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113-436: Plasma calcium levels in mammals are tightly regulated, with bone acting as the major mineral storage site. Calcium ions , Ca, are released from bone into the bloodstream under controlled conditions. Calcium is transported through the bloodstream as dissolved ions or bound to proteins such as serum albumin . Parathyroid hormone secreted by the parathyroid gland regulates the resorption of Ca from bone, reabsorption in

226-566: A "public consultation on transparency in relation to risk assessments conducted by EFSA," it was evident that consumers wanted enhanced public access "to EFSA evaluations and documents." Chearnaigh concludes that the public's demands for direct transparency from the EFSA resulted in the creation of Regulation (EU) No. 2019/1381. This legal document outlines the importance of inclusive communication regarding chemical risk assessment to all parties involved: both government bodies and citizens. Residents of

339-599: A cell may damage it or even cause it to undergo apoptosis , or death by necrosis . Calcium also acts as one of the primary regulators of osmotic stress ( osmotic shock ). Chronically elevated plasma calcium ( hypercalcemia ) is associated with cardiac arrhythmias and decreased neuromuscular excitability. One cause of hypercalcemia is a condition known as hyperparathyroidism . Some invertebrates use calcium compounds for building their exoskeleton ( shells and carapaces ) or endoskeleton ( echinoderm plates and poriferan calcareous spicules ). When abscisic acid signals

452-450: A general rule, dietary supplement labeling and marketing are not allowed to make disease prevention or treatment claims, the FDA has for some foods and dietary supplements reviewed the science, concluded that there is significant scientific agreement, and published specifically worded allowed health claims. An initial ruling allowing a health claim for calcium dietary supplements and osteoporosis

565-402: A higher need for calcium, older leaves contain higher amounts of calcium because calcium is relatively immobile through the plant. It is not transported through the phloem because it can bind with other nutrient ions and precipitate out of liquid solutions. Ca ions are an essential component of plant cell walls and cell membranes , and are used as cations to balance organic anions in

678-479: A long bone are separated by a growing zone of cartilage (the epiphyseal plate ). At skeletal maturity (18 to 25 years of age), all of the cartilage is replaced by bone, fusing the diaphysis and both epiphyses together (epiphyseal closure). In the upper limbs, only the diaphyses of the long bones and scapula are ossified. The epiphyses, carpal bones, coracoid process, medial border of the scapula, and acromion are still cartilaginous. The following steps are followed in

791-509: A mineralized organic matrix. The primary inorganic component of human bone is hydroxyapatite , the dominant bone mineral , having the nominal composition of Ca 10 (PO 4 ) 6 (OH) 2 . The organic components of this matrix consist mainly of type I collagen —"organic" referring to materials produced as a result of the human body—and inorganic components, which alongside the dominant hydroxyapatite phase, include other compounds of calcium and phosphate including salts. Approximately 30% of

904-419: A more fulfilling and healthier lifestyle. Bone is constantly being created and replaced in a process known as remodeling . This ongoing turnover of bone is a process of resorption followed by replacement of bone with little change in shape. This is accomplished through osteoblasts and osteoclasts. Cells are stimulated by a variety of signals , and together referred to as a remodeling unit. Approximately 10% of

1017-420: A normal serving. The amount of calcium in blood (more specifically, in blood plasma ) can be measured as total calcium , which includes both protein-bound and free calcium. In contrast, ionized calcium is a measure of free calcium. An abnormally high level of calcium in plasma is termed hypercalcemia and an abnormally low level is termed hypocalcemia , with "abnormal" generally referring to levels outside

1130-457: A number of anatomical terms to describe the appearance, shape and function of bones. Other anatomical terms are also used to describe the location of bones . Like other anatomical terms, many of these derive from Latin and Greek . Some anatomists still use Latin to refer to bones. The term "osseous", and the prefix "osteo-", referring to things related to bone, are still used commonly today. Some examples of terms used to describe bones include

1243-422: A number of chemical enzymes that either promote or inhibit the activity of the bone remodeling cells, controlling the rate at which bone is made, destroyed, or changed in shape. The cells also use paracrine signalling to control the activity of each other. For example, the rate at which osteoclasts resorb bone is inhibited by calcitonin and osteoprotegerin . Calcitonin is produced by parafollicular cells in

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1356-574: A number of signal transduction pathways as second messengers . Bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells , store minerals , provide structure and support for the body, and enable mobility . Bones come in a variety of shapes and sizes and have complex internal and external structures. They are lightweight yet strong and hard and serve multiple functions . Bone tissue (osseous tissue), which

1469-529: A positive correlation between the adaptations of resistance training and bone density. While nutritional and pharmacological approaches may also improve bone health, the strength and balance adaptations from resistance training are a substantial added benefit. Weight-bearing exercise may assist in osteoblast (bone-forming cells) formation and help to increase bone mineral content. High-impact sports, which involve quick changes in direction, jumping, and running, are particularly effective with stimulating bone growth in

1582-623: A prefix—such as osteopathy . In anatomical terminology , including the Terminologia Anatomica international standard, the word for a bone is os (for example, os breve , os longum , os sesamoideum ). Bone is not uniformly solid, but consists of a flexible matrix (about 30%) and bound minerals (about 70%), which are intricately woven and continuously remodeled by a group of specialized bone cells. Their unique composition and design allows bones to be relatively hard and strong, while remaining lightweight. Bone matrix

1695-552: A protein with calcium coordination is von Willebrand factor (vWF) which has an essential role in blood clot formation process. It was discovered using single molecule optical tweezers measurement that calcium-bound vWF acts as a shear force sensor in the blood. Shear force leads to unfolding of the A2 domain of vWF whose refolding rate is dramatically enhanced in the presence of calcium. Ca ion flow regulates several secondary messenger systems in neural adaptation for visual, auditory, and

1808-419: A recent study, there was a strong correlation between calcium intake and BMD across a variety of diverse populations of children and adolescence ultimately coming to the conclusion that fundamentally, achieving optimal bone health is necessary for providing our youth with the ability to undergo hormonal changes as well. They found in a study of over 10,000 children ages 8-19 that in females, African Americans, and

1921-664: A sizable storage within intracellular compartments. In electrically excitable cells , such as skeletal and cardiac muscles and neurons, membrane depolarization leads to a Ca transient with cytosolic Ca concentration reaching around 1 μM. Mitochondria are capable of sequestering and storing some of that Ca. It has been estimated that mitochondrial matrix free calcium concentration rises to the tens of micromolar levels in situ during neuronal activity. The effects of calcium on human cells are specific, meaning that different types of cells respond in different ways. However, in certain circumstances, its action may be more general. Ca ions are one of

2034-408: A smaller number of randomly oriented collagen fibers, but forms quickly; it is for this appearance of the fibrous matrix that the bone is termed woven . It is soon replaced by lamellar bone, which is highly organized in concentric sheets with a much lower proportion of osteocytes to surrounding tissue. Lamellar bone, which makes its first appearance in humans in the fetus during the third trimester,

2147-401: A strong nutritional plan with adequate amounts of Calcium sources can lead to strong bones but also can be a worth-while strategy into preventing further damage or degradation of bone stores as we age. The connection between Calcium intake & BMD and its effects on youth as a whole is a very world-wide issue and has been shown to affect different ethnicities in a variety of differing ways. In

2260-523: A variety of doctors, including rheumatologists for joints, and orthopedic surgeons, who may conduct surgery to fix broken bones. Other doctors, such as rehabilitation specialists may be involved in recovery, radiologists in interpreting the findings on imaging, and pathologists in investigating the cause of the disease, and family doctors may play a role in preventing complications of bone disease such as osteoporosis. European Food Safety Authority The European Food Safety Authority ( EFSA )

2373-456: A very low shear stress strength (51.6 MPa). This means that bone resists pushing (compressional) stress well, resist pulling (tensional) stress less well, but only poorly resists shear stress (such as due to torsional loads). While bone is essentially brittle , bone does have a significant degree of elasticity , contributed chiefly by collagen . Mechanically, bones also have a special role in hearing . The ossicles are three small bones in

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2486-403: Is 90 to 95% composed of elastic collagen fibers, also known as ossein, and the remainder is ground substance . The elasticity of collagen improves fracture resistance. The matrix is hardened by the binding of inorganic mineral salt, calcium phosphate , in a chemical arrangement known as bone mineral , a form of calcium apatite . It is the mineralization that gives bones rigidity. Bone

2599-579: Is EFSA's legal representative and is responsible for day-to-day administration, drafting and implementing work programmes, and implementing other decisions adopted by the Management Board. They are appointed by the Management Board. The Advisory Forum advises the Executive Director, in particular in drafting a proposal for the EFSA's work programmes. It is composed of representatives of national bodies responsible for risk assessment in

2712-426: Is actively constructed and remodeled throughout life by special bone cells known as osteoblasts and osteoclasts. Within any single bone, the tissue is woven into two main patterns, known as cortical and cancellous bone, each with a different appearance and characteristics. The hard outer layer of bones is composed of cortical bone , which is also called compact bone as it is much denser than cancellous bone. It forms

2825-462: Is also called bone in the uncountable sense of that word, is hard tissue , a type of specialised connective tissue . It has a honeycomb -like matrix internally, which helps to give the bone rigidity. Bone tissue is made up of different types of bone cells . Osteoblasts and osteocytes are involved in the formation and mineralisation of bone; osteoclasts are involved in the resorption of bone tissue. Modified (flattened) osteoblasts become

2938-474: Is called "osteoid". Around and inside collagen fibrils calcium and phosphate eventually precipitate within days to weeks becoming then fully mineralized bone with an overall carbonate substituted hydroxyapatite inorganic phase. In order to mineralise the bone, the osteoblasts secrete alkaline phosphatase, some of which is carried by vesicles . This cleaves the inhibitory pyrophosphate and simultaneously generates free phosphate ions for mineralization, acting as

3051-418: Is composed of a network of rod- and plate-like elements that make the overall organ lighter and allow room for blood vessels and marrow. Trabecular bone accounts for the remaining 20% of total bone mass but has nearly ten times the surface area of compact bone. The words cancellous and trabecular refer to the tiny lattice-shaped units (trabeculae) that form the tissue. It was first illustrated accurately in

3164-583: Is considered a sports food supplement, also known as an ergogenic aid. Some popular examples of sports food supplements include protein powder/bars, creatine , and electrolyte beverages. Similar to the established food laws, the European Union has laws in place to ensure that sports supplements do not mislead consumers with false information. In an analytical assessment article, it states that supplement labels and advertisements often make false health claims, and about 70% of athletes are heavily influenced by

3277-485: Is dubious. Intracellular calcium is stored in organelles which repetitively release and then reaccumulate Ca ions in response to specific cellular events: storage sites include mitochondria and the endoplasmic reticulum . Characteristic concentrations of calcium in model organisms are: in E. coli 3  mM (bound), 100  nM (free), in budding yeast 2 mM (bound), in mammalian cell 10–100 nM (free) and in blood plasma 2 mM. In 2021, calcium

3390-474: Is less dense . This makes it weaker and more flexible. The greater surface area also makes it suitable for metabolic activities such as the exchange of calcium ions. Cancellous bone is typically found at the ends of long bones, near joints, and in the interior of vertebrae. Cancellous bone is highly vascular and often contains red bone marrow where hematopoiesis , the production of blood cells, occurs. The primary anatomical and functional unit of cancellous bone

3503-589: Is less common to see, the necessity for a healthy routine especially when it comes to bone development is essential in our youth. Children that naturally have lower bone mineral density have a lower quality of life and therefore lead a life that is less fulfilling and uncomfortable. Factors such as increases in Calcium intake has been shown to increase BMD stores. Studies have shown that increasing calcium stores whether that be through supplementation or intake via foods and beverages such as leafy greens and milk have pushed

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3616-426: Is limited and not conclusive." Evidence for breast cancer and prostate cancer was considered inconclusive. Proposals for QHCs for calcium as protective against kidney stones or against menstrual disorders or pain were rejected. The European Food Safety Authority (EFSA) concluded that "Calcium contributes to the normal development of bones." The EFSA rejected a claim that a cause-and-effect relationship existed between

3729-518: Is mostly found in the bone marrow of the femur, the ribs, the vertebrae and pelvic bones . Bone receives about 10% of cardiac output. Blood enters the endosteum , flows through the marrow, and exits through small vessels in the cortex. In humans, blood oxygen tension in bone marrow is about 6.6%, compared to about 12% in arterial blood, and 5% in venous and capillary blood. Bone is metabolically active tissue composed of several types of cells. These cells include osteoblasts , which are involved in

3842-434: Is multiple layers of osteoblasts and osteocytes around a central canal called the osteonic canal . Volkmann's canals at right angles connect the osteons together. The columns are metabolically active, and as bone is reabsorbed and created the nature and location of the cells within the osteon will change. Cortical bone is covered by a periosteum on its outer surface, and an endosteum on its inner surface. The endosteum

3955-527: Is necessary during our childhood as these factors lead to a supportive and healthy lifestyle/bone health. Up till the age of 30, the bone stores that we have will ultimately start to decrease as we surpass this age. Influencing factors that can help us have larger stores and higher amounts of BMD will allow us to see less harmful results as we reach older adulthood. The issue of having fragile bones during our childhood leads to an increase in certain disorders and conditions such as juvenile osteoporosis , though it

4068-405: Is not always available a corrected calcium may be used instead. To calculate a corrected calcium in mmol/L one takes the total calcium in mmol/L and adds it to ((40 minus the serum albumin in g/L) multiplied by 0.02). There is, however, controversy around the usefulness of corrected calcium as it may be no better than total calcium. It may be more useful to correct total calcium for both albumin and

4181-455: Is not fully known. Two types of bone can be identified microscopically according to the arrangement of collagen: woven and lamellar. Woven bone is produced when osteoblasts produce osteoid rapidly, which occurs initially in all fetal bones, but is later replaced by more resilient lamellar bone. In adults, woven bone is created after fractures or in Paget's disease . Woven bone is weaker, with

4294-406: Is present mostly in the form of bone mineral (roughly 99%). In this state, it is largely unavailable for exchange/bioavailability. The way to overcome this is through the process of bone resorption , in which calcium is liberated into the bloodstream through the action of bone osteoclasts . The remainder of calcium is present within the extracellular and intracellular fluids. Within a typical cell,

4407-730: Is stimulated by the secretion of 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 that promote reabsorption of bone by stimulating osteoclast activity and differentiation from progenitor cells. Vitamin D , parathyroid hormone and stimulation from osteocytes induce osteoblasts to increase secretion of RANK- ligand and interleukin 6 , which cytokines then stimulate increased reabsorption of bone by osteoclasts. These same compounds also increase secretion of macrophage colony-stimulating factor by osteoblasts, which promotes

4520-561: 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 directions in alternating layers, much like in plywood , assisting in 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, lamellar bone formation takes place more slowly. The orderly deposition of collagen fibers restricts

4633-690: Is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain . EFSA was established in February 2002, is based in Parma , Italy, and for 2021 it has a budget of €118.6 million, and a total staff of 542. The work of EFSA covers all matters with a direct or indirect impact on food and feed safety, including animal health and welfare , plant protection and plant health and nutrition . EFSA supports

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4746-533: Is the trabecula . The trabeculae are aligned towards the mechanical load distribution that a bone experiences within long bones such as the femur . As far as short bones are concerned, trabecular alignment has been studied in the vertebral pedicle . Thin formations of osteoblasts covered in endosteum create an irregular network of spaces, known as trabeculae. Within these spaces are bone marrow and hematopoietic stem cells that give rise to platelets , red blood cells and white blood cells . Trabecular marrow

4859-438: Is the boundary between the cortical bone and the cancellous bone. The primary anatomical and functional unit of cortical bone is the osteon . Cancellous bone or spongy bone , also known as trabecular bone , is the internal tissue of the skeletal bone and is an open cell porous network that follows the material properties of biofoams . Cancellous bone has a higher surface-area-to-volume ratio than cortical bone and it

4972-492: Is very minimal. Being able to consistently meet calcium needs while also engaging in weight-bearing exercise is essential for building a strong initial bone foundation at which to build upon. Being able to reach our daily value of 1300mg for ages 9-18 is becoming more and more necessary and as we progress in health, the chance that osteoporosis and other factors such as bone fragility or potential for stunted growth can be greatly reduced through these resources, ultimately leading to

5085-584: The European Commission , the European Parliament and EU member states in taking effective and timely risk management decisions that ensure the protection of the health of European consumers and the safety of the food and feed chain. EFSA also communicates to the public in an open and transparent way on all matters within its remit. Based on a regulation of 2002, the EFSA is composed of four bodies: The Management Board sets

5198-614: The European Court of Auditors in 2012, for "frequent conflicts of interests ", some of them undeclared. A number of undisclosed conflicts of interest involved the International Life Sciences Institute . According to Corporate Europe Observatory , in 2013, 58% of the experts of the agency were in situation of conflict of interests . In 2017, they were still 46% in situation of conflict of interests. EFSA has also been criticised by

5311-499: The anion gap . In vertebrates , calcium ions, like many other ions, are of such vital importance to many physiological processes that its concentration is maintained within specific limits to ensure adequate homeostasis. This is evidenced by human plasma calcium, which is one of the most closely regulated physiological variables in the human body. Normal plasma levels vary between 1 and 2% over any given time. Approximately half of all ionized calcium circulates in its unbound form, with

5424-412: The human body at birth, approximately 300 bones are present. Many of these fuse together during development, leaving a total of 206 separate bones in the adult, not counting numerous small sesamoid bones . The largest bone in the body is the femur or thigh-bone, and the smallest is the stapes in the middle ear . The Greek word for bone is ὀστέον (" osteon "), hence the many terms that use it as

5537-724: The middle ear which are involved in sound transduction. The cancellous part of bones contain bone marrow . Bone marrow produces blood cells in a process called hematopoiesis . Blood cells that are created in bone marrow include red blood cells , platelets and white blood cells . Progenitor cells such as the hematopoietic stem cell divide in a process called mitosis to produce precursor cells. These include precursors which eventually give rise to white blood cells , and erythroblasts which give rise to red blood cells. Unlike red and white blood cells, created by mitosis, platelets are shed from very large cells called megakaryocytes . This process of progressive differentiation occurs within

5650-583: The reference range . The main methods to measure serum calcium are: The total amount of Ca present in a tissue may be measured using Atomic absorption spectroscopy , in which the tissue is vaporized and combusted. To measure Ca concentration or spatial distribution within the cell cytoplasm in vivo or in vitro , a range of fluorescent reporters may be used. These include cell permeable, calcium-binding fluorescent dyes such as Fura-2 or genetically engineered variant of green fluorescent protein (GFP) named Cameleon . As access to an ionized calcium

5763-420: 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 osteoclast stimulation. Osteoblasts can also be stimulated to increase bone mass through increased secretion of osteoid and by inhibiting the ability of osteoclasts to break down osseous tissue . Increased secretion of osteoid

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5876-448: The 12-15 adolescent groups that at 2.6-2.8g/kg of body weight, they began to see a decrease in BMD. They elaborate on this by determining that this is strongly influenced by a lower baseline in calcium intake throughout puberty. Genetic factors have also been shown to influence lower acceptance of calcium stores. Ultimately, the window that youth have for accruing and building resilient bones

5989-515: The EFSA Focal Point network: The following countries' national food safety authorities are observers of the EFSA Focal Point network: The EFSA is responsible for maintaining the safety of all food-related items to ensure the public health of all European Union residents and citizens. This includes meat processing, pesticide residue, vitamins, and other supplements. Any substance used to benefit an athletic performance or fitness goal

6102-672: The EFSA is an independent agency but overseen by representatives of the European Commission and Council of the European Union, the EFSA must abide by the transparency policy. According to author Blánaid Ní Chearnaigh, prior to 2018, only some EFSA documents were accessible to the public, such as risk assessments for specific chemicals. These risk assessments were detailed scientific reports that analyzed chemicals' safety levels and potential risk for causing harm, such as cancer. They were difficult to understand and poorly formatted, which frustrated consumers. She articulates that during

6215-495: The European Commission at EFSA's request. The independent scientific experts are appointed by the Management Board upon a proposal from the Executive Director for three-year terms. Public transparency is the practice of informing citizens of all governmental action, and providing public access to government documents. It enables democratic accountability, meaning that citizens can hold the government accountable for doing its job to protect them. Transparency increases citizens' trust in

6328-541: The European Union want to feel confident that their government will protect them from all potential health hazards and prioritize consumers' needs, and through transparency, the EFSA can provide that confidence. As stated by Hanna Schebesta and Kai Purnhagen, the authors of EU Food Law , the EFSA contributes to a public Food Additives list posted by the European Commission that catalogs all food-related chemicals and relevant information for each of them. This additional information includes specific conditions for use, food items

6441-579: The FICR handles more of the legislative side of these transparency policies, the EFSA is consulted because the overall public health is involved. Both the EFSA and FICR ensure that all packaging of food available in the European Union includes the following aspects: an ingredient list and the amount of specific ingredients, food name, the date, allergens, total quantity, place of origin, food business operator information, nutrition information, alcoholic content (if applicable), and directions for how to store and use

6554-461: The IOM and EFSA both set Tolerable Upper Intake Levels (ULs) for the combination of dietary and supplemental calcium. From the IOM, people ages 9–18 years are not supposed to exceed 3,000 mg/day; for ages 19–50 not to exceed 2,500 mg/day; for ages 51 and older, not to exceed 2,000 mg/day. The EFSA set UL at 2,500 mg/day for adults but decided the information for children and adolescents

6667-530: The Member States, with observers from Norway, Iceland, Switzerland and the European Commission. The Scientific Committee and its Scientific Panels provide scientific opinions and advice, each within their own sphere of competence, and are composed of independent scientific experts. The number and names of the Scientific Panels are adapted in the light of technical and scientific development by

6780-526: The NGO CHEM Trust for misrepresenting the results of their expert committee's report on bisphenol A (BPA) in January 2015. EFSA claimed in the abstract, press release and briefing that bisphenol A 'posed no risk' to health, when the expert report actually stated the risk was 'low' when considering aggregate exposure (beyond just food). EFSA later modified the abstract to correct this error, though

6893-420: The acellular component of bone consists of organic matter, while roughly 70% by mass is attributed to the inorganic phase. The collagen fibers give bone its tensile strength , and the interspersed crystals of hydroxyapatite give bone its compressive strength . These effects are synergistic . The exact composition of the matrix may be subject to change over time due to nutrition and biomineralization , with

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7006-463: The advertised benefits. In other words, manufacturers advertise gains of using their products, such as increased endurance, knowing that it will increase sales without having any scientific evidence to prove the posted benefits. The EU prevents false health benefit claims through tasking the EFSA with fact-checking advertised health statements, such as a supplement increasing endurance. Both the EFSA and other research organizations "have previously studied

7119-416: The bone marrow. After the cells are matured, they enter the circulation . Every day, over 2.5 billion red blood cells and platelets, and 50–100 billion granulocytes are produced in this way. As well as creating cells, bone marrow is also one of the major sites where defective or aged red blood cells are destroyed. Determined by the species, age, and the type of bone, bone cells make up to 15 percent of

7232-548: The bone matrix. The release of these growth factors from the bone matrix could cause the proliferation of osteoblast precursors. Essentially, bone growth factors may act as potential determinants of local bone formation. Cancellous bone volume in postmenopausal osteoporosis may be determined by the relationship between the total bone forming surface and the percent of surface resorption. A number of diseases can affect bone, including arthritis, fractures, infections, osteoporosis and tumors. Conditions relating to bone can be managed by

7345-429: The bone. Growth factor storage—mineralized bone matrix stores important growth factors such as insulin -like growth factors, transforming growth factor, bone morphogenetic proteins and others. Strong bones during our youth is essential for preventing osteoporosis and bone fragility as we age. The importance of insuring factors that could influence increases in BMD while lowering our risks for further bone degradation

7458-426: The breakdown of bones by the process of bone resorption . New bone is then formed by the osteoblasts. Bone is constantly remodeled by the resorption of osteoclasts and created by osteoblasts. Osteoclasts are large cells with multiple nuclei located on bone surfaces in what are called Howship's lacunae (or resorption pits ). These lacunae are the result of surrounding bone tissue that has been reabsorbed. Because

7571-518: The budget, approves work programmes, and is responsible for ensuring that EFSA co-operates successfully with partner organisations across the EU and beyond. It is composed of fourteen members appointed by the Council of the European Union in consultation with the European Parliament from a list drawn up by the European Commission , plus one representative of the European Commission. The Executive Director

7684-458: 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 extremities of irregular and flat bones. The diaphysis and both epiphyses of

7797-602: The cell at that time. Substantial decreases in extracellular Ca ion concentrations may result in a condition known as hypocalcemic tetany , which is marked by spontaneous motor neuron discharge. In addition, severe hypocalcaemia will begin to affect aspects of blood coagulation and signal transduction. Ca ions can damage cells if they enter in excessive numbers (for example, in the case of excitotoxicity , or over-excitation of neural circuits , which can occur in neurodegenerative diseases , or after insults such as brain trauma or stroke ). Excessive entry of calcium into

7910-430: The cell walls are unable to stabilize and hold their contents. This is particularly important in developing fruits. Without calcium, the cell walls are weak and unable to hold the contents of the fruit. Some plants accumulate Ca in their tissues, thus making them more firm. Calcium is stored as Ca- oxalate crystals in plastids . Ca ions are usually kept at nanomolar levels in the cytosol of plant cells , and act in

8023-503: The cell. For example, the sodium-calcium exchanger uses energy from the electrochemical gradient of sodium by coupling the influx of sodium into cell (and down its concentration gradient) with the transport of calcium out of the cell. In addition, the plasma membrane Ca ATPase (PMCA) obtains energy to pump calcium out of the cell by hydrolysing adenosine triphosphate (ATP). In neurons , voltage-dependent, calcium-selective ion channels are important for synaptic transmission through

8136-809: The characteristics of the different substances added or isolated in supplements, as well as the safety of their consumption." The EFSA and European Commission then both assess whether advertised statements are true or false based on the EFSA's scientific data. The scientific output of the European Food Safety Authority is published in the EFSA Journal , an open-access , online scientific journal . This concerns risk assessment in relation to food and feed and includes nutrition, animal health and welfare, plant health and plant protection. The EFSA has been criticised for its alleged "overregulation". The EFSA has been criticised, including by

8249-477: The chemical may be found in, and restrictions on the amount that can be used. Transparency also applies to how food is presented to consumers, such as through packaging and advertisements. The EFSA works alongside the Food Information to Consumers Regulation (FICR), a separate agency, to enforce that all food information given to the public is easy to understand, and more importantly, accurate. Although

8362-447: The conversion of cartilage to bone: Bone development in youth is extremely important in preventing future complications of the skeletal system. Regular exercise during childhood and adolescence can help improve bone architecture, making bones more resilient and less prone to fractures in adulthood. Physical activity, specifically resistance training, stimulates growth of bones by increasing both bone density and strength. Studies have shown

8475-567: The creation and mineralization of bone tissue, osteocytes , and osteoclasts , which are involved in the reabsorption of bone tissue. Osteoblasts and osteocytes are derived from osteoprogenitor cells, but osteoclasts are derived from the same cells that differentiate to form macrophages and monocytes . Within the marrow of the bone there are also hematopoietic stem cells . These cells give rise to other cells, including white blood cells , red blood cells , and platelets . Osteoblasts are mononucleate bone-forming cells. They are located on

8588-407: The dietary intake of calcium and potassium and maintenance of normal acid-base balance. The EFSA also rejected claims for calcium and nails, hair, blood lipids, premenstrual syndrome and body weight maintenance. The United States Department of Agriculture (USDA) web site has a very complete searchable table of calcium content (in milligrams) in foods, per common measures such as per 100 grams or per

8701-641: The differentiation of progenitor cells into osteoclasts, and decrease secretion of osteoprotegerin. Bone volume is determined by the rates of bone formation and bone resorption. Certain growth factors may work to locally alter bone formation by increasing osteoblast activity. Numerous bone-derived growth factors have been isolated and classified via bone cultures. These factors include insulin-like growth factors I and II, transforming growth factor-beta, fibroblast growth factor, platelet-derived growth factor, and bone morphogenetic proteins. Evidence suggests that bone cells produce growth factors for extracellular storage in

8814-425: The endothelial cells which line the inside of blood vessels, Ca ions can regulate several signaling pathways which cause the smooth muscle surrounding blood vessels to relax. Some of these Ca-activated pathways include the stimulation of eNOS to produce nitric oxide, as well as the stimulation of K ca channels to efflux K and cause hyperpolarization of the cell membrane. Both nitric oxide and hyperpolarization cause

8927-453: The engravings of Crisóstomo Martinez . Bone marrow , also known as myeloid tissue in red bone marrow, can be found in almost any bone that holds cancellous tissue . In newborns , all such bones are filled exclusively with red marrow or hematopoietic marrow, but as the child ages the hematopoietic fraction decreases in quantity and the fatty/ yellow fraction called marrow adipose tissue (MAT) increases in quantity. In adults, red marrow

9040-410: The foci for calcium and phosphate deposition. Vesicles may initiate some of the early mineralization events by rupturing and acting as a centre for crystals to grow on. Bone mineral may be formed from globular and plate structures, and via initially amorphous phases. Five types of bones are found in the human body: long, short, flat, irregular, and sesamoid. In the study of anatomy , anatomists use

9153-410: The formation of bone from cartilage . Intramembranous ossification mainly occurs during formation of the flat bones of the skull but also the mandible, maxilla, and clavicles; the bone is formed from connective tissue such as mesenchyme tissue rather than from cartilage. The process includes: the development of the ossification center , calcification , trabeculae formation and the development of

9266-590: The formation of osteoid to about 1 to 2  μm per day. Lamellar bone also requires a relatively flat surface to lay the collagen fibers in parallel or concentric layers. The extracellular matrix of bone is laid down by osteoblasts , which secrete both collagen and ground substance. These cells synthesise collagen alpha polypetpide chains and then secrete collagen molecules. The collagen molecules associate with their neighbors and crosslink via lysyl oxidase to form collagen fibrils. At this stage, they are not yet mineralized, and this zone of unmineralized collagen fibrils

9379-555: The government and keeps them well-informed. Transparency is a fundamental value in the European Union , as stated in the Treaty on the Functioning of the European Union (TFEU). The European Commission declares that all European Union citizens/residents have the freedom of information, which entitles them to have access to all governmental documents from the European Commission, European Parliament , and European Council . Since

9492-475: The groundwork for bone health later in life, reducing the risk of bone-related conditions such as osteoporosis. Bones have a variety of functions: Bones serve a variety of mechanical functions. Together the bones in the body form the skeleton . They provide a frame to keep the body supported, and an attachment point for skeletal muscles , tendons , ligaments and joints , which function together to generate and transfer forces so that individual body parts or

9605-454: The guard cells, free Ca ions enter the cytosol from both outside the cell and internal stores, reversing the concentration gradient so the K+ ions begin exiting the cell. The loss of solutes makes the cell flaccid and closes the stomatal pores. Calcium is a necessary ion in the formation of the mitotic spindle . Without the mitotic spindle, cellular division cannot occur. Although young leaves have

9718-460: The hard exterior (cortex) of bones. The cortical bone gives bone its smooth, white, and solid appearance, and accounts for 80% of the total bone mass of an adult human skeleton . It facilitates bone's main functions—to support the whole body, to protect organs, to provide levers for movement, and to store and release chemical elements, mainly calcium. It consists of multiple microscopic columns, each called an osteon or Haversian system. Each column

9831-409: The intracellular concentration of ionized calcium is roughly 100 nM, but is subject to increases of 10- to 100-fold during various cellular functions. The intracellular calcium level is kept relatively low with respect to the extracellular fluid, by an approximate magnitude of 12,000-fold. This gradient is maintained through various plasma membrane calcium pumps that utilize ATP for energy, as well as

9944-593: The item. The EFSA cooperates with the national food safety authorities of the 27 EU member states, Iceland and Norway, as well as observers from Switzerland and EU candidate countries, through its Focal Points, who also communicate with research institutes and other stakeholders. They "assist in the exchange of scientific information and experts, advise on cooperation activities and scientific projects, promote training in risk assessment and raise EFSA's scientific visibility and outreach in Member States." The following countries' national food safety authorities are members of

10057-401: The kidney back into circulation, and increases in the activation of vitamin D 3 to calcitriol . Calcitriol, the active form of vitamin D 3 , promotes absorption of calcium from the intestines and bones. Calcitonin secreted from the parafollicular cells of the thyroid gland also affects calcium levels by opposing parathyroid hormone; however, its physiological significance in humans

10170-461: The lining cells that form a protective layer on the bone surface. The mineralised matrix of bone tissue has an organic component of mainly collagen called ossein and an inorganic component of bone mineral made up of various salts. Bone tissue is mineralized tissue of two types, cortical bone and cancellous bone . Other types of tissue found in bones include bone marrow , endosteum , periosteum , nerves , blood vessels and cartilage . In

10283-453: The most widespread second messengers used in signal transduction . They make their entrance into the cytoplasm either from outside the cell through the cell membrane via calcium channels (such as calcium-binding proteins or voltage-gated calcium channels), or from some internal calcium storages such as the endoplasmic reticulum and mitochondria . Levels of intracellular calcium are regulated by transport proteins that remove it from

10396-487: The notion that prepuberty or even early pubertal children will see increases in BMD with the addition of increase Calcium intake. Another research study goes on to show that long-term calcium intake has been proven to significantly contribute to overall BMD in children without certain conditions or disorders. This data shows that ensuring adequate calcium intake in children reinforces the structure and rate at which bones will begin to densify. Further detailing how structuring

10509-517: The olfactory system. It may often be bound to calmodulin such as in the olfactory system to either enhance or repress cation channels. Other times the calcium level change can actually release guanylyl cyclase from inhibition, like in the photoreception system. Ca ion can also determine the speed of adaptation in a neural system depending on the receptors and proteins that have varied affinity for detecting levels of calcium to open or close channels at high concentration and low concentration of calcium in

10622-478: The osteoblast puts up collagen fibers. These collagen fibers are used as a framework for the osteoblasts' work. The osteoblast then deposits calcium phosphate which is hardened by hydroxide and bicarbonate ions. The brand-new bone created by the osteoblast is called osteoid . Once the osteoblast is finished working it is actually trapped inside the bone once it hardens. When the osteoblast becomes trapped, it becomes known as an osteocyte. Other osteoblasts remain on

10735-502: 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 surfaces. Upon arrival, active enzymes, such as tartrate-resistant acid phosphatase , are secreted against the mineral substrate. The reabsorption of bone by osteoclasts also plays a role in calcium homeostasis . Bones consist of living cells (osteoblasts and osteocytes) embedded in

10848-456: The osteocyte cell processes occupy channels called canaliculi. The many processes of osteocytes reach out to meet osteoblasts, osteoclasts, bone lining cells, and other osteocytes probably for the purposes of communication. Osteocytes remain in contact with other osteocytes in the bone through gap junctions—coupled cell processes which pass through the canalicular channels. Osteoclasts are very large multinucleate cells that are responsible for

10961-421: The other half being complexed with plasma proteins such as albumin , as well as anions including bicarbonate , citrate , phosphate , and sulfate . Different tissues contain calcium in different concentrations. For instance, Ca (mostly calcium phosphate and some calcium sulfate ) is the most important (and specific) element of bone and calcified cartilage . In humans, the total body content of calcium

11074-427: The periosteum. Endochondral ossification occurs in long bones and most other bones in the body; it involves the development of bone from cartilage. This process includes the development of a cartilage model, its growth and development, development of the primary and secondary ossification centers , and the formation of articular cartilage and the epiphyseal plates . Endochondral ossification begins with points in

11187-450: The plant vacuole . The Ca concentration of the vacuole may reach millimolar levels. The most striking use of Ca ions as a structural element in algae occurs in the marine coccolithophores , which use Ca to form the calcium carbonate plates, with which they are covered. Calcium is needed to form the pectin in the middle lamella of newly formed cells. Calcium is needed to stabilize the permeability of cell membranes. Without calcium,

11300-684: The ratio of calcium to phosphate varying between 1.3 and 2.0 (per weight), and trace minerals such as magnesium , sodium , potassium and carbonate also be found. Type I collagen composes 90–95% of the organic matrix, with the remainder of the matrix being a homogenous liquid called ground substance consisting of proteoglycans such as hyaluronic acid and chondroitin sulfate , as well as non-collagenous proteins such as osteocalcin , osteopontin or bone sialoprotein . Collagen consists of strands of repeating units, which give bone tensile strength, and are arranged in an overlapping fashion that prevents shear stress. The function of ground substance

11413-570: The release of neurotransmitters into the synaptic cleft by vesicle fusion of synaptic vesicles . Calcium's function in muscle contraction was found as early as 1882 by Ringer. Subsequent investigations were to reveal its role as a messenger about a century later. Because its action is interconnected with cAMP , they are called synarchic messengers. Calcium can bind to several different calcium-modulated proteins such as troponin-C (the first one to be identified) and calmodulin , proteins that are necessary for promoting contraction in muscle. In

11526-429: The risk of hypertension. However, FDA has determined that the evidence is inconsistent and not conclusive." Evidence for pregnancy-induced hypertension and preeclampsia was considered inconclusive. The same year, the FDA approved a QHC for calcium and colon cancer, with suggested wording "Some evidence suggests that calcium supplements may reduce the risk of colon/rectal cancer, however, FDA has determined that this evidence

11639-578: The skeletal mass of an adult is remodelled each year. The purpose of remodeling is to regulate calcium homeostasis , repair microdamaged bones from everyday stress, and to shape the skeleton during growth. Repeated stress, such as weight-bearing exercise or bone healing, results in the bone thickening at the points of maximum stress ( Wolff's law ). It has been hypothesized that this is a result of bone's piezoelectric properties, which cause bone to generate small electrical potentials under stress. The action of osteoblasts and osteoclasts are controlled by

11752-426: The smooth muscle to relax in order to regulate the amount of tone in blood vessels. However, dysfunction within these Ca-activated pathways can lead to an increase in tone caused by unregulated smooth muscle contraction. This type of dysfunction can be seen in cardiovascular diseases, hypertension, and diabetes. Calcium coordination plays an important role in defining the structure and function of proteins. An example

11865-469: The surface of osteon seams and make a protein mixture known as osteoid , which mineralizes to become bone. The osteoid seam is a narrow region of a newly formed organic matrix, not yet mineralized, located on the surface of a bone. Osteoid is primarily composed of Type I collagen . Osteoblasts also manufacture hormones , such as prostaglandins , to act on the bone itself. The osteoblast creates and repairs new bone by actually building around itself. First,

11978-450: The term "foramen" to describe a hole through which something passes, and a "canal" or "meatus" to describe a tunnel-like structure. A protrusion from a bone can be called a number of terms, including a "condyle", "crest", "spine", "eminence", "tubercle" or "tuberosity", depending on the protrusion's shape and location. In general, long bones are said to have a "head", "neck", and "body". When two bones join, they are said to "articulate". If

12091-417: The top of the new bone and are used to protect the underlying bone, these become known as bone lining cells. Osteocytes are cells of mesenchymal origin and originate from osteoblasts that have migrated into and become trapped and surrounded by a bone matrix that they themselves produced. The spaces the cell body of osteocytes occupy within the mineralized collagen type I matrix are known as lacunae , while

12204-418: The two bones have a fibrous connection and are relatively immobile, then the joint is called a "suture". The formation of bone is called ossification . During the fetal stage of development this occurs by two processes: intramembranous ossification and endochondral ossification . Intramembranous ossification involves the formation of bone from connective tissue whereas endochondral ossification involves

12317-430: The whole body can be manipulated in three-dimensional space (the interaction between bone and muscle is studied in biomechanics ). Bones protect internal organs, such as the skull protecting the brain or the ribs protecting the heart and lungs . Because of the way that bone is formed, bone has a high compressive strength of about 170  MPa (1,700  kgf/cm ), poor tensile strength of 104–121 MPa, and

12430-421: The youth. Sports such as soccer, basketball, and tennis have shown to have positive effects on bone mineral density as well as bone mineral content in teenagers. Engaging in physical activity during childhood years, particularly in these high-impact osteogenic sports, can help to positively influence bone mineral density in adulthood. Children and adolescents who participate in regular physical activity will place

12543-575: Was later amended to include calcium and vitamin D supplements, effective January 1, 2010. Examples of allowed wording are shown below. In order to qualify for the calcium health claim, a dietary supplement must contain at least 20% of the Reference Dietary Intake, which for calcium means at least 260 mg/serving. In 2005, the FDA approved a Qualified Health Claim for calcium and hypertension, with suggested wording "Some scientific evidence suggests that calcium supplements may reduce

12656-545: Was not sufficient to determine ULs. For U.S. food and dietary supplement labeling purposes, the amount in a serving is expressed as a percent of Daily Value (%DV). For calcium labeling purposes, 100% of the Daily Value was 1000 mg, but as of May 27, 2016, it was revised to 1300 mg to bring it into agreement with the RDA. A table of the old and new adult daily values is provided at Reference Daily Intake . Although as

12769-696: Was the 243rd most commonly prescribed medication in the United States, with more than 1   million prescriptions. The U.S. Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. See table. The European Food Safety Authority (EFSA) uses the term Population Reference Intake (PRIs) instead of RDAs and sets slightly different numbers: ages 4–10 800 mg, ages 11–17 1150 mg, ages 18–24 1000 mg, and >25 years 950 mg. Because of concerns of long-term adverse side effects such as calcification of arteries and kidney stones,

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