AnP Chapter 7 (LO7) Flashcards
Strength of bone is similar to…
As strong as —- and as light as ——
makes up –% of body weight
— bones in adult body
Strength of bone is similar to reinforced concrete
As strong as steel and as light as aluminum
makes up 14% of body weight
206 bones in adult body
BONE FUNCTIONS
shape
support
protection
movement
Shape: bones give the body its structure
Support: bones of legs, pelvis and vertebral column support the body and hold it upright
Protection: bones protect delicate internal organs such as heart, lungs, brain and spinal cord
Movement: movement of the arms and legs as well as the ability to breathe results from the interaction between muscles and bones
BONE FUNCTIONS
Electrolyte balance
Blood production
Acid-base balance
Electrolyte balance: bones store and release minerals such as calcium and phosphorus necessary ingredients for a variety of chemical reactions throughout the body
Blood production: bones encase bone marrow, a major site of blood cell formation
Acid-base balance: bone absorbs and releases alkaline salts to help maintain a stable pH
LONG BONES
Very long axis, longer than they are wide
Ex) femur and humerus
Work like levers to move bones
SHORT BONES
As broad as they are long
Shaped like cubes
Ex) carpal bones and tarsal bones
FLAT BONES
Thin, flat, often curved to protect organs
Ex) skull, ribs and breastbone
Provide a large surface for muscle attachment
Ex) scapulae
IRREGULAR BONES
Often clustered in groups, various sizes/shapes
Ex) vertebral and facial bones
Sesamoid bone: small bones embedded in tendons
Ex) kneecap
Epiphysis
head of each end of a long bone
Bulbous structure strengthens the joint and allows an expanded area for the attachment of tendons and ligaments
Made of porous looking spongy bone
Diaphysis
central shaft-like portion of the bone
Central shaft like portion of the bone, hollow cylinder
Gives bone the strength to support a large amount of weight
Articular cartilage
thin layer of hyaline cartilage that covers the surface of epiphysis
Eases the movement of the bone within a joint
Medullary cavity: central hollow portion
Endosteum
thin epithelial membrane that lines inside of the medullary cavity
Red bone marrow
medullary cavity is filled with blood cell-producing red bone marrow
In children
Yellow bone marrow
bone marrow which is rich in fat
Periosteum
a dense fibrous membrane that covers diaphysis
Some fibers of the periosteum penetrate the bone ensuring that the membrane stays fully anchored
Other fibers weave together with the fibers of tendons which ensures a strong connection between muscle and bone
Contains bone forming cells and blood vessels
Epiphyseal plate/growth plate
in growing children a layer of cartilage
Separates the epiphysis from the diaphysis at the end of a long bone
Replaced with an epiphyseal line once growth stops
Osteomyelitis
inflammation of bone and marrow
Usually the result of a bacterial infection
Bone infections are often difficult to treat and typically require prolonged intravenous antibiotics
Osseous tissue
type of connective tissue; consists of cells, fibers and extracellular material
Bone cells include osteoblasts, osteoclasts and osteocytes
Osteoblast
help form bone by secreting substances that comprise the bones matrix
Osteoclasts
dissolved unwanted or unhealthy bone
Osteocytes
are mature osteoblasts that have become entrapped in the hardened bone matrix
Dual role: some dissolved bone, others deposit new bone
Contribute to maintenance of bone density
Assists with the regulation of blood levels of calcium and phosphate
Matrix of bone
is hard and calcified because it contains collagen fibers and crystalline salts (calcium and phosphate)
Tensile strength
collagen fibers in the matrix make bone highly resistant to stretching forces
Bone has significant tensile and compressional strength but lacks torsional strength
Compressional strength
bone lacks the ability to endure twisting
Most bone fractures result when torsional forces are exerted
Osteoporosis
a disease characterized by a loss of bone density
Increased load on bone
osteocytes stimulate the creation of new bone
FACTORS THAT AFFECT BONE GROWTH AND MAINTENANCE
Heredity: every individual inherits genes that determines his maximum height potential
Nutrition: children who are malnourished grow very slow and may not reach their full height-calcium, phosphorus and vitamins D,C and A necessary for bone growth
Hormones: hormones that contribute to bone growth include growth hormone, thyroxine, parathyroid hormone, insulin, estrogen and testosterone
Exercise: without adequate physical stress (weight bearing exercise) bone destruction will outpace bone creation
Spongy bone
light and porous
Found in the ends of long bones and middle of other bones
Always surrounded by the more durable compact bone
Also known as cancellous bone
Trabeculae
latticework of bone
Adds strength without adding weight
Cavities between trabeculae are filled with red bone marrow
Red bone marrow supplies spongy bone with blood and produces blood cells
Compact bone
dense and solid
Density offers strength
Forms the shafts of long bones and outer surface of others
Consists of network of passageways containing nerves/blood vessels
Bone injuries heal quickly because bones are well supplied with oxygen and nutrients
Lacunae
tiny gaps between rings of the lamellae
Contain osteocytes
Canaliculi
microscopic passageways
Connect the lamellae to each other
Volkmann’s canals
transverse passageways
Connect the haversian canals
Transport blood and nutrients from bone’s exterior to osteocytes locked inside
BONE MARROW
Type of soft tissue that fills the medullary cavity of long bones
Fills spaces of spongy bone
Red bone marrow
charged with producing red blood cells
Nearly all of child’s bones contain red bone marrow
in adults can be found only in ribs, sternum, vertebrae, skull, pelvis, upper parts of humerus and femur
Yellow bone marrow
gradually replaces red bone marrow
No longer produces blood cells because the cells are saturated with fat
In severe chronic blood loss or anemia it can change back into red marrow
Ossifications
skeleton evolves into bone
Intramembranous ossification
ossification of fibrous connective tissue
Begins when groups of stem cells in the tissue differentiate into osteoblasts
Start out as fibrous connective tissue
Skull and face
Centers for ossifications
ossification of fibrous connective tissue
Calcium salts are deposited and the bone is calcified
Not all bones are completely ossified at birth ex) rib cage
Fontanels (soft spot)
allow for safe compression of fetus head during birth
Allows for skull to expand while brain grows
Age 2 skull is completely ossified
Endochondral ossifications
cartilage turns to bone
Begins in long bones
After 3 months cartilage begins turning into bone
Steps of process of Endochondral ossification
- Early life fetus
Long bones are composed of cartilage and are models for development - Osteoblasts start to replace the chondrocytes ( cartilage cells)
- -Osteoblasts coat the diaphysis in a thin layer of bone
- -Then create a ring of bone the encircles the diaphysis
- -Cartilage begins to calcify - Blood vessels then penetrate the cartilage
- -Primarily ossification center develops in the middle of the diaphysis - The bone marrow cavity fills with blood and stem cells
- -Ossification continues from the diaphysis toward each epiphysis
- -Bone grows in length
- -Secondary ossification centers appear in the epiphysis
BONE WIDENING AND THICKENING
Continues throughout lifespan
Occurs when osteoblasts in periosteum lay new layers of bone outside of the bone
Osteoclasts on inner bone tissue work to dissolve bone tissue widening marrow cavity
Epiphyseal fracture
epiphyseal plate can separate from the diaphysis or epiphysis when overstressed
This can affect future bone growth
BONE LENGTHENING
Occurs at epiphyseal plate
Chondrocytes continue to multiply on epiphyseal side of the cartilage plate
These cells move towards diaphysis
Minerals are deposited and the cartilage becomes calcified
Bone continues to lengthen as long as chondrocytes are produced in epiphyseal plate
Between age 16 and 25 all cartilage is replaced with spongy bone
When this happens bone lengthening stops and the epiphyses have “closed”
Epiphyseal plate
layer of hyaline cartilage at end of each bone
Epiphyseal line
remaining line of spongy bone
bone remodelling:
- Resorption
- Ossification
- Remodeling
- Osteoclasts
- Osteoblasts
Resorption: bone cells destroying old bone
Ossification: depositing new cells
Remodeling: resorption and ossification
Osteoclasts remove matrix and reduce the mass of little used bones
Osteoblasts deposit new bone tissue on the body’s surface, thickening heavily used bone
Fracture
Closed reduction
Open reduction
Fracture: a break in a bone
Closed reduction: broken bones can be manipulated into their original position without surgery
Open reduction: surgery is needed to reposition the bones with screws/pins/plates
types of fractures
- simple
- compund
- greenstick
- comminuted
- spiral
- pathologic
Simple: bone dose not pierce the skin
Compound: bone pierces the skin
- -Damage to surrounding tissue, nerves and blood vessels may be extensive
- -Because of broken skin, increased risk for infection
Greenstick: the fracture is incomplete
- -Typically in young children because of soft/flexible bones
- -Bone splinters rather than breaks completely
Comminuted: bone breaks into pieces (usually from high impact trauma)
Spiral: fracture line spirals around bone (twisted force)
Pathologic: fracture in a diseased/weakened bone from force that wouldn’t fracture a healthy bone
FRACTURE REPAIR steps
- When fracture occurs, blood vessels are torn resulting in a hematoma (clot)
- -Hematoma transforms into a soft mass of granulation tissue containing inflammatory cells and bone forming cells aid in the healing process - Collagen and fibrocartilage are deposited in the granulation tissue transforming it into a soft callus
- Bone forming cells produce a bony/hand callus around fracture
- -Splits the two bone ends together as healing continues - Remodeling eventually replaces the callus tissue with bone
