...Bone turnover is carried out by osteoclasts, cells that resorb old bone, and osteoblasts, cells that lay down new bone matrix. Osteoclasts are large multi-nucleated cells derived from mononuclear hematopoietic cells that, upon stimulation, secrete lysosomal enzymes during bone resorption. Bone is resorbed by acidification and proteolysis of the collagen bone matrix and hydroxyapatite crystals [8]. Osteoblasts evolve from mesenchymal stem cell (MSC) lineage, along with adipocytes, chondrocytes, myoblasts and fibroblasts. Bone formation takes place in three stages: 1) production of osteoid matrix, 2) maturation of osteoid matrix, and 3) mineralization of the matrix. After the completion of bone formation, osteoblasts assume one of three fates: 1) undergo apoptosis, 2) remain on the bone surface as bone lining cells, or 3) are buried in the newly formed bone matrix as terminally differentiated osteocytes....
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...Chapter 6: Skeletal System: Bones and Bone Tissue Multiple Choice 1. Important functions of the skeletal system include A) protection of the brain and soft organs. B) storage of water. C) production of Vitamin E. D) regulation of acid-base balance. E) integration of other systems. Answer: a Level: 1 2. A band of connective tissue that attaches a muscle to a bone is a(n) A) aponeurosis. B) ligament. C) bursa. D) epimysium. E) tendon. Answer: e Level: 1 3. Ligaments attach A) muscle to muscle. B) bone to bone. C) muscle to bone. D) nerve to bone. E) nerve to muscle. Answer: b Level: 1 4. Chondroblasts produce A) ligaments. B) cartilage matrix. C) bone tissue. D) blood cells. E) synovial fluid. Answer: b Level: 1 5. The type of cartilage associated with bone function and development is A) elastic cartilage. B) fibrocartilage. C) hyaline cartilage. D) interstitial cartilage. E) osteocartilage. Answer: c Level: 1 6. The connective tissue sheath of cartilage is called the A) matrix. B) chondrocyte. C) ligamentous cord. D) lacuna. E) perichondrium. Answer: e Level: 1 7. Cartilage A) is composed of osteons. B) is surrounded by a membrane called the periosteum. C) contains chondrocytes located in lacunae. D) does not need nutrients and oxygen so it has no blood vessels. E) is well vascularized. Answer: c Level: 1 8. Proteoglycan molecules in the matrix of cartilage A) replace collagen fibers in the matrix...
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...Medications That Affect Bone Mineral Density Drug-induced osteoporosis is common and may result in significant morbidity and mortality for patients. The World Health Organization (WHO) has defined osteoporosis as bone density less than 2.5 standard deviations (SD) of the mean gender-matched, young healthy population (T-score at or below -2.5). Osteopenia is defined as loss of bone with T-score between -1 and -2.5.1 Many drugs have the potential to decrease bone mineral density (BMD). TABLE 1 lists the agents discussed in this lesson. Most of the disease states that are treated with these drugs also predispose the patient to low BMD, so the medication may be adversely affecting an already compromised bone structure.2 The most significant consequence of low BMD is a fracture.3 [pic] Bones provide support for movement, protect vital organs, and are the largest repository for calcium and other minerals.3 Ninety percent of the body's calcium is in the skeleton.4 Bone is constantly being remodeled, with old bone being resorbed and new bone forming.4,5 The rate of annual calcium turnover is 100% in infants and 18% in adults. The cycle of bone resorption and consequent formation is approximately 100 days.4 Process of Bone Remodeling Bone remodeling is a complex, highly orchestrated process involving the balance of many factors. The cycle of bone remodeling occurs in stages, beginning with the formation of osteoclasts, bone resorption (by osteoclasts), a reversal period, bone matrix formation...
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...Musculoskeletal Pathophysiology Bones Bone remodeling Minerals have to be deposited into the bones and to be remodeled Osteoblasts = builds the bone Osteoclasts = corroding the bone, originate from stem cell * Big cells, a number of nuclei * Ruffled edges to increase surface area * Mineral resorption (dissolves crystals and releases minerals into the blood) * Acid dissolves the bone minerals Things can do wrong * Preventing bones from generating in other parts of the body * Inhibitors include hydroxyapatite crystal deposition and thus not calcify * Calcification of arteries SMC (Smooth muscle cells) in calcification Media Contractile phenotype Low proliferation, low synthesis, expression of SMC markers Intima Synthetic phenotype Proliferative, migratory, secretory Osteoblast-like phenotype Mineralising, expression of osteoblast markers It is more common to have hypocalcemia than hypercalcemia Common cause of hypercalcemia is thyroid tumour Calcium homeostasis * Controlled by 3 hormones: calcitriol, calcitonin and PTH (parathyroid hormone) Calcium is not strong/high enough weak bones Calcium into blood from our bones (99% Ca stored) * Two hormones to tell osteoclast to reabsorb Ca out of the bones and back into the blood (PRH and Calcitriol) or redeposited into the bones via osteoblast * Adults have low levels of calcitonin (children have higher levels since their bones are still forming, stronger effect...
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...Health 1: Electronic literature Search Bone Formation Absence of bone sialoprotein (BSP) impairs primary bone formation and resorption: the marrow ablation model under PTH challenge. Wade-Gueye NM, Boudiffa M, Vanden-Bossche A, Laroche N, Aubin JE, Vico L, Lafage-Proust MH, Malaval L. Source: INSERM U1059/SFR IFRESIS, F42023, Saint-Etienne, France. Abstract: Bone sialoprotein (BSP) is highly expressed in early bone deposition and may play a part in primary bone mineralization. We previously showed that while BSP−/− mice have a mild secondary bone phenotype and are responsive to mechanical (unloading) and hormonal (ovariectomy, parathyroid hormone (PTH)) challenges, repair of a cortical bone defect, which involves primary bone deposition is significantly delayed in these mice. In the present study, we investigated the role of BSP in a pure model of primary bone modeling. Bone marrow was ablated by trans-epiphysis aspiration in the femora of BSP+/+ and BSP−/− mice, and 7 days post surgery μCT analysis showed vigorous new bone formation in the shaft of BSP+/+ animals but much less in BSP−/− mice. After 14 days, the volume of medullary bone was significantly decreased as expected in BSP+/+ mice, while it remained stable in the BSP−/−. Osteoid thickness and surface were higher in BSP−/− at day 7, suggesting delayed mineralization, while osteoclast surface and number were significantly lower at day 14, a stage of high medullary bone resorption. At day 7, mRNA expression...
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...Bone formation also known as ossification and osteogenesis, is the process by which bone tissue replaces with fibrous or cartilage structure to form the bony skeleton to early childhood to adulthood. It takes about 8 weeks or so, for the bone tissue to begin developing in the fetal state. In addition, as the body grows so does the bone in thickness and length, this is called bone growth. There are multiple of factors influencing bone development, growth, and repair. These include nutrition, exposure to sunlight, hormonal secretions, and physical exercise. (p 183-198) Nutrion: Calcium is the most abundant mineral in the bone and constitute its structure and strength, it is vital for muscle contraction and nerve transmission, besides other roles. Magnesium is needed for bone structure and strength, (Integration.”)Trace minerals are also important for encouraging bone growth in lesser amount. These type of nutrition helps to maintain and balance vitamin D in the body between bone resorption and formation, the two key processes of bone remodeling. Vitamins and minerals, also help bone formation, strength and mineralization, and decrease the risk of bone fractures. It helps harden bone. promotes bone growth, protects vitamin D levels and contributes to calcium absorption....
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...2.1 Bone classification and its cellular structure There are two major types of bone. They denote different stages of a bone lifecycle. 1. Woven Bone – It is an unorganized and premature bone that is found in either growing bones or at fracture sites as newly-formed bone. 2. Lamellar Bone – It is a mature bone that results from the further remodeling of woven bone. Lamellar bone may be further divided into: a. Cortical Bone – It is a dense or compact bone, which constitutes approximately 80% of the skeleton. It is approximately 20% porous and consists of a dense bundle of vascular channels containing blood vessels surrounded by mature bone. It forms the middle 80% of long bones of the body – tibia, fibula in the lower leg, femur in the upper leg, the radius and ulna in the lower arm, and the humerus in the upper arm. b. Cancellous Bone – It is a spongy bone, which constitutes approximately 20% of the skeleton. It is approximately 70% porous, highly vascularized and consists of loosely formed matrix of beams designed to withstand the principal stresses and strains applied to the bone. The density of cortical bone is four to six times higher than cancellous bone. Cancellous bone constitutes the remaining 20% of bone located at the ends of the long bones and predominates in the pelvis and the 33 vertebrae from the neck to the tailbone. A fibrous membrane called the periosteum covers bone. In general, bone constitutes minerals, proteins, hormones, water, other molecules...
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...Kaemia Howard (19075564) Anatomy and Physiology The Aging Musculoskeletal System At the age of 84, your bones have taken a toll throughout your life time. This leaves you susceptible to a few bone diseases. Three of the most common diseases are Osteoporosis, Osteoarthritis and Muscular Atrophy. With Osteoporosis, it is a disease in which bones become fragile and more likely to fracture. Usually the bone loses density, which measures the amount of calcium and minerals in the bone. Since our bones undergo bone remodeling quite often in the younger years we do not think of the potential or likelihood of being diagnosed with Osteoporosis or Osteoarthritis. However as we age our bones do not recover and remodel as fast, causing loss of bone density. The more mass that is “banked” when younger leads to the smaller risk of having the disease. Much like Osteoporosis is Osteoarthritis. The more wear and tear you put on your bones and joints the more susceptible you are to Osteoarthritis. With these disorders maintain a popular quo among the elderly; the future diagnosis is almost certain to happen. An 84 year old thin female has more than likely already been diagnosed with one of the two disorders, if not both. Osteoarthritis can be very painful and can on more than one occasion hinder any plans that have been set forth, from a trip to the grocery store or an entire vacation. This is especially true of those who have the arthritis in their hands, fingers and knees. The final...
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...The skeletal system is made up of 206 bones. There are many conditions and diseases that can affect our bones, short term and long term, including; arthritis, osteoporosis and bone cancer just to name a few. “Bones, tendons, ligaments and cartilage make up the skeletal system. …The skeletal system protects the internal organs such as the brain and heart,” says Aubri John of the Live Strong organization. One disease that affects the skeletal system is arthritis. Arthritis is commonly found in elderly people because as the body ages the bones start to become more brittle. “The breakdown of cartilage in this form of arthritis leads to the bones rubbing together, causing stiffness, pain and eventual loss of movement in the joint…The cause of arthritis...
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...Osteoporosis Author's Name Institutional Affiliation Osteoporosis Introduction Osteoporosis is a bone disease whereby the bone is prone to fracture. The name “osteoporosis”comes from a Greek word that means “ bone pore” (Rubenstein, et al 2007). What happens here is the bone mineral density (BMD) starts to reduce. The microarchitecture also reduces in the bone prompting the protein variety to be changed. WHO (1994) defines this condition as having a BMD of 2.5 standard deviation from the normal bone mass. Typically, there two types of osteoporosis namely: type 1 and type 2 .Type 1 osteoporosis mainly occurs in women after menopause. It is also referred to as “postmenopause osteoporosis”. Type 2 often happens after the age of 75. The latter affects men and women in the ratio of 1:2 respectively. There is also secondary osteoporosis which occurs in both men and women of all ages. This type of osteoporosis is rare as it is mostly as a result of lifestyle (Rubenstein, et al. 2007). Lifestyle change is key in the reduction of secondary osteoporosis (Calvert & Old, 2004). Diet change is essential in keeping the disease away. This entails a more healthy diet full of nutrients and loads of water. Exercise is also important but one has to keep in mind that the exercise regime has to be safe. By doing this one avoids fractures. History of Osteoporosis A biologist called Astley Cooper was the first to discover the existence of this condition. Nevertheless, Jean lobstein a...
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... Integumentary System 1. Describe the structure of the skin. Be able to compare and contrast the dermis and the epidermis. Relate the structure of the skin to its function. 2. Describe the role of the hypodermis 3. Describe the structure of a hair and hair follicle. 4. Explain how hair and nails grow. 5. Describe the location, secretion type, secretion mechanism and function of the sweat glands. 6. Briefly explain reasons for differences in skin color. 7. List the functions of the integumentary system. Skeletal System 1. List functions of bones. Relate to structure. 2. Describe gross anatomy of typical long and flat bones 3. Describe location and function of yellow marrow, red marrow, periosteum, endosteum, and articular cartilage. 4. Compare and contrast the histology of compact and spongy bone. 5. Describe the...
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...spongy bone. Compact bone is dense bone with very few spaces and is covered by a nourishing membrane called the periosteum. Spongy bone is identified by its many spaces that are filled with red bone marrow, which produces red blood cells. 3. Describe the structure of a long bone. Where are the yellow and red marrow found in adults? A long bone in the human body contains both compact bone and spongy bone. The compact bone is found on the outer surface of the bone and compose the shaft. The spongy bone is found at the ends of the long bone. Yellow bone marrow it found in the central shaft of the long bone surrounded by the compact bone. Red bone marrow is found in spaces of the spongy bone. 4. Describe the structure of an osteon, and explain the function of osteocytes and the central canal. The osteon consists of a central canal surrounded by concentric rings of osteocytes (mature bone cells) in a rigid matrix. O steocytes are located within a lacuna in the matrix. Canals connect the lacunae to each other and to the central canal. This allows for the transport of items between the cells and the blood vesels in the central canal. 5. Describe the formation of bone in a fetus. Explain how bone growth continues after birth. During fetal development, most of the skeleton is first formed of cartilage. Cartilage cells actively divide, allowing the skeleton to grow as the fetus does. Beginning around the third month of development, osteoblasts (bone-forming...
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...Stones May Break My Bones… The skeleton plays an important role in human physiology and function. Bone structure is vital as the human body rests on a framework made of bones. Healthy bones contribute to the overall health of an individual and a fully functional skeletal system is vital to physical health. Bones can get infections and other diseases just like any other part or organ of the human body. These illnesses can range from bone cancers to the degenerative bone disease of osteoporosis. This paper presents the disease of osteoporosis by defining it, and outlining its causes, symptoms, testing and diagnosis, and treatment. Bones consist of living tissue and are constantly being broken down and replaced. Bone building cells called osteoblasts help to build and strengthen bones while bone cells called osteoclasts role is to reabsorb bone cells. This process is constant throughout one’s lifetime. Osteoporosis is a disease characterized by reduced bone strength that makes it more vulnerable to fracture. Bone strength is measured by establishing bone mineral density (BMD), which is also called bone mass. People suffering from osteoporosis have low bone mass. Osteoporosis is a significant health problem that affects more than 25 million people in the United States alone. 80% of those affected by osteoporosis are women. (Melton) Osteoporosis is most prevalent in women 50 years and older. Osteoporosis is also responsible for numerous fractures around bones such as vertebrae,...
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...Skeletal.eap3am 8/20/02 1:20 PM Page 50 50 The Body Systems: Clinical and Applied Topics The Skeletal System 6 The skeletal framework of the body is composed of at least 206 bones and the associated tendons, ligaments, and cartilages. The skeletal system has a variety of important functions, including the support of soft tissues, blood cell production, mineral and lipid storage, and, through its relationships with the muscular system, the support and movement of the body as a whole. Skeletal system disorders can thus affect many other systems. The skeletal system is in turn influenced by the activities of other systems. For example, weakness or paralysis of skeletal muscles will lead to a weakening of the associated bones. Although the bones you study in the lab may seem rigid and permanent structures, the living skeleton is dynamic and undergoing continual remodeling. The remodeling process involves bone deposition by osteoblasts and bone resorption by osteoclasts. As indicated in Figure A-16, the net result of the remodeling varies depending on: 2. The applied physical stresses: Heavily stressed bones become thicker and stronger, and lightly stressed bones become thinner and weaker. Skeletal weakness can therefore result from muscular disorders, such as myasthenia gravis (p. 66) or the muscular dystrophies (p. 65), and conditions that affect CNS motor neurons, such as spinal cord injuries (p. 75), demyelination disorders (p. 72), or multiple sclerosis (pp. 72, 82). 3....
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...2. What are the functions of the bones? 3. What are the two types of osseous tissue? 4. What are the classifications of bones? 5. What are the parts of a long bone? Know the diagram of a long bone on pg. 118, Fig. 5.2(a) 6. What two factors are responsible for bone remodeling? Explain the role of PTH.. 7. What are Rickets? 8. What is Osteoarthritis? What is Rheumatoid arthritis? What is gout? 9. What is Osteoporosis? 10. What makes up a Haversian system (osteon)? 11. What are osteoclasts? What are osteoblasts? 12. What are the 6 types of fractures? What are their characteristics? Use table 5.2 on p. 123 to help you. 13. What is the difference between a closed (simple) fracture and an open (compound) fracture? 14. What are the 4 major events in bone fracture repair? 15. What bones make up the axial skeleton? 16. What bones make up the appendicular skeleton? 17. How many bones make up the cranium? What are they? 18. How many bones compose the face? What are they? 19. What is so special about the hyoid bone? 20. What are fontanels? Which is the largest? 21. How many bones are in the cervical vertebrae? 22. What is special about the atlas and axis? Which one is C1 and which is C2? 23. What are the 6 common features of all vertebrae? 24. How many bones are in the thoracic vertebrae? 25. How many bones are in the lumbar vertebrae? 26. How many bones are in the Sacrum? 27. How many bones are in the coccyx? 28. What is...
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