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AGNES ZONDO
PROFESSIONAL STUDIES 3ASTUDENT NUMBER: 201106453
SKELETAL SYSTEM OF
HUMANS
LIFE SCIENCES
GRADE 11BONES
WHAT IS A BONE?
Is a specialized connective tissue and is one of the hardest tissues of the body
Second only to cartilage in its ability to withstand stress
FUNCTIONS OF THE BONE
Provides mechanical support
Provides levers for the action of muscles/help in locomotion
Serves as site for storage of calcium in the body
Protects vital organs
Encloses the blood forming elements of the bone marrow
STRUCTURAL ELEMENTS OF THE BONE
Bone cells
Osteoprogenitor cells – stem cells
Osteoblasts – forms bone
Osteocytes – maintains bone
Osteoclasts – resorbs bone
Bone matrix
Sharpey’s fibers
Blood vessels, nerves, lymph vessels (Haversian canals)
BONE CELLS
OSTEOPROGENITOR CELLS
Stem cells derived from the mesenchyme
Possess mitotic potential and the ability to differentiate into mature bone
cells
Resemble mesenchymal cells and are spindle-shaped, with pale-staining
elongated nuclei and sparse cytoplasm (small amount of rough ER and poorly
developed golgi complex)
Mostly found in the inner portion of the periosteum, in the endosteum, and
within vascular canals of compact bone
TYPES OF OSTEOPROGRNITOR CELLS
Preosteoblasts
Possess some
endoplasmic
reticulum and
gives rise to the
osteoblasts
Preosteoclasts
Has more
mitochondria and
free ribosomes
and give rise to
the osteoclasts
OSTEOBLAST
Associated with bone formation
Found where osseous matrix is being deposited
Vary in shape, some being cuboidal and others pyramidal, and are frequently
in continuous layer suggestive of an epithelial arrangement
FUNCTIONS OF OSTEOBLAST
Contain ribose nucleoprotein concerned with the synthesis of the organic
components of bone matrix, i.e. collagen and glycoproteins
Contain the enzyme alkaline phosphatase concerned not only with the
elaboration of matrix but also with its calcification
OSTEOCYTES
Principal bone cells
Are osteoblasts which have become imprisoned within the bone matrix and
are lodged inside cavities called LACUNA
Have faintly basophilic cytoplasm which can be shown to contain fat droplets,
some glycogen and fine granules similar to those of or are present within
osteoblasts
OSTEOCYTES
Has fine cytoplasmic processes which extend for some distance and are called
radiating canaliculi. These form an extensive continuous communication
system among osteocytes
TWO TYPES OF BONE: COMPACT AND
SPONGY BONE
COMPACT BONE
Compact Bone
•Compact bone is arranged in units called osteons or Haversian systems.
•Osteons (Haversian canal) contain blood vessels, lymphatic vessels, nerves
•Surrounding this canal are concentric rings of osteocytes along with the
calcified matrix.
•Osteons are aligned in the same direction along lines of stress. These lines
can slowly change as the stresses on the bone changes.
SPONGY BONE
Spongy Bone
•Spongy(cancellous)bonedoesnotcontainosteons.
•Itconsistsoftrabeculaesurroundingmanyredmarrowfilledspaces.
•Itformsmostofthestructureofshort,flat,andirregularbones,andtheepiphyse
soflongbones.
•Spongybonetissueislightandsupportsandprotectstheredbonemarrow.
Spongy bone -irregular lattice work of bone called trabecula-spaces filled
with red bone marrow-osteocytes trapped within calcium matrix
Factors that affect bone growth
1.Minerals
2.Vitamins
3.Hormones
4.Exercise
Factors that affect bone growth:
calcium
Calcium Makes bone matrix hard
Hypocalcemia: low blood calcium levels.
Hypercalcemia: high blood calcium levels.
PhosphorusMakes bone matrix hard
MagnesiumDeficiency inhibits osteoblasts
BoronMay inhibit calcium loss,
increase levels of estrogens
ManganeseInhibits formation of new bone tissue
Factors that affect bone growth:
vitamins
Vitamin AControls activity, distribution, and coordination of
osteoblasts/osteoclasts
Vitamin B12May inhibit osteoblast activity
Vitamin CHelps maintain bone matrix, deficiency leads to decreased collagen
production which inhibits bone growth and repair
(scury) disorder due to a lack of Vitamin C
Vitamin D(Calcitriol) Helps build bone byincreasing calcium absorption.
Deficiencies result in “Rickets” in children
Factors that affect bone growth:
hormones
Hormones
Human Growth HormonePromotes general growth of all body tissue and
normal growth in children
Insulin-like Growth FactorStimulates uptake of amino acids and protein
synthesis
InsulinPromotes normal bone growth and maturity
Thyroid HormonesPromotes normal bone growth and maturity
Estrogen andIncreases osteogenesis at puberty Testosteroneand is responsible
for gender differences of skeletons
Bone fracture terms
Closed/Open
Partial/Complete
Displaced/Non-displaced
Simple/Compound
Other Fractures:
Spiral
Transverse
Longitudinal
Pathologic
BONE FRACTURE REPAIR
Steps in fracture repair 1
. Formation of a fracture hematomaImmediately after the fracture, there is a
sharp fracture line with associated soft tissue swelling. At the fracture Site,
there is abundant hematoma with beginning fibroblastic penetration.
Steps in fracture repair 2
Fibrocartilaginous CallusFormation
At 2 weeks there is much visible callus. There is also bone resorption and
osteoporosis, both difficult to see in this case because of the overlying callus.
There has been migration of chondroblasts into the area and cartilage is
beginning to cover the ends of the fracture. New osteous tissue is produced
enchondrally.
Bone Fracture Repair
END OF THE LESSON
I HOPE THAT WHAT I HAVE PRESENTED TO YOU IS WORTHY AND WILL PROMOTE
AWARENESS IN THE PROTECTION AND KNOWLEDGE OF BONES
PLEASE TAKE CARE OF YOUR BONES
CALCIUM!!!!!!!!!!!!!
Internal structure of a compact bone
REFERENCES
Shinson Kelly, applied autonomy and physiology: a case study approach, paradigm publishers, 14 july2012http://www.slideshare.net/KellySHinson/ap-ch05
Dieter95, skeletal system, adams publishers, 19 june2012http://www.slideshare.net/dieter95/skeletalsystem-13385835?qid=1e510902-4081-4834-8643-f49e03e658b2&v=qf1&b=&from_search=1
Dawn Chipchase, anatomy and physiology, 18 September 2001http://www.slideshare.net/dchipchase/lesson-1-skeletal-system
Ronaldo Quitco, anatomy and physiology, mc graw-hill companies, 15 December 2008
http://www.slideshare.net/ronaldoquitco/skeletal-system-presentation