ch. 7

The anterior pituitary gland secretes ____________, which stimulates the formation of _______________.

growth hormone; somatomedin

In an adult, red bone marrow is found in all of the following bones except the

radius of forearm.

flat bones

scapula sternum

long bones

ulna and radius

Put the following events in the correct order

1. Some mesenchymal cells in the membrane become osteochondral progenitor cells. 2.Osteochondral progenitor cells become osteoblasts. 3. Osteoblasts produce bone matrix that surrounds collagen fibers of the mesenchyme. 4. Trabeculae develop. 5. Osteoblasts form a ring on the outer surface of the trabeculae. 6. Spongy bone forms as trabeculae join together. 7. Osteoblasts from the periosteum lay down bone matrix to form an outer surface of compact bone.

Put the steps of bone repair in the correct order.

1. When the bone is fractured, damage occurs to blood vessels and the periosteum. 2. A localized mass of blood called a hematoma is formed. 3. An internal callus forms between the ends of the bones and an external callus forms a collar around the break. 4. Fibers and cartilage of the calluses are replaced by spongy bone. 5. Woven bone is replaced by compact bone.

1. Intramembranous ossification is completed by birth. 2. Within the spongy bone that is formed by intramembranous ossification, there are spaces that contain developing red bone marrow. 3. The end products of intramembranous bone formation are bones with outer compact bone surfaces and spongy centers.

1. false 2. true 3. true

1. Hydroxyapatite 2. Collagen 3. Proteoglycans 4. Provides flexible strength 5. Provides weight bearing strength

1. inorganic 2. organic 3. organic 4. organic 5. inorganic

Fibrocartilage

A weight-bearing cartilage that withstands compression; forms the intervertebral discs, the pubic symphysis & cartilage pads of the knee joints (menisci)

Which of the following would not be considered part of the skeletal system?

Elastic cartilage

Select all that are true of calcitonin

Helps decrease blood calcium More effective in children than adults

Select all that are true regarding the endosteum.

It lines the medullary cavity. It surrounds the periosteum. It contains osteoblasts. It contains osteoclasts.

The organization of the trabeculae in spongy bone serves what purposes? Check all that are correct

It provides resistance to stresses from many different directions. It decreases the weight of long bones. It makes the bones slightly flexible.

Lack of sunlight will directly affect the formation of

Vitamin D3 (cholecalciferol).

Bones in the legs, arms, spine, and pelvis grow

at different rates

Contained within the spongy sections of bones, marrow is responsible for blood formation

blood formation

Indicate the parts of the skeletal system.

bones Hyaline cartilage Fibrocartilage Elastic cartilage

Depositions of collagen and fibrocartilage will then turn the tissue into a soft __________

callus

Osteocytes maintain contact with neighboring osteocytes in adjacent lamellae via dendrite-like extensions called ___________

canaliculi

short bones

capitate and talus

The cylindrical channel that lies in the center of the osteon is the

central canal.

Located in the middle of osteons, the_________contain the arterial, venous, and nervous supply of the compact bones.

central canals

Hyaline cartilage consists of specialized cells called __________ that produce a matrix surrounding themselves. When matrix surrounds these cells, they become __________ that are trapped in lacunae.

chondroblasts; chondrocytes

Interstitial Growth

chondrocytes in lacunae are stimulated to undergo mitosis two cells occupy lacuna and are now chondroblasts chondroblasts are pushed apart into their own lacuna growth within the cartilage

Minerals can be stored in the skeleton, which acts as a reservoir, storing or releasing minerals as needed to maintain electrolyte balance throughout the body.

electrolyte balance

Calcitonin

encourages calcium deposition from blood into bone

Mechanical stress occurs in the form of weight-bearing movement and ___________, and it is required for normal bone _____________ Stress is detected by ___________ and communicated to ____________ These cells then ___________ synthesis of osteoid, and this is followed by _____________ of mineral salts. Bone strength ___________ over a period of time in response to mechanical stress.

exercise remodeling osteocytes osteoblasts. increase deposition increases

If you look at the cross section of a long bone under a microscope, the rings of bone immediately internal to the periosteum of the bone are called

external circumferential lamellae.

Bone building cells beneath the endosteum lay down bone to form ridges around a blood vessel.

false

Compact bone is found on the internal surfaces of spongy bone, often lining the marrow cavities.

false

Once the epiphyseal plate fuses and forms an epiphyseal line, the long bone continues to grow in length, but at a slower rate.

false

Parathyroid hormone is released in response to elevated blood calcium levels and will help the body return to homeostasis.

false

The medullary cavity of a flat bone contains red or yellow bone marrow.

false

Endochondral Ossification

femur ribs fibula phalanges

Hyaline Cartilage

forms articular cartilage composes epiphyseal plates attaches ribs to sternum

Any break in a bone is called a __________, and repair is done in stages by the body.

fracture

Hyaline cartilage contains cells in a________ ground substance. The ground substance is similar to that of bone in that it includes ___________, such as chondroitin sulfate, but it differs from bone because its inorganic salts do not contain __________. Cartilage contains a high percentage of __________ (60—70% by weight). The cells that produce the cartilage matrix are _________. These are derived from ________________. Once the matrix-forming cells become encased in the matrix, they are known as ______________. The cavities that these mature cells occupy are _____________

gel-like proteoglycans calcium water chondroblasts mesenchymal cells chondrocytes lacunae

A ________ will form and will turn into granulation tissue at the site of injury.

hematoma

Elongation of bones through endochondral ossification requires the zone of reserve cartilage where normal ____________ cartilage persists in the metaphysis

hyaline

Articular cartilage, found on the ends of long bones, consists of

hyaline cartilage.

Appositional Growth

increase in width of cartilage stem cells at internal edge of perichrondrium divide stem cells and committed cells differentiate into chondroblasts cartilage growth into the periphery

Thyroid Hormone

influences the basal metabolic rate of bone cells

A flat bone of the skull is produced by ___________ ossification.

intramembranous

Filled with osteocytes, which are osteoblasts encased in matrix, _________ are found between layers of concentric lamellae.

lacunae

The most common bone shape in the body is the ______ bone shape. One of the principal features is a shaft called a(n) __________ that contains a hollow, cylindrical space inside called the medullary cavity. In children, this cavity contains_____ bone marrow, which is later replaced by______ bone marrow in adults. An end of these bones is called a(n) ________. The other three bone shapes in the body generally have an external surface composed of________bone and the interior is composed entirely of _________ bone.

long diaphysis medullary red yellow epiphysis compact spongy

The ___________ are found deep in the diaphyses of long bones and are filled with yellow marrow in the adult.

medullary cavities

Intramembranous ossification takes place in the embryonic tissue _______________. This process is also called _____________ because the embryonic tissue that is the source for these bones will be in the area of the future dermis. Intramembranous ossification produces the ________ bones of the skull, some of the facial bones (zygomatic bone and __________), the ___________(lower jaw), and the central part of the _________(collarbone).

mesenchyme dermal ossification flat maxilla mandible clavicle

The _____________ of the entire skeleton or skeletal elements utilizes the anchoring of muscles to attachment sites on the bones, which then serve as levers.

movement

A nutrient artery enters the bone at the (two words) ______ ______.

nutrient foramen

Bones of the skeleton are the primary _________ of the skeletal system. Two types of bone __________tissue are present in most of the bones in the body: compact bone and spongy bone. The bone tissue that appears white, smooth, and solid is ________ bone whereas, ________ bone appears porous.

organs connective compact spongy

Decreases Blood Calcium

osteoblast activity calcitonin

A temporary bony collar is deposited by ___________ around the fracture while ossification occurs

osteoblasts

Bone cells that become surrounded by bone matrix and are located in cavities called lacunae are

osteocytes.

Parathyroid hormone is released from the __________ glands.

parathyroid

increases Blood Calcium

parathyroid hormone osteoclast activity calcitriol increased bone resorption

Intramembranous Ossification

parietal bones clavicle maxilla

The skull, pelvis, ribs, vertebral column, and sternum provide__________ to many delicate organs of the body by encasing them in hardened shell-like or caged structures.

protection

Aging affects bone in two ways. First, the tensile strength of bone decreases due to a reduced rate of ____________ by osteoblasts. Consequently, the relative amount of inorganic minerals in the bone matrix ________. The bones of the skeleton become ________ and susceptable to _________. Second, bone _________(loses calcium and other minerals). The bones of the skeleton become thinner and weaker, resulting in insufficient ___________, a condition called ____________

protein synthesis increases brittle fracture demineralizes ossification osteopenia

the process finishes with bone _________ converting spongy to compact bone.

remodeling

Hyaline cartilage

serves as a precursor for the formation of long bones in the body.

Based on their shape, bones that have a length about equal to their width are classified as _____ bones.

short

Weaken/Reduce Bone Mass

sitting sedentary lifestyle astronauts in space limb immobilization

Bone remodeling is important for all of the following reasons except

sodium ion regulation in the body.

Irregular Bones

sphenoid and vertebra

Parathyroid Hormone

stimulates osteoclasts to resorb bone and increase blood calcium

The bones of the skeleton provide structure to the body and serve as a ____________to hold up the body and maintain proper positioning of some organs.

support

The epiphyseal plate is composed of cartilage.

true

Build/Retain Bone Mass

weight lifting walking gravitational forces

Mineralization of the cartilaginous walls between lacunae provides a temporary framework in the ____________ by which the final stages of ossification will take place.

zone of calcification

Nearer to the medullary cavity, the ____________ is marked by an expansive production of chondrocytes that align in rows in order to replenish those undergoing calcification.

zone of cell proliferation

The ____________ demonstrates the area where the chondrocytes die and are replaced by blood vessels and osteoblasts, which then form the final trabeculae and osteoclasts that refine the distal contours of the medullary chamber.

zone of deposition

The next layer is the ____________ where the existing, columnar chondrocytes enlarge and thus force the separations between lacunae to become very thin.

zone of hypertrophy

In the epiphyseal plate, the microscopic zone in which chondrocytes undergo rapid cell division and become aligned into longitudinal columns of flattened lacunae is called the

zone of proliferating cartilage.