ABSTRACT
This
project work introduced some knowledge about the basics involved in finding the
contents of bone. This project work deals with the principle of qualitative analysis
of cations and anions. Skeletal system plays an integral part of most of the
animals “what is it that makes It to form an integral part?”. The solution to
this question can be understood more succinctly from this project work.
This project indeed would be a revolution
in the world, where there is increasing worry about problems of bone like
osteoporosis and osteomalacia. In this industrial age amount of calcium content
in bone is also reducing; this project work would indeed be a very good
solution.
TABLES
OF CONTENTS
CHAPTER
ONE
1.0 INTRODUCTION
1.1 FORMATION OF BONE
1.1.0 INTRAMEMBRANOUS OSSIFICATION
1.1.1
ENDOCHONDRAL
OSSIFICATION
1.1.2
BONE
MARROW
1.1.3
REMODELING
1.1.4
PURPOSE
1.1.5
CALCIUM
BALANCE
1.1.6
REPAIR
1.1.7
PARACRINE
CELL SIGNAL
1.1.8
OSTEOBLAST
STIMULATION
1.1.9
OSTEOCLAST
INHIBITION
1.2 INDIVIDUAL BONE STRUCTURE
1.2.1 CELLULAR STRUCTURE
1.2.2 MOLECULAR STRUCTURE
1.3 CHARACTERISTIC OF BONE
1.4 TYPES OF BONE
1.5 FUNCTIONS OF BONE
1.6 USES OF BONE
CHAPTER
TWO
2.0 MATERIAL REQUIRED
2.1 EXPERIMENTAL ANALYSIS
.
CHAPTER
THREE
3.0 RESULT OF ANALYSIS AND DISCUSSION
3.1 ESTIMATION OF CONTENTS OF COW BONE ASH
3.2 ESTIMATION
OF CONTENT OF GOAT BONE
CHAPTER FOUR
4.0 CONCLUSION
4.2 RECOMMENDATION
Several terms are used to
referred to features and components of bones throughout the body
s/no
|
Bone features
|
Definition
|
1
|
Articular process
|
A projection that contacts an adjacent bone .
|
2
|
Articulation
|
The region where adjacent bones contact each other- a joint.
|
3
|
Canal
|
A long, tunnel-like foramen, usually
a passage for notable nerves or blood
vessels.
|
4
|
Condyle
|
A large, rounded articular process.
|
5
|
Crest
|
A prominent ridge.
|
6
|
Eminence
|
A relatively small projection or bump
|
7
|
Facet
|
A small, flattened articular
surface
|
8
|
Epicondyle
|
A projection near to a condyle but not part of the joint.
|
9
|
Foramen
|
An opening through a bone.
|
10
|
Fossa
|
A broad shallow depressed area.
|
11
|
Fovea
|
A small pit on the head
of a bone.
|
12
|
Labyrinth
|
A cavity within a bone.
|
13
|
Line
|
A long, thin projection, often with a rough surface. also known as a ridge
|
14
|
Malleolus
|
One of two specific protuberansces of bone in the ankle.
|
15
|
Meatus
|
A short canal
|
16
|
Process
|
A relatively large projection or prominent bump (gen.)
|
17
|
Ramus
|
An arm-like branch of the body of a bone
|
18
|
Sinus
|
A cavity within a cranial bone.
|
19
|
Spine
|
A relatively long, thin projection or bump.
|
20
|
Suture
|
Articulation between cranial bones.
|
21
|
Trochanter
|
One of two specific tuberosities
located on the fermur.
|
22
|
Tubercle
|
A projection or bump with a
roughened s surface, generally smaller
than a tuberosity.
|
23
|
Tuberosity
|
A projection or bump with a roughened surface.
|
CHAPTER
ONE
1.0 INTRODUCTION
Bones
are rigid organs from part of the endoskeleton of the vertebrates. They support
and protect the various organs of body production red and white blood cells and
store minerals. Bone tissue is a type of tense connective tissue. Bone comes in
a variety of shapes and has a complex internal and external structure, are light
weight yet strong and hard and serve multiple functions. One of the types of
tissue that makes up bone is the mineralized osseous tissue, also called bone
tissue that gives it rigidity and a coral-like three dimensional internal
structure. Other types of tissue found in bones include marrow endosteum,
periosteum, nerves, blood vessel and cartilage. “At birth, there are over 270
bones in an infant human’s body”. (steele D. Gentry et. al (1998). The Anatomy and
Biology of the Human skeleton, Texas
A&M University
press page 4 ISBN-0-89096-300-2), but many of these bones fused together as the
child grows, leaving a total of 206 separate bones in an adult. “The largest
bone in the human body is the femur and the smallest bones are auditory
ossicles.” (Schmiedder et. al (1934) parent and child. An Introductory Study of
Parent Education page 31).
Bones are also a dynamic
tissue that performs mechanical, biological and chemical functions and it
depends on chemical and physical properties and are affected by age, nutrition,
hormonal status and diseases. (Loveridge 1999), the skeletal system forms the
external structure and appearance of mammalian vertebrate species and has the
obvious functions locomotion, structural support of the body and protection of
soft tissue such as brain, heart, spinal cord and lungs. Bone also serves as metabolic
reservoir of Calcium (Ca), Phosphorus (P) and other minerals. Also, it houses
cells responsible for bone formation and resorption (Decke et. al 1993).
1.1 FORMATION OF BONE
The
formation of bone during the fetal stage of development occurs by two processes:
i.
Intra membranous Ossification
ii.
Endochondral Ossification
1.1.0 INTRAMEMBRANOUS OSSIFICATION
This mainly occurs
during formation of the flat bones of the skull; the bone is formed from
mesenchyme tissue. The steps in intramembranous ossification are:
1. Development
of ossification centre
2. Calcification
3. Formation
of trabeculae
4. Development
of periosteum
1.1.10
ENDOCHONDRAL
OSSIFICATION
Endochondral
ossification on the other hand, occurs in long bones such as limbs; the bone is
formed from cartilage. The steps in endochondral ossification are:
1. Development
of cartilage model
2. Growth
of cartilage model
3. Development
of primary ossification center
4. Development
of secondary center
5. Formation
of articular cartilage and epiphyseal plate.
Endochondral
ossification begins with points in the cartilage called primary ossification
centers” they mostly appear during fetal development, though a few short bones
begin their primary ossification after birth. They are responsible for the
formation of the diaphyses of long bones, short bones and certain parts of
irregular bones.
Secondary
ossification occurs after birth, and forms the epiphyses of long bones and the
extrimities of irregular and flat bones. The diaphysis and both epiphyses and a
long bone are separated by a growing zone of cartilage (the epiphyseal plate).
When the child reaches skeletal maturity (18-25 years of age), all of the
cartilage is replaced by bone, fusing the diaphysis and both epiphyses together
(epiphyseal closure).
1.1.11
BONE
MARROW
Bone marrow can be
found in almost any bone that holds cancellous tissue. In newborns, all such
bones are filled exclusively with red marrow, but as the child ages it is
mostly replaced by yellow of fatty marrow. In adults, red marrow is mostly
found in the marrow bones of the femur, the ribs, the vertebrae and pelvic
bones.
1.1.12
REMODELING
Remodeling or bone
turnover is the process of resorption followed by replacement of bone with
little change in shape and occurs throughout a person’s life. Osteoblasts and
osteoclasts, coupled together via pancrine cell signaling, are referred to as
bone remodeling units. Approximately 10% of the skeletal mass of an adult is
remodeling each year.
1.1.13
PURPOSE
The purpose of
remodeling is to regulate calcium homeostasis, repair micro-damaged bones (from
every day stress) but also to shape and sculpture the skeleton during growth.
1.1.14
CALCIUM
BALANCE
The process of bone
resorption by the osteoclasts releases stored calcium into the systematic
circulation and is an important process in regulating calcium balance. As bone
formation actively fixes circulating calcium in its mineral form, removing it
from the blood stream, resorption actively unfixes it thereby increasing circulating
calcium levels. These processes occur in tandem at site specific locations.
1.1.15
REPAIR
Repeated stress such
as weight bearing exercise or bone healing result in the bone thickening at the
point of maximum stress (Wolff’s law). It has been hypothesized that this is a
result of bones piezoelectric properties which cause bone to generate small
electrical potential under stress.
1.1.16
PARACRINE
CELL SIGNAL
The action of
osteoclasts and osteoblasts are controlled by a number of chemical factors
which either promote or inhibit the activity of the bone remodeling cells,
controlling the rate at which the bone is made, destroyed or changed in shape.
The cells also use paracrine signaling to control the activity of each other.
1.1.17
OSTEOBLAST
STIMULATION
Osteoblast can be stimulated
to increase bone mass through increased secretion of osteoid and by inhibiting
the ability of osteoclasts to breakdown osseous tissue.
Bone building through
increase secretion of osteoid is stimulated by the secretion growth hormone by
the pituitary, thyroid hormone and the sex hormones (estrogens and androgens).
These hormones also promote increased secretion of osteoprotegerin. Osteoblasts
can also be induced to secrete a number of cytokines to promote reabsorbtion of
bone by stimulating osteoclast activity and differentiation from progenitor
cells. Vitamin D, parathyroid hormone and stimulation from osteocytes induce osteblasts
to increase secretion of RANK ligand and interleukin 6, which cytokines then
stimulate increased reabsorbtion of bone by osteoclasts. These same compounds
also increase secretion of macrophage colony-stimulating factor by osteoblasts,
which promotes the differentiation of progenitor cells into osteoclasts and
decrease secretion of osteoprotegerin.
1.1.18
OSTEOCLAST
INHIBITION
The rate at which
osteoclast reabsorb bone is inhibited by calcitonin and osteoprotegerin.
Calcitonin is produced by parafollicular cells in the thyroid gland and can
bind to receptors on osteoclasts to directly inhibit osteoclast activity. Osteoprotegerin
is secreted by osteoblasts and is able to bind RANK-L, inhibiting the
osteoclast stimulation.
1.2 INDIVIDUAL BONE STRUCTURE
Bones is not a
uniformly solid material, but rather has some spaces between its hard elements.
a.
Compact
Bone (cortical bone): The hard outer layer of bone is
composed of compact bone tissue, so-called due to its minimal gaps and spaces.
This tissue gives bones their smooth, white and solid appearance and account
for 80% of the total bone mass of an adult skeleton. Compact bone may also be
referred to as dense bone.
b.
Trabecular
Bone: Filling the interior of the bone is the trabecular
bone tissue (an open cell porous network also called cancellous or spongy
bone), which is composed of a network rod and plate-like element that make the
overall organ lighter and allowing room for blood vessels and marrow.
Trabecular bone account for the remaining 20% of the total bone mass but has
nearly ten times the surface area of compact bone. If for any reason there is
an alteration in the strain to which the cancellous subjected there is a
rearrangement of the trabeculae. Although adult bone exist in both cancellous
and compact bone forms, there is no microscopic different between the two.
1.2.1 CELLULAR STRUCTURE
There
are several types of cells constituting the bone;
i.
Osteoblasts and mononucleate
bone-forming cells that descend from osteoprogenitor cells. They are located on
the surface of osteoid seams and make a protein mixture known as osteoid, which
mineralizes to become bone. The osteoid seam is a narrow region of newly formed
organic matrix that is not yet mineralized. Located on the surface of a bone.
Osteoid is primarily composed of Type I collagen. Osteobalsts also manufacture
hormones, such as prostaglandins to act on the bone itself. They robustly
produce alkaline phosphate, an enzyme that has a role in the mineralization of
bone, as well as many matrix proteins. Osteoblasts are the immature bone cells.
ii.
Bone lining cells are essential
inactive osteoblasts. They cover all of the available bone surface and function
as barrier for certain ions.
iii.
Osteocytes originate from osteoblasts
that have migrated into and become trapped and surrounded by bone matrix that
they themselves produce. The spaces they occupy are known as lacunae. Osteocytes
have many processes that reach out to meet osteoblast and other osteocytes
probably for the purpose of communication. Their functions include to varying
degrees: formation of bones; matrix maintenance and calcium homeostasis. They
have also been shown to act as machano-sensory receptors that regulate the bone’s
response to stress and mechanical load. They are mature cells.
iv.
Osteoclasts are the cells responsible
for bone resorption (remodeling of bone to reduce its volume). Osteoclasts are
large, multinucleated cells located in bone surfaces in what are called Howship’s
lacunae or resorption pits. These lacunae, or resoprtion pits are left behind
after the breakdown of the bone of the bone surface. Because the osteoclasts
are derived from a monocyte stem-cell lineage, they are equipped with
phagocytic-like mechanisms similar to circulating macrophages. Osteoclasts
mature and/or migrate to discrete bone surface. Upon arrival active enzymes,
such as tartrate resistant acid phosphatase, are secreted against the mineral
substrate.
1.2.2 MOLECULAR STRUCTURE
i.
Matrix:
The
majority of bone is made of the bone matrix. It is composed primarily of
inorganic Hydroxyapatite (Ca10(PO4)6(OH)2)
and organic collagen. Bone is formed by the hardening of this matrix around entrapped
cells. When these cells become entrapped from osteoblasts they become
osteocytes.
ii.
Inorganic:
The
inorganic is mainly crystalline mineral salts and calcium, which is present in
the form hydroxyapatite. The matrix is initially laid down as unmineralized osteoid
(manufactured by osteoblasts). Mineralization involves osteoblasts secreting
vesicles containing alkaline phosphate. This cleaves the phosphate groups and
acts as the foci for calcium and phosphate deposition. The vesicles the rupture
and act as a center for crystals grow on.
iii. Organic: The
organic part of matrix is mainly composed of Type I collagen. This is
synthesized intracellularly as tropocollagen and then exported, forming
fibrils. The organic part is also composed of various growth factors, the
functions of which are not fully known. Factor present include Glucosaminoglycans.
Osteonectin, Osteocalcin, bone sialo protein, Osteopontin and cell attachment
factor. One of the main things that distinguishes the matrix of a bone from
that of another cell is that the matrix in bone is hard.
iv.
Woven
and Lamella: Two types of bone can be identified
microscopically according to the pattern of collagen forming the osteoid
(collagenous support tissue of Type I collagen embedded in Glycosaminoglycan gel).
a. Woven
bone, which is characterized by haphazard organization of collagen fibers and
is mechanically weak.
b. Lamellar
bone which has a regular parallel alignment of collagen into sheets (Lamellae)
and is mechanically strong.
Woven bone is produed when osteoblasts
produce osteoid rapidly which occurs initially in all fetal bones (but is later
replaced by more resilent lamellar bone). In adult woven bone is created after
fractures or in paget’s disease. Woven bone is weaker, with a smaller number of
randomly oriented collagen fibers, but forms quickly; it is this appearance of
the fibrous matrix that the bone is termed woven. It is soon replaced by
lamellar bones, which is highly organized in concentric sheets with a much
lower proportion of osteocytes to surrounding tissue. Lamellar bone, which
makes it first appearance in the fetus during the third trimester, is stronger
and filled with many collagen fibers parallel to other fibers in the same layer
(these parallel columns are called osteons). In cross-section the fibers run in
opposite direction in alternating layers, much like in plywood, assisting the
bone’s ability to resist torsion forces. After a fracture, woven bone forms
initially and is gradually replaced by lamellar bone during a process known as
“bony substitution”. Compared to woven bone, lamella bone formation takes more
slowly. The orderly deposition of collagen fibers restricts the formation of
osteoid to about 1 to 2 micro meter per
day. Lamellar bone also requires a relatively flat surface to lay the collagen
fibers in parallel or concentric layers. These
terms are histogic, in that a microscope is necessary to differentiate between
the two types
1.3 CHARACTERISTIC OF BONE
The
primary tissue of bone, osseous tissue, is a relatively hard and has light
weight composite material formed mostly of calcium phosphate in the chemical
arrangement termed Calcium Hydroxyapatite (Ca10(PO4)(OH)2)
(this is the osseous tissue that gives bone their rigidity).
It
has relatively high compressive strength but poor tensile strength of 104-121
Mpa meaning it resists pushing force well, but not pulling forces. While bone
is essentially brittle, it does have a significant degree of elasticity,
contributed chiefly by collagen. All bones consist of living and dead cells
embedded in the mineralized organic matrix that make up osseous tissue.
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