones  Tendons ◦ Attach muscle to bone

4. cartilage ligaments Tendons

5.  Long Bones ◦ Long & thinner but with expanded ends ◦ Ex: forearm & thigh bones  Short Bones ◦ Cubelike: length & width roughly equal ◦ Ex: wrists & ankles  Flat Bones ◦ Platelike ◦ Ex: ribs, scapulae, & some of skull bones  Irregular Bones ◦ Variety of shapes & are usually connected to several other bones

6. Long bone- femur Irregular bone- patella Flat bone- scapula Short bones- wrist

7.  Epiphysis ◦ Articulates with another bone (joint) ◦ Covered with articular cartilage  Layer of hyaline cartilage  Diaphysis ◦ Shaft of bone

9.  Long bones are very useful in lifting heavy loads ◦ Act as a lever when lifting a weight Resistance force fulcrom First-class lever

10. Resistance FulcromForce Second- class Lever Fulcrom Force Resistance Third-class Lever

11.  Lever ◦ Has 4 basic components  Rigid bar  Pivot or fulcrum (what the bar turns on)  Object that is moved against resistance  Force that supplies energy for the movement of the bar  Only first-class & second-class lever movements are found in the human body

12.  Periosteum ◦ Fibrovascular membrane that covers a bone  Endosteum ◦ Line the medullary cavity  Medullary Cavity ◦ Center of bone ◦ Contains bone marrow

13. periosteum endosteum Medullary Canal

14.  Osteoblasts ◦ Precursors to osteocytes ◦ Bone forming cells which deposit bony matrix around themselves ◦ Deposit bone in the endosteum (area of cells that line the medullary cavity)  Osteocytes ◦ Bone cells ◦ Located in tiny chambers called lacunae

15.  Osteoclasts ◦ Responsible for reabsorption of bone ◦ Remove bone and replace it during remodeling  Occurs especially when repairing a broken bone  Also occurs when bone is reshaped (bow-legs)  Osteocytes deposit new bone

16.  Red bone marrow ◦ Fills spaces within cancellous bone ◦ Well supplied with blood ◦ Produces blood cells = hematopoiesis  White & red blood cells ◦ Found in adults, but only in select bones  Ribs, vertebrae, sternum, and pelvic bones ◦ Found in humerus & femur but decreases with age

19.  Yellow Marrow ◦ Connective tissue that consists largely of fat cells ◦ Found predominantly in shafts of long bones in medullary cavity ◦ Can become red marrow in times of need (major loss of blood) and produce blood cells if necessary

21.  Intramembraneous Ossification ◦ Dense connective tissue membranes are replaced by deposits of inorganic calcium ◦ Only bones of skull ◦ Does not occur until a few months after birth  Soft spot = fontanelle

23.  Endochondral Ossification ◦ Cartilage is formed first and then replaced by mature bone cells  Primary ossification center ◦ Found in center of a long bone ◦ Bone develops from 1 ̊ ossification center toward the ends of cartilaginous structure  Secondary ossification center ◦ Appear later than 1 ̊ossicification centers ◦ Are found in epiphyses ◦ Spongy bone forms in all directions from 2 ̊ ossification center

25.  Types of bone ◦ Compact/dense bone  Dense & strong ◦ Cancellous/spongy bone  Many open spaces

28.  Structure ◦ Haversian Canal (osteon)  Allows for metabolism of surrounding mineral salts within compact bone  Looks similar to rings around central blood vessels  Blood vessels found within haversian or central canal  Concentric (circular) rings are called lamella  Lacunae  Tiny cavities that contain the osteocytes  Located between two lamella or rings of bone

31.  Each lacunae are connected to all other lacunae through smaller canals= canaliculi ◦ Canaliculi run horizontally between haversian canals  Also contain blood vessels  Same as Volkmann’s or perforating canals  Canaliculi ◦ Allow osteocytes to get oxygen & nutrients and dispose of waste products & CO 2

32.  Also called spongy bone  Located at ends of long bones and also forms center of all other bones  Trabeculae ◦ Network that forms the network of interconnecting sections of bone ◦ Creates sponelike appearance to bone ◦ Gives bone strength without adding weight

34.  Red bone marrow ◦ Fills spaces within cancellous bone ◦ Well supplied with blood ◦ Produces blood cells = hematopoiesis  White & red blood cells ◦ Found in adults, but only in select bones  Ribs, vertebrae, sternum, and pelvic bones ◦ Found in humerus & femur but decreases with age

37.  Yellow Marrow ◦ Connective tissue that consists largely of fat cells ◦ Found predominantly in shafts of long bones in medullary cavity ◦ Can become red marrow in times of need (major loss of blood) and produce blood cells if necessary

39.  Separates diaphysis & epiphysis in long bones  Area of new cell growth in growing bones  Layers of cartilaginous cells ◦ Layer 1- resting cells (found closest to end of epiphysis) ◦ Layer 2- cells undergoing mitosis ◦ Layer 3- older cells enlarging & becoming calicified ◦ Layer 4- dead cells & calcified intercellular substance

40. Resting cells Cells under going mitosis II III Older cells enlarging and becoming calcified Dead cells and calcified intercellular substance III IV

41.  Healthy body ◦ Balance between amount of calcium in blood and calcium stored in bones  Excess calcium secrete via kidneys  Balance controlled by endocrine system  Parathyroid & calcitonin hormones

42.  Growth hormone (GH) ◦ Secreted by pituitary gland ◦ Stimulates division of cartilage cells found within epiphyseal plates ◦ Absence of GH  Long bones fail to develop normally and individual fails to grow, leading to pituitary dwarfism ◦ Over production of GH (too much)  Pituitary gigantism  Height over 8 ft tall  Acromegaly  Hands, feet, & jaw enlarge

43.  Thyroid hormone ◦ Stimulates replacement of cartilage in epiphyseal plates ◦ Halts bone growth by causing premature ossification ◦ Deficiency (not enough) thyroid hormone may stunt growth ◦ Secreted by thyroid gland  Parathyroid Hormone ◦ Stimulates increase in number & activity of osteoclasts

44.  Sex hormones ◦ Estrogen & testosterone  Secreted from ovaries, testes, & adrenal glands  Promotes formation of bone tissue  Increase in abundance at puberty  Also stop bone lengthening at a relatively early age  This effect is stronger in females, because estrogen is stronger than testosterone, so females stop growing sooner than males

45.  Physical stress ◦ Stimulates bone growth ◦ Lack of exercise leads to thinner & weaker bones (atrophy)  Vitamin D ◦ Necessary for absorption of calcium in small intestine ◦ In vitamin D poor diet, calcium is not absorbed properly and deforms bones ◦ Active form of Vit D requires exposure to ultraviolet light  Vitamin A & C ◦ Vitamin A necessary for osteoblast & osteoclast activity (lack may prevent normal bone development) ◦ Vitamin C required for collagen synthesis (also may prevent normal bone development)

46.  Formation of blood cells  Occurs in bone marrow  Red marrow ◦ Produces red blood cells (erythrocytes), white blood cells (leukocytes), and blood platelets ◦ Called red marrow due to red, oxygen-carrying pigement (hemoglobin) that is found inside of the red blood cells

47.  Inorganic mineral salts account for 70 % of weight of bones  Inorganic salts are mostly tiny crystals of calcium phosphate (hydroxyapatite)  Low blood calcium results in parathyroid hormone stimulating osteoclasts to break down bone matrix releasing calcium into blood stream  High blood calcium results in calcitonin from the thyroid gland, which stimulates osteoblasts to form bone tissue