Fisiologia do Sistema Endócrino Regulação endócrina da Calcemia Profa. Adjunto do Depto. Ciências Fisiológicas-CCB-UFSC Como citar este documento: PINTO, Cristina Maria Henrique. Fisiologia Humana: Endocrinofisiologia. Disponível em: <http://www.cristina.prof.ufsc.br>. Acesso em: coloque a data aqui
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Fisiologia do Sistema Endócrino
Regulação endócrina da Calcemia
Profa. Adjunto do Depto. Ciências Fisiológicas-CCB-UFSCComo citar este documento:
PINTO, Cristina Maria Henrique. Fisiologia Humana: Endocrinofisiologia. Disponível em: <http://www.cristina.prof.ufsc.br>. Acesso em: coloque a
data aqui
ESQUEMAS PARA FACILITAR O ESTUDO E O ACOMPANHAMENTO DE MINHAS AULAS
Os números referem-se aos níveis da cálcio diários em humanos. Repare o balanço entre a ingestão e a excreção de cálcio assim como para a remoção e reposição de cálcio nos ossos
(remodelagem óssea). Fig. 42-1 Berne et al., 2004
Órgãos e mecanismos envolvidos na regulação da Calcemia (níveis de cálcio no sangue)
Visão geral do intercâmbio de cálcio...
... entre diferentes compartimentos teciduais em uma pessoa com ingestão de 1.000mg de Cálcio por dia. Grande parte do cálcio ingerido é normalmente eliminada pelas fezes, embora os rins tenham a capacidade de excretar quantidades abundantes de cálcio por meio da redução.
Guyton e Hall, 2006
Órgãos e hormônios envolvidos na regulação da calcemia
Veja mais em: http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/thyroid/calcium.html
Biossíntese do Calcitriol(Hormônio derivado da Vitamina D ou1,25(OH)2-Vitamina D)
Dietary Sources. Only a few foods naturally contain significant amounts of vitamin D, including fatty fish and fish oils. Other dietary sources include fortified milk and margarine, liver, butter, cream and egg yolks.
Vitamin D is a fat-soluble vitamin that exists in various forms. Some forms are relatively inactive in the body, and have limited ability to function as a vitamin. Exposure to sunlight is an important source of vitamin D. Ultraviolet (UV) rays from sunlight trigger vitamin D synthesis in the skin. The liver and kidney help convert vitamin D to its active hormone form, also called CALCITRIOL.
They are found in the interstitial spaces outside the thyroid follicles in the middle third of the lateral lobes. As all endocrine cells, they lie next to capillaries so they
can secrete their hormone into the bloodstream.
The hormone they produce is "CALCITONIN". They respond to high blood levels of calcium. When calcium levels are too high, they secrete calcitonin and this
hormone inhibits osteoclastic activity. What is the function of osteoclasts? Osteoclastic activity releases calcium that goes into the blood stream for use by
Process of bone remodeling. Signals carried by canalicular and syncytial routes from interior osteocytes, and endocrine signals to resting osteoblasts and lining cells generate local paracrine cytokine signals to nearby osteoclasts and osteoclast precursors. Osteoclasts also recruit their own precursors by paracrine signals. The osteoclasts resorb an area of mineralized bone, and local macrophages complete the clean-up of dissolved elements. The process then reverses to formation as osteoblast precursors are recruited to the site and differentiate into active osteoblasts. These lay down new organic matrix and mineralize it. Thus, new bone replaces the previously resorbed mature bone. Levy et al., 2006
Remodelagem óssea
Progenitoras da matriz óssea
precursor de osteoblastos precursor de osteoclastos
Osteoblastos
Formação de osso novo
Osteócito
Osteoclasto
Resorção óssea
Development of osteoblasts and osteoclasts from bone marrow progenitors. Factors affecting the development and function of these cells, bone resorption by osteoclast and new bone formation by osteoblasts. Abbreviations: GH: growth hormone, IGF: insulin like growth factors,PTH: parathyroid hormone Valsamis et al. 2006. http://www.nutritionandmetabolism.com/content/3/1/36#
precursor de osteoblastos precursor de osteoclastos
Osteoblastos
Formação de osso novo
Osteócito
Osteoclasto
Resorção óssea
Development of osteoblasts and osteoclasts from bone marrow progenitors. Factors affecting the development and function of these cells, bone resorption by osteoclast and new bone formation by osteoblasts. Abbreviations: GH: growth hormone, IGF:
insulin like growth factors,PTH: parathyroid hormone Valsamis et al. 2006. http://www.nutritionandmetabolism.com/content/3/1/36
precursor de osteoblastos precursor de osteoclastos
Osteoblastos
Formação de osso novo
Osteócito
Osteoclasto
Resorção óssea
Development of osteoblasts and osteoclasts from bone marrow progenitors. Factors affecting the development and function of these cells, bone resorption by osteoclast and new bone formation by osteoblasts. Abbreviations: GH: growth hormone, IGF:
insulin like growth factors,PTH: parathyroid hormone Valsamis et al. 2006. http://www.nutritionandmetabolism.com/content/3/1/36 #
precursor de osteoblastos precursor de osteoclastos
Osteoblastos
Formação de osso novo
Osteócito
Osteoclasto
Resorção óssea
Development of osteoblasts and osteoclasts from bone marrow progenitors. Factors affecting the development and function of these cells, bone resorption by osteoclast and new bone formation by osteoblasts. Abbreviations: GH: growth hormone, IGF: insulin like growth factors, PTH: parathyroid hormone. Valsamis et al. 2006. http://www.nutritionandmetabolism.com/content/3/1/36#
Deficiência na infância de Vitamina D/Calcitriol causa o Raquitismo
Raquitismo:Raquitismo é uma doença do metabolismo da Vitamina D, vital para a
mineralização óssea. Deficiência de Vitamina D na dieta é a forma mais comum de raquitismo mas também pode ser devido a alterações genéticas que afetam os vários aspectos do metabolismo da Vitamina D. Veja mais