Anatomy and Physiology Chapter 5!

What is the difference between spongy bones and compact bones?

1. Spongy Bone is light, spongy, and soft in nature, while Compact Bones are hard, heavy and tough in nature. 2. Spongy Bones are made up of trabeculae, while Compact Bones are made up of osteons. 3. Spongy Bones fill the inner most layer of most bones, while Compact Bones fill the outer layer of most bones.

The femur can withstand ___ times the body's weight without breaking?

10-15

which is the last phase of endochondral ossification?

An epiphyseal cartilage separates the epiphysis from the diaphyis.

What is the cause of Andrea's stoppage of growth?

Andrea's osteoblasts have outpaced the chondrocytes in her epiphyseal plates, turning the entire region into bone. This is known as epiphyseal closure and prevents any further increase in length.

What is responsible for appositional growth??

Bone is deposited by superficial osteoblasts.

What 2 things interact together to form crystals of hydroxyapatite?

Calcium phosphate and calcium hydroxide

what are stronger than steel when stretched??

Collagen fibers

Compare gigantism with acromegaly

Gigantism results from an overproduction of growth hormone before puberty, whereas acromegaly results from an overproduction of growth hormone after puberty.

compact bone

Hard, dense bone tissue that is beneath the outer membrane of a bone

What is the role of the kidney and the small intestine in PTH growth?

Has something to do with Calcium. Increase blood calcium by increasing the activity of the enzyme in the intestines that activates vitamin D. parathyroid hormone reduces loss of calcium in urine (kidney)

Bill, age 15, is still growing, but his older sister Andrea, age 19, has stopped. What has changed in Andrea's bones?

Her epiphyseal plates have ossified.

spongy bone

Layer of bone tissue having many small spaces and found just inside the layer of compact bone.

Which condition, due to excessive cartilage formation at the epiphyseal cartilages, results in individuals who are very tall, with long, slender limbs?

Marfan syndrome

What are the functions of osteocytes?

Osteocytes are mature bone cells that maintain the bone matrix.

In endochondral ossification, what is the original source of osteoblasts?

The differentiation of cells in the inner layer of the perichondrium

As a bone increases in diameter, what happens to the medullary cavity??

The medullary cavity increases in diameter because bone matrix is removed by osteoclasts.

Explain the primary difference between endochondral ossification and intramembranous ossification.

The primary difference is that in endochondral ossification, bone develops from a cartilage model, whereas in intramembranous ossification, bone develops from mesenchymal cells.

What do new osteoblast do?

They begin to deposit bone around the surface of the cartilage model.

In the compact bone, the osteons are...

arranged in concentric lamellae.

At which point during embryonic development can most of the bones of the adult skeleton be identified?

at about 16 weeks

What is formed by intramembranous ossification?

both the roof of he skull and the clavicle

What substance accounts for almost two-thirds of the weight of bone?

calcium salts

During the early stages of endochondral ossification, which cells enlarge, then die and disintegrate?

chondrocytes

To form perforating fibers, osteoblasts from the cellular layer of the periosteum cement collagen fibers form tendons, ligaments, and join capsules into which structures?

circumferential lamellae

A prominent ridge, as seen on the pelvis, is a...

crest

The lining of the medullary cavity is called the what?

endosteum

What structure allows a bone to grow in length?

epiphyseal cartilages

Ectopic bones may occur in which of the following conditions?

fibrodysplasia ossificans progressiva (FOP)

What characteristic may cause life-threatening issues in individuals with Marfan syndrome?

genetic mutation that affects the structure of connective tissue throughout the body.

What cartilage is produced at the epiphyseal side of the metaphysis at the same rate as bone iss deposited on the opposite side, bones...

grow longer.

Where does Internal ossification occur first?

in the diaphysis and that region is called the primary ossification center.

Remnants of osteons, which have been almost completely recycled by osteoclasts, are known as what?

interstitial lamellae

All of the following are characteristics of periosteum EXCEPT

it is an incomplete cellular layer that lines the medullary cavity.

Tuberosity

large rounded projection. A small rough bump on bone where tendon attaches.

Canaliculi

little channels that connect lacunae

In intramembranous ossification, which cells first cluster together and start to secret the organic components of the matrix?

mesenchymal cells.

Cells of the perichondrium need to take on a new role as ossification begins. They will become...

osteoblasts ad begin to deposit bone matrix

At puberty...

osteoblasts begin producing bone faster than chondrocytes are producing new epiphyseal cartilage

The process of osteolysis is performed by which cell population?

osteoclasts

What is the organic component of the matrix in developing or repairing bone?

osteoid

Which component is NOT present in spongy bone?

osteons

Blood is distributed from the surface of a bone to deeper central canals through channels known as...

perforating canals

Lacunae

small cavities in bone that contain osteocytes

The type of bone taht is adapted to withstand stresses that arrive from many directions is??

spongy bone

As blood vessels extend into spaces left by dying chondrocytes, the models begin to ossify internally. Where does internal ossification begin?

the primary ossification center in the diaphysis

Which structural features of spongy bone are oriented along stress lines and are cross-braced extensively?

trabeculae