Name: how hormones control bone turnover
Uploaded: 2025-10-23T11:49:19.000Z
Duration: 1 min 40 s
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from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

HS-LS1-2

Bone Remodeling

- [Instructor] Incluso
en el esqueleto adulto,

los huesos son tejidos activos,

que experimentan cambios en
su arquitectura continuamente.

Este proceso llamado remodelado óseo

consiste en fases iguales
de reabsorción ósea,

su eliminación y depósito de tejido nuevo.

Cuando las células óseas
maduras, osteocitos,

sienten estrés mecánico,

mandan señales a las
células del hueso del sitio,

por ejemplo, los extremos del fémur,

las cuales son reemplazadas
cada seis meses.

Durante la reabsorción
ósea, un tipo celular,

los osteoclastos, se adhieren
fuertemente a la superficie,

secretando enzimas lisosomales
y protones de hidrógeno,

pueden degradar compuestos orgánicos,

creando cavidades de erosión

al degradar la matriz vieja o dañada.

También se libera calcio a la sangre

e interviene en los bucles de
retroalimentación hormonal.

Cuando el material se disuelve,

el osteoclasto se autodestruye
mediante apoptosis,

lo cual previene la destrucción
continuada del hueso.

Para iniciar la inversión,

células mononucleares
aparecen en la superficie

en preparación para el siguiente paso.

En la fase de formación, los
osteoblastos se mueven hacia

dentro de la cavidad y depositan
hueso nuevo mediante la

la osificación de la matriz
orgánica conocida como osteoide.

Esta parte incluye fibras de colágeno

contribuyen a la
estructura y flexibilidad.

Después de la síntesis de la
matriz, los osteoblastos pueden

diferenciarse en células de
revestimiento ósea aplanadas

o sepultarse en el hueso como osteocitos.

Crockett, Julie C., Michael J. Rogers, Fraser P. Coxon, Lynne J. Hocking y Miep H. Helfrich. "La remodelación ósea de un vistazo". J Cell Sci 124, no. 7 (1 de abril de 2011): 991–98. [<a href="https://doi.org/10.1242/jcs.063032">Fuente</a>]

Fierro, F. A., J. A. Nolta e I. E. Adamopoulos. "Revisión concisa: Células madre en osteoinmunología". Stem Cells (Dayton, Ohio) 35, no. 6 (junio de 2017): 1461–67. [<a href="https://doi.org/10.1002/stem.2625" target="__blank">Fuente</a>]

remodelación ósea

La remodelación ósea es un proceso continuo y equilibrado de resorción ósea por osteoclastos y formación ósea por osteoblastos. En adultos ayuda a mantener la masa ósea y la homeostasis del calcio. Si bien el estrés mecánico puede estimular el recambio como parte del proceso normal de mantenimiento y reparación, varias hormonas también regulan la remodelación ósea. <h4>Control hormonal de la remodelación ósea</h4> La hormona paratiroidea (PTH) mantiene el control homeostático de los niveles de calcio en sangre regulando la resorción ósea. La PTH se libera de las glándulas paratiroides en respuesta a niveles bajos de calcio en la sangre. Estimula a los osteoblastos para que produzcan moléculas inmunes que promuevan la diferenciación de células precursoras en osteoclastos. La activación de los osteoclastos promueve la resorción ósea, lo que hace que la matriz ósea mineralizada se descomponga y libere calcio a la sangre. Cuando se restablecen los niveles de calcio en sangre, un circuito de retroalimentación negativa impide una mayor liberación de PTH. <h4>Osteoporosis</h4> La osteoporosis es una enfermedad en la que la resorción ósea excede la formación ósea, lo que resulta en una reducción de la densidad ósea. La osteoporosis es más frecuente en las mujeres, especialmente después de la menopausia. Esto se debe al papel fundamental que desempeña la hormona sexual femenina, el estrógeno, en la remodelación ósea. Los estrógenos limitan la formación de osteoclastos y promueven su destrucción mediante apoptosis. Esto asegura que la formación de hueso sea mayor que la resorción ósea. Sin embargo, los niveles de estrógeno disminuyen gravemente en las mujeres menopáusicas. Por lo tanto, la resorción ósea supera su creación, lo que provoca una pérdida de resistencia ósea y un mayor riesgo de fracturas.

Remodelación ósea

El remodelado óseo es un proceso continuo y equilibrado de resorción ósea por osteoclastos y formación ósea por osteoblastos. En los adultos, ayuda a mantener ...

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how hormones control bone turnover

Bone turnover is a continuous process in which old bone is broken down and new bone is built. Osteoclasts carry out bone resorption, and osteoblasts carry out bone formation. In adults, this balanced cycle helps maintain bone mass and calcium homeostasis. Mechanical stress can also stimulate turnover as part of normal maintenance and repair.

Parathyroid hormone, or PTH, helps control blood calcium levels by increasing bone resorption when calcium is low. It is released from the parathyroid glands in response to low calcium in the blood. PTH stimulates osteoblasts to produce immune molecules that promote the differentiation of precursor cells into osteoclasts. Once osteoclasts become active, they break down the mineralized bone matrix and release calcium into the blood. When calcium levels return to normal, a negative-feedback loop reduces further PTH release.

Osteoporosis develops when bone resorption becomes greater than bone formation, which lowers bone density. It is more common in women, especially after menopause. Estrogen, the female sex hormone, helps limit the formation of osteoclasts and also promotes their destruction by apoptosis, or programmed cell death. When estrogen levels drop after menopause, bone resorption can outpace bone creation. This weakens bone strength and raises the risk of fractures.

How Hormones Control Bone Turnover

what is the skeletal system?

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bone remodeling

Bone turnover is a continuous process in which old bone is broken down and new bone is built. Osteoclasts carry out bone resorption, and osteoblasts carry out bone formation. In adults, this balanced cycle helps maintain bone mass and calcium homeostasis. Mechanical stress can also stimulate turnover as part of normal maintenance and repair. Parathyroid hormone, or PTH, helps control blood calcium levels by increasing bone resorption when calcium is low. It is released from the parathyroid...

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muscle contraction

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cross-bridge cycle

Calcium Control in Muscle Contraction

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motor units

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the spinal cord

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key terms and concepts

Learn how PTH and estrogen regulate bone turnover, calcium balance, and osteoporosis. Clear high school biology coverage of osteoclasts and osteoblasts.

How Hormones Control Bone Turnover | JoVE K12

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HS-LS1-3

How Hormones Control Bone Turnover

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