CH. 5 H.W.

Which of these allow nutrients to diffuse from the central canal to all the osteocytes within an osteon?

perforating canals lacunae lamellae canaliculi******

What step occurs first in the embryonic development of most bones?

Cartilage is digested away. A bony collar forms.******* Appositional growth occurs. The medullary cavity is formed.

What type of joint is found between the atlas and the dens of the axis?

plane hinge pivot******* condylar

What causes the pain associated with a herniated disc?

pressure on spinal nerves by the protruding disc

Which of these is a function of the skeletal system?

storage site for calcium

Ossification is a dynamic process involving several different cell types with roles related to bone growth.

. Osteocyte: a mature bone cell trapped in bone matrix. 2. Osteoblast: a cell that stores calcium in bone by making bone matrix. 3. Osteoclast: a cell that releases calcium from bone, increasing blood calcium levels. 4. Osteoclast: parathyroid hormone (PTH) activates this type of cell. Osteoblasts use excess calcium in blood to build new bone matrix. During this process, some bone cells become trapped as mature osteocytes. When blood calcium is low, PTH stimulates osteoclasts to break down bone matrix, releasing calcium into the blood.

Vocabulary terms

A(n) osteoclast is a cell that breaks down bone matrix. The mallet-shaped protrusion on the inside of the ankle is the medial malleolus. A joint that is slightly moveable is classified as a(n) amphiarthrosis joint. A membrane that holds the elbow joint together is called a(n) synovial membrane. The bones between the phalanges and tarsals are the metatarsal.

There are four major events in the repair of bone fractures.

Bone is extremely vascular tissue, so it makes sense that when a bone fractures, there is a lot of local bleeding. The hematoma that forms is soon replaced by fibrocartilage, a temporary patch. A temporary bony callus then replaces the fibrocartilage before bone remodeling permanently repairs the site of the break.

Bones grow both lengthwise and in diameter. Bone growth is described by two mechanisms: appositional growth and ossification. Though bone growth and remodeling are continuous processes, bones do stop lengthening in adulthood.

Bones increase in diameter through the process of appositional growth. 2. Bones increase in length by the process of ossification. 3. A person with epiphyseal lines is not growing taller. 4. A person with epiphyseal plates is growing taller. Appositional growth occurs during bone remodeling. New bone matrix is added to the outside of the bone surface while the medullary cavity is increased, broadening the diameter of the bone overall. Ossification at the epiphyseal plate involves removing the hyaline cartilage "model" before laying down new bone matrix, which results in a longer bone overall. Once the epiphyseal plate calcifies into an epiphyseal line, ossification at the bone epiphyses can no longer take place.

Ossification is dependent on both cartilage and bone growth and replacement. The interplay of these events on either side of the epiphyseal plate allows bones to grow longer.

Healthy bone growth requires the addition of both cartilage and bone. Let's look at the humerus as an example. As cartilage is added to the articular surface at the shoulder joint, bone will be added just under the articular cartilage. At the same time, cartilage is added on the epiphysis side of the epiphyseal plate, while bone is added on the diaphysis side. However, if either the articular cartilage or the epiphyseal plate is compromised, there could be joint problems, or a lack of ossification, respectively.

During soccer practice, Sadie tripped and tried to stop her fall with her outstretched arms. Her humerus broke and the broken ends were forced into each other. Sadie suffered a(n) __________ fracture. compressioncomminutedimpactedspiral

IMPACTED This is a common fracture that results when someone attempts to break their fall with outstretched arms.

Part of the process of fracture repair is the formation of a fibrocartilage callus and a bony callus.

Major events in fibrocartilage callus formation include the growth of new capillaries (granulation tissue) and the removal of dead tissue. The fibrocartilage callus itself contains some cartilage matrix, some bony matrix, and collagen fibers to temporarily patch the break. To form the bony callus, osteoblasts and osteoclasts migrate to the site, multiply, and replace the fibrocartilage callus with spongy bone. Over time, bone remodeling will widen and thicken the bone in response to stress.

Prefixes, Roots and Suffixes

The prefix osteo- means "bone." The prefix meta- means "between," "along" or "after." The prefix amphi- means "both." The prefix syn- means together. The prefix malle- means "hammer."

Which bones form the shoulder joint?

Which bones form the shoulder joint? clavicle and humerus scapula and humerus ***** scapula, clavicle, and humerus scapula and clavicle

What is the distinguishing feature of a synovial joint?

fibrocartilage fibrous connective tissue joint cavity****** epiphyseal plate