2. FOUR TYPES OF BONES:
Short bones: carpals and tarsals (bones in your fingers and toes)
Flat bones: Calvarium (skull bone), sternum, or scapula
Long bones: femur, tibia and fibula (all leg bones) or humerus, radius and ulna
(arm bones)
Irregular bones: bones that can't fit into the above categories: vertebrae
(spine), hyoid, maxilla and mandible (jaw), and the bones of your sinuses:
Six Major structures of a
typical long bone:
ethmoid, zygomatic, and sphenoid (1)
Diaphysis: main or midsection/ shaft of a long bone. Made up of cortical bone
and usually contains bone marrow and adipose tissue.
Epiphyses: End of a long bone that is originally separated from the main bone.
(1)
Articular Cartilage: smooth, white tissue that covers the ends of bones in joints.
(1)
Periosteum: a specialized connective tissue covering all bones and having
bone-forming potentialities. (1)
Medullary (marrow) Cavity: space in a bone where a soft, flexible substance
called marrow is stored. (1)
5. HaversianCanal; nutrients and oxygen move through canaliculi to the Lacunae
and their bone cells--- a short distance of about 0.1 mm or less.
Volkmann’s canal and communicating canals that contain nerves and vessels
that carry blood and lymph from the exterior surface of the bone to the
Osteons.
Osteons- Compact bones that contain many cylinder-shaped structural units.
Homeostatic Functions of
Bones
1. Support – bones act as the framework for our body, creating the shape of our
skeleton
2. Protection –our bones help protect our vital organs, like the rib cage protects
our lungs and heart
3. Movement – Our muscles are attached to our bones which allow us to move
at the joints
4. Mineral Storage – Bones store many minerals, such as calcium and
phosphorus. Homeostasis blood calcium concentration is vital to living, it has
to be equal levels in the bone and the blood (1.)
5. Hematopoiesis (blood cell formation)– a vital process carried out by red
bone marrow(1.)
6. Ossification
Intramembranous ossification takes place in a connective tissue membrane. It
usually involves the flat bones while endochondral ossification usually deals with long
bones.
Intramembranous ossification deals with the fetus. Ground substance and the
collagenous fiber make the organic bone matrix. Calcification of the matrix forms
and continues until the trabeculae appear and form spongy bone. (1)
Endochondral ossification is from cartilage models with bone formation
spreading from the center to the ends. The bone continues to grow through primary
ossification center and secondary ossification center. An epiphyseal plate remains
Repair of Bone
Fractures
between the epiphysis and diaphysis. (1)
A bone fracture tears and destroys blood vessels that carry nutrients to osteocytes,
which is what initiates the repair sequence. The fracture itself is the first step in the
bone repair process. The next step is the formation of a fracture hematoma. Then it is
the formation of internal and external callus, which bind the broken fragment
together which stabilizes the wound and allows the healing process to procede. And
after that the bone remodeling is complete. (1)
7. CARTILAGE
Hyaline Cartilage - provides firm support with some pliability. It covers
the ends of the long bones as articular cartilage , providing springy pads
that absorb compression at joints . Has resilient cushioning properties ;
resists compressive stress. Supports the tips of the nose , connects the ribs
to the sternum , and supports most of the respiratory system passages. The
skeletal hyaline comes during childhood as the epiphyseal plates , provide
for continued growth in length. Covers the ends of long bones in joint
cavities ; forms costal cartilages of ribs , nose , trachea , and larynx. (1)
Elastic Cartilage - Found where strength and exceptional stretch ability are
needed. Elastic cartilage forms the skeletons of the external ear and the
epiglottis. Maintain the shape of a structure while allowing great flexibility.
Similar to hyaline but more elastic fibers in matrix. (1)
Fibrocartilage- Compressible and resists tension well , found where strong
support and the ability to with strand heavy pressure are required. EX: the
spongy cartilage of the knee , Intervertebral discs Strength with the ability
to absorb compressive shock.
Less firm than the hyaline; thick collagen fibers predominate. (1)
8. Growth of Cartilage
Interstitial Growth: The cartilage cells within the substance of the tissue
mass divide and begin to secrete additional matrix. Internal division of
chondrocytes is possible because of the soft, pliable nature of cartilage
tissue. This type of growth is mostly seen during childhood and early
adolescence, when the majority of the cartilage is still soft and capable of
expansion from within (1)
Appositional Growth: This occurs when chondrocytes in the deep layer of
the perichondrium begin to divide and secrete additional matrix. The new
matrix is then deposited on the surface of the cartilage, causing it to
increase in size. This type of growth is unusual in early childhood but, once
it starts it continues beyond adolescence and throughout an individual’s
life. (1)
Classification of joints
Joints are classified into 3 major categories using a structural or a functional
scheme. If a structural classification is employed, joints are named
according to the type of connective tissue that joins the bones together,
(fibrous and cartilaginous) or by the presence of a fluid-filled joint capsule.
(synovial joints) (1)
If a functional classification scheme is used, joints are divided into three
classes according to the degree of movement they permit. (synarthroses,
amphiarthroses, and diarthroses) (Immovable, slightly movable and freely
moveable) (1)
9. Fibrous joints are synarthroses. The articulating surfaces of these joints fit
closely together.
The three types of fibrous joints are:
Syndesmoses- Joints on which fibrous bands connect two bones
Sutures- Found only in the skull, teeth like projections jut out from
adjacent bones and interlock with each other with only a thin layer of
fibrous tissue between them. (1)
Gomphoses: unique joints that occur between the root of a tooth and the
alveolar process of the mandible and maxilla. (1)
Cartilaginous Joints are amphiarthroses: The bones that articulate to form a
cartilaginous joint are joined together by either hyaline cartilage or
fibrocartilage. There are two types of these
Sychondroses: Joints that are characterized by the presence hyaline cartilage
between articulating bones
Symphyses: a joint in which a pad or disk of fibrocartilage connects two
bones (1)
Synovial joints
They are the body’s most moveable, numerous and the most anatomically
complex joints.
Seven types of structures for synovial joins
10. joint capsules, synovial membrane, articular cartilage, joint cavity, menisci
(articular disks), ligaments and bursea(1)
Synovial joints are divided into three main groups: Uniaxial, biaxial, and
multiaxial
Uniaxial joints: Synovial Joints that permit movement around only one
axis and in only one plane. EX: Hinge Joints and Pivot Joints
Biaxial joints: Diaphroses that permit movement around two perpendicular
axes in two perpendicular planes EX: Saddle Joints and Condyloid Joints
Multiaxial Joints: Joints that permit movement around three or more axes
and in three or more planes EX: Ball and Socket joints and Gliding joints
(1)
Questions
The 2 functions that have gone awry that cause the need for a bone
marrow transplant and osteoporosis are low bone mineral density due to
not enough calcification. The normal process should be the calcification of
highly specialized crystals of calcium and phosphate. A bone marrow
transplant is performed if someone has damaged bone marrow, normally
red blood marrow produces red blood cells and yellow bone marrow is
saturated in fat not involved in blood cell production but can change to red
bone marrow
if needed. (1)
11. A fracture in the epiphyseal plate can cause problems in kids because
their bones have not finished growing, the epiphyseal plate is there as a
barrier between the shaft and end of the bone and if it gets fractured it can
cause problems in the ossification process.
As you get older your bones start to weaken and you start to have
bone loss. With this bone loss comes changes in your skeletal frame, you
get shorter and can have a humped back. You also have remodeling of in
compact bone which involves new haverian systems. (1)
