BIOL 4 CH. 6

The kneecap, or patella, is an example of

a sesamoid bone

In an adult, the perichondrium

acts like a girdle to prevent the matrix from pushing outward when the cartilage is compressed.

Which of the following cells is secreting cartilage matrix?

chondroblast.

Cartilage repairs slowly after adolescence because

chondrocytes no longer are able to divide and secrete new matrix.

The only bones formed by intramembranous ossification that are NOT in the skull are the __________.

clavicles

A fracture in which the bone fragments into three or more pieces is a __________ fracture.

comminuted

Perforating canals within compact bone __________.

connect the blood and nerve supply of the periosteum to that of the central canals

Compact bone

dense outer layer or bone

The type of cartilage that can withstand the strongest compression and tension forces is

fibrocartilage

If a bone is thin, flattened, and somewhat curved, that bone is a(n) ________ bone.

flat

A round or oval opening through a bone is a __________.

foramen

All of the following are true regarding cartilage except: it is primarily composed of water. it contains no nerves or blood vessels.it is easily deformed with compression and does not return to its original shape. it is more abundant in an infant than in an adult.

is easily deformed with compression and does not return to its original shape.

Blood vessels to the diaphysis move through the

nutrient foramen

The cell responsible for secreting the matrix of bone is the

osteoblasts

Which osteogenic cells are located in the endosteum?

osteoblasts

A large, multinucleate cell with a ruffled border is an

osteoclasts

In the bone matrix, osteoblasts become

osteocytes

Which of the following is not present in the central canals of osteons?

osteocytes

The periosteum is attached to underlying bone by __________ fibers.

perforating

Sesamoid bones are examples of __________ bones.

short

Bones in the wrists and ankles are

short bones

What is the function of the bone markings illustrated on this rib: head and facets?

surfaces that form joints

In what way does healing of cartilage occur in adults (a person who has stopped growing)?

surviving chondrocytes secrete more extracellular matrix

Which bone cell type secretes hydrochloric acid?

Osteoclasts

What is the effect of parathyroid hormone (PTH) on bone tissue?

PTH stimulates osteoclasts to resorb bone and release calcium into the blood when the concentration of calcium in body fluids is low.

Which component of bone tissue makes bone hard?

mineral salts

Chemical Composition of Bone

- 35% organic components: composed of cells, fibers, and organic substances, collagen (abundant) - 65% inorganic mineral salts: primarily calcium phosphate, resists compression

Endochondral Ossification

- All bones except some bones of the skull and clavicles - Bones are modeled in hyaline cartilage - Begins forming late in the second month of embryonic development - Continues forming until early adulthood

Bone Remodeling

- Bone deposit and removal (occurs at periosteal and endosteal surfaces) - Bone remodeling - Bone deposition: accomplished by osteoblasts - Bone reabsorption: accomplished by osteoclasts

Osteoporosis

- Characterized by low bone mass - Bone reabsorption outpaces bone deposition - Occurs most often in women after menopause

Bones contain several types of tissues

- Dominated by bone CT - Contain nervous tissue and blood CT - Contain cartilage in articular cartilages - Contains ET lining in blood vessels

Structure of Short, Irregular, and Flat Bones

- Flat bones, short bones, and irregular bones - Contain bone marrow but no marrow cavity - Diploe: internal spongy bone of flat bones

Bone Development

- Ossification (osteogenesis): bone tissue formation - Membrane bones: formed directly from mesenchyme - Intramembranous ossification - Other bones: develop initially from hyaline cartilage - Endochondral ossification

Repair of Bone Fractures

- Simple and compound fractures - Treatment by reduction (closed reduction, open reduction)

Bone Markings

- Superficial surfaces of bones reflect stresses on them - There are three broad categories of bone markings: projections for muscle attachment, surfaces that form joints, depressions and openings

Put the steps of endochondral ossification in the correct order. 1: Formation of medullary cavity and appearance of secondary ossification centers 2: Cavitation of hyaline cartilage within the cartilage model 3: Invasion of internal cavities by periosteal bud and spongy bone formation 4: Ossification of epiphyses; hyaline cartilage remains at epiphyseal plates and articular cartilages 5: Formation of bone collar around hyaline cartilage model

5: Formation of bone collar around hyaline cartilage model 2: Cavitation of hyaline cartilage within the cartilage model 3: Invasion of internal cavities by periosteal bud and spongy bone formation 1: Formation of medullary cavity and appearance of secondary ossification centers 4: Ossification of epiphyses; hyaline cartilage remains at epiphyseal plates and articular cartilages

Osteosarcoma

A form of bone cancer

Which characteristic is a similarity among all types of cartilage?

All types of cartilages consist of 60-80% water.

Paget's disease

Characterized by excessive rate of bone deposition

Structure of a Typical Long Bone

Diaphysis: "shaft" of a bone Epiphysis: ends of a bone Blood vessels: well vascularized Medullary cavity: hollow cavity filled with yellow marrow Membranes: Periosteum, perforating fibers (Sharpey's fibers), and endosteum

A long bone may be characterized by two diaphyses and one epiphysis.

False

As cartilage ages, calcium salts are deposited and calcify the cartilage, turning it into bone. True or False?

False

Cartilage is strong in resisting twisting and bending but weak in resisting tension and compression. True or False?

False

Circumferential lamellae occur around the entire outer and inner surfaces of compact bone, and they are considered remnants of old osteons that have been disrupted by bone remodeling.

False

In appositional growth, chondrocytes within cartilage divide and secrete new matrix.

False

Microscopic inspection of hyaline cartilage would show prominent parallel bundles of collagen fibers. True or False?

False

The bones of your hand and fingers would all be categorized as long bones.

False

Which of the following statements about woven bone is false?

It contains no trabeculae.

What is the importance of the perichondrium that surrounds cartilage?

It resists outward expansion when cartilage is subjected to pressure and functions in growth and repair of cartilage.

Classification of Bones

Long bones: longer than wide, a shaft plus ends (ex. humerus) Short bones: roughly cube-shaped (ex. triquetral) Flat bones: thin and flattened, usually curved (ex. sternum) Irregular bones: various shapes, do not fit into other categories (ex. vertebra)

Osteomalacia

Occurs in adults: bones are inadequately mineralized

Rickets

Occurs in children: analogous to osteomalacia

Function of Bones

Support: provides hard framework Movement: skeletal muscles use bones as levers Protection of underlying organs Mineral storage: reservoir for important minerals Blood-cell formation: bone contains red marrow

Fibrocartilage is designed to withstand repeated compressive forces.

True

Membrane bones form directly from mesenchyme without being modeled in cartilage.

True

Osteocytes, residing within lacunae, are connected via canaliculi.

True

What are two locations in the body where fibrocartilage is located?

annulus fibrosis of intervertebral discs and menisci of the knee

In growing cartilage, the chondroblasts associated with the perichondrium are responsible for

appositional growth

Primary ossification centers occur in the __________ of long bones.

diaphysis

The type of cartilage that comprises the epiglottis is

elastic cartilage

Which of the following boney markings is a site for muscle attachment?

epicondyle

The types of fractures that are common in children are __________.

epiphyseal and greenstick

All of the following structures in the body contain cartilage except

esophagus

Which of the following is the correct progression in the healing of a skeletal fracture?

hematoma, fibrocartilage callus, bony callus, bone remodeling

During endochondral ossification, which of the listed types of tissue is replaced by bone?

hyaline cartilage

The type of cartilage that forms the costal cartilages at the ends of the ribs is

hyaline cartilage

The type of cartilage that forms the long bones of the embryonic skeleton is

hyaline cartilage

The primary center of ossification

in the diaphysis

Spongy (cancellous) bone

internal network of bone

If a bone located in a limb is longer than it is wide, that bone is a(n) ________ bone.

long

Osteoblasts originate from what type of precursor cells?

mesenchyme cells

Osteoblasts originate from

mesenchyme cells.

Functions of bones include all of the following, EXCEPT __________.

protein storage

Flat bones include all of the following examples, EXCEPT __________.

wrist bones