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