Ch. 6 Mastering A and P

Which is the last phase of endochondral ossification? -Chondrocytes near the center of the shaft increase greatly in size. -An epiphyseal cartilage separates the epiphysis from the diaphysis. -A secondary ossification center is formed. -A primary ossification center is formed.

An epiphyseal cartilage separates the epiphysis from the diaphysis.

All the following result in decreased calcium levels in the bloodstream EXCEPT __________. -decreased PTH or calcitriol levels -PTH stimulation of osteoclasts -calcitonin inhibition of osteoclasts -increased calcitonin levels

PTH stimulation of osteoclasts

Which statement regarding the internal structure of long bone is correct? -The medullary cavity is avascular. -The wall of the diaphysis consists only of a layer of spongy bone. -Metaphysis is the term used for the shaft of the bone. -The epiphysis consists largely of trabecular bone.

The epiphysis consists largely of trabecular bone.

A hard ossified bone in an adult actually begins within the embryo as a miniature version composed of __________.

hyaline cartilage

All the following are characteristics of periosteum EXCEPT __________. -it actively participates in bone growth and repair -it is an incomplete cellular layer that lines the medullary cavity -it has two layers, an inner layer and an outer layer -it provides a route for the blood and nervous supply

it is an incomplete cellular layer that lines the medullary cavity

Which organ prevents calcium loss in response to PTH stimulation? -intestines -kidney -bone -heart

kidney

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

mesenchymal cells

The process of osteolysis is performed by which cell population?

osteoclasts

Which component is NOT present in spongy bone? -trabeculae -osteons -lamellae -canaliculi

osteons

Which structural features of spongy bone are oriented along stress lines and are cross-braced extensively? -perforating canals -trabeculae -canaliculi -concentric lamellae

trabeculae

What is responsible for appositional growth?

Bone is deposited by superficial osteoblasts.

Ankle fractures that affect both bones of the leg are called __________

Pott's fractures

Which of the following statements regarding the homeostasis regulation of blood calcium is FALSE? -The three main organs that serve as the site for the regulation of blood calcium levels are the bones, the intestines, and the pancreas. -PTH is secreted by the parathyroid glands and raises blood calcium levels that are below 8.5 mg/dL. -Calcitonin inhibits the action of osteoclasts while having no effect on osteoblast activity. This helps to lower the blood calcium level whenever it exceeds 11 mg/dL. -The homeostasis of blood calcium is regulated by a negative feedback mechanism.

The three main organs that serve as the site for the regulation of blood calcium levels are the bones, the intestines, and the pancreas.

C cells of the thyroid gland secrete which of the following? -calcium -calcitriol -PTH -calcitonin

calcitonin

Which substance accounts for almost two-thirds of the weight of bone? -osteocytes -fibroblasts -calcium salts -collagen fibers

calcium salts

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

chondrocytes

Which type of fracture occurs in vertebrae that are subjected to extreme stresses? -Pott's fracture -Colles fracture -epiphyseal fracture -compression fracture

compression fracture

Osteoprogenitor cells are characterized by the following EXCEPT __________. -present in small numbers in the lining of vascular passageways that penetrate the matrix of compact bone -divide to produce daughter cells that differentiate into osteoclasts -mesenchymal cells present in small numbers in the inner cellular layer of the periosteum -important in the repair of a fracture

divide to produce daughter cells that differentiate into osteoclasts

Which bone is NOT formed via intramembranous ossification? -clavicle -femur -mandible -patella

femur

Which of the following describes spiral fractures? -fractures in which only one side of the shaft is broken and the other is bent -fractures that produce new and abnormal bone arrangements -fractures that are produced by twisting stresses that spread along the length of the bone -fractures that break the bone shaft across its long axis

fractures that are produced by twisting stresses that spread along the length of the bone

The periosteum contains all the following EXCEPT __________. -blood vessels -motor nerves -lymphatic vessels -sensory nerves

motor nerves

Which class of bones develops inside tendons and is most commonly located near joints at the knees, the hands, and the feet? -sesamoid bones -short bones -sutural bones -flat bones

sesamoid bones

What supplies the articular cartilage of long bones with oxygen and nutrients?

synovial fluid