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Flashcards in Skeletal System Deck (23)
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What are the (5) functions of the skeletal system?

1. Support 2. Protection 3. Levers for muscular action 4. Storehouse for minerals (calcium & phosphorus) 5. Site for fat storage & blood cell formation (marrow cavities)


How are bones classified?

Location and shape. Axial skeleton includes flat and irregular bones, appendicular skeleton includes long, short and sesamoid bones.


What makes up the axial skeleton?

The skull, vertebral column, hyoid apparatus, ribs and sternum


What makes up the appendicular skeleton?

Pectoral limbs, pelvic limbs


What is the structure of the long bones?

The long bone is made up of a diaphysis (the long shaft), epiphyses (the flared ends), metaphysis (where epiphysis and diaphysis meet, where the growth plate is/was)


Describe how the growth plate functions in young to mature bones.

During growth, each epiphysis is separated from diaphysis by a plate of growing cartilage called the epiphyseal plate. At maturity, cartilage stops growing and epiphysis fuses with diaphysis, leaving the metaphysis.


What are the characteristics of long bones that assist in articulation?

The ends of long bones are enlarged and smooth and covered by hyaline cartilage to diminish risk of dislocation and to increase weight bearing surface.


Where are the short bones and what characterizes them?

Short bones are found in the carpus and tarsus (hands and feet) and characterized by having many surfaces or being flat.


What are the characteristics and locations of sesamoid bones?

Found near freely moveable joints, formed in tendons, usually only possess one articular surface which glides on a flat or convex surface of one or more of the long bones. They alter the course of tendons and protect them where greatest friction is developed.


What is the functions and locations of flat bones?

Flat bones are found in the skull and rib for protection of organs and cavities.


What are the locations and characteristics of irregular bones?

Irregular bones are found in the vertebral column, pelvis and bones of skull that are not flat. They are characterized by processes for muscular and ligament attachments and articulations.


What are the three cells found in the bone?

Osteocytes, Osteoblasts and Osteoclasts


Where are osteocytes found and how do they exchange with blood capillaries since diffusion cannot take place in calcified matrix?

Osteocytes are found in cavities called lacunae (lacuna, singular) throughout the lamellae (layers) of the bone matrix. They exchange blood and nutrients with blood capillaries through canaliculis, little "rivers" that flow from the Haversian canals to the lacunae.


Where are the osteoblasts located, formed?

Osteoblasts are located along the surface of the bone tissue, lined up like simple epithelium. As cell matures and secretes matrix, cells remain in contact with each other by cytoplasmic extensions. Once trapped in matrix, cells become osteocytes.


Where are osteoclasts found and what is their purpose?

Osteoclasts are giant cells with 6-50 nuclei that resorb bones, break them down. They are found on bone surfaces where remodeling occurs.


What is the bone matrix made up of?

The bone matrix is made up of 1/3 organic matter called osteoid which is 95% collagen and 5% amorphous ground substance and 2/3 inorganic matter called hydroxyapatite, Ca10(PO4)6(OH)2.


What are periosteum and endosteum?

Internal and external surface of bones covered with layers of connective tissue, functions to provide nutrition to osseous tissue and provision of continuing supply of osteoblast for growth and repair.


Explain what Volkmann's canals are.

Blood vessels within the periosteum and endosteum penetrate bone through Volksmann's canals.


What are the two types of bone tissue?

There is compact bone/cortical bone, dense bone without cavities, makes up diaphysis.
Spongey bone/trabecular bone, bone with interconnecting cavities, Haversian systems run in assortment of directions, makes up epiphyses.


What is within cavities of spongy bone and marrow cavities?

Red bone marrow, where blood cells are formed fills the spaces in spongy bone.
Yellow bone marrow is made up of fat cells and fills the shafts of long bones. Prenatally was red bone marrow.


Histologically, there are two kinds of bone tissue, explain what primary bone tissue is.

Primary bone tissue, woven bone, is immature bone. It is the first to appear in formation of bone or in repair. It is characterized by irregular array of collagen fibers, less minerals and more cells. Replaced by secondary/mature bone.


Explain what secondary bone tissue is.

Secondary bone/lamellar bone/mature bone has collagen fibers arranged in layers, the Haversian system.


Describe the Haversian system.

A complex of concentric lamellae surrounding a canal containing blood vessels, nerves, loose connective tissue. Haversian canals communicate with the marrow cavity, periosteum and each other through Voksmann's canal. The Haversian canal is a blood vessel channel and when surrounded by 4-20 concentric lamellae of bone is called the Haversian system.