Growth of Cartilage

1) Appositional growth results in outward expansion due to the production of a. cartilage matrix on the outside of the tissue.

2) During appositional growth of cartilage, the cells that produce the matrix are the:  A. chondrocytes. B.  osteocytes. C.  fibroblasts. D.  chondroblasts.

3) Place the following steps in the process of appositional growth of cartilage in correct order. a: New matrix is produced and secreted. b: Chondrocytes differentiate, each in its own lacuna. c: Stem cells undergo mitosis. d: Committed cells differentiate into chondroblasts.  

4) Interstitial growth results in expansion from within the cartilage matrix due to division ofa. lacunae-bound chondrocytes and secretion of matrix.

5) Interstitial growth of cartilage increases its ______ and occurs in the _______ region of the cartilage.  

Compact and Spongy Bone

1) All bone has a dense outer layer consisting of compact bone that appears smooth and solid.

2) Internal to compact bone is spongy bone

which consists of honeycomb, needle-like, or flat pieces, called _______________

Structure of a Typical Long Bone

1. tubular bone shaft2. consisting of a bone collar surrounding a hollow medullary cavity

a. which is filled with ____________bone marrow in adults.3. Epiphyses are at the ends of the bone, and consist of

a. internal spongy bone covered by an outer layer of compact bone.4. The epiphyseal line is located between the

a. epiphyses diaphysis, and is a remnant of the : epiphyseal plate.5. The external surface of the bone is covered by the periosteum.

6. The internal surface of the bone is lined by a connective tissue membrane called the endosteum.

Structure of Short, Flat, and Irregular Bones

Short, flat, and irregular bones consist of thin plates of periosteum-covered compact bone:

on the outside, and endosteum-covered spongy bone inside

which houses bone marrow between the trabeculae.

***Cartilage plate that serves as a growth area along the bone lengthening, it allows the dialysis of the bone to increase in length until early adulthood.

When growth stops the epiphyseal plate is replaced with bone then becoming the epiphseal line.***

1) What is the thin layer of connective tissue that lines the medullary cavity of a long bone?  

A.  Diaphysis B.  Epiphysis C.  Endosteum

2) Consider the classifications of bone, and examples of each. Which classification comprises bones used primarily for movement rather than protection?  A.  Short bones B.  Long bones C.  Flat bones

3) The flat bones of the cranium form by intramembranous ossification.  TRUE/FALSE

BONE

1) The structural unit of compact bone is the osteon, or ________________system

which consists of concentric tubes of bone matrix (the lamellae) surrounding a central Haversian canal that serves as a passageway for blood vessels and nerves.

Perforating, or ___________________ lie at right angles to the long axis of the bone, and connect the blood and nerve supply of the _________________ to that of the central canals and medullary cavity.

Osteocytes occupy lacunae at the junctions of the lamellae, and are connected to each other and the central canal via a series of hair-like channels, _____________

_________________ lamellae are located just beneath the periosteum, extending around the entire circumference of the bone, while interstitial lamellae lie between intact osteons, filling the spaces in between.

Spongy bone lacks osteons but has trabeculae that align along lines of stress

which contain irregular lamellae.

Chemical Composition of Bone

1) Organic components of bone include cells : which contribute to the flexibility and tensile strength of bone.

osteoblasts, osteocytes, and osteoclasts and osteoid (ground substance and collagen fibers),

1) Osteoid is the:  A.  organic part of the bone matrix that gives it rigidity. B.  organic part of the bone matrix that gives it tensile strength.

2) f a bone is immersed in a weak acid such as vinegar for several days, its inorganic components will dissolve. What will be the result of such an experiment?  A.  The bone will dissolve completely. B.  The compact bone will dissolve, leaving only the inner spongy bone. C.  The bone will become extremely brittle. D.  The bone will become soft and bendable.

2) Inorganic components make up:

65% of bone by mass, and consist of ____________________ a mineral salt that is largely calcium phosphate, which accounts

for the hardness and compression resistance of bone.

Formation of the Bony Skeleton

1) Which type of cell produces new bone tissue by secreting matrix?  A.  Osteocytes B.  Osteoclasts C.  Osteoblasts D.  Osteoprogenitor cells

2) Bone cells called __________ break down bone by secreting hydrochloric acid and enzymes that dissolve the matrix.  A.  osteoprogenitor cells B.  osteoid cells C.  osteocytes D.  osteoclasts

3) An osteoclast has a ruffled border and multiple nuclei.  TRUE/FALSE4) As the bone matrix calcifies and the secreting cells become walled in:  A. osteoblasts become osteocytes. B.  osteogenic

progenitors become osteoclasts. C.  osteoblasts become osteoclasts.

6) The type of bone tissue that is replaced more frequently is ________ bone; the part of the femur that is replaced more frequently is the __________.  

-Intramembranous ossification forms membrane bone from fibrous connective tissue membranes, and results in the cranial bones and clavicles.

1) 1) Which choice places the steps of intramembranous ossification in correct chronological order?

a: Formation of lamellar bone b: Osteoid undergoes calcification c: Ossification centers form d: Formation of woven bone and its periosteum  

In endochondral ossification bone tissue replaces _________________, forming all bones below the skull except for the clavicles.

1) osteoblasts secrete osteoid, creating a bone collar around the diaphysis of the hyaline cartilage model.

2) Cartilage in the center of the diaphysis calcifies and deteriorates, forming cavities.

3) periosteal bud invades the internal cavities and spongy bone forms around the remaining fragments of hyaline cartilage.

4) diaphysis elongates as the cartilage in the epiphyses continues to lengthen and a medullary cavity forms through the action of osteoclasts within the center of the diaphysis.

The epiphyses ossify shortly after birth through the development of secondary ossification centers.

Postnatal Bone Growth

1) Growth in length of long bones occurs at the ossification zone through the a. rapid division of the upper cells in the columns of:

i. Chondrocytesii. Calcification

b. deterioration of cartilage at the bottom of the columnsc. subsequent replacement by

i. bone tissue.

1) When during human development does the process of ossification begin?  

A.  12 weeks after birth B.  12th-13th week of embryonic development C.  8th-9th month of fetal development

2) Growth in width, or thickness, occurs through appositional growth due to deposition of bone

matrix by __________________beneath the periosteum.

Hormonal Regulation of Bone Growth

1) During infancy and childhood, the most important stimulus of epiphyseal plate activity is growth hormone from the anterior pituitary, whose effects are modulated by thyroid hormone.

2) At puberty testosterone and estrogen promote a growth spurt, but ultimately induct the closure of the epiphyseal plate.

Bone Remodeling

1) Adult skeletons: bone remodeling is balanced bone deposit and removala. bone deposit occurs at a greater rate when bone is injured, and bone resorption allows minerals of

degraded bone matrix to move into the blood.

Control of Remodeling

The hormonal mechanism is mostly used to maintain blood calcium homeostasis, and balances activity of parathyroid hormone and calcitonin.

In response to mechanical stress and gravity, bone remodels in ways that allow it to withstand the stresses it experiences.

1) In the kidneys, parathyroid hormone acts to ____(INCREASE/DECREASE)____ production of calcitriol and to ____(INCREASE/DECREASE)____ excretion of calcium in urine.  

2) Parathyroid hormone and calcitriol:  

A.  stimulate osteoclasts to resorb bone and release calcium into the blood.

B.  stimulate osteoblasts to deposit bone by producing calcified matrix.

1) To trigger bone growth, growth hormone stimulates the:  A.  liver to produce somatomedin. B.  liver to produce calcitonin. C.  brain to produce serotonin.

2) What explains the dramatic acceleration in lengthwise bone growth at puberty?  A.  Increased activity of osteoclasts occurs in response to parathyroid hormone stimulation. B.  Increased rate of calcium deposition occurs due to high blood calcium levels. C.  Increased secretion of sex hormones promotes epiphyseal plate growth.

3) Calcitonin _________ osteoclast activity and _______ excretion of calcium from the kidney.  

Bone Repair

Fractures are breaks in bones, and are classified by:

1. the position of the bone ends after fracture2. completeness of break3. orientation of the break relative to the long axis of the bone4. whether the bone ends penetrate the skin.

Repair o f fractures involves four major stages:

1. hematoma formation2. fibrocartilaginous callus formation3. bony callus formation4. emodeling of the bony callus.

1) The process of bone repair includes these steps: PRACE IN ORDERa: Fracture hematoma formsb: Bone is remodeledc: Fibrocartilaginous callus formsd: Bony callus forms

2) Once we reach adulthood and our bones are fully formed and hardened, they cannot be remodeled.  TRUE/FALSE

3) Found within both the periosteum and endosteum, _________ cells are derived from mesenchyme and serve as the stem cells of bone.  

1) Which is the definition for a greenstick fracture?  A.  The bone is twisted as it fractures. B.  The fracture is at right angles to the long axis of the bone. C.  The bone is splintered into several fragments. D.  Only one side of the bone is broken; the other side is bent.

2) A fracture parallel to the long axis of the bone is a(n) _________ fracture.  A.  transverse B.  oblique C.  linear3) The break of a bone that has been weakened by disease is a ________fracture; when a broken end of the bone pierces the

skin, the fracure is ________.  A.  stress, greenstick. B.  epiphyseal, stress. C.  greenstick, simple. D.  pathologic, compound.4) Which is not involved in the process of bone repair following a fracture?  A.  Fibroblasts produce collagen fibers to connect

broken pieces of bone. B.  A fibrocartilaginous callus serves as a model for new bone growth. C.  Osteoclasts remove excess bone from the hard callus. D.  The fracture hematoma reorganizes to form a procallus. E.  No exceptions; all of the choices are involved in the process of bone repair.

Osteomalacia and Rickets

Osteomalacia includes a number of disorders in adults in which the bone is inadequately mineralized.

Rickets is inadequate mineralization of bones in children caused by insufficient calcium or vitamin D deficiency.

1) Rickets, a disease characterized by overproduction and deficient calcification of osteoid tissue, is caused by a lack of sufficient:  A.  Vitamin D. B.  Calcitonin. C.  Thyroid hormone.

1) Osteoporosis refers to a group of disorders in which the rate of bone resorption exceeds the rate of formation

2) Bones have normal bone matrix, but bone mass is reduced and the bones become more porous and lighter increasing the likelihood of fractures.

3) Older women are especially vulnerable to osteoporosis, due to the decline in estrogen after menopause.

4) Other factors that contribute to osteoporosis include:

petite body form nsufficient exercise or immobility a diet poor in calcium and vitamin D abnormal vitamin D receptors smoking certain hormone-related conditions.

5) With aging comes insufficient ossification of bone, a condition known as _________.  6) Which is a change in bone architecture or mass related to aging?  A.  Insufficient calcification B.  Demineralization C. 

Reduction in the organic content of the matrix D.  Loss of flexibility and increase in brittleness E.  All of the choices are correct

***1) Since cartilage must be continuously replaced in the body, appositional and interstitial growth of cartilage continues throughout life.  TRUE/ FALSE ***