Anatomy and Physiology Chapter 6 PDF

Chapter 6: Bones and Skeletal Tissue Cranium Skull Facial bones Clavicle Thoracic cage (ribs, sternum...

Chapter 6: Bones and Skeletal Tissue Cranium Skull Facial bones Clavicle Thoracic cage (ribs, sternum Scapula and thoracic vertebrae) Sternum Rib Humerus Vertebra Vertebral column Radius Ulna Sacru m Carpals Phalanges Metacarpals Femur Patella Tibia Fibula Tarsals Metatarsals (a) Anterior Phalanges view  Functions of Bones and Skeletal Cartilage Figure 6.1 The bones and cartilages of the human skeleton. There are seven important functions of bones: 1. Support 2. Protection 3. Movement 4. Mineral and growth factor storage 5. Blood cell formation 6. Triglyceride (fat) storage 7. Hormone production  Osteocalcin secreted by bones helps to regulate insulin secretion, glucose levels, and metabolism © 2019 Pearson Education, Inc.  Classification of Bones on the Basis of Shape Figure 6.2 Classification of bones on the basis of shape.  Compact and Spongy Bone Figure 6.3 Compact and spongy bone. Figure 6.4 Structure of a flat bone.  The Structure of a Long Bone (Humerus of Arm) Figure 6.5a The structure of a long bone (humerus of arm).  Figure 6.7 Microscopic anatomy of compact bone. Compact bone Spongy bone Central Perforating (Haversian) canal (Volkmann’s) canal Endosteum lining bony canals Osteon and covering trabeculae (Haversian system) Circumferential lamellae Perforating (Sharpey’s) fibers Lamellae Periosteal blood vessel Periosteum Nerve Vein Artery Lamellae Central Canaliculi canal Osteocyte Lacunae in a lacuna Interstitial Lacuna lamella© 2013(with osteocyte) Pearson Education, Inc.  Figure 6.6 A single osteon. Artery with capillaries Structures in the Vein central Nerve fiber canal Lamellae Collagen fibers run in different directions Twisting force © 2013 Pearson Education, Inc.  Microscopic Anatomy of Bone: Cells of Bone Tissue Five major cell types 1. Osteogenic cells 2. Osteoblasts 3. Osteocytes 4. Bone lining cells 5. Osteoclasts  Chemical Composition of Bone: Organic Components  Includes cells and osteoid  Cells- Osteogenic cells, osteoblasts, osteocytes, bone- lining cells, and osteoclasts  Osteoid—1/3 of organic bone matrix secreted by osteoblasts  Collagen fibers  Contributes to structure; provides tensile strength and flexibility  Resilience of bone is due to sacrificial bonds in or between collagen molecules  Mineral salts  65% of bone by mass  Mainly of tiny calcium phosphate crystals in and around collagen fibers  Responsible for hardness and resistance to compression  Bone Development: Two Types of Ossification  Endochondral ossification- forms most of the skeleton  Bone forms by replacing hyaline cartilage  Bone Development: Two Types of Ossification  Intramembranous ossification-Bone develops from fibrous membrane  Forms flat bones: clavicles and cranial bones © 2019 Pearson Education, Inc.  Postnatal Bone Growth Interstitial (longitudinal) growth  Increase in length of long bones How Do We Regulate Bone Growth?  Control of Remodeling Occurs continuously but regulated by genetic factors and two control loops 1. Negative feedback hormonal loop for Ca2+ homeostasis  Controls blood Ca2+ levels; Not bone integrity 2. Responses to mechanical and gravitational forces  Importance of Calcium Functions in  Nerve impulse transmission  Muscle contraction  Blood coagulation  Secretion by glands and nerve cells  Cell division 1200 – 1400 grams of calcium in body (18-24)  99% as bone minerals  Amount in blood tightly regulated (9-11 mg/dl) (100ml)  Intestinal absorption requires Vitamin D metabolites  Dietary intake required  Hormonal Control of Blood Ca2+  Parathyroid hormone (PTH)-Produced by parathyroid glands  Removes calcium from bone regardless of bone integrity  Results of Mechanical Stressors: Appositional Growth and Wolff's Law Appositional Growth- Growth in thickness or width  Continues throughout a lifetime Wolff’s Law: Bones grow or remodel in response to demands placed on it. Explains  Handedness (right or left-handed) results in thicker and stronger bone of that upper limb  Curved bones thickest where most likely to buckle  Trabeculae form trusses along lines of stress  Large, bony projections occur where heavy, active muscles attach  Bones of fetus and bedridden featureless  Bone Repair Fractures or “Breaks”  During Youth  Most result from trauma  During Old Age  Most result of weakness from bone thinning  Fracture Classification Three "either/or" fracture classifications  Position of bone ends after fracture  Nondisplaced—ends retain normal position  Displaced—ends out of normal alignment  Completeness of break  Complete—broken all the way through  Incomplete—not broken all the way through  Whether skin is penetrated  Open (compound) - skin is penetrated  Closed (simple) – skin is not penetrated  Table 6.3-1 Common Types of Fractures Table 6.3-1 Common Types of Fractures.  Table 6.3-2 Common Types of Fractures Table 6.3-2 Common Types of Fractures.  Table 6.3-3 Common Types of Fractures Table 6.3-3 Common Types of Fractures.  Fracture Treatment and Repair Treatment Reduction Realignment of broken bone ends  Closed reduction – physician manipulates to correct position  Open reduction – surgical pins or wires secure ends Immobilization by cast or traction for healing  Depends on break severity, bone broken, and age of patient  Stages of Bone Repair: HEMATOMA Forms Torn blood vessels hemorrhage Clot (hematoma) forms Site swollen, painful, and inflamed https://www.youtube.com/watch?v=-P6LsendHxU  Homeostatic Imbalances  Osteomalacia Rickets Disease  Calcium salts not adequate, poorly mineralized bone  Soft, weak bones  Pain upon bearing weight  Rickets (osteomalacia of children)  Bowed legs and other bone deformities  Bones ends enlarged and abnormally long  Cause: Vitamin D deficiency or insufficient dietary calcium  Homeostatic Imbalances  Osteoporosis  Group of diseases  Bone resorption outpaces deposit  Spongy bone of spine and neck of femur most susceptible  Vertebral and hip fractures common  Risk factors  Most often aged, postmenopausal women  30% 60 – 70 years of age; 70% by age 80  30% Caucasian women will fracture bone because of it  Men to lesser degree  Sex hormones maintain normal bone health and density  As secretion wanes with age osteoporosis can develop