This document provides an overview of bone formation, resorption, and remodeling. It discusses the classification of bones based on shape and development. It describes the composition of bone including cells like osteoblasts, osteoclasts, and osteocytes. Bone formation is mediated by growth factors while resorption involves acid secretion and enzyme activity by osteoclasts. Remodeling is a continuous process where old bone is replaced, maintaining bone strength through the coupled activities of formation and resorption. Markers of bone turnover provide information about these dynamic processes.
The presentation include general definition of bone and it's functions. Also, describe the chemical composition of bone and then specifically describe alveolar process.
The presentation include general definition of bone and it's functions. Also, describe the chemical composition of bone and then specifically describe alveolar process.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Ossification (Intracartilaginous and Intramembranous)Mohiuddin Masum
This presentation includes:
* Ossification definition
* Types of ossification
* Center of ossification
* Intramembranous ossification process
* Intracartilaginous ossification process
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Coronal and radicular pulp
Apical foramen
Accessory canal
Functions of dental pulp
Components of dental pulp
Functions of pulpal extracellular matrix
Organization of cells in the pulp
The principle cells of the pulp
The pathways of collagen synthesis
Matrix and ground substances
Vasculature and lymphatic supply
Innervation of Dentin- pulp complex
Disorders of the dental pulp
Advances in pulp vitality testing
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Ossification (Intracartilaginous and Intramembranous)Mohiuddin Masum
This presentation includes:
* Ossification definition
* Types of ossification
* Center of ossification
* Intramembranous ossification process
* Intracartilaginous ossification process
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Coronal and radicular pulp
Apical foramen
Accessory canal
Functions of dental pulp
Components of dental pulp
Functions of pulpal extracellular matrix
Organization of cells in the pulp
The principle cells of the pulp
The pathways of collagen synthesis
Matrix and ground substances
Vasculature and lymphatic supply
Innervation of Dentin- pulp complex
Disorders of the dental pulp
Advances in pulp vitality testing
all the stages of bone formation described in easiest way possible for better understanding including graphical representation for better understanding. description of each and very thing.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Bone physiology and calcium homeostasisAbdulla Kamal
Bone is a highly specialized supporting framework of the body, characterized by its rigidity, hardness, and power of regeneration and repair.
It protects the vital organs, provides an environment for marrow ,acts as a mineral reservoir for calcium homeostasis and a reservoir of growth factors and cytokines, and also takes part in acid–base balance.
Bone constantly undergoes modeling (reshaping) during life to help it adapt to changing biomechanical forces, as well as remodeling to remove old, micro-damaged bone and replace it with new, mechanically stronger bone to help preserve bone strength.
Bone changes during ortho. tooth movement dr.anusha /certified fixed orthodon...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
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Osteoprogenitor cells: pre-osteoblast, are bone stem cells derived from mesenchymal cells that eventually differentiate into mature osteoblast and osteocyte.
Osteoblast: large metabolically active cell with increased endoplasmic reticulum(ER)
1- Produce high level of alkaline phosphatase.
2- Produce type I collagen which is necessary for calcification.
3- Produce osteocalcine, produce signal to activate osteoclast.
= osteoblast has receptors for hormones such as parathyroid hormone, Vit. D, osteogen, cytokines and growth factors
= after osteoblast have secrete un-mineralized bone they usually become inactive, a few osteoblasts remain in the mineralized osteoid and become osteocyte.
Osteocyte: are osteoblast that have become surrounded by the calcified matrix of bone, these cells acts as mechanoreceptor identifying the loads placed on the individual bones and establishing the nature of such loads.
Osteoclasts: are large multi-nucleated cells, found attached to the surface of active bone formation.
= Found in well-defined pits known as Howships Lacuna.
= Derived from mono-nuclear stem cells in bone marrow and travel through blood vessels to the site of activity. It is activated by: inter-luckin II,I, cytokines.
= decreased endoplasmic reticulum.
Bone lining cells: elongated cells covering bone surface, they are inactive and have a high nucleus to cytoplasmic ratio, these cells has a major impact on calcium metabolism within the body.
Bone development:
Cellular mechanisms:
= skeleton formation begins when mesenchymal cells migrate to the site of skeleton-genesis. The cells then interact with epithelial cells, which in then trigger the mesenchymal cells to cluster together and undergo condensation to form compact mass of cells.
= each step is regulated by special type of genes such as member of home box genes.
= condensed cell then undergo differentiation either chondrocyte or osteoblast.
Core bonding factor-1 (CBFA-1)— (now known as Runx2)
One of the most important bone specified genes in differentiation of mesenchymal cells into – osteoblast.
Core bonding factor -1: CBFA-1 now is known as Runx2.
One of the most important bone specific genes in differentiation of mesenchymal cells into------osteoblast.
Bone morphogenetic protein: BMP:
= Play important role in the developing skeleton.
= BMP has been used ti improving healing and bone defect.
= BMP’s are probably involved in intramembranous bone formation.
= BMP-7 is found in area of brain to induce formation of cranial bones
= BMP’S 2—4 and 5 are expressed in some regions where mesenchymal condensation later give rise to craniofacial bone.
Novel mechanisms of osteoblast and osteoclast interaction:
Osteoblast interact with osteoclast to regulate the osteoclastic action.
Receptor activator of nuclear factor ligand (RANKL) is produced by pre-osteoblast and osteoblast and cell membrane of osteoblastic precursors.
This factor is essential factor for differentiation, fusion into multinucleated
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Bone replacement grafts are widely used to promote
bone formation and periodontal regeneration.
Xenografts are grafts shared between different species.
Currently, there are two available sources of xenografts
used as bone replacement grafts in periodontics: bovine
bone and natural coral.
Dentists play an important role in the diagnosis and management of desquamative gingivitis. The importance of being able to recognise and properly diagnose this condition is accentuated by the fact that a serious and life threatening disease may initially manifest as desquamative gingivitis.
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
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Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
3. •Bone formation and factors affecting bone formation
•Bone resorption
Differences between resorbed and unresorbed
surfaces
Role of TRAP in bone resorption
Factors affecting bone resorption
•Bone remodelling
Sequence of events
Mediators
Markers of bone turn over
•Conclusion
• References
5. CLASSIFICATION OF BONES:
Shape development histology
Long flat irregular endochondral Intramembranous sutural mature immature
compact cancellous
short
12. Composition of Bone…
Inorganic component:
Hydroxyapatite crystals with carbonate content
Organic component:
- Osteoid
Type I collagen (95%)
type V collagen (<5%)
Non collagenous proteins
Osteocalcin,
Osteopontin,
Bone sialoprotein,
Osteonectin.(SPARC)- Cell adhesion ,proliferation,
modulation of cytokine activity.
13. Osteoblasts :
Derived from osteoprogenitor cells
Periosteum serves as important reservoir .
Morphology :
basophilic
cuboidal or slightly elongated cells
contain prominent bundles of actin, myosin
BONE CELLS:
16. FUNCTIONS
New bone formation
Controls bone mineralization at 3 levels-
i. In its initial phase, by production of matrix vesicle.
ii. At a later stage, by controlling the ongoing process of
mineralization.
iii. By regulating the number of ions available.
Regulation of bone remodeling and mineral metabolism.
17. FUNCTIONS
Osteoblasts secrete type I collagen, small amount of
type V collagen, osteonectin, osteopontin, RANKL,
osteoprotegerin, Proteoglycans, latent proteases and
growth factors including bone morphogenic proteins.
Osteoblasts exhibit high levels of alkaline phosphatase -
cytochemical marker.
18. Vitamin D3:
Stimulates bone resorption.
essential for normal bone growth and mineralization
Stimulates osteopontin and osteocalcin – suppresses collagen
production
Growth hormone:
required for attaining normal bone mass - mediated by local
production of IGF-1.
Insulin:
stimulates bone matrix formation and mineralization
19. Bone morphogenic proteins :
TGF-β family
migration, aggregation and proliferation of mesenchymal
type cells and their differentiation in to osteogenic cells
Insulin growth factor I and II (IGF):
Effects similar to TGF-β
They also stimulate proliferation of osteoblast precursors
Fibroblast growth factor (FGF) :
increases proliferation of osteoprogenitor cells.
promotes osteogenic differentiation
20. BONE LINING CELLS:
Osteoblasts flatten, when bone is not forming and extend
along the bone surface and hence the name.
They are present on periosteal as well as endosteal
surfaces.
21. OSTEOCYTES:
Nerve cells
Sense the change in environment and send signals that affect
response of other cells involved in bone remodelling
Maintains balance between
resorption and remodelling
Bone that forms more rapidly
shows more osteocytes.
22. Osteocytic lacunae
Canaliculi- narrow extension of lacunae, permits
diffusion of gases and nutrients
Maintains bone integrity and vitality
Failure of inter connecting system between osteocytes
and osteoblasts leads to sclerosis and death of bone
23. OSTEOCLAST:
In Greek it means “ bone and broken ’’
Morphology
Howship’s lacunae
Diameter – 50-100 um
15 to 20 nuclei ( more nuclei more
resorption)
TRAP – distinguishes from other
multinucleated giant cells
24. MORPHOLOGY
Extensive mitochondria except below the ruffled border
Ruffled border – deep folds
Cathepsin containing vesicles and vacuoles are present
close to ruffled border – resorptive capacity
Clear or sealing zone
27. Cells of monocyte macrophage lineage differentiate into
osteoclast by cell to cell interaction
RANKL and M-CSF are produced by osteoblasts. These are
required for formation of osteoclasts
M-CSF – proliferation and differentiation. It acts through c-fms
present on osteoclasts
RANKL- differentiation in to matured osteoclast and their activity.
RANKL/ ODF / TRANCE( TNF related induced cytokine) /
OPGL
Formation of osteoclast
29. BONE FORMATION AND FACTORS AFFECTING BONE
FORMATION
Two theories have been put forward for how the bone is formed
and calcified.
1st theory:
Matrix vacuoles, which are produced as an outgrowth of
osteoblasts or chondroblasts or odontoblasts are responsible for
calcification.
2nd theory
Macromolecular constituents of bone and cartilage matrix
directly implicates in calcification
30. Factors regulating bone formation:
Platelet derived growth factor
Cationic heparin binding polypeptide
Collagen synthesis and rate of bone apposition
Acidic fibroblast growth factors and basic fibroblast
growth factor
Increases collagen synthesis
31. Insulin like growth factor
Increase preosteoblasts replication and stimulates collagen
synthesis
Transforming growth factor
TGF-α – resorption
TGF-β – formation
Bone morphogenetic proteins (BMPs)
during repair they are released and are required for healing
32. BONE RESORPTION:
Sequence of events of bone resorption: Involves 3 phases
First phase -
formation of osteoclast
Second phase-
activation of osteoclast
Third phase -
resorption of bone
33. Alterations in the osteoclast
Removal of hydroxyapatite
acidic environment by proton pump
Degradation of organic matrix
acid phosphatase, cathepsin B
Removal of degradation products from lacunae
endocytosis
Translocation of degraded products and extracellular release
34. Alterations in the osteoclast:
The osteoclasts create - Howship’s lacunae.
assumes polarity of structure and function.
The two distinct alterations are the
development of a ruffled border
sealing zone at the plasma membrane.
The cytoplasm adjacent to ruffled border is devoid of cell
organelles, contains actin microfilaments surrounded by vinculin
rings- clear zone.
When osteoclasts arrive at resorption site, they use the sealing
zone to attach themselves to the bone surface.
35.
36. Removal of hydroxyapatite:
The initial phase involves the dissolution of the mineral phase –
HCl
The protons for the acid arise from the activity of cytoplasmic
carbonic anhydrase II, which is synthesized in osteoclast.
The protons are then released across the ruffled border into the
resorption zone by an ATP consuming proton pump.
This leads to a fall in pH to 2.5 to 3.0 in the osteoclast resorption
space.
37. Degradation of organic matrix:
Proteolytic enzymes are synthesized by osteoclasts- cathepsin
k and MMP-9.
cathepsin k is the most important enzyme in bone. It degrades
major amount of type I collagen and other non collagen proteins
MMP-9(collagenase B) - osteoclast migration.
MMP-13 -bone resorption and osteoclast differentiation.
38. Removal of degradation products from lacunae:
Once liberated from bone, the free organic and non organic
particles of bone matrix are taken in or endocytosed from
resorption lacunae, across the ruffled border, into the osteoclast.
These are then packed into membrane bound vesicles within
cytoplasm of osteoclast.
These vesicles and their contents pass across the cell and fuse
with functional secretory domain (FSD) a specialized region of
the basement membrane.
Then the vesicles are released by exocytosis.
39. Factors associated with mechanism of bone Resorption:
Interleukin 1 – IL-1α, IL-1β. It stimulates production and release of
prostaglandin PGE2
Interleukin-6 (IL-6)
Tumor necrosis factor
lymphotoxin
Gamma interferon – inhibits resorption
Colony stimulating factors
Prostaglandins and other arachidonic acid metabolites
40. Role of trap in bone resorption:
Synthesized as inactive pro enzyme
Bone resorption inside and outside the cell
Concentration of TRAP in serum can be assessed which
indicates resorption day by day basis
41. BONE REMODELLING
The process by which overall size and shape of bone is
established- bone modelling.
Embryo to pre-adult period.
Rapidly formed on periosteal surface simultaneous destruction
on endosteal surface at focal points and with in the osteon.
Bone formation greater than resorption.
Bone turnover or remodelling – replacement of old bone by new
bone.
42. As age increases resorption exceeds
Cortical bone turnover-5% per year
Trabecular and endosteal surface – 15% per year
Coupling
The processes of bone synthesis and bone breakdown go on
simultaneously and the status of the bone represents the net result
of a balance between the two processes. This phenomenon is
called coupling.
43. Hormones and coupling
With the exception of calcitonin, all the hormones, cytokines, and
growth factors that act on bone, as an organ, mediate their activity
through osteoblasts.
Resorbing hormones act directly on osteoblasts, which then
produce other factors that regulate osteoclast activity.
This results in both bone formation and bone resorption being
coupled.
44. The coupling theory is based on the observation that once
resorption occurs, osteoblasts respond by making bone matrix.
That is, any change in resorption or formation results in
change in the other.
A hypothetical mechanism for explaining the coupling
phenomenon is that resorbing bone produces a factor that
influence the rate or extent of osteoblastic activity.
45. Functions of remodelling
To prevent accumulation of damaged bone by regenerating
new bone.
Allowing to respond to the changes in mechanical forces.
Mineral homeostasis.
46. •First the osteoclasts tunnel into surface of bone, which lasts for 3
weeks- resorb the haversian lamellae, and form a resorption
tunnel or cutting cone.
•After sometime resorption ceases and osteoclasts are replaced by
osteoblasts. These osteoblasts lay down a new set of haversian
lamellae, encircling a vessel upon a reversal line.
•This cement line is a thin layer of glycoproteins comprising bone
sialoprotein and osteopontin that acts as a cohesive mineralized
layer between the old bone and new bone to be secreted.
47. •The entire area of osteon, where active formation occurs is
termed the filling cone.
•The osteoblasts get entrapped in new bone and are called
osteocytes. Fragments of lamellae from old bone haversian
systems are left behind as interstitial lamellae
49. MEDIATORS OF BONE REMODELLING:
Parathyroid hormone
Calcitonin
Vitamin D metabolites i.e., 1, 25-dihydroxycholecalciferol
Cytokines
Prostaglandins
Growth factors
Mechanical factors
Bacterial products.
50. MARKERS OF BONE TURNOVER:
The markers of bone formation are: (serum markers)
•Alkaline phosphatase (total)
•Alkaline phosphatase (skeletal isoenzymes)
•Osteocalcin
•Procollagen I extension peptide
51. The markers of bone resorption are: (urinary markers)
•Urine calcium
•Urine hydroxy proline
•Collagen cross linking fragments
•Urine N – telopeptide
•Urine C- telopeptide
•Urine total pyridinoline
•Urine free deoxypyridinoline
52. Serum markers of bone resorption:
•Serum TRAP
•Serum β2 macroglobulin
Pathologies caused due to improper control of remodelling are:
•Osteoporosis
•Osteopetrosis
•Malignant bone tumors
•Inflammatory joint diseases
53. CONCLUSION :
The response of bone to inflammation includes bone
formation as well as resorption. Thus bone loss in disease is not
simply a destructive process, but results from the predominance
of resorption over formation
Proper understanding of changes seen in the bone in
variety of diseases will help in finding new therapeutic
strategies
54. REFERENCES:
•Carranza’s clinical periodontology-10th edition
•Lindhe – Textbook of periodontology-5th edition
•Orban’s oral histology & embryology-13th edition
•Tencate oral histology-8th edition
•Fundamentals of Periodontics.- Thomas G. Wilson, Kenneth S. Kornman
-2nd Edition
•Biology of periodontal tissues. P. Mark Bartold and A.SampathNarayanan-1st
edition
•Periodontology 2000, Vol. 24, 2000, 99-126
Editor's Notes
Intramembranous bone formation occurs directly within the mesenchyme in this type, the bone develops directly within the soft connective tissue rather than on a cartilaginous model.