endocrino_calcio
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endocrino_calcio


DisciplinaFisiologia II707 materiais16.920 seguidores
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Fisiologia do Sistema 
Endócrino
Regulação endócrina da 
Calcemia
Fisiologia do Sistema Endócrino
REGULAÇÃO ENDÓCRINA DA
CALCEMIA 
(níveis plasmáticos de cálcio)
Hormônios: 
Paratireoideano (PTH)
Calcitriol e 
Calcitonina
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
http://cwx.prenhall.com/bookbind/pubbooks/silverthorn2/
extraído, enquanto disponível, de: http://www.owensboro.kctcs.edu/gcaplan/anat2/Study%20Guides/APII%20Endocrine%20Glands.htm
Glândulas Paratireóides
Secreção de Paratormônio
Paratireóides
Paratormônio
(PTH)
http://cwx.prenhall.com/bookbind/pubbooks/silverthorn2/
Regulação da calcemia pelo Paratormônio (PTH)
Regulação da calcemia pelo Calcitriol
http://cwx.prenhall.com/bookbind/pubbooks/silverthorn2/
Veja mais em: http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/thyroid/calcium.html
Biossíntese do Calcitriol
(Hormônio derivado da Vitamina D ou
1,25(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.
+ PTH
+ PTH
Parafollicular cells are also called "C cells".
Regulação da calcemia pela Calcitonina
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 
the cells in the body. How does it do this?
Veja em: http://www.cytochemistry.net/Endocrine_System/thyroid_and_parathyroid.htm#Locate
Alguns conceitos sobre fisiologia do tecido ósseo
extraído, quando disponível, de: http://www.medes.fr/Eristo/Osteoporosis/BoneRemodeling.html
Remodelagem óssea
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#
Osteoblastos 
iniciam a 
formação óssea
AS CÉLULAS ENVOLVIDAS NA 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
osteócitos
monitoram estresse 
mecânico ósseo
AS CÉLULAS ENVOLVIDAS NA 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 #
osteoclastos 
reabsorvem osso
AS CÉLULAS ENVOLVIDAS NA REMODELAGEM ÓSSEA
extraído, enquanto disponível, de: http://www.abdn.ac.uk/medicine_therapeutics
As células no microambiente ósseo
extraído, enquanto disponível, de: http://www.abdn.ac.uk/medicine_therapeutics
Formação e reabsorção óssea
O ciclo da remodelagem óssea
Two main types of cells are responsible for bone renewal: 
the osteoblasts involved in bone formation and the osteoclasts involved in 
bone resorption.
\u2022Activation: Preosteoclasts are stimulated and differentiated under the influence 
of cytokine and growth factors to mature into active osteoclasts.
\u2022
\u2022Resorption: Osteoclasts digest mineral matrix, old bone.
\u2022Reversal: End of resorption 
\u2022Formation: Osteoblasts are responsible for bone matrix synthesis (collagen). 
Two other non-collagenous proteins are also formed: ostocalcin and 
osteonectin.
extraído, enquanto disponível, de: http://www.medes.fr/Eristo/Osteoporosis/BoneRemodeling.html
extraído, enquanto disponível, de: http://www.abdn.ac.uk/medicine_therapeutics
O ciclo da remodelagem óssea
extraído, quando disponível, de: http://www.abdn.ac.uk/medicine_therapeutics
Porque ocorre a remodelagem óssea?
extraído, enquanto disponível, de: http://www.abdn.ac.uk/medicine_therapeutics
Remodelagem óssea e regulação 
da massa óssea
Decrease in peak bone mass with age and increase in fracture risk with increasing age. Valsamis et al, 2006
Efeito da idade na massa óssea e risco de 
ocorrência de fraturas
http://www.nutritionandmetabolism.com/content/3/1/36
extraído, enquanto disponível, de: http://www.abdn.ac.uk/medicine_therapeutics
Osso e regulação da homeostase 
do cálcio
Progenitoras da matriz óssea
precursor de osteoblastos precursor de osteoclastos
Osteoblastos
Formação de 
osso