Lesson presentation

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