AP 1 Chapter 7

long, short, flat, irregular

Bones appear in various shapes and sizes. The four classes of bones are determined by shape and are

perichondrium

Hyaline cartilage except articular cartilage is covered by a dense irregular connective tissue sheet called the ____. that helps maintains its shape.

bone connective tissue of skeleton, kidneys, small intestines

The 3 major organs that pth and calcitriol interact with are

the central canal, concentric lamellae, osteocytes, lacuunae, canaliculi

The 4 components of an osteon are

support and protection, movement, hemopoiesis, and storage of mineral and energy reserves

The 4 functions of bones are

inorganic

The ___ component of the bone connective tissue is made up of salt crystals that are primarily calcium phosphate.

osteopenia

The bones of the skeleton become thinner and weaker resulting in insufficient ossification called___

D, C, phosphate

The entire process of bone formation requires a number of substances including vitamin ___ and vitamin ___ and ___.

periosteal bud

The growth of capillaries and osteoblasts are called _____

red, yellow

The interior cavity of bone contains a connective tissue that is either ___ or ___ bone marrow.

organic

The matrix of bone connective tissue has both organic and inorganic components. The ___ component is the osteiod which is composed of both collagen protein plus a semisolid ground substance of proteoglycans and glycoproteins that suspends and supports collagen fibers. These components five bone tensile strength by resisting stretching and twisting, and contribute to its overall flexibility.

compact, spongy

Two types of bone connective tissue that are present in most of the bones in the body are

zone of hypertrophic cartilage

chondrocytes cease dividing and begin to hypertrophy (enlarge in size) in this zone. the walls of the lacunae become thin because the chondrocytes resorb matrix as they hypertrophy.

zone of proliferating cartialge

chondrocytes in this zone undergo rapid mitotic cell division, enlarge slightly and become aligned like a stack of coins into longitudinal columns of flattened lacunae. these columns are parallel to the diaphysis

osteons

compact bone is composed of small cylindrical structures called ____ or haversian systems. This is the basic functional and structural unit of mature compact bone. They are oriented parallel to the diaphysis of the long bone.

avulsion fracture

complete severing of a body part (typically a toe or finger)

epiphyseal fracture

epiphysis is separated from the diaphysis at the epiphyseal plate

hairline fracture

fine crack in which sections of bone remain aligned (common in skull)

primary ossification center

first major center of bone formation in the diaphysis.

secondary ossification centers

form as bone displaces calcified cartilage. happens in the epiphyses.

transverse fracture

fracture is at right angles to the long axis of the bone.

pott fracture

fracture is at the distal ends of the tibia and fibula

linear fracture

fracture is parallel to the long axis of the bone.

colles fracture

fracture of the distal end of the lateral forearm bone; produces a dinner fork deformity

spiral fracture

fracture spirals around axis of long bone; result from twisting stress

displaced fracture

fractured bone parts are out of anatomic alignment

osteocyte

is a mature bone cell found in small spaces between adjacnt concentric lamellae of an osteon. These cells maintain the bone matrix.

compact bone

is a relatively dense connective bone tissue that appears white, smooth, and solid. It makes up approximately 80% of the total bone mass.

cartilage

is a semi-rigid connective tissue that is more flexible than bone. Hyaline and fibrocartilage are the two cartilages that are found in skeletons.

stress fracture

is a thin break caused by increased physical activity in which the bone experiences repetitive loads. repeated, stressful impact such as running. These fractures often are difficult to see on x-rays, and a bone scan may be necessary to accurately identify their presence.

fibrocartilage

is a weight-bearing cartilage that withstands compressions. It forms the intervertebral discs, the pubic symphysis (cartilage between bones of the pelvis), and cartilage pads of the knee joints (menisci).

circumferential lamellae

__ are the rings of only compact bone immediately internal to the periosteum of the bone (external) or internal to the endosteum (internal). Both external and internal run the entire circumference of the bone itself.

bone formation

__ begins when osteoblasts secrete the initial semisolid organic form of bone matrix called osteoid.

Calcium

__ is essential mineral for such body functions as muscle contraction, blood clotting, and nerve impulse transmission.

phosphate

__ is required for ATP utilization and is an important component of the plasma membrane.

bone resorption

__ is the process whereby bone matrix is destroyed by substances released from osteoclasts into the extracellular space adjacent to the bone. Proteolytic enzymes released from lysosomes within the osteoclasts chemically digest organic components of the matrix while HCL dissolves calcium and phosphate. The liberated calcium and phosphate ions enter the blood.

Bones

__ of the skeleton are the primary organs of the skeletal system. They form the rigid framework of the body and perform other functions.

intramembranous ossification

___ literally means bone growth within a membrane. It is so named because the thin layer of mesenchyme in these areas is sometimes known as a membrane. It has 4 steps.

the central canal

___ of the osteon is a cylindrical channel that lies in the center of the osteon and runs parallel to it. Traveling within it are the blood vessels and nerves that supply the bone.

ossification, osteogenesis

___ or ___ refers to the formation and development of bone connective tissue. It begins in the embryo and continues as the skeleton grows during childhood and adolescence.

calcification

___ or mineralization, subsequently occurs to osteoid formation when hydroxapatite crystals deposit in the bone matrix. This occurs when the concentration of calcium ions and phosphate ions reach critical levels and precipitate out of solution, thus forming the hydroxyapatite crystals that deposit in and around the collagen fibers.

severe anemia

a condition in which erthrocyte (red blood cell) numbers are lower than normal, resulting in insufficient oxygen reaching the cells of the body- may trigger conversion of yellow bone marrow back to red bone marrow, a change that facilitates the production of additional erythrocytes.

brittle

a loss of protein in bones represents ___ bones or when baked.

osteoporosis

a significant percentage of older women and a smaller proportion of older men suffer from ____, a condition characterized by reduction in bone mass sufficient to compromise normal function. In addition vitamin d and numerous hormones including growth hormone, estrogen, and testosterone decrease with age. This decrease in hormone levels contributes to reduction in bone mass.

sesamoid bones

a type of short bones which are small, sesame seed-shaped bones along the tendons of some muscles. The largest type of this bone is the patella (kneecap).

hydroxyapatite

calcium phosphate and calcium hydroxide interact to form crystals of ____ . These crystals deposit around the long axis of collagen fibers in the exracellular matrix. The crystals harden the matrix and account for the rigidity or relative inflexibility of bone that provide its compressional strength.

fractures

bone has great mineral strength, but it may break as a result of unusual stress or a sudden impact. breaks in bones are called ____ .

complete fracture

bone is broken into two or more pieces

vascularized

bone is highly____(meaning it is supplied by many blood vessels), especially in regions containing spongy bone. blood vessels enter bones from the periosteum.

comminuted fracture

bone is splintered into several small pieces between the main parts

compression fracture

bone is squashed (may occur in a vertebra during a fall)

depressed fracture

broken part of the bone forms a concavity (as in skull fracture)

incomplete fracture

partial fracture extends only partway across the bone

greenstick fracture

partial fracture; one side of bone breaks- the other side is bent

estrogen, testosterone

sex hormones ___ and ___ which begin being secreted in relatively large amounts at puberty dramatically accelerate bone growth. stimulate osteoblasts, promote epiphyseal plate growth and closure.

bone fracture repair

4 steps. step 1 a fracture hematoma forms (bleeding), step 2 a fibrocartilaginous (soft) callus forms lasts at least 3 weeks; step 3 hard callus forms; step 4 the bone is remodeled.

osteoprogenitor, osteoblasts, osteocytes, osteoclasts

4 types of cells found in bone connective tissue are

red bone marrow

(also called myeloid tissue)soft connective tissue of bone that is hemopoietic (blood cell forming) and contains reticular connective tissue, immature blood cells, and fat. Also contains white blood cells.

zone of resting cartilage

1st epiphyseal plate zone; it is the farthest from the medullary cavity of the diaphysis and nearest the epiphysis. It is composed of small chondrocytes distributed throughout the cartilage matrix. It resembles mature and healthy hyaline cartilage. This region secures the epiphysis to the epiphyseal plate.

periosteum

A tough sheath called the ____ covers the outer surface of the bone except for the areas covered by articular cartilage. It consists of 2 layers. The outer layer of dense irregular connective tissue protects the bone from surrounding structures and serves as an attachment site for ligaments and tendons. The inner cellular layer includes osteoprogenitor cells, osteoblasts, and osteoclasts.

resorption lacuna

An osteoclast is often located within or adjacent to a depression or pit on the bone surface called ______.

articular cartilage

Covering the joint surface of an epiphysis is a thin layer of hyaline cartilage called the _____. This cartilage helps reduce friction and absorb shock in moveable joints.

bone remodeling

Even when adult bone size has been shaped, the bone continues to renew and reshape itself throughout a person's lifetime. This constant, dynamic process of continual addition of new bone tissue and removal of old bone tissue is called _____. 20% adult replaced yearly and does not occur in same rate everywhere in the skeleton. Also dependent on hormones and mechanical stress.

perforating fibers

The periosteum is anchored to the bone by numerous collagen layers called ___ or sharpey's fibers, which run perpendicular to the diaphysis.

bone connective tissue

The primary component of bone is ___ also called osseous. Bones are composed of both cells and extracellular matrix, like all connective tissue. contains osteoblasts, the mature cells are osteocytes, contains calcium, and is extensive in blood supply.

epiphyseal line

The remnant of the epiphyseal plate in adults is a thin, defined area of compact bone called the ____

storage of mineral and energy reserves

This is the function of bones because most of the body's reserves of the minerals calcium and phosphate are stored within and then released from bone.

hemopoiesis

This is the function of the bones because it is involved in the process of blood cell production. It occurs in red bone marrow connective tissue that contains stem cells that form blood cells and platelets.

support and protection

This is the function when bones provide structural support and serve as a framework for the entire body. Bones also protect many delicate tissues and organs from injury and trauma.

movement

This is the function when bones serve as attachment sites for skeletal muscles, other soft tissues, and some organs. Muscles attached to the bones of the skeleton contract and exert a pull on the skeleton that then functions as a system of levers.

diaphysis

This is the shaft of the long bone. It is elongated, usually cylindrical, and provides for the leverage and major weight support of the long bone.

external circumferential

appositi0nal growth occurs with the periosteum. in this process osteoblasts in the inner cellular layer of the periosteum produce and deposit bone matrix within layers parallel to the surface, called ____. As new bone grow in diameter osteoclasts along the medullary cavity resorb bone matrix expanding the medullary cavity to create an adult bone.

ligaments

are dense regular connective tissue that anchors bone to bone

tendons

are dense regular connective tissue that anchors muscle to bone.

chondroblasts

are derived from mesenchymal cells and they produce the cartilage matrix.

interstitial lamellae

are either the components of compact bone that are between osteons or are the leftover parts of osteons that have been partially resorbed- thus they often look like a bite has been taken out of them. These are incomplete and typically have no central canal.

osteoblasts

are formed from osteoprogenitor stem cells. Often, are positioned side by side on bone surfaces. Active ones may exhibit a somewhat cuboidal shape and have abundant rough ER and Golgi apparati.

long bones

are greater in length than width. These bones have an elongated, cylindrical shaft (diaphysis). This is the most common bone shape. Their sizes vary.

osteoclasts

are large multinuceal phagocytic cells. (klastos = broken). They are derived from fused bone marrow cells. These cells exhibit a ruffled border where they contact the bone, which increases their surface area exposure to the bone.

osteocytes

are mature bone cells derived from osteoblasts that have lost their bone-forming ability when enveloped by calcified osteoid. Connection between the neighboring osteoblasts are maintained. They maintian the bone matrix and detect mechanical stress on a bone. If stress is detected, they signal osteoblasts.

lacuunae

are small spaces that house an osteocyte

flat bones

are so named because they have flat, thin surfaces that may be slightly curved. They provide extensive sufaces for muscle attachment and protect underlying soft tissues. They form the roof of the skull, the scapula (shoulder blade), the sternum (breastbone), and ribs.

osteoprogenitor cells

are stem cells dervied from mesenchyme. When they divide through the process of mitosis, another stem cell is produced along with a "commited cell" that matures to become an osteoblasts.

concentric lamellae

are the rings of the bone connective tissue that surround the central canal and form the bulk of the osteon. The number vary among osteon. Each one contains collagen fibers oriented at an angle in one direction, then another direction, this alternating pattern of collagen fibers gives the bone strength and resilience.

canaliculi

are tiny interconnecting channels within the bone connective tissue that extend from each lacuna, travel through the lamellae, and connect to other lacuunae and the central canal. they house cytoplasmic projections that permit intercellular contact and communcation. nutrients, minerals, gases and wastes can travel through the cytoplasmic projections between the blood vessels.

hyaline cartilage

attaches ribs to the sternum (costal cartilage), covers the end of some bones (articular cartilage), and is the cartilage within growth plates (epiphyseal plates). This cartilage also provides a model for the formation of most of the bones in the body. glass appearing matrix, , avascular, no calcium, contains chondroblasts and chondrocytes

cartilage growth

begins during the embryologic development and can grow in length through interstitial growth or can grow in width by appositional growth.

endochondral ossification

begins with a hyaline cartilage model and produces most bones of the skeleton, including those of the upper and lower limbs, the pelvis, the vertebrae, and the ends of the clavicle.

oblique fracture

diagonal fracture is at an angle

rickets

disease due to lack of vitamin D causes deficient calcification of bones- bowing in lower limbs in children since don't have sunlight and not exposed to vitamin d

paget

disease results from a disruption in the balance between osteoclast and osteoblast function.

short bones

have a length nearly equal to their width. Examples are carpals (wrist bones), and tarsals (foot bones).

irregular bones

have elaborate, sometimes complex shapes and do not fit into any of the other categories. Examples are the vertebrae, ossa coxae (hip bones), and several bones in the skull, such as the ethmoid, sphenoid, and sutural bones.

bone scans

hot spots = increased metabolism as may be caused by a stress fracture or cancer; cold spots=indicate less activity or death of a bone.

woven bone

immature and not well organized bone is called ___ or primary bone.

diploe

in a flat bone of the skull, the spongy bone is also called ____ (meaning double).

glucocorticoids

increase bone loss and in children, impair bone growth when there are chronically high levels (cortisol, cortisone)

parathyroid hormone

increases blood calcium levels by encouraging bone resorption by osteoclasts

serotonin

inhibits osteoprogenitor cells from differentiating into osteoblasts when there are chronically high levels of serotonin

soft

insufficient calcium results in ___ bones or when put in acid.

flat bones of skull, facial bones (zygomatic, maxilla), the mandible (lower jaw), central part of clavicle (collar bone)

intramembranous ossification creates the following 4 types of bones.

growth hormone

is also called somatotropin, and is produced by the anterior pituitary gland. It affects bone growth by stimulating the liver to form another hormone somatomedin. Both are needed to stimulate the growth of cartilage in the epiphyseal plate and resulting in bone elongation.

endosteum

is an incomplete layer of cells that covers all internal surfaces of the bone within the medullary cavity. It contains osteoprogenitor cells, osteoblasts, and osteoclasts.

appositional growth

is an increase in width along the cartilage's outside edge or periphery. 3 steps. Step 1 undifferentiated stem cells at internal edge of perichondrium begin to divide; Step 2 new undifferentiated stem cells and committed cells that differentiate into chondroblasts are formed which secrete new matrix; Step 3 the chondroblasts as a result of matrix formation push apart and become chondrocytes with each occupying its own lacuna. The cartilage continues to grow at the periphery.

achondroplastic dwarfism

is characterized by abnormal conversion of hyaline cartilage to bone. the long bones of the limbs stop growing in childhood, while the other bones usually continue to grow normally.

spongy bone

is located internal to compact bone, appears porous, and makes up approximately 20% of the total bone mass.

thyroid hormone

is secreted by the thyroid gland and stimulates bone growth by influencing the basal metabolic rate of bone cells. (osteoblasts)

proximal epiphysis

is the epiphysis end of bone closest to the body trunk.

distal epiphysis

is the epiphysis end of the bone farthest from the trunk.

epiphysis

is the expanded knobby region of the long bone and is at each end. It is composed of an outer thin layer of compact bone and an inner more extensive region of spongy bone.

epiphyseal plate

is the growth plate in a growing bone. It is a thin layer of hyaline cartilage that provides for continued growth lengthwise of the bone.

medullary cavity

is the hollow, cylindrical space within the diaphysis. In children, this cavity contains red bone marrow, which is replaced by yellow bone marrow in adults.

metaphysis

is the region in a mature bone sandwiched between the diaphysis and the epiphysis. it includes the epiphyseal plate.

regulating calcium

is very important for initiation of muscle contraction, exocytosis of molecules from cells, including nerve cells, stimulation of the heart by pacemaker cells, and blood clotting.

mechanical stress

occurs in the form of weight bearing movement and exercise, and it is required for normal bone remodeling. Stress is detected by osteocytes and communicated to osteoblasts. Osteoblasts increase synthesis of osteoid, and this is followed by deposition of mineral salts. Bone strength increases over a period of time in response to this.

interstitial growth

occurs within the internal regions of cartilage through 4 steps. Step 1 Chondrocytes housed within lacunae under go mitoitic cell division; Step 2 after cell division the 2 cells that occupy the lacuna are called chondroblasts; Step 3 as chondroblasts begin to synthesize and secrete new cartilage matrix they are pushed apart. now the cells are in their own lacuna and are called chondrocytes; Step 4 the cartilage continues to grow in the internal regions as chondrocytes continue to produce more matrix.

chondrocytes

once chondroblasts become encased within the matrix they have produced and secreted they are called_____ and occupy small spaces called lacunae.

impacted fracture

one fragment of bone is firmly driven into the other

perforating canals

only part of compact bone. they resemble central canals in that they also contain blood vessels and nerves. However, they run perpendicular to the central canals and help connect multiple central canals within different osteons, thus creating a vascular and innervation connection among the multiple osteons.

osteoid

osteoblasts synthesize and secrete the initial semisolid organic form of bone matrix called____ which later calcifies as a result of salt crystal deposition. Because of this mineral deposition, they become entrapped within the matrix they produce and secrete.

flat bones of skull, vertebrae, ribs sternum, ossa coxae, and proximal epiphyses of humerus and femur.

places where red bone marrow is in adults.

calcitonin

promotes calcium deposition in bone and inhibits osteoclast activity. used as a receptors in bone connective tissue, and kidneys use to decrease calcium levels.

compact, spongy, no

short, flat, and irregular bones differ in their gross anatomic structure from long bones. the external surface generally is composed of ___ bone, the interior is composed entirely of ___ bone and there is ___ medullary cavity.

yellow bone marrow

soft connective tissue of bone that has degenerated from red bone marrow and turns into a fatty substance called_____.

trabeculae

spongy bone contains no osteons. rather its structure is an open lattice of narrow rods and plates of bone called____. bone marrow fills this . It also has parallel lamellae. Offers a meshwork of crisscrossing bars and plates of small bone pieces. This structure provides great resistance to stresses applied to many directions by distributing the stress throughout the entire framework.

many

spongy bone within the epiphysis resists stress that is applied from ___ directions.

4 steps of intramembranous ossification

step 1 ossification centers from within thickened regions of mesenchyme beginning at the eight week of development; step 2 osteoid undergoes calcification; step 3 woven bone and its surrounding periosteum; step 4 lamellar bone replaces woven bone as compact bone and spongy bone form.

6 steps of long bone development

step 1 the fetal hlyaline cartilage model develops; step 2 cartilage calcifies, and a periosteal bone collar forms; step 3 the primary ossification center forms in the diaphysis. step 4 secondary ossification centers form in the epiphyses, step 5 bone replaces almost all cartilage, except the articular cartilage and epiphyseal cartilage, step lengthwise growth continue until the epiphyseal plates ossify and form epiphyseal lines.

simple fracture (closed)

the bone does not penetrate the skin. takes 2 to 3 months to heal

compound fracture (open)

the broken bone does penetrate the skin. takes longer than 3 months to heal.

interstitial growth of bone

this is dependent upon growth of cartilage within the epiphyseal plate. It has 4 distinct microscopic zones.

zone of calcified cartialge

this zone is usually composed of 2 to 3 layers of chondrocytes. Minerals are deposited in the matrix between the columns of lacunae; this calcification destroys the chondrocytes and makes the matrix appear opaque.

zone of ossification

this zone the walls break down between lacunae in the columns, forming longitudinal channels. These spaces are invaded by capillaries and osteoprogenitor cells form the medullary cavity. new matrix of bone is deposited on the remaining calcified cartilage matrix.

nutrient foramen

typically, only one nutrient artery enters, and one nutrient vein exits the bone via a small opening or hole in the bone called _____. blood vessels supply nutrients and oxygen required by cells and remove waste products from bone cells. Nerves that supply bones accompany blood vessels also through this hole.

pathologic fracture

usually occurs in bone that has been weakened by disease. example cancer

vitamin D to calcitriol

vitamin D3 converted to cholecalciferol from uv light in skin then converted to calcidiol in liver, then converted to calcitriol in the kidney. Now as calcitriol it stimulates absorption of calcium ions from the small intestine into the blood.

lamellar bone

woven bone is replaced by ___ or secondary bone.