Chapter 5: The Skeletal System

Flat bones

- Thin, roughly parallel surfaces of compact bone. -Stong but light -Sternum, skull, and ribs

Lacunae

-"Little lake" -Small cavities in bone that contain osteocytes.

Colles fracture

-A break at the distal portion of the radius.

Epiphyseal plate

-Area of cartilage in the metaphysis. -Cartilage near diaphysis converted to bone. -Width of this zone gets narrower as we age. -Marks the former location of the epiphyseal cartilage.

Spongy bone structure and function

-Arranged in parallel struts (interwoven). -Forms branching plates called trabeculae. -Trabeculae form an open network. -Creates the lightweight nature of bones.

Concentric lamellae

-Arranged parallel to the long axis of the bone in each osteon. -Form a series of concentric rings, resembiling "bull's eye" target, around central canal. -Have collagen fibers

Projections

-Beefy, bigger muscles attached, stick.

Compression fractures

-Bone "jam" together

Osseous tissue

-Bone tissue Supporting connective tissue: -Specialized cells -Solid matrix Outer lining: -Periosteum Inner lining: -Endoesteum

Spiral fractures

-Bones twist along the length of the bone.

Short bones

-Boxlike in appearance. -Covered by compact bone, contains spongy bone. -Capal bone or patella

Transverse Fractures

-Break transverse to the long axis.

Osteoclasts

-Breaking bone down -Multinucleated cells -Secrete acids, which dissolve the bones thereby causing the release of stored calcium ions and phosphate ions into the blood. (osteolysis)

Matrix of bone

-Calcium phosphate converts to hydroxyapatite crystals. -Calcium phosphate makes up 2/3 of the bone mass. -Hydroxyapatite crystals resist compression.

Medullary cavity

-Cavity containing marrow within the diaphysis of a long bone. -Contains yellow marrow of the shaft.

Irregular bones

-Complex shapes with short, flat, notched, or ridged surfaces. -vertebra

Lamellae

-Concentric rings made up of groups of hollow tubes of bone matrix. -"Thin plate"

Epiphysis

-Consists of red marrow -Ends of long bones -Larger in diameter than the shaft.

Compact bone

-Dense and solid -Forms the walls of bone. -Lie beneath periosteum.

Nutrient vessels

-Enter diaphysis and branch toward epiphysis. -Enter through nutrient foramen of the bone. -Penetrates shaft and enters medullary cavity. -Divides into ascending and descending branches to go toward epiphysis regions. -Vessels branch to form perforating vessels.

Interstitial lamellae

-Fill in spaces between osteons in compact bone. -Depending location, either have been produced during growth of the bone. -Or may represent what is left of osetons thave have been recycled by osteoclasts during bone repair and remodeling.

Collagen fibers

-Flexibility -Contributeto the tensile strength of bones. -Collagen and hydroxyapatite make bone tissue extremely strong.

Depressions

-Fossa (shallow depression)

Epiphyseal fractures

-Fractures within the epiphyseal region.

Canaliculi

-Hairlike canals that connect lacunae to each other and the central canal. -"Little canals"

Central canal

-Haversian canal -Contains blood vessels that supply the osteon. -Run parallel to surface of the bone.

Pneumatized bones

-Hollow or contain numerous air pockets. -Ethmoid

Osteoblasts

-Immature bone cells -Found on inner and outer surfaces of bones. -Produce osteoid, which is involved in making the matrix. -Osteoblasts are involved in making new bone. This is a process called osteogenesis

Appositional growth

-Inner layer of periosteum differentiates to form osteoblasts and adds bone matrix to the surface. -This forms circumferential lamellae to the outer surface. -Osteons form -Bone continues to enlarge in diameter.

Endosteum

-Inner surface of bone. -Lines the medullary cavity. -Consists of osteoprogenitor cells. -Involved in repair and growth.

Comminuted fractures

-Little ones -The fractured area shatters into many bondy fractures.

Long bones

-Long and slender -Upper and lower limbs. (humerus).

Osteocytes

-Mature bone cells -Maintain protein and mineral content of the matrix. -Cause release of calcium ions from the bone to the blood. -Sit in depressions called lacunae (little lake). -Matrix layer associated with osteocytes is lamellae (layers). -Small channels extending from the osteocytes to the bone capillaries are called canaliculi.

Metaphysis

-Middle of long bone -Narrow growth zone between the epiphysis and the diaphysis.

Factors Regulating Bone Growth

-Nutrition -Calcium ions (intake)(want lactate) -Phosphate ions -Magnesium ions -Citrate -Carbonate ions -Sodium ions -Vitamins A, C, D (calcitriol)

Circumferential lamellae

-Occur at the external and internal surface of the bone. -Humerus or femur, form outer surface of shaft.

Pott fracture

-Occurs at the ankles and affects both the tibia and fibula.

Greenstick fractures

-Only one edge of the bone breaks while the other edge bends.

Spongy bone

-Open network of plates. -Surrounds the medullary cavity. -Layer of bone tissue having many small spaces and found just inside the layer of compact bone. -Trabeular ("little beams", plates) -Has yellow and red marrow.

Osteoid

-Organic bone matrix secreted by osteoblasts.

Osteogenesis

-Osteoblasts are responsible fo the production of new bone through this process.

Compact bone of:

-Osteons -Central canal -Canaliculi -Osteocytes -Lacunae -Lamellae (Owen, Ceric, and Candice Opened Lanes Lunch box)

Periosteum

-Outer surface of bone. -Isolates/protects bone from surrounding tissue. -Provides a route and place for attachment for circulatory and nervous supply. -Participates in bone growth/repair. -Attaches bone to connective tissue network of the deep fascia.

Displaced fractures

-Produces new and abnormal bone arrangements.

Remodeling of Bone

-Realignment of teeth can change the shape of tooth sockets. -Increased muscular development. -Bone changes occur due to stress (exercising repeatedly). -Different features develop on the bone. -Attachment of ligaments(bone to bone)(Knee) -Attachment of tendons(Muscle to bone) -Stressed bones become thicker and stronger. -Inactivity of bones can cause degeneration. -After a few weeks, unstressed bones can lose about a third of their mass.

Growth hormone

-Released from the pituitary gland. -Stimulates bone growth. -Maintains normal activity of the epiphyseal cartilage.

Diaphysis

-Shaft of long bones -The medullary cavity of diaphysis consists of yellow marrow.

Openings

-Sinuses/canals/fissures(long cleft)/foramen

Skeletal system is made of?

-Skeletal bones -Carilatge -Ligaments -Connective tissue to stabilize the skeleton.

Sesamoid bone

-Small, round, and flat. -Develope inside tendons and are most often encountered near joints at the knee, hands, and feet. -Patella

Estrogen and testosterone

-Stimulate oseoblast activity -Osteoblast activity produces bone faster than epiphyseal cartilage expansion. -Ultimately the epiphyseal cartilage narrows and bone growth ceases.

Epiphyseal vessels

-Supply nutrients to the cavities of the epiphysis.

Metaphyseal

-Supply nutrients to the diaphyseal edge of the epiphysis.

Periosteal vessels

-Supply nutrients to the superficial osteons.

Osteoprogenitor cells

-These are bone stem cells. -Found on innermost layer of periosteum and inner lining of endosteum. -Differentiate to form new osteoblasts. -Heavily involved in the repair of bones after a break.

Processes

-Trochanter/crest -Spine/line -Tubercle/tuberosity -Head/neck -Facet/condyle/trochlea

Perferating canal

-Volkmann's canal -Extend perpendicular to the suface. -Its blood vessels deliver blood to osteons deeper in the bone. -Also Service the medullary cavity.

Injury and Repair and how it happens

-When a bone is broken, bleeding occurs. -A network of spongy bone forms. -Osteoblasts are overly activated, thus resulting in enlarged callused area. -This area is now stronger and thicker than normal bone.

Bone development and growth

1)Before six weeks of development, the skeleton is hyaline cartilage. -Cartilage cells will be replaced by bone cells (ossification) 2)Osteogenesis -Bone formation 3)Calcification -The deposition of calcium ions into the bone tissue.

Endochondral ossification

1)Chondrocytes near the center of the diaphysis increase in size. 2)Blood vessels begin to grow around the cartilage. 3)The perichondrial cells begin to form the periosteum. -A thin layer of compact bone begins to form. 4)Cartilage cells die and are replaced by osteoblasts. -Osteoblasts begin to form spongy bone. -This is the primary ossification center. 5)The cartilage in the metaphysis region is invaded by osteoblasts. 6)An increase in bone length and diameter begins(longer and thicker). 7)Osteoblasts begin to migrate into the epiphysis region. -This is the secondary ossification center (the ends) 8)Osteoblasts begin to replace cartilage with bone. 9)This results in pushing the epiphysis away from the diaphysis thus resulting in longer bones.

Two types of Osseous tissue

1)Compact bone 2)Spongy bone

Two types of ossification

1)Intramembranous ossification: Invoved in development of clavicle, mandible, skull, and face. 2)Endochondral ossification: Involved in development of limbs, vertebrae, and hips.

Intramembranous ossification

1)Mesenchymal cells differentiate to form osteoblasts. 2)Osteoblasts begin secreting a matrix. -Osteoblasts become trapped in the matrix. -Osteoblasts differentiate and form osteocytes. -More osteoblasts are produced, thus move outward. 3)Blood vessels are trapped by the formation of spicules.

Four major sets of blood vessels with long bones

1)Nutrient vessels 2)Metaphyseal vessels 3)Epipheseal vessels 4)Periosteal vessels

Functions of skeletal system

1)Support: Framework for attachment of other organs. 2)Storage of minerals: Calcium and phosphate ions. 3)Blood cell production: Bone marrow produces erythrocytes, leurocytes, and platelts. 4)Leverage: Muscles pull on bones to produce movement. 5)Protection: -Ribs protecct heart and lungs. -Skull protects the brain. -Vertebreae protects spinal cord. -Pelvic bone protect reproductive organs. (Sara Stole Billy's Last Popsicle)

Types of Fractures

1)Transverse 2)Displaced 3)Compression 4)Spiral 5)Epiphyseal 6)Comminuted 7)Greenstick 8)Colles 9)Pott

Bones of skeleton

Axial and Appendicular skeleton

osteoporosis

Bone resorption and deposit More severe in spongy bone, bones are porous and thin but bone composition is normal

Axial skeleton

Bones of skull, vertebral column, rib cage, protect, support, carry other body parts

Functional differences between Compact and Spongy bone

Compact Bone: -Conducts stress from one end of the long bone to the other end. Generates strength from end to end. -Weak strength when stress is applied to the side. -Osteon arrangment is parallel to the bone axis. Spongy Bone: -Trabeuclae create strength to deal with stress from the side. -Trabeculae oriented along the stress lines. -Has extensive cross-bracing -Supports yellow marrow in the shaft of the bone. -Supports red marrow in epiphysis of the bone.

Osteosarcoma (bone cancer)

abnormal proliferation of osteoblasts

greenstick fracture type

bone breaks incompletely, only one side of the shaft breaks, the other side bends, common in children

organic components include ____________

bone cells and osteoid

endochondral ossification in a long bone

bone collar forms around the diaphysis of the hyaline cartilage model, cartilage in the center of the diaphysis calcifies and then develops cavities, the periosteal bud invades the internal cavities and spongy bone forms, the diaphysis elongates and a medullary cavity forms and secondary ossification centers appear in the epiphyses, the epiphyses ossify and when completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages.

comminuted fracture type

bone fragments into 3 or more pieces, common in the aged

compression fracture type

bone is crushed, common in porous bones (osteoporotic bones in a fall, crushed vertebra)

appendicular skeleton

bones of the upper and lower limbs and girdles (shoulder and hip bones), locomotion, manipulation

depressed fracture type

broken bone portion is pressed inward, typical of skull fracture

bone deposit

by osteoblast, occurs wherever bone is injured and extra strength is required

bone resorption

by osteoclast, releasing enzymes and hydrochloric acid, which enter the blood stream where they can be used (Ca) or eliminated (dead cell fragments)

common types of fractures

comminuted, spiral, depressed, compression, epiphyseal, greenstick

periosteum covers the _______________.

diaphysis

bone growth and bone remodeling

endochondral ossification occurs at the articular cartilages and epiphyseal plates as the bone lengthens

epiphyseal fracture type

epiphysis separates from the diaphysis along the epiphyseal plate, tends to occur where cartilage cells are dying and calcification of the matrix is occurring.

ligaments

fibrous connective tissue, attach bone to bone, hold structures together and keep them stable

tendons

fibrous connective tissue, attach muscle to bone, muscle to structures, move the bone or structure

depressions and openings for passage

foramen, notch, meatus

depressions and openings for joint

fossa

inorganic components include mineral salts or hydroxyapatites in and around collagen fibers in the extracellular matrix.

hardness, resist compression and tension

projections for joints

head, facet, condyle

stages in the healing of a bone fracture

hematoma forms, fibrocartilaginous callus forms, bony callus forms, bone remodeling occurs.

cartilages types

hyaline, elastic, fibrocartilage

osteomalacia and Ricket

inadequate bone mineralization

Osteogenesis imperfacta

inherited genetic disorder, lack of proper collagen fibers, brittle bone disease

endosteum lines __________________.

inner bone cavities

hyaline cartilage covers _________________.

joint surfaces

avascular necrosis

loss of blood supply to the bone

factors that affect bone remodeling

low blood Ca2+ concentration, parathyroid hormone, mechanical stress

osteoid

makes up approximately one third of the matrix, includes ground substance and collagen fibers, both of which are secreted by osteoblasts.

intramembranous ossification

ossification centers appear in the fibrous connective tissue membrane, osteoid is secreted within the fibrous membrane and calcifies, woven bone and periosteum form, lamellar bone replaces woven bone, just deep to the periosteum and red marrow appears.

5 major cell types that populate bone tissue

osteogenic cell, osteoblast, osteocyte, osteoclast

osteoid's ground substance

proteoglycans and glycoproteins

the organic portion of matrix is important in _______

providing tensile strength, ability to resist stretch and flexibility (collagen)

spiral fracture type

ragged break occurs when excessive twisting forces are applied to a bone, common sports fracture

diploe (spongy bone) cavities contain ____________.

red marrow

4 zones of long bone growth in length

resting, proliferation, hypertonic, calcification, ossification

parathyroid hormone (PTH) control of blood calcium levels

the hormonal controls of bone remodeling serve blood calcium homeostasis. When blood calcium levels decline, PTH is released and stimulates osteoclasts to digest bone matrix, releasing ionic calcium. As blood calcium levels rise, PTH secretion declines.

projections for muscle and ligament

tuberosity, trochanter, crest, process, epicondyle

medullary cavity of the diaphysis contains ________.

yellow marrow