Chapter 6 Osseous Tissue and Bone Structure Lecture

Chapter 6 Osseous Tissue and Bone Structure Lecture

Chapter 6 Osseous Tissue and Bone Structure Lecture Presentation by Lee Ann Frederick University of Texas at Arlington 2015 Pearson Education, Inc. An Introduction to the Skeletal System Learning Outcomes 6-1 Describe the primary functions of the skeletal system. 6-2 Classify bones according to shape and internal organization, giving examples of each type,

and explain the functional significance of each of the major types of bone markings. 6-3 Identify the cell types in bone, and list their major functions. 2015 Pearson Education, Inc. An Introduction to the Skeletal System Learning Outcomes 6-4 Compare the structures and functions of compact bone and spongy bone. 6-5 Compare the mechanisms of endochondral ossification and intramembranous ossification. 6-6 Describe the remodeling and homeostatic mechanisms of the skeletal system. 6-7 Discuss the effects of exercise, hormones, and nutrition on bone development and on the

skeletal system. 2015 Pearson Education, Inc. An Introduction to the Skeletal System Learning Outcomes 6-8 to the Explain the role of calcium as it relates skeletal system. 6-9 explain Describe the types of fractures, and how fractures heal.

6-10 Summarize the effects of the aging process on the skeletal system. 2015 Pearson Education, Inc. An Introduction to the Skeletal System The Skeletal System Includes: Bones of the skeleton Cartilages, ligaments, and connective tissues 2015 Pearson Education, Inc. 6-1 Functions of the Skeletal System Five Primary Functions of the Skeletal System 1. Support 2. Storage of Minerals (calcium) and Lipids (yellow

marrow) 3. Blood Cell Production (red marrow) 4. Protection 5. Leverage (force of motion) 2015 Pearson Education, Inc. 6-2 Classification of Bones Bones Are classified by: Shape Internal tissue organization Bone markings (surface features; marks) 2015 Pearson Education, Inc. 6-2 Classification of Bones

Six Bone Shapes 1. Sutural bones 2. Irregular bones 3. Short bones 4. Flat bones 5. Long bones 6. Sesamoid bones 2015 Pearson Education, Inc. Figure 6-1 A Classification of Bones by Shape. (d) Flat Bones (a) Sutural Bones Sutural bones, or Wormian bones, are

small, flat, oddly shaped bones found between the flat bones of the skull. They range in size from a grain of sand to a quarter. Their borders are like pieces of a jigsaw puzzle. Sutural bone Sutures Flat bones have thin, parallel surfaces. Flat bones form the roof of the skull, the sternum (breastbone), the ribs, and scapulae (shoulder blades). They

provide protection for underlying soft tissues and offer an extensive surface area for the attachment of skeletal muscles. Parietal bone Sectional view (b) Irregular Bones Irregular bones have complex shapes with short, flat, notched, or ridged surfaces. The vertebrae that form the spinal column, the bones of the pelvis, and several bones in the skull are

examples of irregular bones. (e) Long Bones Vertebra Humerus Long bones are relatively long and slender. They are located in the arm and forearm, thigh and leg, palms, soles, fingers, and toes. The femur, the long bone of the thigh, is the largest and heaviest bone In the body.

(c) Short Bones Short bones are boxlike in appearance. Examples of short bones include the carpal bones (wrists) and tarsal bones (ankles). 2015 Pearson Education, Inc. (f) Sesamoid Bones Carpal bones Patella

Sesamoid bones are usually small, round, and flat. They develop inside tendons and are most often encountered near joints at the knee, the hands, and the feet. Few individuals have sesamoid bones at every possible location, but everyone has sesamoid patellae (pa-TEL-e; singular, patella, a small shallow dish), or kneecaps. 6-2 Classification of Bones Sutural Bones Small, irregular bones Found between the flat bones of the skull

Irregular Bones Have complex shapes Examples: spinal vertebrae, pelvic bones 2015 Pearson Education, Inc. Figure 6-1a A Classification of Bones by Shape. (a) Sutural Bones Sutural bones, or Wormian bones, are small, flat, oddly shaped bones found between the flat bones of the skull. They range in size from a grain of

sand to a quarter. Their borders are like pieces of a jigsaw puzzle. 2015 Pearson Education, Inc. Sutural bone Sutures Figure 6-1b A Classification of Bones by Shape. (b) Irregular Bones Irregular bones have complex shapes with short, flat, notched, or

ridged surfaces. The vertebrae that form the spinal column, the bones of the pelvis, and several bones in the skull are examples of irregular bones. 2015 Pearson Education, Inc. Vertebra Figure 6-1c A Classification of Bones by Shape. (c) Short Bones Short bones are boxlike in appearance. Examples of short

bones include the carpal bones (wrists) and tarsal bones (ankles). 2015 Pearson Education, Inc. Carpal bones 6-2 Classification of Bones Short Bones Small and thick Examples: ankle and wrist bones Flat Bones Thin with parallel surfaces

Found in the skull, sternum, ribs, and scapulae 2015 Pearson Education, Inc. 6-2 Classification of Bones Long Bones Long and thin Found in arms, legs, hands, feet, fingers, and toes Sesamoid Bones Small and flat Develop inside tendons near joints of knees, hands, and feet 2015 Pearson Education, Inc. Figure 6-1d A Classification of Bones by Shape.

(d) Flat Bones Flat bones have thin, parallel surfaces. Flat bones form the roof of the skull, the sternum (breastbone), the ribs, and scapulae (shoulder blades). They provide protection for underlying soft tissues and offer an extensive surface area for the attachment of skeletal muscles. Parietal bone Sectional view 2015 Pearson Education, Inc. Figure 6-1e A Classification of Bones by Shape.

(e) Long Bones Humerus 2015 Pearson Education, Inc. Long bones are relatively long and slender. They are located in the arm and forearm, thigh and leg, palms, soles, fingers, and toes. The femur, the long bone of the thigh, is the largest and heaviest bone In the body. Figure 6-1f A Classification of Bones by Shape.

(f) Sesamoid Bones Patella 2015 Pearson Education, Inc. Sesamoid bones are usually small, round, and flat. They develop inside tendons and are most often encountered near joints at the knee, the hands, and the feet. Few individuals have sesamoid bones at every possible location, but everyone has sesamoid patellae (pa-TEL-e; singular, patella, a small shallow dish), or kneecaps.

6-2 Classification of Bones Bone Markings Depressions or grooves Along bone surface Elevations or projections Where tendons and ligaments attach At articulations with other bones Tunnels Where blood and nerves enter bone 2015 Pearson Education, Inc. Figure 6-2 An Introduction to Bone Markings (Part 1 of 2).

Openings Sinus: Elevations and Projections Foramen: Rounded passageway for blood vessels and/or nerves Process: Projection or bump Ramus: Extension of a bone that forms an angle with the rest of the structure

Skull, anterior view 2015 Pearson Education, Inc. Chamber within a bone, normally filled with air Fissure: Deep furrow, cleft, or slit Meatus: Passage or channel, especially the opening of a canal

Canal: Duct or channel Skull, lateral view Figure 6-2 An Introduction to Bone Markings (Part 2 of 2). Head Pelvis Neck Processes formed where tendons or ligaments attach

Processes formed where joints (articulations) occur between adjacent bones Trochanter: Large, rough projection Head: Expanded articular end of an epiphysis, often separated from the shaft by a narrower neck (see Figure 63a) Neck:

Narrow connection between the epiphysis And diaphysis (see Figure 63a) Facet: Small, flat articular surface Crest: Prominent ridge Spine:

Pointed process Line: Low ridge Tubercle: Small, rounded projection Depressions Sulcus: Narrow groove

Fossa: Shallow depression Tuberosity: Rough projection Humerus Condyle 2015 Pearson Education, Inc. Femur Condyle: Smooth, rounded articular process

Trochlea: Smooth, grooved articular process shaped like a pulley 6-2 Classification of Bones Structure of a Long Bone Diaphysis The shaft A heavy wall of compact bone, or dense bone A central space called medullary (marrow) cavity Epiphysis Wide part at each end Articulation with other bones Mostly spongy (cancellous) bone Covered with compact bone (cortex)

Metaphysis Where diaphysis and epiphysis meet 2015 Pearson Education, Inc. Figure 6-3a Bone Structure. Spongy bone Epiphysis Metaphysis Compact bone Diaphysis (shaft)

Medullary cavity Metaphysis Epiphysis a The structure of a representative long bone (the femur) in longitudinal section 2015 Pearson Education, Inc. 6-2 Classification of Bones Structure of a Flat Bone The parietal bone of the skull Resembles a sandwich of spongy bone Between two layers of compact bone Within the cranium, the layer of spongy bone

between the compact bone is called the diplo 2015 Pearson Education, Inc. Figure 6-3b Bone Structure. Cortex (compact bone) Diplo (spongy bone) b The structure of a flat bone (the parietal bone) 2015 Pearson Education, Inc. 6-3 Bone (Osseous) Tissue

Bone (Osseous) Tissue Dense, supportive connective tissue Contains specialized cells Produces solid matrix of calcium salt deposits Around collagen fibers 2015 Pearson Education, Inc. 6-3 Bone (Osseous) Tissue Characteristics of Bone Tissue Dense matrix, containing: Deposits of calcium salts Osteocytes (bone cells) within lacunae organized around blood vessels Canaliculi Form pathways for blood vessels

Exchange nutrients and wastes 2015 Pearson Education, Inc. 6-3 Bone (Osseous) Tissue Characteristics of Bone Tissue Periosteum Covers outer surfaces of bones Consists of outer fibrous and inner cellular layers 2015 Pearson Education, Inc. 6-3 Bone (Osseous) Tissue Bone Matrix Minerals Two-thirds of bone matrix is calcium phosphate, Ca3(PO4)2

Reacts with calcium hydroxide, Ca(OH)2 To form crystals of hydroxyapatite, Ca10(PO4)6(OH)2 Which incorporates other calcium salts and ions 2015 Pearson Education, Inc. 6-3 Bone (Osseous) Tissue Bone Matrix Matrix proteins One-third of bone matrix is protein fibers (collagen) 2015 Pearson Education, Inc. 6-3 Bone (Osseous) Tissue Bone Cells Make up only 2 percent of bone mass Bone contains four types of cells

1. Osteocytes 2. Osteoblasts 3. Osteoprogenitor cells 4. Osteoclasts 2015 Pearson Education, Inc. Figure 6-4 Types of Bone Cells. Canaliculi Osteocyte Matrix Osteocyte: Mature bone cell that maintains the bone matrix Osteogenic cell Medullary cavity Endosteum

Osteogenic cell: Stem cell whose divisions produce osteoblasts 2015 Pearson Education, Inc. Matrix Osteoid Osteoblast Osteoblast: Immature bone cell that secretes osteoid, the organic component of bone matrix Osteoclast

Matrix Medullary cavity Osteoclast: Multinucleate cell that secretes acids and enzymes to dissolve bone matrix 6-3 Bone (Osseous) Tissue Osteocytes Mature bone cells that maintain the bone matrix Live in lacunae Are between layers (lamellae) of matrix Connect by cytoplasmic extensions through canaliculi in lamellae Do not divide

Two major functions of osteocytes 1. To maintain protein and mineral content of matrix 2. To help repair damaged bone 2015 Pearson Education, Inc. Figure 6-4 Types of Bone Cells (Part 1 of 4). Canaliculi Osteocyte Matrix Osteocyte: Mature bone cell that maintains the bone matrix 2015 Pearson Education, Inc. 6-3 Bone (Osseous) Tissue Osteoblasts Immature bone cells that secrete matrix

compounds (osteogenesis) Osteoid matrix produced by osteoblasts, but not yet calcified to form bone Osteoblasts surrounded by bone become osteocytes 2015 Pearson Education, Inc. Figure 6-4 Types of Bone Cells (Part 2 of 4). Matrix Osteoid Osteoblast Osteoblast: Immature bone cell

that secretes osteoid, the organic component of bone matrix 2015 Pearson Education, Inc. 6-3 Bone (Osseous) Tissue Osteoprogenitor Cells Mesenchymal stem cells that divide to produce osteoblasts Located in endosteum, the inner cellular layer of periosteum Assist in fracture repair 2015 Pearson Education, Inc. Figure 6-4 Types of Bone Cells (Part 3 of 4).

Osteogenic cell Medullary cavity Endosteum Osteogenic cell: Stem cell whose divisions produce osteoblasts 2015 Pearson Education, Inc. 6-3 Bone (Osseous) Tissue Osteoclasts Secrete acids and protein-digesting enzymes Giant, multinucleate cells Dissolve bone matrix and release stored minerals (osteolysis) Derived from stem cells that produce

macrophages 2015 Pearson Education, Inc. Figure 6-4 Types of Bone Cells (Part 4 of 4). Osteoclast Matrix Medullary cavity Osteoclast: Multinucleate cell that secretes acids and enzymes to dissolve bone matrix

2015 Pearson Education, Inc. 6-3 Bone (Osseous) Tissue Homeostasis Bone building (by osteoblasts) and bone recycling (by osteoclasts) must balance More breakdown than building, bones become weak Exercise, particularly weight-bearing exercise, causes osteoblasts to build bone 2015 Pearson Education, Inc. 6-4 Compact Bone and Spongy Bone The Structure of Compact Bone Osteon is the basic unit Osteocytes are arranged in concentric lamellae

Around a central canal containing blood vessels Perforating canals Perpendicular to the central canal Carry blood vessels into bone and marrow 2015 Pearson Education, Inc. 6-4 Compact Bone and Spongy Bone The Structure of Compact Bone Circumferential lamellae Lamellae wrapped around the long bone Bind osteons together 2015 Pearson Education, Inc. Figure 6-5a The Histology of Compact Bone.

Central canal Canaliculi Concentric lamellae Osteon Lacunae Osteon LM 343 a A thin section through compact bone. By this procedure the intact matrix making up the lamellae appear white, and the central

canal, lacunae, and canaliculi appear black due to the presence of bone dust. 2015 Pearson Education, Inc. Figure 6-5b The Histology of Compact Bone. Osteon Lacunae Central canals Lamellae Osteons

SEM 182 b Several osteons in compact bone. 2015 Pearson Education, Inc. Figure 6-6a The Structure of Compact Bone (Part 1 of 2). Venule Circumferential lamellae Capillary Osteons

Periosteum Perforating fibers Interstitial lamellae Concentric lamellae Trabeculae of spongy bone (see Fig. 67) Vein Artery Arteriole

Central Perforating canal canal a The organization of osteons and lamellae in compact bone 2015 Pearson Education, Inc. Figure 6-6a The Structure of Compact Bone (Part 2 of 2). Central canal Concentric lamellae Endosteum a The organization of osteons

and lamellae in compact bone 2015 Pearson Education, Inc. Figure 6-6b The Structure of Compact Bone. Collagen fiber orientation b The orientation of collagen fibers in adjacent lamellae 2015 Pearson Education, Inc. 6-4 Compact Bone and Spongy Bone The Structure of Spongy Bone Does not have osteons

The matrix forms an open network of trabeculae Trabeculae have no blood vessels The space between trabeculae is filled with red bone marrow Which has blood vessels Forms red blood cells And supplies nutrients to osteocytes Yellow bone marrow In some bones, spongy bone holds yellow bone marrow Is yellow because it stores fat 2015 Pearson Education, Inc. Figure 6-7 The Structure of Spongy Bone. Trabeculae of spongy bone

Canaliculi opening on surface 2015 Pearson Education, Inc. Endosteum Lamellae 6-4 Compact Bone and Spongy Bone Weight-Bearing Bones The femur transfers weight from hip joint to knee joint Causing tension on the lateral side of the shaft And compression on the medial side 2015 Pearson Education, Inc.

Figure 6-8 The Distribution of Forces on a Long Bone. Body weight (applied force) Tension on lateral side of shaft Compression on medial side of shaft 2015 Pearson Education, Inc. 6-4 Compact Bone and Spongy Bone Compact Bone Is Covered with a Membrane Periosteum on the outside

Covers all bones except parts enclosed in joint capsules Made up of an outer, fibrous layer and an inner, cellular layer Perforating fibers: collagen fibers of the periosteum Connect with collagen fibers in bone And with fibers of joint capsules; attach tendons, and ligaments 2015 Pearson Education, Inc. 6-4 Compact Bone and Spongy Bone Functions of Periosteum 1. Isolates bone from surrounding tissues 2. Provides a route for circulatory and nervous supply 3. Participates in bone growth and repair

2015 Pearson Education, Inc. Figure 6-9a The Periosteum and Endosteum. Circumferential lamellae Periosteum Fibrous layer Cellular layer Canaliculi Osteocyte in lacuna Perforating fibers a The periosteum contains outer

(fibrous) and inner (cellular) layers. Collagen fibers of the periosteum are continuous with those of the bone, adjacent joint capsules, and attached tendons and ligaments. 2015 Pearson Education, Inc. 6-4 Compact Bone and Spongy Bone Compact Bone Is Covered with a Membrane Endosteum on the inside An incomplete cellular layer: Lines the medullary (marrow) cavity Covers trabeculae of spongy bone Lines central canals Contains osteoblasts, osteoprogenitor cells, and osteoclasts Is active in bone growth and repair

2015 Pearson Education, Inc. Figure 6-9b The Periosteum and Endosteum. Endosteum Osteoclast Bone matrix Osteocyte Osteogenic cell Osteoid Osteoblast 2015 Pearson Education, Inc. b The endosteum is an incomplete

cellular layer containing osteoblasts, osteogenic cells, and osteoclasts. 6-5 Bone Formation and Growth Bone Development Human bones grow until about age 25 Osteogenesis Bone formation Ossification The process of replacing other tissues with bone 2015 Pearson Education, Inc. 6-5 Bone Formation and Growth Bone Development

Calcification The process of depositing calcium salts Occurs during bone ossification and in other tissues Ossification Two main forms of ossification 1. Endochondral ossification 2. Intramembranous ossification 2015 Pearson Education, Inc. 6-5 Bone Formation and Growth Endochondral Ossification Ossifies bones that originate as hyaline cartilage Most bones originate as hyaline cartilage There are seven main steps in endochondral

ossification 2015 Pearson Education, Inc. Figure 6-11 Endochondral Ossification (Part 5 of 11). 1 As the cartilage enlarges, chondrocytes near the center of the shaft increases greatly in size. The matrix is reduced to a series of small struts that soon begin to calcify. The enlarged chondrocytes

then die and disintegrate, leaving cavities within the cartilage. Enlarging chondrocytes within calcifying matrix Hyaline cartilage Disintegrating chondrocytes of the cartilage model 2015 Pearson Education, Inc.

Figure 6-11 Endochondral Ossification (Part 6 of 11). 2 Blood vessels grow around the edges of the cartilage, and the cells of the perichondrium convert to osteoblasts. The shaft of the cartilage then becomes ensheathed in a superficial layer of bone. Perichondrium

Epiphysis Bone collar Diaphysis Blood vessel Periosteum formed from perichondrium 2015 Pearson Education, Inc. Figure 6-11 Endochondral Ossification (Part 7 of 11). 3

Blood vessels penetrate the cartilage and invade the central region. Fibroblasts migrating with the blood vessels differentiate into osteoblasts and begin producing spongy bone at a primary ossification center. Bone formation then spreads along the shaft toward both ends of the former cartilage model. Medullary

cavity Primary ossification center Superficial bone Spongy bone 2015 Pearson Education, Inc. Figure 6-11 Endochondral Ossification (Part 8 of 11). 4 Remodeling occurs as growth continues, creating

a medullary cavity. The osseous tissue of the shaft becomes thicker, and the cartilage near each epiphysis is replaced by shafts of bone. Further growth involves increases in length and diameter. Medullary cavity Metaphysis 2015 Pearson Education, Inc. Figure 6-11 Endochondral Ossification (Part 9 of 11).

5 Capillaries and osteoblasts migrate into the epiphyses, creating secondary ossification centers. Hyaline cartilage Epiphysis Metaphysis Periosteum Compact

bone Secondary ossification center 2015 Pearson Education, Inc. Figure 6-11 Endochondral Ossification (Part 10 of 11). 6 The epiphyses eventually become filled with spongy bone. The metaphysis, a relatively narrow cartilaginous region called the epiphyseal cartilage, or epiphyseal plate, now separates the epiphysis from the

diaphysis. On the shaft side of the metaphysis, osteoblasts continuously invade the cartilage and replace it with bone. New cartilage is produced at the same rate on the epiphyseal side. Articular cartilage Spongy bone Epiphyseal cartilage Diaphysis Within the epiphyseal cartilage, the chondrocytes are organized into zones. Chondrocytes at the

epiphyseal side of the cartilage continue to divide and enlarge. Chondrocytes degenerate at the diaphyseal side. Osteoblasts migrate upward from the diaphysis and cartilage is gradually replaced by bone. 2015 Pearson Education, Inc. Figure 6-11 Endochondral Ossification (Part 11 of 11). 7 At puberty, the rate of epiphyseal cartilage production slows and the

rate of osteoblast activity accelerates. As a result, the epiphyseal cartilage gets narrower and narrower, until it ultimately disappears. This event is called epiphyseal closure. The former location of the epiphyseal cartilage becomes a distinct epiphyseal line that remains after epiphyseal growth has ended. Articular cartilage Epiphyseal line Spongy bone Medullary cavity

A thin cap of the original cartilage model remains exposed to the joint cavity as the articular cartilage. This cartilage prevents damaging the joint from bone-to-bone contact. 2015 Pearson Education, Inc. 6-5 Bone Formation and Growth Appositional Growth Compact bone thickens and strengthens long bone with layers of circumferential lamellae 2015 Pearson Education, Inc. 6-5 Bone Formation and Growth Epiphyseal Lines When long bone stops growing, after puberty:

Epiphyseal cartilage disappears Is visible on x-rays as an epiphyseal line Mature Bones As long bone matures: Osteoclasts enlarge medullary (marrow) cavity Osteons form around blood vessels in compact bone 2015 Pearson Education, Inc. Figure 6-10a Bone Growth at an Epiphyseal Cartilage. a An x-ray of growing epiphyseal cartilages (arrows) 2015 Pearson Education, Inc. Figure 6-10b Bone Growth at an Epiphyseal Cartilage.

b Epiphyseal lines in an adult (arrows) 2015 Pearson Education, Inc. 6-5 Bone Formation and Growth Intramembranous Ossification Also called dermal ossification Because it occurs in the dermis Produces dermal bones such as mandible (lower jaw) and clavicle (collarbone) There are five main steps in intramembranous ossification 2015 Pearson Education, Inc.

Figure 6-12 Intramembranous Ossification (Part 1 of 5). Parietal bone Frontal bone Occipital bone Mandible Intramembranous ossification starts about the eighth week of embryonic development. This type of ossification occurs in the deeper layers of the dermis, forming dermal bones. 2015 Pearson Education, Inc.

1 Mesenchymal cells cluster together, differentiate into osteoblasts, and start to secrete the organic components of the matrix. The resulting osteoid then becomes mineralized with calcium salts forming bone matrix. Bone matrix Osteoid Mesenchymal cell Ossification center

Blood vessel Osteoblast Figure 6-12 Intramembranous Ossification (Part 2 of 5). 2 As ossification proceeds, some osteoblasts are trapped inside bony pockets where they differentiate into osteocytes. The developing bone grows outward from the ossification center in small struts called spicules. 2015 Pearson Education, Inc.

Spicules Osteocyte Figure 6-12 Intramembranous Ossification (Part 3 of 5). 3 Blood vessels begin to branch within the region and grow between the spicules. The rate of bone growth accelerates with oxygen and a reliable supply of nutrients. As spicules interconnect, they

trap blood vessels within the bone. 2015 Pearson Education, Inc. Blood vessel trapped within bone matrix Figure 6-12 Intramembranous Ossification (Part 4 of 5). 4 Continued deposition of bone by osteoblasts located close to blood vessels results in a plate

of spongy bone with blood vessels weaving throughout. 2015 Pearson Education, Inc. Figure 6-12 Intramembranous Ossification (Part 5 of 5). 5 Areas of spongy bone are remodeled forming the diplo and a thin covering of compact (cortical) bone. 2015 Pearson Education, Inc.

Subsequent remodeling around blood vessels produces osteons typical of compact bone. Osteoblasts on the bone surface along with connective tissue around the bone become the periosteum. Fibrous periosteum Blood vessels trapped within bone matrix Cellular periosteum

6-5 Bone Formation and Growth Blood Supply of Mature Bones 1. Nutrient artery and vein A single pair of large blood vessels Enter the diaphysis through the nutrient foramen Femur has more than one pair 2. Metaphyseal vessels Supply the epiphyseal cartilage Where bone growth occurs 3. Periosteal vessels Blood to superficial osteons Secondary ossification centers 2015 Pearson Education, Inc. Figure 6-13 The Blood Supply to a Mature Bone.

Vessels in Bone Epiphyseal artery and vein Articular cartilage Metaphyseal artery and vein Branches of nutrient artery and vein Nutrient artery and vein Periosteal arteries and veins

Periosteum Connections to superficial osteons Metaphyseal artery and vein 2015 Pearson Education, Inc. Periosteum Compact bone Medullary cavity Nutrient foramen Metaphysis

Epiphyseal line 6-5 Bone Formation and Growth Lymph and Nerves The periosteum also contains: Networks of lymphatic vessels Sensory nerves 2015 Pearson Education, Inc. 6-6 Bone Remodeling Process of Remodeling The adult skeleton: Maintains itself Replaces mineral reserves Recycles and renews bone matrix

Involves osteocytes, osteoblasts, and osteoclasts 2015 Pearson Education, Inc. 6-6 Bone Remodeling Process of Remodeling Bone continually remodels, recycles, and replaces Turnover rate varies: If deposition is greater than removal, bones get stronger If removal is faster than replacement, bones get weaker 2015 Pearson Education, Inc. 6-7 Exercise, Hormones, and Nutrition Effects of Exercise on Bone

Mineral recycling allows bones to adapt to stress Heavily stressed bones become thicker and stronger Bone Degeneration Bone degenerates quickly Up to one-third of bone mass can be lost in a few weeks of inactivity 2015 Pearson Education, Inc. 6-7 Exercise, Hormones, and Nutrition Normal Bone Growth and Maintenance Depend on Nutritional and Hormonal Factors A dietary source of calcium and phosphate salts Plus small amounts of magnesium, fluoride, iron, and manganese

2015 Pearson Education, Inc. 6-7 Exercise, Hormones, and Nutrition Normal Bone Growth and Maintenance Depend on Nutritional and Hormonal Factors The hormone calcitriol Made in the kidneys Helps absorb calcium and phosphorus from digestive tract Synthesis requires vitamin D3 (cholecalciferol) 2015 Pearson Education, Inc. 6-7 Exercise, Hormones, and Nutrition Normal Bone Growth and Maintenance Depend on Nutritional and Hormonal Factors

Vitamin C is required for collagen synthesis and stimulation of osteoblast differentiation Vitamin A stimulates osteoblast activity Vitamins K and B12 help synthesize bone proteins 2015 Pearson Education, Inc. 6-7 Exercise, Hormones, and Nutrition Normal Bone Growth and Maintenance Depend on Nutritional and Hormonal Factors Growth hormone and thyroxine stimulate bone growth Estrogens and androgens stimulate osteoblasts Calcitonin and parathyroid hormone regulate calcium and phosphate levels 2015 Pearson Education, Inc.

Table 6-1 Hormones Involved in Bone Growth and Maintenance. 2015 Pearson Education, Inc. 6-8 Calcium Homeostasis The Skeleton as a Calcium Reserve Bones store calcium and other minerals Calcium is the most abundant mineral in the body Calcium ions are vital to: Membranes Neurons Muscle cells, especially heart cells 2015 Pearson Education, Inc. Figure 6-14 A Chemical Analysis of Bone.

Composition of Bone Bone Contains Calcium 39% Potassium 0.2% Sodium 0.7% Organic compounds (mostly collagen) 33% 4% of the bodys Potassium 35% of the bodys Sodium Magnesium 0.5%

50% of the bodys Magnesium Carbonate 9.8% 80% of the bodys Carbonate Phosphate 17% 99% of the bodys Phosphate Total inorganic 67% components 2015 Pearson Education, Inc. 99% of the bodys Calcium

6-8 Calcium Homeostasis Calcium Regulation Calcium ions in body fluids Must be closely regulated Homeostasis is maintained By calcitonin and parathyroid hormone (PTH) Which control storage, absorption, and excretion 2015 Pearson Education, Inc. 6-8 Calcium Homeostasis Calcitonin and Parathyroid Hormone Control Affect: 1. Bones Where calcium is stored

2. Digestive tract Where calcium is absorbed 3. Kidneys Where calcium is excreted 2015 Pearson Education, Inc. 6-8 Calcium Homeostasis Parathyroid Hormone (PTH) Produced by parathyroid glands in neck Increases calcium ion levels by: 1. Stimulating osteoclasts 2. Increasing intestinal absorption of calcium 3. Decreasing calcium excretion at kidneys

Calcitonin Secreted by C cells (parafollicular cells) in thyroid Decreases calcium ion levels by: 1. Inhibiting osteoclast activity 2. Increasing calcium excretion at kidneys 2015 Pearson Education, Inc. Figure 6-15a Factors That Alter the Concentration of Calcium Ions in Blood. a Factors That Increase Blood Calcium Levels These responses are triggered when blood calcium ion concentrations decrease below 8.5 mg/dL. Low Calcium Ion Levels in Blood (below 8.5 mg/dL)

Parathyroid Gland Response Low calcium levels cause the parathyroid glands to secrete parathyroid hormone (PTH). PTH Bone Response Intestinal Response Kidney Response Osteoclasts stimulated to release stored calcium ions from bone

Rate of intestinal absorption of calcium increases Kidneys retain calcium ions Osteoclast more Bone Calcium released

calcitriol Calcium absorbed quickly Ca2+ levels in blood increase 2015 Pearson Education, Inc. Calcium conserved Decreased calcium loss in urine Figure 6-15b Factors That Alter the Concentration of Calcium Ions in Blood.

b Factors That Decrease Blood Calcium Levels These responses are triggered when blood calcium ion concentrations increase above 11 mg/dL. High Calcium Ion Levels in Blood (above 11 mg/dL) Thyroid Gland Response Parafollicular cells (C cells) in the thyroid gland secrete calcitonin. Calcitonin Bone Response

Intestinal Response Kidney Response Osteoclasts inhibited while osteoblasts continue to lock calcium ions in bone matrix Rate of intestinal absorption of calcium decreases Kidneys allow calcium

loss less Bone calcitriol Calcium absorbed slowly Calcium excreted Calcium stored Ca2+ levels in blood decrease

2015 Pearson Education, Inc. Increased calcium loss in urine 6-9 Fractures Fractures Cracks or breaks in bones Caused by physical stress Fractures are repaired in four steps 1. Bleeding 2. Cells of the endosteum and periosteum 3. Osteoblasts 4. Osteoblasts and osteocytes remodel the fracture for up to a year

2015 Pearson Education, Inc. 6-9 Fractures Bleeding Produces a clot (fracture hematoma) Establishes a fibrous network Bone cells in the area die Cells of the endosteum and periosteum Divide and migrate into fracture zone Calluses stabilize the break External callus of cartilage and bone surrounds break Internal callus develops in medullary cavity 2015 Pearson Education, Inc. 6-9 Fractures Osteoblasts

Replace central cartilage of external callus With spongy bone Osteoblasts and osteocytes remodel the fracture for up to a year Reducing bone calluses 2015 Pearson Education, Inc. 2015 Pearson Education, Inc. Spiral fracture Compression fracture Displaced fracture

Transverse fracture Figure 6-16 Types of Fractures and Steps in Repair (Part 1 of 17). Figure 6-16 Types of Fractures and Steps in Repair (Part 2 of 17). Comminuted fracture 2015 Pearson Education, Inc. ctu Greenstick fra re Epiphyseal

fracture 6-9 Fractures Major Types of Fractures Transverse fractures Displaced fractures Compression fractures Spiral fractures Epiphyseal fractures Comminuted fractures Greenstick fractures Colles fractures Potts fractures 2015 Pearson Education, Inc. 2015 Pearson Education, Inc.

Spiral fracture Potts fracture Compression fracture Colles fracture Comminuted fracture Greenstick fracture Epiphyseal fracture Displaced fracture

Transverse fracture Figure 6-16 Types of Fractures and Steps in Repair (Part 3 of 17). Transverse fracture Figure 6-16 Types of Fractures and Steps in Repair (Part 4 of 17). 2015 Pearson Education, Inc. Displaced fracture Figure 6-16 Types of Fractures and Steps in Repair (Part 5 of 17). 2015 Pearson Education, Inc. Figure 6-16 Types of Fractures and Steps in Repair (Part 6 of 17).

Compression fracture 2015 Pearson Education, Inc. Spiral fracture Figure 6-16 Types of Fractures and Steps in Repair (Part 7 of 17). 2015 Pearson Education, Inc. Figure 6-16 Types of Fractures and Steps in Repair (Part 8 of 17). Epiphyseal fracture 2015 Pearson Education, Inc.

Figure 6-16 Types of Fractures and Steps in Repair (Part 9 of 17). Comminuted fracture 2015 Pearson Education, Inc. Greenstick fracture Figure 6-16 Types of Fractures and Steps in Repair (Part 10 of 17). 2015 Pearson Education, Inc. Colles fracture Figure 6-16 Types of Fractures and Steps in Repair (Part 11 of 17).

2015 Pearson Education, Inc. Potts fracture Figure 6-16 Types of Fractures and Steps in Repair (Part 12 of 17). 2015 Pearson Education, Inc. Figure 6-16 Types of Fractures and Steps in Repair (Part 13 of 17). Spongy bone of internal callus Cartilage of external callus

Fracture hematoma External callus Dead bone 1 Bone fragments Fracture hematoma formation. 2015 Pearson Education, Inc. Spongy bone of

external callus 2 Periosteum Callus formation. Internal callus 3 External callus Spongy bone formation. 4

Compact bone formation. Figure 6-16 Types of Fractures and Steps in Repair (Part 14 of 17). Fracture hematoma Dead bone Bone fragments 1 Fracture hematoma formation. 2015 Pearson Education, Inc.

Figure 6-16 Types of Fractures and Steps in Repair (Part 15 of 17). Spongy bone of internal callus Spongy bone of external callus 2 Callus formation. 2015 Pearson Education, Inc. Cartilage of external callus Periosteum

Figure 6-16 Types of Fractures and Steps in Repair (Part 16 of 17). Internal callus External callus 3 Spongy bone formation. 2015 Pearson Education, Inc. Figure 6-16 Types of Fractures and Steps in Repair (Part 17 of 17). External callus 4 Compact bone formation.

2015 Pearson Education, Inc. 6-10 Effects of Aging on the Skeletal System Age-Related Changes Bones become thinner and weaker with age Osteopenia begins between ages 30 and 40 Women lose 8 percent of bone mass per decade; men lose 3 percent The epiphyses, vertebrae, and jaws are most affected Resulting in fragile limbs Reduction in height Tooth loss 2015 Pearson Education, Inc. 6-10 Effects of Aging on the Skeletal System

Osteoporosis Severe bone loss Affects normal function Over age 45, occurs in: 29 percent of women 18 percent of men 2015 Pearson Education, Inc. Figure 6-17 The Effects of Osteoporosis on Spongy Bone. 2015 Pearson Education, Inc. Normal spongy bone SEM 25

Spongy bone in osteoporosis SEM 21 6-10 Effects of Aging on the Skeletal System Hormones and Bone Loss Estrogens and androgens help maintain bone mass Bone loss in women accelerates after menopause Cancer and Bone Loss Cancerous tissues release osteoclast-activating factor That stimulates osteoclasts And produces severe osteoporosis

2015 Pearson Education, Inc.

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