1) There are four main types of bones - long, short, flat, and irregular. Long bones such as the femur and humerus are named based on their length and shape. 2) The structure of long bones includes a shaft (diaphysis), bulbous ends (epiphyses), articular cartilage covering joint surfaces, and bone marrow cavity (medullary cavity) containing blood vessels. 3) Bone tissue consists of cells, fibers, and a mineralized organic matrix. The matrix includes collagen fibers and hydroxyapatite calcium crystals which harden the bones and provide strength.

1. © Many football players are able to name their long bones (like the
humerus) because of incidents that they may have experienced in a game.
For those of us who have not broken or fractured enough bones to have memorized what they
are, here is a list of the four different types of bones…
©
1) Types of bones- all bones contain two types of bone tissue (compact and
spongy)
Long bones
o The name really says it all
o Name is based off of the shape and length of the bones
o Examples: femur and humerus
Short bones
o Not long bones
o Are small, “box shaped” (1)

2. o Length is about = to the width
o Examples: wrist and ankle bones
Flat bones
o Are usually quite large
o “Generally broad and thin with a flattened and often curved surface” (1)
o Examples: shoulder blades, ribs, and breastbone
Irregular bones
o “various sizes and shapes” (1)
o Examples: spine and facial bones
o Sesamoid- kneecap/patella
2) Structure of Long Bone
o Diaphyis- shaft, cylinder shape, provides support
o Epiphyses- top and bottom, bulbous shape, mainly spongy bone
o Articular cartilage- covers joint surfaces
o Periostereum- “dense, white fibrous membrane that covers bone except at joint surfaces”
(1)
o Medullary- hollow tube space, in the diaphysis, necessary for survival of the bone
o Endosteum- lines the medullary cavity, epithelial membrane
o (1)
3) Bone Tissue
-“Consists of cells, fibers, and extracellular material, or matrix” (1)

3. o Inorganic Salts- hydroxyapatite calcium crystals give the bone structure by being
hardened in a process known as calcification in order to give the bones their
strength (the crystals are hardened) (1).
o Measuring density- Osteoporosis is a disease that forms over time where the
bones lose density.
o Organic matrix- made up of “collagenous fibers… protein and polysaccharides
called ground substance” (1), adds to strength and flexibility of bones.
©
Haversian systems
Lamelle: concentric, cylinder-shaped layers of calcified matrix
Lasunae: small spaces containing tissue fluid in which bone cells lie imprisoned between
the hard layers of the lamellae
Canaliculi: ultrasmall canals radiating in all directions from the lacunae and connecting
them to each other and into a larger canal, the Haversian canal
Haversian canal: extends lengthwise through the center of each Haversian system;
contains blood vessels, lymphatic vessels, and nerves from the Harversian canal;
nutrients and oxygen move through canaliculi to the lacunae and their bone cells—a short
distance of about 0.1 mm or less
Bone Cells
Osteoblasts: small cells that synthesize and secrete a specialized organic matrix, called
osteoid

4. Osteoclasts: giant multinucleate cells that are responsible for the active erosion of bone
minerals
Osteocytes: mature, nondividing osteoblasts that have become surrounded by matrix and
now lie within lacunae
Five homeostatic functions of bones:
1. Mechanical support of soft tissues
2. Levers for muscle action
3. Protection of the central nervous system
4. Release of calcium and other ions for the maintenance of a constant ionic environment in
the extracellular fluid
5. Housing and support of hemopoiesis
(2)
Intramembranous vs. Endochondral bone
Intramembranous bones are always flat bones
Endochondral bones include the long, short, and irregular bones (3)
©
 Describe steps involved in bone fracture repair.
“How fracture healing happens
Bone fracture healing is a complex process with four steps. All bone fractures must go through
this process.” (4)

5. “Step 1: “Step 2: Soft
Inflammation callus
When a bone As blood cells
fractures, white divide and
blood cells move multiply near
in to the area to the break, new
clean up debris blood vessels
created by the develop to fuel
break. This creates the repair
© (4)
© (4) inflammation, process. The
which triggers the body also
growth of new begins to create
blood cells — the cartilage around
first stage of the bone
healing.” (4) fracture to
bridge the gap
in the bone.
Called the soft
callus, this
cartilage is
simply fibrous
tissue.” (4)
“Step 3: Hard “Step 4:
callus Remodeling
Eventually, the In the final
body replaces the stage of bone
soft callus with a fracture healing,
hard callus, the body
connecting the replaces old
bone fragments bone with new
more solidly. This bone in a
© (4) © (4)
stronger callus, continual
which creates a process called
bulge at the site of remodeling.

6. the fracture, can Remodeling
generally be seen makes bones
in X-rays just a stronger and
few weeks after more compact
the bone fracture and blood
occurs.” (4) circulation in
the bone
improves.” (4)
“When a patient breaks a bone, doctors take measures to encourage strong, quick repair. These
measures include:
Setting and immobilizing the break. If necessary, a physician will move bone segments
back into place before immobilizing the fracture using a cast or brace.
Surgery. Some patients may need surgery to set and stabilize a fracture — a process that
can involve metal plates, screws or nails. If fractures do not show signs of healing,
additional intervention is necessary. Some doctors choose to perform additional surgeries;
others turn to devices like EXOGEN.
Bone growth stimulation. To help heal fractures, many doctors prescribe a device like
EXOGEN — the only stimulator that uses ultrasound waves to stimulate the body’s natural
healing process, helping boost bone growth.
Therapy. If a patient is in a cast for a long period of time, he or she may benefit from
physical therapy to regain full use of stiff or weak muscles.” (4)
 Compare the basic structural units of bone and
cartilage.
1.Cartilage: Collagenous fibers embedded in a rubbery ground-substance called
Chondrin, which is a protein-carbohydrate complex. The chondron is secreted by chondrocytes.
2.Bone: mineralized connective tissue. Cells called osteocytes deposit a matrix of collagen and
calcium-phosphate which harden to form crystals of a substance called hydroxyapatite.
Mammalian bone is constructed from repeated units called HaversianUnits.The process of
making new bone is called ossification.

7.  Identify the three specialized types of cartilage, give
examples of each, andsummarize the structural
andfunctional differences among them.
Cartilage is a specialized form of connective tissue containing chondrocytes which
secrete, and are surrounded by, an extensive intercellular matrix. Chondrocytes occur singly or in
isogenous groups, composed of 2-8 cells derived by mitosis from a single chondrocyte. The
cells are in the lacunae (cavities) within the matrix. Matrix stains more intensely immediately
adjacent to the lacunae and the dark staining zone is called the capsule. The strength and
durability of cartilage are properties of the matrix, which is an interlaced network of collagenous
and/or elastic fibers in a ground substance, a gel of complex proteoglycans. The collagen is
mostly Type II. How does this differ from dense C.T.?
There are three types of cartilage characterized by the composition of the intercellular matrix.
(1) hyaline, (2) elastic and (3) fibrocartilage.
Hyaline cartilage is found lining articular surfaces, and in the nasal septum,
tracheal rings, costal cartilages, and the epiphyseal cartilage of growing bone.
Study the trachea on slide #72 (trachea). Even numbered boxes usually contain
slides stained for elastic tissues, odd numbered boxes have slides stained with
hematoxylin and eosin. The former will have a brown coloration, the latter, the
pink and blue you are familiar with. In this slide considerable fading has
occurred, and the normal basophilia of freshly stained cartilage is almost absent.
The trachea is a large open tube, with cartilage constituting the principal
component of its wall.
Using the scanning lens, locate the cartilage rings. At higher power, identify
single chondrocytes and locate isogenous groups. There are clear areas
between many of the chondrocytes and the walls of their lacunae because of
shrinkage of the cells brought about by fixation, and because some chondrocytes
had lipid droplets which dissolved during histological preparation.
Identify the perichondrium. Note the gradation of cell shape changes from fibroblast-like in the
outer layer to the round cell shape within the cartilage. The perichondrium is acidophilic due to
the preponderance of collagen fibers. At the interface between perichondrium and cartilage,
transitional cells can be seen which are still elongated but are beginning to be surrounded by
matrix.

8. The cartilage matrix contains collagen fibers, but these are very difficult or impossible to see.
Some areas may show some dark-staining material which could be indicative of elastic fibers,
but these are best seen in a later slide. Note that the cartilage matrix should be slightly
basophilic, especially around the chondrocytes, due to anionic properties of proteoglycans.
Elastic cartilage is found in the ear and epiglottis, where it provides a rigid but
elastic, framework. Its principal components are elastic fibers but type II
collagen is also present. Some elastic fibers may be present in the tracheal
cartilage. Examine a section through infant ear, slide #11 (even boxes only),
which has been stained for elastin with resorcinfuchsin. The purple staining
interlaced fibers run in all directions, and appear as dots when cut transversely.
The nuclei and cytoplasm of the cells are not stained well. The cartilage in this
section is immature and therefore richer in cells than adult cartilage. Compare
this arrangement of cells and fibers of elastic cartilage with that of hyaline
cartilage of the trachea.
Fibrocartilage is found in intervertebral discs, the pubic symphysis, in menisci of
joints, and often occurs where tendon and ligament are joined to bones. It
resembles a dense C.T. which contains islands of chondrocytes embedded in
cartilage matrix. Its appearance varies with its location. The major and
characteristic intercellular component of this tissue consists of thick, interlaced
collagenous fibers. The ground substance is much less abundant than in hyaline
cartilage due to the preponderance of fibers.
©
Bone Growth-During development, there are two patterns of bone formation:
intramembranous and endochondral ossification. Intramembranous bones originate between
sheet-like layers of connective tissues, and endochondral bones begin as masses of hyaline

9. cartilage that bone tissue later replaces.
Cartilage Growth- cartilage is formed from condensed mesenchyme tissue, which
differentiates into chondrocytes and begins secreting the molecules that form the extracellular
matrix
· Ball-&-socket joint: allows freedom to rotate in a back-and-forth movement
· Condyloid joint:this allows the bones to move in any direction, but they cannot
rotate
· Plane joint:this allows them to move in all directions and rotate.
· Hinge joint: allows back and forth movement. (no twisting or side to side. For example
your elbow)
· Pivot joint: this allows one bone to spin around another
· Saddle joint: both of the bones that meet have odd shapes, but they are totally
complementary to one another.