Ch. 6 Flashcards
What are the functions of the skeletal system?
Body support
Organ protection
Body movement
Mineral storage
Blood cell production
What are the four components of the skeletal system?
Bones
Cartilage
Tendons
And ligaments
Ligament
Short band of tough, flexible fibrous connective tissue which connects 2 bones or cartilages or holds together a joint
Allows for some movement but prevents excessive amount
Tendons
Strong bands of connective tissue which attached skeletal muscles to bones
Joints
Where 2 or more bones come together, allow movement between bones
What are the principle minerals store in bone?
Calcium and phosphorus
Also stores adipose tissue in the form of yellow bone marrow that we use for energy
What tissue is stored in bone cavities?
Adipose tissue
How do bones produce blood cells?
Many bones are filled with red bone marrow which gives rise to blood cells and platelets
What are the 3 types of cartilage?
Fibrocartilage, hyaline cartilage, elastic cartilage
Which cartilage is most intimately associated with bone?
Hyaline cartilage
Why is understanding the structure of hyaline cartilage important when talking about bones?
Most bones in body start out as a hyaline cartilage model.
Also bone repair and growth often involves making hyaline cartilage first
Chrondroblasts
Cartilage cells which secrete a matrix which surrounds them
Once they secrete enough matrix around themselves and they are housed in their lacuna they become chondrocytes
Chondrocytes
Once the matrix surrounds the condor last it becomes a chondrocytes.
Chondrocytes are well rounded cells which occupy a space called the lacunae
What does the matrix of hyaline cartilage contain?
Collagen which provides strength
Proteoglycans which make cartilage resilient by trapping water
Perichondrium
A protective connective tissue sheath that covers cartilage
Perichondrium has what tissue and cells?
Double layer
outer layer is of dense irregular connective tissue and fibroblast
Inner layer is chondroblasts
Articular cartilage
Hyaline cartilage that covers the ends of bones where they come together to form joints, has no perichondrium, blood vessels or nerves
Appositional growth
Chonroblasts in perichondrium add new cartilage to the outside edge of the existing cartilage
Getting wider
Interstital growth
Chondrocytes in center of tissue divide and add more matrix between them
Getting longer
What is the organic material in bones?
Collagen and protoglycans
Osteoblasts
Build bone (ossification)
Until they build bone matrix around themselves and are living in a lacuna then they become Osteocytes
Osteocytes
Enclose itself in lacunae. Connected to other cells via cytoplasmic extensions called canaliculi
Osteoclasts
Type of macrophage - eating cells
Bone destroying cells, Makes acid and enzymes to break down bone to release minerals into the bloodstream
Plays a role in bone remodeling
Massive multinucleated cells
Derived from red bone marrow cells
Ossification
The formation of new bone by osteoblasts
Ossification occurs by which type of growth?
Appositional growth on the surface of previously existing material
Once Osteoblasts secrete enough bone martix they become?
Osteocytes
Canaliculi
Osteocyte extensions - long narrow spaces
from the lacunae to the osteonic (haversian) canal to provide passageways through the hard matrix
What deposits calcium into the bone?
Osteoblasts deposit calcium into the bone
What releases calcium into the blood stream?
Oseoclasts release calcuim into the bloodstream
How do nutrients and gases pass in bone?
Through canaliculi and lacunae or from gap junction
Bone reabsorption
What is the bone reaborpion process?
- Osteoclasts must access the bone matrix
- Osteoclasts form attachement structures called integrins
- Structures call podosomes develop and form a sealed compartment under the osteoclasts
- The osteoclast plasma membrane further differentiates into a highly folded form called ruffled border
- Acidic vesicle fuse with the membrane of ruffled border, while enzymes are inserted into the membrane.
- The acidic environment causes decalcification of the bone matrix.
- The enzymes digest organic protien component of bone
- The degradation products are secreted into the exracellular space enter the blood and are used elsewhere in the body.
Stem cells
are the body’s raw materials — cells from which all other cells with specialized functions are generated
Osteochondral pregenitor cells
Stem cells that become osteblasts or chondroblasts
Bone remodeling
Disordered woven bone is remodeled based on stress applied to bone
Lamellar bone
Mature bone organized into thin concentric layers called lamelle
organized into rings
Woven bone
Is the first type of bone formed during ossification
Fairly weak
What are the 2 types of bone formed during ossification?
Woven bone and lamellar bone
Lamellar Bone
Is mature bone
Organized into thin circles called Lamellae
Lamellae
a thin layer, membrane, or plate of tissue
Made of collagen and hydroiapitite
Spongy Bone
Forms the inner layer of all bones
Interlocking rods or plates of bone called trabeculae. In between the trabeculae are spaces that are filled with bone marrow and blood vessels
Trabeculae consists of several lamellae with osteocytes in lacunae between the lamellae. The osteocytes associate with other osteocytes through canaliculi
Trabeculae
Thin and consists of several lamellae with osteocytes in lacunae between the lamellae.
Trabeculae are orientated along the lines of stress within a bone, if the force of the bones changes the trabecular pattern realigns with the new lines of stress
Compact Bone
Solid outer layer surrounding each bone
Has more matrix and fewer pores than spongy bone
Blood vessels enter the substance of the bone itself and the lamellae are primarily orientaed around those blood vessels.
Osteon
Functional unit of compact bone
composed of rings of matrix which surround a central tunnel and contain osetocytes
Concentric Lamellae
Layers of compact bone arranged concentrically around blood vessels in the Haversian canal
Each osteon has 4-20 concerntric lamellae
Circumferential lamellae
Form the outer surfaces of compact bone
Interstitial lamellae
Remnants of concentric or circumferenial lamellae that were partially removed during bone remodeling
How many types of lamellae are there and where are they?
Concentric lamellae - rings of bone matrix, In an osteon surrounding central canal
Circumferential lamellae - form outer surfaces of compact bone
Interstitial Lamellae - remnants of concentric or circumfrential lamellae that were partially removed during bone remodeling
Perforating canals
Deliver blood to the central canals of the osteons
Run perpendicular to the length of the bone
Contain blood vessels from periosteum or medullary cavity
Diaphysis
Center portion of long bone
Composed primarily of compact bone
Medullary cavity
is the central cavity of bone shafts where red bone marrow and/or yellow bone marrow (adipose tissue) is stored
AKA marrow cavity.
Some spongy bone can be found lining the medullary cavity
Epiphyses
Ends of long bone
Mostly spongy bone, with an outer layer of compact bone
Develops from its own center of ossification
Articular cartilage
smooth, white tissue that covers the ends of bones where they come together to form joints.
Each long bone of the foot or hand has one epiphysis, which end of the bone is it located?
Proxmial or distal end
Epiphyseal plate or growth plate
located between the epiphysis and the disphysis
Where growth in bone length happens
When bone growth stops epiphyseal plate becomes ossified and becomes epiphyseal line
Epiphyseal line
When bone stops growing in length, the epiphyseal plate becomes ossified
What is in the cavity of spongy bone and the medullary cavity?
Marrow
Red marrow
The site of blood cell formation
Yellow Marrow
mostly adipose tissue
What type of marrow is found in fetus?
Red marrow
The conversion of Red to Yellow marrow begins just before birth and continues to adulthoos
Periosteum
connective tissue membrane covering the outer surface of a bone
The outer fibrous layer is dense irregular connective tissues that contains blood vessels and nerves.
The inner layer is a single layer of bone cells
Perforating fibers
bundles of collagen fibers from tendons or ligaments that penetrate the periosteum into the outer part of the bone
Endosteum
a single cell layer of connective tisse that lines the internal surfaces of all cavities with in bones, such as medullary cavity
Includes: Osteoblasts, osetoclasts, and esteochondral progenitor cells
