Biology 227 Chapter 6 Review

The fibrocartilaginous callus is the first repair mass to splint the broken bone.

true

Tiny canals connecting lacunae.

D. canaliculi

Location of compact bone in an adult's bone.

A. diaphysis

Scientific name for bone shaft.

A. diaphysis

The following events apply to the endochondrial ossification process as it occurs in the primary ossification center.

1. Cavity formation occurs within the hyaline cartilage [this occurs before blood vessel invasion because the cartilage cells in the middle of the model cannot receive enough nutrients by diffusion to stay alive. When they die the hyaline protein they maintain breaks down]. 2. Perichondrium becomes vascularized to a greater degree [this increased vascularization stimulates the perichondrial cells to differentiate to become osteogenic cells (osteoblasts) that lay down bone; the perichondrium now covers bone so it can be renamed periosteum]. 3. Collar of bone is laid down around the hyaline cartilage model just beneath the periosteum. 4. Periosteal bud invades the marrow cavity. 5. Osteoblasts lay down bone around the cartilage spicules in the bone's interior. 6. Osteoclasts remove the cancellous bone from the shaft interior, leaving a marrow cavity that then houses fat [you need to lay down the bone in e above before it can be removed to form a complete cavity].

List and explain five important functions of bones.

1. They support the body by providing a rigid skeletal framework. 2. They protect the brain, spinal cord, lungs, and other internal organs. 3. They act as levers and provide attachments for muscles in movement. 4. They serve as a reservoir for fat and minerals. 5. They are the sites of formation of blood cells.

Identify each of the following bones as a member of one of the four major bone categories.

1. long bone: -humerus -radius -femur - metacarpal 2. short bone: -calcaneus 3. flat bone: -frontal -mandible -sternum 4. irregular bone -vertebra

The initial supporting structure for this type of ossification is a fibrous membrane formed by ________________ . The first recognizable event is a clustering of the _______________cells to form a(n) ______________ in the fibrous membrane. These cells then differentiate into ______________, which begin secreting ________________ around the fibers of the membrane. Within a few days, calcium salt deposit or ________________ occurs, producing true _________________ . The first network of trabeculae formed are arranged irregularly. This early membrane bone is referred to as _______________ bone. As it forms, a layer of vascular ________________ condenses on the external face of the bone structure, forming a ________________ . Eventually lamellar bone replaces ___________________ , and the vascular tissue within the _________________ differentiates into red marrow. The final result is a flat bone.

1. mesenchymal cells 2. mesenchymal 3. ossification center 4. osteoblasts 5. osteoid 6. mineralization 7. bone matrix 8. woven 9. mesenchyme 10. periosteum 11. woven bone 12. dipole

Most hyaline cartilage "long bones" show primary ossification centers by 8 weeks.

12 weeks

Disuse such as that caused by paralysis or severe lack of exercise results in muscle and bone _________.

A. atrophy

Longitudinal canal, carrying blood vessels and nerves.

A. central (haversian) canal

What single structural characteristic account for the resilience of cartilage and its ability to grow rapidly in the developing skeleton?

Although collagen fibers form cartilage's supporting framework, its proteoglycons and hyalouronic acid attract and organize huge amounts of water, which becomes the main component of cartilage. This water "saves space" for bone development and is responsible for cartilage's resilience throughout life.

_____________ causes blood calcium to be deposited in bones as calcium salts.

B. calcitonin

Layers of calcified matrix.

B. concentric lamellae

Composed of hyaline cartilage until the end of adolescence.

B. epiphyseal plate

Region of longitudinal growth in a child.

B. epiphyseal plate

Location of spongy bone in an adult's bone.

C. epiphysis

Site of hematopoiesis in an adult's bone.

C. epiphysis & D. red marrow

Astronauts must perform isometric exercises when in outer space because bones atrophy under conditions of weightlessness or lack of ______________.

C. gravity

Residences" of osteocytes.

C. lacunae

Immature, or matrix-depositing, bone cells are referred to as _____________.

D. osteoblasts

Nonliving, structural part of bone.

E. bone matrix

Bone cells that liquefy bone matrix and release calcium to the blood are called _____________.

E. osteoclasts

Site of fat storage.

E. yellow marrow cavity

Mature bone cells, called ______________, maintain bone in a viable state.

F. osteocytes

When blood calcium levels begin to drop below homeostatic levels, ___________ is released, causing calcium to be released from bones.

G. parathyroid hormone

Large tubercles and/or increased deposit of bony matrix occur at sites of _______.

H. stress and/or tension

Crest

projection

According to Wolff's law: Bones grow or remodel in response to the forces or demands placed on them. A bone's anatomy therefore reflects the most common stresses it encounters. This concept explains differences in bone structure found throughout the body ______________________.

and as seen in comparisons of active humans, bed-ridden people, and human fetus

At birth, bones generally lack ossification centers.

bone markings

The enzyme alkaline phosphatase encourages the deposit of collagen fibers within the matrix of developing bone.

calcium salts

Fossa

depression

Forming the epiglottis.

elastic cartilage

The skeleton of the external ear.

elastic cartilage

Membrane bones develop from hyaline cartilage structures.

endochondral

In appositional growth, bone reabsorption occurs on the periosteal surface.

endosteal

Cartilage is especially strong in resisting shear (bending and twisting) forces.

false

In the adult skeleton, cartilage regenerates faster than bone when damaged.

false

Neither bone nor cartilage contains capillaries.

false

Nutrients diffuse quickly through cartilage matrix but very poorly through solid bone matrix.

false

Osteocytes produce collagen fibers that span the break.

fibroblasts

Forming the intervertebral discs.

fibrocartilage

Knee menisci

fibrocartilage

At the ends of long bones.

hyaline cartilage

At the junction of a rib and the sternum.

hyaline cartilage

Epiphyseal plates are made of spongy bone.

hyaline cartilage

Most of the fetal skeleton.

hyaline cartilage

Supporting the trachea walls.

hyaline cartilage

Facet

projection

Head

projection

Ramus

projection

Spine

projection

Tuberosity

projection

When a bone forms from a fibrous membrane, the process is called endochondral ossification.

intramembranous

Large numbers of osteocytes are found in the inner periosteum layer.

mesenchymal cells (or osteoblasts)

Fissure

opening

Foramen

opening

Meatus

opening

Sinus

opening

Osteoblasts from the medullary cavity migrate to the fracture site.

periosteum (endosteum)

Nonbony debris at the fracture site is removed by fibroblasts.

phagocytes (macrophages)

Condyle

projection

Primary ossification centers appear in the epiphyses.

secondary

The bony callus is composed of compact bone.

spongy

"Maturation" of newly formed (noncalcified) bone matrix takes about 7-10 days.

true

A hematoma usually forms at a fracture site.

true

Appositional growth, which continues after the cessation of longitudinal long bone growth, means that long bones increase in diameter.

true

Bone tissue contains relatively little water compared to cartilage tissue, which contains a large amount of water.

true

Cartilage can grow faster than bone in the growing skeleton.

true

Cartilage is more resilient than bone.

true

Deprived of nutrition, osteocytes at the fracture site die.

true

During endochondral ossification, the periosteal bud invades the deteriorating hyaline cartilage shaft.

true

Long bone growth during childhood and adolescence is provided by persistence of the epiphyseal plates.

true

The embryonic skeleton arises from the mesoderm.

true

The longitudinal growth of long bones ceases when the epiphyses and the diaphyses fuse.

true

The organic bone matrix is called the osteoid.

true

When trapped in lacunae, osteoblasts change into osteocytes.

true