Ch. 6 The Skeletal System
Terms in this set (177)
List the order in which intramembranous ossification occurs.
1. Ossification center develops
3. Formation of trabeculae
4. Development of new periosteum
What is the renewal rate for compact bone tissue?
4% per year
Bone increases in length through ______?
Bone increases in diameter through ______?
Calcium is involved in all of the following EXCEPT:
- blood clotting
- nervous system communication
- muscle contraction
- acting as a cofactor in some enzymatic reactions
- being primary cation that regulates osmotic balance in cells
Being primary cation that regulates osmotic balance in cells
Which is stored in the structure of adult bones for the use by other tissues in the body?
- more than one
More than one!
What is the renewal rate for spongy bone?
20% per year
T/F? Bone remodeling includes bone resorption and bone deposition?
T/F? Bone remodeling occurs at a faster rate in compact bone than in spongy bone?
F- compact: 4%/yr spongy: 20%/yr
Condition that is observed in adults when new bone formed during bone remodeling fails to calcify?
Layer of hyaline cartilage that allows the diaphysis to grow in length?
Which does not significantly contribute to bone remodeling and growth during adulthood?
-human growth hormone
T/F? Bone remodeling requires the activity of both osteoblasts and osteoclasts.
Process by which bone forms?
Osteons in compact bone tissue are aligned _____.
parallel to the length of the diaphysis
The fibrous covering on the surface of bone that is involved in the thickening of the bone?
What is the relationship between nerves and bone?
Nerves accompany the blood vessels that supply bones.
Condition that is characterized by reduced bone mass due to a decreased rate of bone synthesis to a level too low to compensate for normal bone resorption?
The activity of the ______ is the only way that the diaphysis can increase in length.
T/F? Bone is a dynamic tissue. It is always remodeling.
The two major tissues of the skeletal system are ____ and ______.
Bone and cartilage
Two different types of bone arrangement are ____ and ______.
compact bone and spongy bone
_____ is highly vascular C.T. with a hard, mineralized extracellular matrix.
Type of bone arrangement that is good at providing protection and support; forms the diaphysis of long bones and the external layer of all bones.
Type of bone arrangement that is lightweight and provides tissue support; forms the epiphysis and the internal cavity of long bones.
________ is poorly vascularized C.T. with a matrix composed of chondroitin sulfate and various fibers.
The fiber types of cartilage distinguish _____ cartilage from ______ cartilage.
hyaline, elastic (fibrocartilage)
thin layer of hyaline cartilage covering the epiphysis of long bones; found where bones form an articular (joint) surface
the bone's shaft or body- the long cylindrical, main portion of the bone
diaphysis (growing between)
proximal and distal ends of the bone
epiphyses (growing over)
regions between the diaphysis and epiphyses; contains an epiphyseal growth plate in growing bone
metaphyses (between physes)
a layer of hyaline cartilage that allows the diaphysis of the bone to grow in length
epiphyseal growth plate
When the bone ceases to grow in length at about ages ______, the cartilage in the epiphyseal plate is replaced by ____; the resulting bony structure is known as the ___________.
Cartilage that reduces friction and absorbs shock at freely moveable joints; lacks perichondrium and blood vessels
Why is repair limited in articular cartilage?
lacks perichondrium and blood vessels
tough C.T. sheath and its associated blood supply that surrounds the bone surface wherever it is not covered by articular cartilage; composed of an outer fibrous layer (dense CT) and an inner osteogenic layer (cells)
The _______ also protects the bone, assists in fracture repair, helps nourish bone tissue, and serves as an attachment point for ligaments and tendons.
thick bundles of collagen that periosteum attaches to; extend from the periosteum into the bone extracellular matrix
perforating (Sharpey's) fibers
a hollow, cylindrical space within the diaphysis that contains fatty yellow bone marrow and numerous blood vessels in adults; minimizes the weight of the bone by reducing the dense bony material where it is least needed.
medullary cavity (marrow)
The long bones' tubular design provides _____ strength with _____ weight.
bone marrow that consists mainly of adipose cells that store triglycerides (potential chemical energy reserve)
yellow bone marrow
bone marrow that consists of developing blood cells, adipocytes, fibroblasts, and macrophages within a network of reticular fibers
red bone marrow
In a fetus, all bone marrow is ____ and is involved in _____.
process by which red bone marrow produces red blood cells, white blood cells, and platelets
hemopoiesis (blood making)
The extracellular matrix of bone is about ___% water, ____% collagen fibers, and ____% crystallized mineral salts.
15, 30, 55
most abundant mineral salt
Bone's hardness depends on ____ while a bone's flexibility depends on its ______.
crystallized mineral salts, collagen fibers
thin membrane that lines the medullary cavity; contains a single layer of bone-forming cells and a small amount of CT
Calcification is initiated by bone-building cells called ____.
unspecialized bone stem cells derived from mesenchyme (tissue from which almost all CT is formed); only bone cells to undergo cell division; develop into osteoblasts
osteogenic cells (producing)
Bone-building cells that synthesize and secrete collagen fibers and other organic components needed to build the extracellular matrix of bone tissue; initiate calcification
osteoblasts (buds, sprouts- secrete e.c. matrix)
Deposition of mineral salts, primarily hydroxyapatite, in a framework formed by collagen fibers in which the tissue hardens. Also called mineralization.
Hydroxyapatite is the combination of two mineral salts:
Calcium phosphate and calcium hydroxide
Vitamin that stimulates activity of osteoblasts
Vitamin that is needed for synthesis of collagen
Vitamin essential to healthy bones; promotes absorption of calcium
Mature bone cells; main cells in bone tissue and maintain its daily metabolism
Osteocytes (maintains tissue)
T/F? Osteoblasts and osteocytes undergo cell division.
Bone cell type that functions in resorption (the breakdown of bone e.c. matrix
Osteoclasts (break down of e.c. matrix
Contains few spaces and is the strongest form of bone tissue; found beneath periosteum of all bones and makes up the bulk of the diaphyses of long bones; provides protection and support and resists the stresses produced by weight and movement.
Each ____ consists of concentric lamellae arranged around a central Haversian canal.
Perforating canals are also known as ___
The vessels and nerves of the _____ connect with those of the medullary cavity, periosteum, and central canals.
Make bone extracellular matrix hard
calcium and phosphorous
helps form bone e.c. matrix
helps strengthen bone ec matrix
activates enzymes involved in synthesis of bone ec matrix
deficiency in this vitamin leads to decreased collagen production
needed for synthesis of bone proteins; deficiency leads to abnormal protein production in bone ec matrix and decreased bone density
secreted by the anterior lobe of the pituitary gland; promotes general growth of all body tissues, including bone, mainly by stimulating production of insulinlike growth factors
human growth hormone (hGH)
secreted by the liver, bones, and other tissues upon stimulation by human growth hormone; promotes normal bone growth by stimulating osteoblasts and by increasing the synthesis of proteins needed to build new bone
insulinlike growth factors (IGFs)
secreted by thyroid gland; promote normal bone growth by stimulating osteoblasts
secreted by the pancreas; promotes normal bone growth by increasing the synthesis of bone proteins
secreted in ovaries in women (estrogens) and by testes in men (testosterone); stimulate osteoblasts and promote sudden "growth spurt" that occurs during the teenage years; shut down growth at the epiphyseal plate around age 18-21, causing lengthwise growth of bone to end; contribute to bone remodeling during adulthood by slowing bone resorption by osteoclasts and promoting bone deposition by osteoblasts
secreted by the parathyroid glands; promotes bone resorption by osteoclasts; enhances recovery of calcium ions from urine; promotes formation of the active form of vitamin D (calcitriol)
parathyroid hormone (PTH)
secreted by the thyroid gland; inhibits bone resorption by osteoclasts
literally a condition of porous bones, affects 10 million people a year in the US
osteoporosis (passageway condition)
the degeneration of articular cartilage such that the bony ends touch; the resulting friction of bone against bone worsens the condition; usually associated with the elderly
In osteoporosis, bone resorption outpaces bone formation, so bone mass _____.
an infection of bone characterized by high fever, sweating, chills, pain, nausea, pus formation, edema, and warmth over the affected bone and rigid overlying muscles. It's often caused by bacteria, usually Staphylococcusaureus. The bacteria may reach the bone from outside the body (through open fractures, penetrating wounds, or orthopedic surgical procedures); from other sites of infection in the body (abscessed teeth, burn infections, UTI, or upper respiratory infections.
a disease of children in which the growing bones become "soft" or rubbery and are easily deformed. Because new bone formed at the epiphyseal plates fails to ossify, bowed legs and deformities of the skull, rib cage, and pelvis are common.
drugs that slow down the progression of bone loss
drugs that promote increasing bone mass
first situation of ossification
initial formation of bones in an embryo and fetus
situation 2 of ossification
growth of bones during infancy, childhood, and adolescence until their adult sizes are reached
situation 3 of ossification
remodeling of bone
situation 4 of ossification
repair of fractures throughout life
Bone development begins during the ______ week of embryonic development.
6th or 7th
two types of ossification are?
intramembranous and endochondral
refers to bone formation directly within mesenchyme arranged in sheetlike layers that resemble membranes.
refers to bone formation within hyaline cartilage that develops from mesenchyme
The primary ossification center of a long bone is in the
the addition of new bone tissue by periosteal osteoblasts around the outer surface of bone
Bone grows in thickness and diameter due to ______.
Four zones of epiphyseal plate?
1. resting cartilage
2. proliferating cartilage
3. hypertrophic cartilage
4. calcified cartilage
Because of the cell division in the _________, the diaphysis of a bone increases in length.
Bone growth in length is called _____ growth, and bone growth in diameter is called _______ growth.
The crystallized inorganic mineral salts in bone contribute to bone's _____ while the collagen fibers and other organic molecules provide bone with ______.
hardness, tensile strength
T/F? Bone resorption involves increased activity of osteoclasts.
T/F? The formation of bone from cartilage is known as endochondral ossification.
T/F? The growth of bone is controlled primarily by hormones.
During childhood, the hormones most important to bone growth are the _______ .
insulinlike growth factors
any break in a bone; named according to their severity, the shape or position of the fracture line, or even the physician who first described them.
series of microscopic fissures in bone that forms without any evidence of injury to other tissues; result from repeated, strenuous activities in healthy adults
About 25% of stress fractures involve the ___.
produced by oversecretion of hGH during childhood; person becomes much taller and heavier than normal
produced by undersecretion of hGH; person has short proportional stature (avg. adult - 4 ft, 10 in tall); can be treated medically with hGH until epiphyseal plate closes
oversecretion of hGH during adulthood
inherited condition in which the conversion of cartilage to bone is abnormal.
achondroplasia (without cartilage to mold)
most common type of dwarfism; unproportional stature (short limbs, avg trunk, slightly enlarged head, prominent forehead, flattened bridge of nose) condition is untreatable, though some people choose limb-lengthening surgery
achondroplastic dwarfism (4 ft adult)
Place steps of intramembranous ossification in order:
1. bony matrices fuse to form trabeculae
2. clusters of osteoblasts form a center of ossification that secretes the organic ec matrix
3. spongy bone is replaced with compact bone on the bone's surface
4. periosteum develops on the bone's periphery
5. the ec matrix hardens by deposition of calcium and mineral salts.
Place steps of endochondral ossification:
1. nutrient artery invades the perichondrium
2. osteoclasts create a marrow cavity
3. chondrocytes enlarge and calcify
4. secondary ossification centers appear at epiphyses
5. osteoblasts become active in the primary ossification center.
3, 1, 5, 2, 4
Spongy bone differs from compact bone because spongy bone is composed of _____ that are oriented along lines of stress.
a broken bone in which one end of the fractured bone is driven into the other end
a condition of porous bones characterized by decreased bone mass and increased susceptibility to fractures
splintered bone, with smaller fragments lying between main fragments
a broken bone that does not break through the skin
closed (simple) fracture
a partial break in a bone in which one side of the bone is broken and the other side bends
a broken bone that protrudes through the skin
open (compound) fracture
microscopic bone breaks resulting from inability to withstand repeated stressful impact
a degeneration of articular cartilage allowing the bony ends to touch; worsens due to friction between the bones
condition characterized by failure of new bone formed by remodeling to calcify in adults
an infection of bone
column-like layer of maturing chondrocytes
zone of hypertrophic cartilage
layer of small, scattered chondrocytes anchoring the epiphyseal plate to the bone
zone of resting cartilage
layer of actively dividing chondrocytes
zone of proliferating cartilage
region of dead chondrocytes
zone of calcified cartilage
Which bones of the body develop by intramembranous ossification?
flat bones of the skull, most facial bones, the mandible, and the medial part of the clavicle
the loss of calcium and other minerals from bone ec matrix; usually begins after age 30 in females, accelerates greatly around age 45 as levels of estrogens decrease, and continues until as much as 30% of the calcium in bones is lost by age 70.
T/F? Removal of mechanical stress weakens bone through demineralization and collagen fiber reduction.
fracture of the distal end of the lateral leg bone (fibula), with serious injury of the distal tibial articulation
fracture of the distal end of the lateral forearm bone (radius) in which the distal fragment is displaced posteriorly
mass of blood (usually clotted) that forms around the site of the fracture
fracture hematoma (blood tumor)
a mass of repair tissue consisting of collagen fibers and cartilage that bridges the broken ends of the bone
fibrocartilaginous (soft) callus
final phase of fracture repair
How does the medullary cavity enlarge during growth in thickness?
by activity of the osteoclasts in the endosteum
If you wanted to develop a drug to lessen the effects of osteoporosis, would you look for a chemical that inhibits the activity of osteoblasts or osteoclasts?
Osteoclasts - responsible for bone resorption. (basic problem of osteoporosis is that bone resorption outpaces deposition.
why does it sometimes take months for a fracture to heal?
because calcium and phosphorous deposition is a slow process and bone cells generally grow and reproduce slowly
commonly referred to as setting a fracture; fractured ends must be brought into alignment
fractured ends of a bone are brought into alignment by manual manipulation, and the skin remains intact.
fractured ends of a bone are brought into alignment by a surgical procedure using internal fixation devices such as screws, plates, pins, rods, and wires.
one end of the fractured bone is forcefully driven into the interior of the other
impacted - one side shoved into the other
disease in which there is an excessive proliferation of osteoclasts so that bone resorption occurs faster than bone deposition.
How does the epiphyseal plate account for the lengthwise growth of the diaphysis?
Lengthwise growth is caused by cell divisions in the zone of proliferating cartilage and replacement of the zone of calcified cartilage with bone. (new diaphysis)
Where in the cartilage model do secondary ossification centers develop during endochondral ossification?
in the regions of the cartilage model that will give rise to the epiphyses
diagnostic procedure that takes advantage of the fact that bone is living tissue
Where do periosteal arteries enter bone tissue?
through perforating (Volkmann's) canals
branch of dentistry concerned with the prevention and correction of poorly aligned teeth
As people age, some central haversian canals may become blocked. What effect would this have on the surrounding osteocytes?
The central canals are the main blood supply to the osteocytes of an osteon (haversian system), so their blockage would lead to death of the osteocytes.
What is the functional significance of the periosteum?
It is essential for growth in bone thickness, bone repair, and bone nutrition; also serves as a point of attachment for ligaments and tendons.
Why is bone resorption important?
It is necessary for the development, maintenance, and repair of bone.
space within the shaft of the bone that contains yellow bone marrow
triglyceride storage tissue
yellow bone marrow
red bone marrow
thin layer of hyaline cartilage covering the ends of bones where they form a joint
proximal and distal ends of bones
the long, cylindrical main portion of the bone; the shaft
in a growing bone, the region that contains the epiphyseal plate
the tough covering that surrounds the bone surface wherever cartilage is not present
a layer of hyaline cartilage in the area between the shaft and end of a growing bone
membrane lining the medullary cavity
a remnant of the active epiphyseal plate; a sign that the bone has stopped growing in length
bundles of collagen fibers that attach periosteum to bone
perforating (Sharpey's) fibers
small spaces between lamellae that contatin osteocytes
tiny canals that penetrate compact bone; carry blood vessels, lymphatic vessels, and nerves from the periosteum
perforating (Volkmann's) canals
areas between osteons; fragments of old osteons
cells that secrete the components required to build bone
microscopic unit of compact bone tissue
osteon (haversian system)
interconnected, tiny canals filled with extracellular fluid; connect lacunae to each other and to the central canal
canals that extend longitudinally through the bone and carry blood vessels and nerves to the central canal
haversian (central) canals
large cells derived from numerous monocytes; involved in resorption by release of lysosomal enzymes and acids
irregular lattice of thin columns of bone found in spongy bone tissue
rings of hard calcified matrix found just beneath the periosteum and lining the medullary cavity
mature cells that maintain the daily metabolism of bone
an opening in the shaft of the bone allowing an artery to pass into the bone
unspecialized stem cells derived from mesenchyme
Place in order steps of repair of bone fracture.
1. osteoblast production of trabeculae and bony callus formation
2. formation of a hematoma at the site of the fracture
3. resorption of remaining bone fragments and remodeling of bone
4. migration of fibroblasts to the fracture site
5. bridging of broken ends of bones by a fibrocartilaginous callus
2, 4, 5, 1, 3
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